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66f2d67bcec5d6c142103d98
|
10.26434/chemrxiv-2024-0xd0x-v3
|
Organozinc reagents in solution: insights from ab initio molecular dynamics and X-ray absorption spectroscopy
|
Organozinc reagents play a critical role in synthesis, yet our comprehension of their structure-reactivity relationships is limited by a lack of information about their structures in solution. This study introduces a computational workflow, validated by X-ray absorption spectroscopy, to investigate organozinc reagents in solution. The solvation states of ZnCl2, ZnMeCl and ZnMe2 were explored using ab initio molecular dynamics (metadynamics and Blue Moon sampling) within an explicit solvent cage. The study revealed the existence of various solvation states at room temperature, providing clarity on the previously debated structure of ZnMe2 in THF solution. These findings were confirmed by near- edge X-ray absorption spectroscopy (XANES) interpreted using time-dependent density functional theory (TD-DFT) calculations.
|
Jordan RIO; Quentin PESSEMESSE; Michele CASCELLA; Pierre-Adrien PAYARD; Marie-Eve L. PERRIN
|
Theoretical and Computational Chemistry; Analytical Chemistry; Organometallic Chemistry; Computational Chemistry and Modeling; Main Group Chemistry (Organomet.); Spectroscopy (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-09-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f2d67bcec5d6c142103d98/original/organozinc-reagents-in-solution-insights-from-ab-initio-molecular-dynamics-and-x-ray-absorption-spectroscopy.pdf
|
6709ca5512ff75c3a12bf78e
|
10.26434/chemrxiv-2024-kcf6c
|
Catalytic Resonance Theory: Turnover Efficiency and the Resonance Frequency
|
Programmable catalysts exhibiting forced oscillation in the free energy of reacting surface species were simulated to understand the general mechanisms leading to efficient use of input energy. Catalytic ratchets with either positive or negative adsorbate scaling exhibited oscillation conditions of both high and low turnover efficiency, yielding catalytic turnover frequencies either close to or significantly lower than the applied catalyst oscillation frequency, respectively. The ‘effective rate,’ defined as the product of the catalytic turnover frequency (TOF) and the turnover efficiency (η,TOE), was limited via two catalytic mechanisms: a leaky catalytic ratchet existed when molecules repeatedly traversed backwards through the catalytic transition state upon catalyst oscillation, while a catalytic ratchet with low surface participation exhibited reduced formation of gas-phase final product due to low surface product coverage. A single applied frequency yielding maximum effective catalytic rate defined as the ‘resonance frequency’ provided maximum combined benefit for catalytic rate and efficiency.
|
Jesse Canavan; Justin Hopkins; Brandon Foley; Omar Abdelrahman; Paul Dauenhauer
|
Catalysis; Electrocatalysis; Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-10-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6709ca5512ff75c3a12bf78e/original/catalytic-resonance-theory-turnover-efficiency-and-the-resonance-frequency.pdf
|
65f08a859138d23161530b18
|
10.26434/chemrxiv-2024-f3r30
|
Self-Replicating DNA-Based Nanoassemblies
|
The properties of DNA that make it an effective genetic material also allow it to be ideal for programmed self-assembly. Accordingly, DNA-programmed assembly has been utilized to construct responsive DNA origami and wireframe nanoassemblies, yet the replication of these hybrid nanomaterials remains a challenge. Here we report a strategy for replicating DNA wireframe nanoassemblies using the isothermal ligase chain reaction lesion-induced DNA amplification (LIDA). In this first generation, we designed a triangle wireframe structure that can be formed in one step by ring-closing its linear analog. Introducing a small amount of the wireframe triangle to an excess of the linear analog and complementary Fragments, one of which contained a destabilizing abasic lesion, led to rapid sigmoidal self-replication of the wireframe triangle via cross-catalysis. Using the same cross-catalytic strategy we also demonstrated rapid self-replication of a hybrid wireframe triangle containing synthetic vertices as well as the self-replication of circular DNA. This work reveals the suitability of isothermal ligase chain reactions such as LIDA to self-replicate complex DNA architectures, opening the door to incorporating self-replication, a hallmark of life, into biomimetic DNA nanotechnology.
|
Nahida Akter; B. Safeenaz Alladin-Mustan; Yuning Liu; Jisu An; Julianne M. Gibbs
|
Nanoscience; Nanostructured Materials - Nanoscience
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-03-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f08a859138d23161530b18/original/self-replicating-dna-based-nanoassemblies.pdf
|
61c3975c02c214225c2eda0d
|
10.26434/chemrxiv-2021-s0tlk
|
Rules of Chemospecificity of Nucleophilc Ring-opening of Dithia-/Oxathia-Phospholane Towards the Selective Synthesis of
Nucleoside 5’-O-Pα-Thio/Dithio/Trithio-Phosphate Ester Conjugates
|
DBU-assisted nucleophilic ring-opening of both uridine-5’-(2-thio-1,3,2-dithia-phospholane), 3, and uridine-(2-thio-1,3,2-oxathia-phospholane), 8, lasted 2 min at RT and resulted in quantitative yields of uridine-5’-phosphoro-di/trithioate esters. Furthermore, it was selective for alcohol and thiol vs. amine nucleophiles. Yet, reaction of mercaptoethanol with 3, was chemo-specific for the oxygen vs. sulfur nucleophile, while for the reaction of mercaptoethanol with 8, the opposite chemo-specificity was observed, probably related to the steric hindrance in the former case. The observed chemospecificity opens facile avenue for the synthesis of nucleoside-5’-O-Pα-thio/dithio/trithio-phosphate ester derivatives
|
Molhm Nassir; Bilha Fischer; Michal Weitman; yulia kabalin
|
Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions
|
CC BY 4.0
|
CHEMRXIV
|
2021-12-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61c3975c02c214225c2eda0d/original/rules-of-chemospecificity-of-nucleophilc-ring-opening-of-dithia-oxathia-phospholane-towards-the-selective-synthesis-of-nucleoside-5-o-p-thio-dithio-trithio-phosphate-ester-conjugates.pdf
|
6278f317a42e9c1f5039e479
|
10.26434/chemrxiv-2022-srdq9
|
Exploration of NaSICON Frameworks as Calcium-ion Battery Electrodes
|
The development of energy storage technologies that are alternative to the state-of-the-art lithium-ion batteries but exhibit similar energy densities, lower cost and better safety, is an important step in ensuring a sustainable energy future. Electrochemical systems based on Calcium (Ca)-intercalation form such an alternative energy storage technology, but require the development of intercalation electrode materials that exhibit reversible Ca-exchange with reasonable energy density and power density performance. To address this issue, we use first-principles calculations, screening over the wide chemical space of sodium superionic conductor (NaSICON) frameworks, with a chemical formula of CaxM2(ZO4)3 (where M = Ti, V, Cr, Mn, Fe, Co, or Ni, and Z = Si, P, or S) for Ca electrode materials. We calculate the average Ca2+ intercalation voltage, and the thermodynamic stability (at 0 K) of charged and discharged Ca-NaSICON compositions. We find CaxMn2(PO4)3 and CaxV2(PO4)3 NaSICONs to be promising as Ca-cathodes given their energy densities and thermodynamic (meta)stabilities, while CaxMn2(SO4)3 and CaxFe2(SO4)3 NaSICONs can also be explored as Ca-intercalation hosts. Additionally, we find all silicate Ca-NaSICONs to be thermodynamically unstable and hence unsuitable as Ca-cathodes. We report the overall trends in Ca-intercalation voltages, thermodynamic stabilities, and the ground state Ca-vacancy configurations in all the NaSICON compositions considered. Our work contributes to unearth strategies for developing practical calcium-ion batteries, involving polyanionic intercalation frameworks.
|
Dereje Bekele Tekliye; Ankit Kumar; Xie Weihang; Thelakkattu Devassy Mercy; Pieremanuele Canepa; Gopalakrishnan Sai Gautam
|
Theoretical and Computational Chemistry; Materials Science; Energy; Computational Chemistry and Modeling; Theory - Computational; Energy Storage
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-05-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6278f317a42e9c1f5039e479/original/exploration-of-na-sicon-frameworks-as-calcium-ion-battery-electrodes.pdf
|
66a154fec9c6a5c07acd84fc
|
10.26434/chemrxiv-2024-200wq
|
Coloring Tetrahedral Semiconductors: Synthesis and Photoluminescence Enhancement of Ternary II-III2-VI4 Colloidal Nanocrystals
|
Ternary tetrahedral II-III2-VI4 semiconductors—where II is Zn or Cd, III In or Ga, and VI S, Se, or Te—are of interest in UV radiation detectors in medicine and space physics as well as CO2 photoreduction under visible light. We synthesize colloidal II-III2-VI4 semiconductor nanocrystals from readily available precursors and ascertain their ternary nature by structural and spectroscopic methods, including 77Se solid-state NMR spectroscopy. The pyramidally shaped nanocrystals range between 2–10 nm and exhibit optical gaps of 2–3.9 eV. The presence of excess anions on the particle surface enables binding of Lewis acidic, Z-type ligands and results in enhanced photoluminescence. Electronic structure computations reveal the most stable, lowest energy polymorphs and coloring patterns. This work will pave the way toward more environmentally friendly, ternary semiconductors for optoelectronics and electrocatalysis.
|
Md Riad Sarkar Pavel; Yunhua Chen; Anuluxan Santhiran; Eunbyeol Gi; Kerly Ochoa-Romero; Gordon Miller; Gonzalo Guirado; Aaron Rossini; Javier Vela
|
Nanoscience; Energy; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-07-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66a154fec9c6a5c07acd84fc/original/coloring-tetrahedral-semiconductors-synthesis-and-photoluminescence-enhancement-of-ternary-ii-iii2-vi4-colloidal-nanocrystals.pdf
|
672c933c5a82cea2fa5d444b
|
10.26434/chemrxiv-2024-wrjln
|
Accelerated Relaxation Kinetics of Anisotropic Colloidal Nanoparticles in Acceleration Fields beyond 7251 Times Gravity: Liquid Crystalline Self-Assembly with Higher Rates and Structural Orderliness
|
Gravity of the Earth (g) drives macroscopic differentiation of multiple phases with different volumetric mass densities in many chemical and physical processes. Herein, liquid crystalline phase separation of colloidal dispersions of rod-shaped cellulose nanoparticles in centrifugal acceleration fields up to 71061 meters per second squared (about 7251 g) was studied. Through non-ionic in-situ free radical polymerization initiated by the time-controllable redox reactions between tert-butyl hydroperoxide (oxidants) and thiourea (reductants) at room temperature (about 298 kelvins), ordered soft microstructures formed by entropy-driven self-assembly were immobilized within crosslinked polyacrylamide matrixes at various evolution stages (e.g., after 10, 30, or 60 minutes) in centrifuge tubes. According to cross-sectional optical and scanning electron microscopy, strong acceleration fields accelerated the movement velocity of discrete liquid crystalline tactoidal microphases, the coalescence of tactoids into continuous chiral nematic structures, as well as the translational and rotational relaxation rates of mesogenic nanorods at kinetically arrested states in high-viscosity concentrated colloidal liquid crystals, leading to the elimination of topological defects and improvements in structural orderliness.
|
Pei-Xi Wang; Ling-Yan Xu; Hongbo Zhao
|
Materials Science; Inorganic Chemistry; Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-11-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672c933c5a82cea2fa5d444b/original/accelerated-relaxation-kinetics-of-anisotropic-colloidal-nanoparticles-in-acceleration-fields-beyond-7251-times-gravity-liquid-crystalline-self-assembly-with-higher-rates-and-structural-orderliness.pdf
|
67603a4181d2151a02f2bdd9
|
10.26434/chemrxiv-2024-fjxmz
|
The Effect of Electric Field on the Frontier Orbitals of Organic Small Molecules: DFT Studies of Triphenylamine Derivatives
|
The effect of strong electric fields on four triphenylamine derivatives was investigated. Using the optimized structures performed via B3LYP/6-31+G(d,p) level of theory in vacuo, single-point energy calculations were performed in this work with CAM-B3LYP/6-311+G(d,p) with electric fields of strength 50x10-4au (c.a 2.57x10^9V/m) parallel and antiparallel to each of the x, y, and z axes. While fields in the y- and z- directions had little effect on molecular orbital (MO) contours, large changes occurred for fields in the x-direction, where the molecule lies. Additional calculations were performed at intermediate x-direction field strengths. The changes of the orbital contours are attributed both the pull of the field on the electrons in an orbital and to the rearrangement of molecular orbitals’ energies relative to one another. Furthermore, a linear relationship between MO energy and electric field strength was discovered, with deviations from linearity at high field strengths due to the near free electron characteristics. The maximum difference in HOMO and LUMO energy for the molecules under a more realistic field strength of 0.4x10^-4au was estimated to be about 0.022eV, which is insignificant to affect the open voltage of a solar cell device.
|
Benjamin Parks; Lichang Wang
|
Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Photosensitizers; Computational Chemistry and Modeling; Physical and Chemical Properties
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67603a4181d2151a02f2bdd9/original/the-effect-of-electric-field-on-the-frontier-orbitals-of-organic-small-molecules-dft-studies-of-triphenylamine-derivatives.pdf
|
63f34a1ffcfb27a31f1b22f1
|
10.26434/chemrxiv-2023-63x5l
|
Comparing Ab Initio Molecular Dynamics and a Semiclassical Grand Canonical Scheme for the Electric Double Layer of the Pt(111)/Water Interface
|
The theoretical modeling of metal/water interfaces centers on an appropriate configuration of the electric double layer (EDL) under grand canonical conditions. In principle, ab initio molecular dynamics (AIMD) simulations would be the appropriate choice for treating the competing water-water and water-metal interactions and explicitly considering the atomic and electronic degrees of freedom. However, this approach only allows simulations of relatively small canonical ensembles over a limited period (shorter than 100 ps). On the other hand, computationally efficient semiclassical approaches can treat the EDL model based on a grand canonical scheme by averaging the microscopic details. Thus, an improved description of the EDL can be obtained by combining AIMD simulations and semiclassical methods based on a grand canonical scheme. By taking the Pt(111)/water interface as an example, we compare these approaches in terms of the electric field, water configuration, and double-layer capacitance. Furthermore, we discuss how the combined merits of the approaches can contribute to advances in EDL theory.
|
Jun Huang; Yufan Zhang; Mengru Li; Axel Groß; Sung Sakong
|
Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Electrochemistry - Mechanisms, Theory & Study
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-02-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63f34a1ffcfb27a31f1b22f1/original/comparing-ab-initio-molecular-dynamics-and-a-semiclassical-grand-canonical-scheme-for-the-electric-double-layer-of-the-pt-111-water-interface.pdf
|
6297857a82f956b733cc5797
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10.26434/chemrxiv-2022-vw0dg
|
Free energy predictions for crystal stability and synthesisability
|
What is the likelihood that a hypothetical material - the combination of a composition and crystal structure - can be formed? Underpinning the reliability of predictions for local or global crystal stability is the choice of thermodynamic potential. Here, we discuss recent advances in free energy descriptions for crystals including both harmonic and anharmonic phonon contributions to the vibrational entropy. We critically discuss some of the techniques and descriptors, including data-driven machine learning approaches, being developed to assess the stability and synthesisability of solids. Avenues are highlighted that deserve further attention including thermodynamic and kinetic factors that govern the accessibility of metastable structures away from equilibrium.
|
Kasper Tolborg; Johan Klarbring; Alex M. Ganose; Aron Walsh
|
Theoretical and Computational Chemistry; Physical Chemistry; Machine Learning; Chemoinformatics - Computational Chemistry; Thermodynamics (Physical Chem.); Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2022-06-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6297857a82f956b733cc5797/original/free-energy-predictions-for-crystal-stability-and-synthesisability.pdf
|
60c74e6cf96a008fdd287af3
|
10.26434/chemrxiv.12752459.v1
|
Structural Determination of an Orphan Natural Product Using Microcrystal Electron Diffraction and Genome Mining
|
<p>More than 60% of pharmaceuticals are related to natural products (NPs), chemicals produced by living organisms.<a></a> Hence, new methods that accelerate natural product discovery are poised to profoundly impact human health. Of the many challenges that remain in natural product discovery, none are as pervasive as structural elucidation, as determination of the molecular structure of a newly discovered natural product can take months, years, or in some cases be altogether unachievable. This challenge can be fueled by lack of sufficient material for spectroscopic analysis, or difficulties in sourcing the producing organism. Even in cases where the analyte is abundant, its physical properties, including molecular structure, can prevent unambiguous structural determination. Here we report the use of microcrystal electron diffraction (MicroED),<a></a> an emerging cryogenic electron microscopy (CryoEM) technique, in combination with genome mining, to address these challenges. As proof-of-principle, we apply these techniques to fischerin (<b>1</b>), an orphan NP isolated more than 30 years ago, with potent cytotoxicity but ambiguous structural assignment.<a></a> We utilize genome mining methods to reconstruct its biosynthetic pathway and highlight the sensitivity of MicroED through the precise determination of the solid-state structure of <b>1</b> from sub-micron thick crystals. This structural solution serves as a powerful demonstration of the synergy of MicroED and synthetic biology in NP discovery, technologies that when taken together will ultimately accelerate the rate at which new drugs are discovered.</p><div><div><p> </p></div></div>
|
Lee Joon Kim; Masao Ohashi; Dan Tan; Matthew Asay; Duilio Cascio; Jose Rodriguez; Yi Tang; Hosea Nelson
|
Natural Products; Stereochemistry; Structure; Crystallography – Organic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-08-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e6cf96a008fdd287af3/original/structural-determination-of-an-orphan-natural-product-using-microcrystal-electron-diffraction-and-genome-mining.pdf
|
61baff8f203b4077108f36c2
|
10.26434/chemrxiv-2021-n0n8c
|
Reduced Molecular Flavins as Single-Electron Reductants after Photo-Excitation
|
Flavoenzymes mediate a multitude of chemical reactions and are catalytically active both in different oxidation states and in covalent adducts with reagents. The transfer of such reactivity to the organic laboratory using simplified molecular flavins is highly desirable and such applications in (photo-)oxidation reactions are already established. However, molecular flavins have not been used for the reduction of organic substrates yet, although this activity is known and well-studied for DNA photolyase enzymes. We report a catalytic method using reduced, molecular flavins as photo-reductants and γ-terpinene as sacrificial reductant. Additionally, we present our design for air-stable, reduced flavin catalysts, which is based on a conformational bias strategy and circumvents the otherwise rapid reduction of O2 from air. Using our catalytic strategy, we were able to replace super-stoichiometric amounts of the rare-earth reductant SmI2 in a 5-exo-trig cyclization of substituted barbituric acid derivatives. Such flavin-catalyzed reductions are anticipated to be of broad applicability and their straightforward synthesis indicates future use in stereo- as well as site-selective transformations.
|
Richard Foja; Alexandra Walter; Christian Jandl; Erling Thyrhaug; Jürgen Hauer; Golo Storch
|
Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Photochemistry (Org.)
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CC BY NC ND 4.0
|
CHEMRXIV
|
2021-12-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61baff8f203b4077108f36c2/original/reduced-molecular-flavins-as-single-electron-reductants-after-photo-excitation.pdf
|
667030f55101a2ffa8c65d13
|
10.26434/chemrxiv-2024-kq40n-v2
|
Effects of Substituted Triarylphosphine Ligands on Electron Transfer in [(p-cymene)Ru] Complexes
|
The consequences of electron transfer in ruthenium-arene catalysts supported by triarylphosphine ligands has not been fully elucidated in coordinating solvents, which are known to engender further transformations in analogous Ru species upon oxidation and may reveal new modes of reactivity in these compounds. Herein, we report electrochemical studies of (p-cymene)RuCl2(PArX3) complexes containing substituted triarylphosphines (PArX3) and the effects of the ligand substituents on ET processes. These complexes undergo ET at potentials that depend on the ligand substituents (X); in CH3CN, electrochemical oxidation generates new products whose formation and ET behavior also depend on these substituents. Based on evidence for loss of cymene in these transformations, the products of these reactions are formulated as the tris(nitrile) complexes (PArX3)RuCl2(NCCH3)3.
|
Anthony Micci; Julia Fumo; Robert Pike; Davide Lionetti
|
Inorganic Chemistry; Catalysis; Organometallic Chemistry; Electrochemistry; Organometallic Compounds; Transition Metal Complexes (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-06-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/667030f55101a2ffa8c65d13/original/effects-of-substituted-triarylphosphine-ligands-on-electron-transfer-in-p-cymene-ru-complexes.pdf
|
63c8e2945ab313c7e1acc3a1
|
10.26434/chemrxiv-2022-9bjg0-v4
|
Microprobe-Capture In-Emitter Elution: An Affinity Capture Technique to Directly Couple a Label-Free Optical Sensing Technology with Mass Spectrometry for Top-Down Protein Analysis
|
Affinity capture of an analyte by a capture agent is one of the most effective sample preparation approaches for protein analytes. We describe a new affinity capture technique for top-down protein analysis, called microprobe-capture in-emitter elution (MPIE), which can directly couple a label-free optical sensing technology (next-generation biolayer interferometry, BLI) with MS. To implement MPIE, an analyte is first captured on the surface of a microprobe, and subsequently eluted from the microprobe inside an electrospray emitter. The capture process is monitored in real-time via BLI. When electrospray is established from the emitter to a mass spectrometer, the analyte is immediately ionized via electrospray ionization (ESI) for HR-MS analysis. By this means, BLI and HR-MS are directly coupled in the form of MPIE-ESI-MS. The performance of MPIE-ESI-MS was demonstrated by the analysis of β-amyloid 1-40 and transferrin using both standard samples and human specimens. In comparison to the conventional affinity capture techniques such as bead-based immunoprecipitation, MPIE innovates the affinity capture methodology by introducing real-time process monitoring and providing binding characteristics of analytes, offering more information-rich experimental results. Thus, MPIE is a valuable addition to the TD-MS sample preparation toolbox, and more applications of MPIE-ESI-MS in top-down protein analysis are expected.
|
Ruben Yiqi Luo; Samuel Yang
|
Analytical Chemistry; Analytical Apparatus; Mass Spectrometry
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CC BY NC ND 4.0
|
CHEMRXIV
|
2023-01-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63c8e2945ab313c7e1acc3a1/original/microprobe-capture-in-emitter-elution-an-affinity-capture-technique-to-directly-couple-a-label-free-optical-sensing-technology-with-mass-spectrometry-for-top-down-protein-analysis.pdf
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66ec990612ff75c3a1dc3aad
|
10.26434/chemrxiv-2024-lqh7l
|
Synthesis of Germoxysilicon Phthalocyanines
|
Phthalocyanines, aromatic, macrocyclic compounds with a wide range of industrial applications, are heavily conjugated ring systems which can chelate metals or metalloids. This chelated center can then act as an attachment site for functionalization or oligomerization. Prior characterization of one such group of siloxysilicon dimeric phthalocyanine crystals via X-ray crystallography found a series of unexpected torsional angles, hypothesized to indicate the presence of a previously unexplored intramolecular interaction. To further explore this phenomenon, a series of synthetic routes for novel dimeric silicon phthalocyanine crystals suitable for X-ray crystallography were investigated. Following unsuccessful attempts to synthesize precursor bis-hydroxy dimeric silicon phthalocyanine, a novel triethyl-germoxy-functionalized silicon phthalocyanine was proposed to explore the impact of solubility and functional group bond strength on dimerization. A novel germoxy-functionalized silicon phthalocyanine product was synthesized, with preliminary characterization revealing the presence of both monomeric and dimeric species suitable for separation, crystallization, and structural analysis. Further investigation into this class of silicon phthalocyanines will generate a parallel set of structural data to those previously documented for analysis of torsional angles and may contribute to a deeper understanding and development of the oligomerization of silicon-chelated phthalocyanines.
|
Ryan J. Anthony; Metin Karayilan; Benjamin Sturtz
|
Organic Chemistry; Inorganic Chemistry; Organometallic Chemistry; Coordination Chemistry (Organomet.); Ligand Design
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CC BY 4.0
|
CHEMRXIV
|
2024-09-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ec990612ff75c3a1dc3aad/original/synthesis-of-germoxysilicon-phthalocyanines.pdf
|
6528f3febda59ceb9a7dae9e
|
10.26434/chemrxiv-2023-lgxmt
|
In situ formation of a melt-solid interface towards stable oxygen reduction in protonic ceramic fuel cells
|
Protonic ceramic fuel cells (PCFCs) are one of the promising routes to generate power efficiently from various fuels at economically viable temperatures (500-700 °C) due to the use of fast proton conducting oxides as electrolytes. However, the power density and durability of the PCFCs are still limited by their cathodes mostly made from solid metal oxides, which are challenging to address the sluggish oxygen reduction reaction and susceptibility to CO2 simultaneously. Here, we report an alternative approach to address this challenge by developing a new melt-solid interface through the in situ alkali metal surface segregation and consecutive eutectic formation at perovskite oxide surface at PCFC operating temperatures. This new approach in cathode engineering is successfully demonstrated over a lithium and sodium co-doped BaCo0.4Fe0.4Zr0.1Y0.1O3-δ perovskite as the model material. Our experimental results unveil that the unique in situ formed melt-solid surface stabilises the catalytically active phase in the bulk and promotes catalytically active site at surface. Our novel engineered melt-solid interface enhanced the stability of the cathode against poisoning in 10% CO2 by a factor of 1.5 in a symmetrical cell configuration and by a factor of more than two in PCFC single cells.
|
Desheng Feng; Mengran Li; Vanessa K Peterson; Rijia Lin; Anita D'Angelo; Olexandra Marenych; Anya Yago; Bin Zulkifli Muhammad Yazid; Shuai Gao; Tianjiu Zhu; Yuming Wu; Zhonghua Zhu
|
Materials Science; Catalysis; Energy; Ceramics; Electrocatalysis; Fuel Cells
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-10-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6528f3febda59ceb9a7dae9e/original/in-situ-formation-of-a-melt-solid-interface-towards-stable-oxygen-reduction-in-protonic-ceramic-fuel-cells.pdf
|
651bd338a69febde9e23dd1c
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10.26434/chemrxiv-2023-s5qnw
|
Anubis: Bayesian optimization with unknown feasibility constraints for scientific experimentation
|
Model-based optimization strategies, such as Bayesian optimization (BO), have been deployed across the natural sciences in design and discovery campaigns due to their sample efficiency and flexibility. The combination of such strategies with automated laboratory equipment and/or high-performance computing in a suggest-make-measure closed-loop constitutes a self-driving laboratory (SDL), which have been endorsed as a next-generation technology for autonomous scientific experimentation. Despite the promise of early SDL prototypes, a lack of flexible experiment planning algorithms prevents certain prevalent optimization problem types from being addressed. For instance, many experiment planning algorithms are unable to intelligently deal with failed measurements resulting from a priori unknown constraints on the parameter space. Such constraint functions are pervasive in chemistry and materials science research, stemming from unexpected equipment failures, failed/abandoned syntheses, or unstable molecules or materials. In this work, we provide a comprehensive discussion and benchmark of BO strategies to deal with a priori unknown constraints, characterized by learning the constraint function on-the-fly using a variational Gaussian process classifier and combining its predictions with the typical BO regression surrogate to parameterize feasibility-aware acquisition functions. These acquisition functions balance sampling parameter space regions deemed to be promising in terms of optimization objectives with avoidance of regions predicted to be infeasible. In addition to benchmarking feasibility-aware acquisition functions on analytic optimization benchmark surfaces, we conduct two realistic optimization benchmarks derived from previously reported studies: inverse design of hybrid organic-inorganic halide perovskite materials with unknown stability constraints, and the design of BCR-Abl kinase inhibitors with unknown synthetic accessibility constraints. We deliver intuitive recommendations to readers on which strategies work best for various scenarios. Overall, this work contributes to advancing the practicality and efficiency of autonomous experimentation in SDLs. All strategies introduced in this work are implemented as part of the open-source Atlas Python library.
|
Riley Hickman; Matteo Aldeghi; Alán Aspuru-Guzik
|
Theoretical and Computational Chemistry; Organic Chemistry; Chemical Engineering and Industrial Chemistry; Process Chemistry; Machine Learning; Artificial Intelligence
|
CC BY 4.0
|
CHEMRXIV
|
2023-10-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651bd338a69febde9e23dd1c/original/anubis-bayesian-optimization-with-unknown-feasibility-constraints-for-scientific-experimentation.pdf
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66b3762301103d79c50896cf
|
10.26434/chemrxiv-2024-jndvt
|
Novel Zircaloy nanomaterials with antibacterial activity
|
The outcome of an implant procedure largely depends on the implant's surface properties. Biomaterials are now required to have surfaces with multifunctionality such as favorable tissue integration and the ability to combat bacterial adhesion and colonization. Herein, we report on a simple approach to improving the antibacterial properties of zirconia nanotubes (ZrNT) coatings via decoration with silver nanoparticles (AgNp/Ag2O). This was done by electrochemical anodization of Zr-Ag alloy at a constant voltage in a fluoride-containing electrolyte. The modified ZrNTs were characterized using SEM, EDS, ToF – SIMS, and XPS to determine their structural morphology and chemical composition, and were further subjected to antibacterial testing The silver and zirconium ion release behavior was also monitored via ICP-MS. ZrNT decorated with AgNp/Ag2O exhibited strong antimicrobial activity (> 99 % bacterial killing) against both S. aureus and E. coli. Antimicrobial tests indicated that the antibacterial activity against the Gram-positive pathogen S. aureus could be improved by a factor of 100 compared to unmodified ZrNT while the unmodified ZrNT showed already a comparable reduction of viable Gram-negative E. coli achieved with the additional AgNp/Ag2O decoration. This modification strategy illustrates a simplified and effective approach toward optimizing the interface between the host environment and the biomaterial surface to meet the very important criteria of biocompatibility and antibacterial properties.
|
Gabriel Onyenso; Jiwar AI-Zawity; Nastaran Farahbakhsh; Annika Schardt; Aydan Yadigarli; Swathi Naidu Vakamulla Raghu; Mareike Müller; Holger Schönherr; Carsten Engelhard ; Manuela Killan
|
Materials Science; Nanoscience; Alloys; Biocompatible Materials; Nanostructured Materials - Nanoscience; Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2024-08-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b3762301103d79c50896cf/original/novel-zircaloy-nanomaterials-with-antibacterial-activity.pdf
|
614365b039ef6a24221e776d
|
10.26434/chemrxiv-2021-z9mc9
|
Spatial control of heat flow at the nanoscale
using Janus particles
|
Janus Nanoparticles (JNP) feature heterogeneous compositions bringing opportunities in technological and medical applications. We investigate using non-equilibrium molecular dynamics simulations the temperature field generated around heated spherical Janus Nanoparticles to assess the performance of the particles in the generation of anisotropic heating. We demonstrate that the contrasting interfacial thermal conductances of the fluid-material interfaces arising from the heterogeneous composition of the JNP can be exploited to control the thermal fields around the nanoparticle leading to a temperature difference between both sides of the nanoparticle (temperature contrast) that is significant for particles comprising regions with disparate hydrophilicity. We illustrate this idea using simplified atomistic and complex models of gold nanoparticles passivated with hydrophobic and hydrophilic ligands in water. Furthermore, we introduce a continuum model to predict the temperature contrast as a function of the interfacial thermal conductance and nanoparticle size. We further show that, unlike homogeneous nanoparticles, the interfacial fluid temperature depends on the interfacial thermal conductance of Janus nanoparticles.
|
Juan D. Olarte-Plata; Jordan Gabriel; Pablo Albella; Fernando Bresme
|
Theoretical and Computational Chemistry; Physical Chemistry; Nanoscience; Plasmonic and Photonic Structures and Devices; Interfaces; Transport phenomena (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-09-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/614365b039ef6a24221e776d/original/spatial-control-of-heat-flow-at-the-nanoscale-using-janus-particles.pdf
|
6733c266f9980725cffb9976
|
10.26434/chemrxiv-2024-rrgfn
|
Ultrasoft, Elastic, and Ionically Conductive Polyethylene Glycol/Ionic Liquid Bottlebrush Ionogels
|
Ultrasoft conductors have revolutionized the field of electronics by achieving a level of softness comparable to that of biological tissues. However, the inherent difference in charge carriers between conventional ultrasoft electronics (utilizing electrons) and tissues (utilizing ions) could yield high contact impedance, hindering electronic performance for physiological signal recordings. Although ionic hydrogels exhibit ionic conductivity, their high-water content could limit their practical applications. This study proposes a new type of ultrasoft and ionically conductive bottlebrush ionogels (BBIs), leveraging polyethylene glycol (PEG) bottlebrushes and ionic liquids (ILs). The incorporation of IL into PEG bottlebrushes results in a simultaneous enhancement of compliance and ionic conductivity. Specifically, the PEG/IL BBI achieves a Young's modulus of 1.08 kPa, akin to the softest biological tissues such as the brain. To the best of our knowledge, this is the softest ionic conductor ever reported. The introduction of ionic liquids enables an ionic conductivity of 0.14 S/m, rendering it well-suited for integration into ultrasoft electronics. The PEG/IL BBI was further applied as sensors on silkworms and as electrodes on the Venus flytrap and human body. These applications facilitated electrocardiogram recordings and plant signal monitoring, showcasing the potential of this innovative ionically conductive BBI in various physiological environments.
|
Pengfei Xu; Siddhartha Challa; Xia Wu; Shaojia Wang; Peng Pan; Xinyu Liu
|
Polymer Science; Chemical Engineering and Industrial Chemistry; Biopolymers; Organic Polymers; Polymer brushes; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-11-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6733c266f9980725cffb9976/original/ultrasoft-elastic-and-ionically-conductive-polyethylene-glycol-ionic-liquid-bottlebrush-ionogels.pdf
|
678f35e7fa469535b9ee6686
|
10.26434/chemrxiv-2025-592mb-v2
|
Functionalization of strained rings via nucleophilic catalysis
|
Nucleophilic addition to strained rings offers a straightforward and effective strategy for synthesizing small aliphatic rings which serve a pivotal role as bioisosteres in medicinal research and drug development. However, incorporating sp³ C–H bonds into strained rings remains challenging due to their lack of electron lone pairs and weak acidity. Additionally, the frequent need for external stoichiometric bases or strong nucleophiles, such as organometallic reagents, presents issues related to practicality, compatibility, limited scope, and waste production. Here, we present a nucleophilic catalysis strategy that unlocks the nucleophilic addition of sp³ C–H bonds to strained rings and eliminates the need for an external stoichiometric base. This approach is also applicable to a wide range of heteroatom-based nucleophiles including carboxylic acids, amides, phosphine oxides, and thiols which typically require an external base for achieving reactivity in previously reported methods. Mechanistic studies suggest that this approach involves a covalent intermediate generated via the nucleophilic addition of the catalyst to the strained ring substrate, which serves as a key step in facilitating the reaction.
|
Cheng Deng; Ping Wang; Zihao Luo; Fangfang Zhang; Ding Chen; Yuanqiang Li; Lin Huang; Peng Yu
|
Organic Chemistry; Organic Synthesis and Reactions
|
CC BY NC 4.0
|
CHEMRXIV
|
2025-01-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678f35e7fa469535b9ee6686/original/functionalization-of-strained-rings-via-nucleophilic-catalysis.pdf
|
6438d40c08c86922fff1f519
|
10.26434/chemrxiv-2023-l0fz9
|
Structure elucidation of olanzapine molecular salts by combining mechanochemistry and MicroED
|
Olanzapine (OLN), an anti-psychotic drug, is one of the most widely studied pharmaceutical materials. Although OLN and most of their multicomponent solids are highly crystalline, some of their molecular salts are difficult to crystallize and optimization takes long time. After several batches of failed crystallization, we applied mechanochemistry and microcrystal electron diffraction (MicroED) for structure elucidation. This combined approach was successful not only in structure determination of the drug molecule but also in characterizing traces of impurity present in a bulk solid. This study demonstrates that the combined approach is fast and efficient for structure elucidation of pharmaceutical materials when generation of suitable single crystals is challenging.
|
Diptajyoti Gogoi; Toshiyuki Sasaki; Takanori Nakane; Akihiro Kawamoto; Hironobu Hojo; Genji Kurisu; Ranjit Thakuria
|
Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6438d40c08c86922fff1f519/original/structure-elucidation-of-olanzapine-molecular-salts-by-combining-mechanochemistry-and-micro-ed.pdf
|
63cee61510cb6a01ffe3cc35
|
10.26434/chemrxiv-2023-42p1j-v2
|
Aromatic aldehydes as tuneable and ppm level potent promoters for zeolite catalysed methanol dehydration to DME
|
Dimethyl ether (DME) is a valuable chemical intermediate and renewable fuel that can be made, via methanol, from many sources of carbon, including carbon dioxide and biomass. Benzaldehyde and its derivatives have been found to be promoters for zeolite catalysed methanol dehydration to DME at low temperature (110 to 150 oC). For the 3-dimensional medium pore zeolite H-ZSM-5 (MFI) the promotion is readily reversible and the potency of the promoter can be tuned by varying the substituent on the aromatic ring of the aldehyde. The most potent promoters are active at concentrations as low as 1 ppm relative to methanol. High throughput experimentation (HTE) is used to screen and rank potential promoters and catalysts and to collect high quality kinetic data for the most promising candidates discovered. The catalytic data and in-situ FT-IR-MS experiments combined with molecular modelling studies indicate a mechanism involving competitive adsorption of the aldehyde promoter on a Brønsted acid (BA) site, followed by reaction with methanol to give a hemi-acetal intermediate. Loss of water from the hemi-acetal intermediate generates a transient and highly reactive methyl oxonium species, [ArC(H)(=O-Me)]+, which then directly reacts with methanol via a SN2 mechanism to give DME and regenerate the aldehyde promoter and BA site. The methyl oxonium species is stabilized by electron-donating groups on the aromatic ring and the solvent like effect of the zeolite pore walls. Molecular descriptors were calculated by molecular modelling for the 22 aromatic aldehyde promoters tested. Multivariate linear regression analysis was used to build an interpretable model for aldehyde promotional activity in H-ZSM-5 and in another 3-dimensional medium pore zeolite, H-ZSM-11 (MEL).
|
Glenn Sunley; Zhiqiang Yang; Benjamin Dennis-Smither; Corneliu Buda; Amie Easey; Fiona Jackson; Gregory Price; Neil Sainty; Xingzhi Tan; Zhuoran Xu
|
Catalysis; Heterogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-01-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63cee61510cb6a01ffe3cc35/original/aromatic-aldehydes-as-tuneable-and-ppm-level-potent-promoters-for-zeolite-catalysed-methanol-dehydration-to-dme.pdf
|
67c4bd27fa469535b9a291e7
|
10.26434/chemrxiv-2025-m1s9w
|
13C Chemical Shift of N-Heterocyclic Carbenes in Coinage Metal (I) Complexes and Clusters: trans-Influence and Spin-Orbit Coupling
|
N-heterocyclic carbenes (NHCs) have emerged as versatile ligands in organometallic chemistry, prized for their strong σ-donating and tunable electronic properties. They stabilize diverse organometallic motifs, as well as clusters, and nanoparticles, particularly those based on the coin-age metals—Cu, Ag, and Au. Importantly, the carbene 13C NMR isotropic chemical shift (δiso) of NHC-coinage metal complexes varies significantly across these elements, reflecting the nuanced interplay of electronic and structural factors. Here, we investigate the nature of the car-bene carbon chemical shift in NHC-Au(I)-X complexes (X = H, OH, Cl, Br, I, CN, N3 and neutral ligands such as pyridine and NHC) compared to the Cu and Ag congeners. Using DFT calculations, the chemical shielding tensor (CST) components are analyzed to uncover the underlying factors influencing the carbene carbon δiso, revealing the roles of σ-donation and spin-orbit coupling in modulating chemical shifts. A clear trend is observed, where stronger σ-donor X-ligands lead to greater deshielding in both paramagnetic and spin-orbit contributions that can reach similar magnitude for Au. A correlation between spin-orbit contribution to the CST (σso) and Au-carbene bond distance highlights how trans-influence drives spin-orbit coupling and the overall chemical shift in this series of compounds. In-depth analysis of σso on each principal component shows that stronger σ-donor ligands, associated with a greater trans-influence and elongated Au-carbene bond, lead to a higher-lying NHC-Au σ-bond and lower-lying π*-bond, ultimately yielding greater deshielding and higher 13C chemical shift. This work provides insight into how structural and electronic factors govern carbene chemical shifts in NHC-based Au complexes and clusters, establishing a direct link between NMR spectroscopic descriptor and electronic structure, thus opening avenues for developing structure-activity relationships in catalysis and material science applications.
|
Shahar Dery; Christian Ehinger; Jeremy Roudin; Yuya Kakiuchi; Domenico Gioffrè; Christophe Copéret
|
Inorganic Chemistry; Organometallic Chemistry; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c4bd27fa469535b9a291e7/original/13c-chemical-shift-of-n-heterocyclic-carbenes-in-coinage-metal-i-complexes-and-clusters-trans-influence-and-spin-orbit-coupling.pdf
|
63d696641a1ead6fe0bbdf5b
|
10.26434/chemrxiv-2023-v0dw9
|
Pyrene and Bipyridine-based Covalent Triazine Framework as Versatile Platform for Photocatalytic Solar Fuels Production
|
The ability to molecularly engineer materials may be one of the most powerful tools in favor of high performing heterogeneous catalysts. Porous organic polymers stand out as photocatalysts due to their high chemical stability, outstanding optoelectronic properties and their easy and tunable syntheses. In photocatalysis, the insertion of photosensitizing π-extended molecules into a molecularly well-defined donor-acceptor junctions is supposed to increase the cata-lytic activity, but yet remain experimentally underdeveloped. Here, we present a pyrene-based Covalent Triazine Framework (CTF) synthesized through a polycondensation approach, which was designed to contain a molecularly defined pyrene-triazine-bipyridine donor-acceptor-acceptor triad as the repetition unit of the CTF. The CTF is an efficient photocatalyst for hydrogen evolution from water reaching a production rate of 61.5 mmolH2/h/gcat. Moreover, the same CTF can easily be used as porous macroligand for an organometallic Rh complex to efficiently catalyze the carbon dioxide photoreduction into formic acid under visible light.
|
Marcelo Alves Fávaro; Jin Yang; Daniel Ditz; Hüseyin Küçükkeçeci; Mohammed H. Alkhurisi; Sebastian Bergwinkl; Arne Thomas; Elsje Alessandra Quadrelli; Regina Palkovits; Jérôme Canivet; Florian M. Wisser
|
Catalysis; Polymer Science; Organic Polymers; Heterogeneous Catalysis; Photocatalysis; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-02-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63d696641a1ead6fe0bbdf5b/original/pyrene-and-bipyridine-based-covalent-triazine-framework-as-versatile-platform-for-photocatalytic-solar-fuels-production.pdf
|
60c7550c0f50dba5d7397e1f
|
10.26434/chemrxiv.14026406.v1
|
Differential Effects of Modified Batrachotoxins on Voltage-gated Sodium Channel Fast and Slow Inactivation
|
Voltage-gated sodium channels
(Na<sub>V</sub>s), large transmembrane protein complexes responsible for the
initiation and propagation of action potentials, are targets for a number of
acute poisons. Many of these agents act as allosteric modulators of channel
activity and serve as powerful chemical tools for understanding channel
function. Batrachotoxin (BTX) is a steroidal amine derivative most commonly
associated with poison dart frogs and is unique as a Na<sub>V</sub> ligand in
that it alters every property of the channel, including threshold potential of
activation, inactivation, ion selectivity, and ion conduction.
Structure-function studies with BTX are limited, however, by the inability to
access preparative quantities of this compound from natural sources. We have
addressed this problem through <i>de novo</i>
synthesis of BTX, which gives access to modified toxin structures. In this
report, we detail electrophysiology studies of three BTX C20-ester derivatives
against recombinant Na<sub>V</sub> subtypes (rat Na<sub>V</sub>1.4 and human Na<sub>V</sub>1.5).
Two of these compounds, BTX-B and BTX-<sup>c</sup>Hx, are functionally
equivalent to BTX, hyperpolarizing channel activation and blocking both fast
and slow inactivation. BTX-yne—a C20-<i>n</i>-heptynoate
ester—is a conspicuous outlier, eliminating fast but not slow inactivation. This
unique property qualifies BTX-yne as the first reported Na<sub>V</sub>
modulator that separates inactivation processes. These findings are supported
by functional studies with bacterial Na<sub>V</sub>s (BacNa<sub>V</sub>s) that lack
a fast inactivation gate. The availability of BTX-yne should advance future
efforts aimed at understanding Na<sub>V</sub> gating mechanisms and designing
allosteric regulators of Na<sub>V</sub> activity.
|
Tim M. G. MacKenzie; Fayal Abderemane-Ali; Catherine
E. Garrison; Daniel L. Minor Jr.; Justin Du Bois
|
Chemical Biology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-02-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7550c0f50dba5d7397e1f/original/differential-effects-of-modified-batrachotoxins-on-voltage-gated-sodium-channel-fast-and-slow-inactivation.pdf
|
672497947be152b1d0a7bc2e
|
10.26434/chemrxiv-2024-fsrnt-v2
|
Stereoselective peptide synthesis in alkaline hydrothermal vent conditions
|
Modern proteins are composed exclusively of L-amino acids but the origin of L-stereospecificity is unresolved. Carbonaceous meteorites were a significant source of organic matter on early Earth and commonly contain ten proteogenic amino acids in racemic mixtures. In conditions relevant to early Earth hydrothermal vents, surface-catalyzed peptide syntheses of these proteogenic mixtures show modest reaction rates and no significant stereoselectivity. However, we show that the presence of cysteine significantly increases peptide synthesis yields in the presence of silicate surfaces, with synthetic yields displaying a strong stereoselective bias towards L-cysteine. In a hydrothermal vent solvent model, L-cysteine doubles the increase in peptide synthetic yields compared to D-cysteine, as indicated by UV absorption, NMR, and mass spectrometry. Solid state NMR confirms that cysteine associates with silicates at alkaline pH via both carboxylate and sulfur groups. This adsorption results in a stereospecific orientation of the reactive amino group for surface-adsorbed bivalently charged amino acids detectable by Polarization-Resolved IRRAS. This stereospecific amino group reorientation provides a novel mechanism for abiotic peptide synthesis favoring L-amino acids on achiral surfaces, which is applicable to any bivalently charged amino acid at alkaline pH. Our findings here, that cysteine is incorporated stereoselectively in surface-catalyzed peptide synthesis, combined with the metal-binding capability of abiotically synthesized cysteine-bearing peptides, emphasizes the potential benefits of amino acids with sulfur functional groups to fundamental processes in early life and the potential usefulness of such amino acids as biosignatures.
|
Daniel P Molland; Isabella B Rhyu; Jon Wade; Jason R. Schnell
|
Catalysis; Earth, Space, and Environmental Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-11-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672497947be152b1d0a7bc2e/original/stereoselective-peptide-synthesis-in-alkaline-hydrothermal-vent-conditions.pdf
|
60c74640f96a003ab9286d16
|
10.26434/chemrxiv.10314239.v1
|
Development of 96 Multiple Injection-GC-MS Technique and Its Application in Protein Engineering of Natural and Non-Natural Enzymatic Reactions
|
Directed evolution requires the screening of enzyme libraries in
biological matrices. Available assays are mostly substrate or enzyme specific.
Chromatographic techniques like LC and GC overcome this limitation, but require
long analysis times. The herein developed multiple injections in a single
experimental run (MISER) using GC coupled to MS allows the injection of samples
every 33 s resulting in 96-well microtiter plate analysis within 50 min. This
technique is implementable in any GC-MS system with autosampling. Since the
GC-MS is far less prone to ion suppression than LCMS, no chromatographic
separation is required. This allows the utilisation of an internal standards and
the detection of main and side-product. To prove the feasibility of the system
in enzyme screening, two libraries were assessed: i) YfeX library in an E. coli
whole cell system for the carbene-transfer reaction on indole revealing the
novel axial ligand tryptophan, ii) a library of 616 chimeras of fungal
unspecific peroxygenase (UPO) in S. cerevisiae supernatant for hydroxylation of
tetralin resulting in novel constructs. The data quality and representation are
automatically assessed by a new R-script.
|
Anja Knorrscheidt; Pascal Püllmann; Eugen Schell; Dominik Homann; Erik Freier; Martin Weissenborn
|
Biochemical Analysis; Mass Spectrometry; High-throughput Screening; Biocatalysis
|
CC BY 4.0
|
CHEMRXIV
|
2019-12-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74640f96a003ab9286d16/original/development-of-96-multiple-injection-gc-ms-technique-and-its-application-in-protein-engineering-of-natural-and-non-natural-enzymatic-reactions.pdf
|
60f8529ed03b3dfd15020a46
|
10.26434/chemrxiv-2021-9j3cn
|
Preparation of Bioderived and Biodegradable Surfactants Based on an Intrinsically Disordered Protein Sequence
|
Surfactants, block-copolymers, and other types of micellar systems are used in a wide variety of biomedical and industrial processes. However, most commonly used surfactants are synthetically derived and pose environmental and toxicological concerns throughout their product life cycle. Because of this, bio-derived and bio-degradable surfactants are promising alternatives. For bio-surfactants to be implemented industrially, they need to be produced on a large scale and also have tailorable properties that match those afforded by the polymerization of synthetic surfactants. In this paper, a scalable and versatile production method for bio-surfactants based on a hydrophilic intrinsically disordered protein (IDP) sequence with a genetically engineered hydrophobic domain is used to study variables that impact their physicochemical and self-assembling properties. These amphiphilic sequences were found to self-assemble into micelles over a broad range of temperatures, pH values, and ionic strengths. To investigate the role of the IDP hydrophilic domain on self-assembly, variants with increased overall charges and systematically decreased IDP domain lengths were produced and examined for their sizes, morphologies, and critical micelle concentrations (CMCs). The results of these studies indicate that decreasing the length of the IDP domain and, consequently, the molecular weight and hydrophilic fraction, leads to smaller micelles. Additionally, significantly increasing the amount of charged residues in the hydrophilic IDP domain results in micelles of similar sizes, but with higher CMC values. This represents an initial step in developing a quantitative model for the future engineering of bio-surfactants based on this IDP sequence.
|
Sarah Klass; Jamie Gleason; Anthony Omole; Bibiana Onoa; Carlos Bustamante; Matthew Francis
|
Biological and Medicinal Chemistry; Bioengineering and Biotechnology; Chemical Biology; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-07-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60f8529ed03b3dfd15020a46/original/preparation-of-bioderived-and-biodegradable-surfactants-based-on-an-intrinsically-disordered-protein-sequence.pdf
|
636cdb0bdeff97a997decf72
|
10.26434/chemrxiv-2022-x3lsc-v2
|
Affinity for Anions Developed in Charcoal by Acid Treatment
|
In this study, we report a two-step method that creates at the surface of charcoal acidic groups that remove nitrate from an aqueous solution. The process used in this work with charcoal includes first an acid treatment followed by a heat treatment in a non-oxidizing atmosphere —a simple method to perform this treatment in a standard laboratory furnace is additionally presented—. As a control group, we use a process that omits the acid treatment and includes only the heat treatment. The precursors and products of the investigated processes were characterized in terms of (a) surface chemistry (zero charge point, Boehm titration), (b) structure (scanning electron microscopy, X-ray diffraction, nitrogen adsorption, Hg porosimetry), and (c) composition (CHN elemental analysis, thermal gravimetric analysis, Energy Dispersive X-ray Fluorescence). Acid-thermal treatment of charcoal creates Lewis acid groups that remove nitrate anions from an aqueous solution. The nitrate-removing Lewis acid groups were absent in the starting material as well as in the material obtained in the control group. The creation of these surface groups occurs without significant damage to the macropore structure of the charcoal particles. A simple process can generate chemical groups with an affinity for anions in an aqueous solution on the charcoal surface.
|
Leonel Andrés Long; Pablo Maximiliano Arnal
|
Materials Science; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-11-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/636cdb0bdeff97a997decf72/original/affinity-for-anions-developed-in-charcoal-by-acid-treatment.pdf
|
66bcae17f3f4b05290dba40e
|
10.26434/chemrxiv-2024-5cwts
|
Synthesis and biological evaluation of lipid A derived from commensal Bacteroides
|
The inflammation-inducing properties of lipopolysaccharides (LPS) of gram-negative bacteria reside in its lipid A moiety. Bacillus fragilis, which is a commensal gram-negative bacterium, biosynthesizes lipid A that is structurally distinct from that of E. coli and other enteric bacteria. It is composed of a beta1,6-linked glucosamine (GlcN) disaccharide that is only phosphorylated at the anomeric center. The major species of B. fragilis has five fatty acids and the amine of the distal GlcN carries the unusual (R)-3-(13-methyltetradecanoyloxy)-1.5-methylhexadecanoic acid. A recent study indicates that LPS of B. fragilis has anti-viral activity by selective induction of Interferon (IFN)- and was protective in mouse models of vesicular stomatitis virus (VSV) and influenza A. Heterogeneity in the structure of LPS and lipid A and possible contamination with other inflammatory components makes it difficult to unambiguously define immune-modulatory properties of LPS or lipid A. Therefore, we developed a synthetic approach for preparation of the unusual lipid A derived from B. fragilis, which includes a synthetic approach for (R)-3-(13-methyltetradecanoyloxy)-1.5-methylhexadecanoic acid by Wittig olefination to install the terminal isopropyl moiety. The proinflammatory and antiviral responses of synthetic B. fragilis lipid A was investigated in several cell lines and primary human monocytes by examining the production of the interleukin (IL)-6 and IFN-beta. It was found that B. fragilis does not induce the production of IL-6 and IFN-beta but can partially antagonize the production of pro-inflammatory cytokines induced by E. coli LPS and lipid A.
|
Enrico Verpalen; Anna Ehlers; Aldo van Wingaarden; Arwin Brouwer; Geert-Jan Boons
|
Organic Chemistry; Bioorganic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-08-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66bcae17f3f4b05290dba40e/original/synthesis-and-biological-evaluation-of-lipid-a-derived-from-commensal-bacteroides.pdf
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66b65fe15101a2ffa8bf7041
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10.26434/chemrxiv-2024-c7bp9
|
Electrocatalytic Grafting of Polyvinyl Chloride Plastics
|
Polyvinyl chloride (PVC) plastics require high loadings of plasticizers and stabilizers to achieve commercially useful bulk properties. However, these non-covalent additives leach from PVC over time, resulting in the loss of their tailored functionality. This work details the electrocatalytic functionalization of PVC to covalently graft plasticizing additives directly onto the polymer backbone. Here, mechanistic insights guided the design of electrocatalysts capable of modifying C–Cl bonds of PVC under mild conditions with high selectivity while suppressing side reactions such as elimination and chain scission. Functional groups that mimic PVC plasticizers are covalently installed into the backbone of PVC to create new materials with distinct bulk properties from the original polymer. The degree of polymer grafting is easily controlled by simply changing the redox capacity that is passed during electrolysis. This strategy is employed to create chemically- and leach-resistant PVC materials by directly electrolyzing mixtures of consumer PVC products.
|
Jordan Zackasee; Valmuri Srivardhan; Blaise Truesdell; Elizabeth Vrana; Christo Sevov
|
Organic Chemistry; Catalysis; Polymer Science; Organic Polymers; Polymer chains; Electrocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-08-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b65fe15101a2ffa8bf7041/original/electrocatalytic-grafting-of-polyvinyl-chloride-plastics.pdf
|
615f41128b620d134647d8c2
|
10.26434/chemrxiv-2021-mthjp-v2
|
Bridging the experiment-calculation divide: machine learning corrections to redox potential calculations in implicit and explicit solvent models
|
Prediction of redox potentials is essential for catalysis and energy storage. Although density functional theory (DFT) calculations have enabled rapid redox potential predictions for numerous compounds, prominent errors persist compared to experimental measurements. In this work, we develop machine learning (ML) models to reduce the errors of redox potential calculations in both implicit and explicit solvent models. Training and testing of the ML correction models are based on the diverse ROP313 dataset with experimental redox potentials measured for organic and organometallic compounds in a variety of solvents. For the implicit solvent approach, our ML models can reduce both the systematic bias and the number of outliers. ML corrected redox potentials also demonstrate less sensitivity to DFT functional choice. For the explicit solvent approach, we significantly reduce the computational costs by embedding the microsolvated cluster in implicit bulk solvent, obtaining converged redox potential results with a smaller solvation shell. This combined implicit-explicit solvent model, together with GPU-accelerated quantum chemistry methods, enabled rapid generation of a large dataset of explicit-solvent-calculated redox potentials for 165 organic compounds, allowing detailed investigation of the error sources in explicit solvent redox potential calculations.
|
Eugen Hruska; Ariel Gale; Fang Liu
|
Theoretical and Computational Chemistry; Catalysis; Organometallic Chemistry; Machine Learning; Electrochemistry - Organometallic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-10-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/615f41128b620d134647d8c2/original/bridging-the-experiment-calculation-divide-machine-learning-corrections-to-redox-potential-calculations-in-implicit-and-explicit-solvent-models.pdf
|
61dd6ea3a1605023db9d1f16
|
10.26434/chemrxiv-2022-4tzsr
|
Total In Vitro Biosynthesis of the Thioamitide Thioholgamide and Investigation of the Pathway
|
Thioholgamides are ribosomally synthesized and post-translationally modified peptides (RiPPs) with potent activity against cancerous cell lines and an unprecedented structure. Despite being one of the most structurally and chemically complex RiPPs, very few biosynthetic steps have been elucidated. Here, we report the complete in vitro reconstitution of the biosynthetic pathway. We demonstrate that thioamidation is the first step and acts as a gatekeeper for downstream processing. Thr dehydration follows thioamidation, and our studies reveal that both these modifications require the formation of protein complexes – ThoH/I and ThoC/D. Harnessing the power of AlphaFold we deduce that ThoD acts as a lyase and also propose putative catalytic residues. ThoF catalyzes the oxidative decarboxylation of the terminal Cys and the subsequent macrocyclization is facilitated by ThoE. This is followed by Ser dehydration, which is also carried out by ThoC/D. ThoG is responsible for histidine bis-N-methylation, which is a prerequisite for His β-hydroxylation – a modification carried out by ThoJ. The last step of the pathway is the removal of the leader peptide by ThoK to afford mature thioholgamide.
|
Asfandyar Sikandar; Maria Lopatniuk; Andriy Luzhetskyy; Rolf Müller; Jesko Koehnke
|
Biological and Medicinal Chemistry; Biochemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-01-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61dd6ea3a1605023db9d1f16/original/total-in-vitro-biosynthesis-of-the-thioamitide-thioholgamide-and-investigation-of-the-pathway.pdf
|
60c757569abda281adf8e6db
|
10.26434/chemrxiv.14394266.v1
|
Dimeric and Trimeric Catenation of Giant Chiral [8+12] Imine Cubes Driven by Weak Supramolecular Interactions
|
Mechanically interlocked structures, such as catenanes or rotaxanes are fascinating synthetic
targets and are the basis of molecular switches and machines. Today, the vast majority of
catenated structures are built upon macrocycles and only a very few examples of three?dimensional shape-persistent organic cages forming such structures are reported. However, the
catenation in all these cases was based on a thermodynamically favoured π-π stacking under
certain reaction conditions. Here, we present our findings that catenane formation can be driven
by even less directional dispersion (Keesom) interactions of methoxy-groups during the
synthesis of chiral [8+12] imine cubes, giving dimeric and also for the first time trimeric
catenated organic cages. To further elucidate the underlying driving forces, twelve differently
1,4-substituted benzene dialdehydes have been reacted with a chiral triamino
tribenzotriquinacene under various conditions to study whether monomeric cages or catenated
cage dimers are the preferred products.
|
Bahiru Punja Benke; Tobias Kirschbaum; Jürgen Graf; Michael Mastalerz
|
Supramolecular Chemistry (Org.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-04-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757569abda281adf8e6db/original/dimeric-and-trimeric-catenation-of-giant-chiral-8-12-imine-cubes-driven-by-weak-supramolecular-interactions.pdf
|
60c73f70469df43f0af42ad2
|
10.26434/chemrxiv.7268396.v2
|
Branch-Selective Addition of Unactivated Olefins into Imines and Aldehydes
|
Radical hydrofunctionalization occurs with ease using met-al-hydride atom transfer (MHAT) catalysis to couple alkenes and competent radicalophilic electrophiles. Traditional two-electron electrophiles have remained unreactive. Herein we report the addition of electronically-unbiased olefins into imines and aldehydes. Iron-catalysis allows addition of alkyl-substituted olefins into imines through the intermediacy of free-radicals, whereas a combination of catalytic Co(Salt-Bu,t-Bu) and chromium salts enable a branch-selective coupling of olefins and aldehydes through the formation of a putative alkyl chromium intermediate.
|
Jeishla Melendez Matos; Suhelen Vásquez-Céspedes; Jieyu Gu; Takuya Oguma; Ryan Shenvi
|
Organic Synthesis and Reactions; Catalysis; Small Molecule Activation (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-10-31
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f70469df43f0af42ad2/original/branch-selective-addition-of-unactivated-olefins-into-imines-and-aldehydes.pdf
|
60c743f5702a9b323a18a70c
|
10.26434/chemrxiv.9728285.v1
|
Arylboronic Acid-Catalyzed C-Allylation of Unprotected Oximes
|
Unprotected keto- and aldoximes are readily <i>C</i>-allylated with allyl diisopropyl boronate in the presence of arylboronic acid catalysts to yield highly-substituted <i>N</i>-alpha-secondary (2°) and tertiary (3°) hydroxylamines. The method’s synthetic utility is demonstrated with the total synthesis of the trace alkaloid <i>N</i>-methyl-euphococcine. Preliminary experimental and computational mechanistic studies point toward the formation of a boroxine as the active allylating species.<br />
|
Juha Siitonen; Padmanabha V. Kattamuri; Muhammed Yousufuddin; Laszlo Kurti
|
Acid Catalysis; Homogeneous Catalysis; Organocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-08-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743f5702a9b323a18a70c/original/arylboronic-acid-catalyzed-c-allylation-of-unprotected-oximes.pdf
|
615c58c1aa918dba5a20a312
|
10.26434/chemrxiv-2021-7qs3m-v2
|
PRISMA: A robust and intuitive tool for high-throughput processing of chemical spectra
|
The popularization of high-throughput spectroscopies to characterize functional materials requires the simultaneous development of new analysis tools to efficiently process large numbers of measurements into scientifically meaningful observables. Here we introduce PRISMA, an open-source tool to rapidly analyze hundreds of spectra in a semi-automated way. PRISMA follows a human-in-the-loop workflow, where the user interacts with an intuitive graphical user interface (GUI) to control multiple steps in the spectrum analysis process: trimming, baseline correction, and peak fitting. The user tunes the analysis in real-time and applies the optimal parameters to all spectra, outputting processed results in an easy-to-read csv format within seconds. Crucially, the tuned parameters are stored to guarantee the full reproducibility of the analysis. We describe the functionalities implemented in PRISMA and test its capabilities with three experimental cases relevant to the study of electrochemical energy storage and conversion devices: temperature-dependent Raman measurement of phase transitions, a linear Raman mapping of a graphite composite electrode, and an operando X-ray diffraction experiment of LiNiO2 Li-ion electrode. Even if X-ray diffraction is not a spectroscopic technique, diffraction patterns are represented as one-dimensional arrays of counts equally suitable for analysis with PRISMA. The case studies demonstrate the robustness of the app and its ability to unearth insightful trends in peak parameters, which are easier to represent, interpret and further analyze with more advanced techniques.
|
Eibar Flores; Nataliia Mozhzhukhina; Xinyu Li; Poul Norby; Aleksandar Matic; Tejs Vegge
|
Physical Chemistry; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.); Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2021-10-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/615c58c1aa918dba5a20a312/original/prisma-a-robust-and-intuitive-tool-for-high-throughput-processing-of-chemical-spectra.pdf
|
6718cd73d433919392f11aa0
|
10.26434/chemrxiv-2024-481l3
|
The Effect of Regioisomerism on the TADF Properties of Organic Dyes
|
The properties of thermally activated delayed fluorescence (TADF) chromophores are highly dependent on the molecular design. The choice of the donor (D) and acceptor (A) group are as important as the choice of the π-linker and the substitution positions. Herein, the influence of regioisomerism through the substitution pattern of 9,9’-spirobi[fluorene] (SBF) on the TADF characteristics is investigated. In our studies, phenothiazine and carbonitrile have been chosen as D and A groups, and their substitution varied among the 2, 2’, 7 and 7’ positions of the spiro core resulting in two pairs of regioisomers. Depending on these changes, the physical properties differ from one to another with changes in emission wavelength maximum, photoluminescence quantum yield (PLQY), fluorescence lifetime and thermal stability. Three of the investigated molecules exhibit TADF properties in solid phase as thin films and crystals.
|
Tim Silies; Silvia Tombolato; Debbie Stappers; Nikos Doltsinis; Constantin Daniliuc; Fabio Rizzo
|
Organic Chemistry; Materials Science; Physical Organic Chemistry; Dyes and Chromophores; Optical Materials; Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-10-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6718cd73d433919392f11aa0/original/the-effect-of-regioisomerism-on-the-tadf-properties-of-organic-dyes.pdf
|
670c327d12ff75c3a151ebfd
|
10.26434/chemrxiv-2024-r037x
|
Bridging the scales within transport-coupled kinetic models for heterogeneous electrocatalysis
|
Optimizing reaction rates in heterogeneous electrocatalysis requires a solid, fundamental understanding of the interplay between mass transport and the intrinsic reaction kinetics at the electrode surface. As these processes occur on disparate scales, however, bridging the two into a (single) comprehensive reaction model is a challenging task and active area of research. In this perspective, we give a current overview of transport-coupled kinetic models while making a distinction between those that describe the surface reaction via an effective phenomenological or first-principles based kinetic model. This choice tends to be accompanied by a correspondingly more or less elaborate inclusion of mass transport. The two modeling approaches thus generally differ in the scientific questions that they aim to answer; whether focusing on elaborate transport effects and resulting design rules at the device level or more detailed mechanistic insight on a microscopic scale. We first discuss these approaches separately, including their pros and cons through notable studies in the existing literature, and conclude with an outlook view on combining the value of both in future research.
|
Hemanth S. Pillai; Hendrik H. Heenen; Karsten Reuter; Vanessa J. Bukas
|
Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Theory - Computational; Electrocatalysis
|
CC BY 4.0
|
CHEMRXIV
|
2024-10-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670c327d12ff75c3a151ebfd/original/bridging-the-scales-within-transport-coupled-kinetic-models-for-heterogeneous-electrocatalysis.pdf
|
60c747be702a9b6e9c18ae41
|
10.26434/chemrxiv.11733432.v1
|
Glass Fiber Stress-Corrosion Setup: Selection of a Polymeric Coating Material for the Pushing Rod
|
Various polymers were tested for leaching of ions via High
Resolution Induced Coupled Plasma Mass Spectrometry (HR-ICP-MS) in order
to determine which coating materials for the pushing rod are compatible
with the glass fiber stress-corrosion setup. The biggest concern is the
leaching of Si ions, and is compared among various commercially
available polymers - four different polyurethanes, polyvinylchloride,
poly(methylmethacrylate) and silicone. Significant amounts of other
elements leached were also noted and reported.
|
Andrejs Krauklis
|
Coating Materials; Composites; Fibers; Polymers
|
CC BY 4.0
|
CHEMRXIV
|
2020-01-31
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c747be702a9b6e9c18ae41/original/glass-fiber-stress-corrosion-setup-selection-of-a-polymeric-coating-material-for-the-pushing-rod.pdf
|
65b7b9fae9ebbb4db937033f
|
10.26434/chemrxiv-2024-xbgq5
|
In and out – new ionic mesogens based on a cyanoborate building block and lipophilic or hydrophilic counter ions
|
Abstract. New ionic mesogens have been prepared based on a cyanoborate head group, which is tethered to a lipophilic periphery via a short flexible spacer. As counter ions, either tetra-n-butyl ammonium cations or sodium and potassium cations stabilized by 18-crown-6 have been used. Although all compounds realise SmA enantiotropic mesomorphism, X-ray diffraction, modelling and solid-state NMR uncover distinct self-assembly of the LC materials in double layers. While the ammonium ions are located in-between the borate anions and are in contact with spacers and aromatic units, the crown ethers with the coordinated alkali metal cations are completely nanosegregated between two borate anion layers. Homogenous and homeotropic alignment has been achieved. Electrical impedance studies confirm two to three orders of magnitude higher conductivity of the correctly-aligned samples in the single-ion conductor. Values of ca. 10-4 Scm-1 in the SmA phase at 85 °C and 10-5 Scm-1 at 40 °C have been obtained.
|
Matthias Lehmann; Pascal Weinberger; Maik Finze; Guinevere A. Giffin; Mario Weller; Stephanie Bachmann; Ann-Christin Pöppler
|
Organic Chemistry; Inorganic Chemistry; Supramolecular Chemistry (Org.); Electrochemistry; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-01-30
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65b7b9fae9ebbb4db937033f/original/in-and-out-new-ionic-mesogens-based-on-a-cyanoborate-building-block-and-lipophilic-or-hydrophilic-counter-ions.pdf
|
66cf46d3f3f4b0529063835d
|
10.26434/chemrxiv-2024-zmn02
|
Towards reliable oxidation state analysis of tin halide perovskites with XPS
|
Tin is the most promising replacement for lead in hybrid halide perovskite solar absorbers. A disadvantage of tin perovskites is ease of oxidation of Sn(II) hampering optoelectronic performance and long-term stability. Quantification of the extent of Sn oxidation in hybrid halide perovskites is therefore an important indicator of material stability but remains a significant challenge. X-ray photoemission spectroscopy (XPS) is commonly used to measure Sn chemical environments; we show here that conventional approaches to fitting the Sn 3d spectra from perovskite surfaces can easily lead to erroneous conclusions about the tin oxidation state. We consider several approaches to developing a robust fitting model for Sn 3d spectra. Furthermore, we identify that tin halide perovskite surfaces can be unstable under XPS measurement conditions, and the chemical state of tin will change significantly over typical analysis times. We use correlation analysis to validate our fitting model and identify phases present.
|
Amanz Azaden; Prajna Bhatt; Yuhan Liu; Jiewen Wei; Saif Haque; Robert Palgrave
|
Analytical Chemistry; Energy; Spectroscopy (Anal. Chem.); Photovoltaics; Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-08-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66cf46d3f3f4b0529063835d/original/towards-reliable-oxidation-state-analysis-of-tin-halide-perovskites-with-xps.pdf
|
64803b57be16ad5c5797d870
|
10.26434/chemrxiv-2023-5t07v
|
Enhancing Bioactivities and Chemical Properties of A Marine Briarane-type Diterpenoid With Late-Stage Diversification
|
Excavatolide B (1, ExcB), a briarane-type diterpenoid isolated from Formosan gorgonian Briareum stechei, exhibits promising anti-inflammatory activity with low cytotoxicity. In this study, we report the structure-activity relationship of ExcB derivatives with late-stage modifications around the carboframe of 1. We identified a potent analog 22 with improved in vitro inhibitory activities against the inducible nitric oxide synthase gene expression, nitric oxide production, IL-6, and TNF- production in LPS-stimulated RAW264.7 macrophages. The esterification of piperidyl with proper spacer length in analog 22 also substantially increased the aqueous solubility >100-fold. More importantly, under similar dosing regimen compared to that of parent 1, 22 in its salt form showed an 80% increase in anti-inflammatory activity to alleviate carrageenan-induced paw edema in rats. Overall, these findings would greatly facilitate the further development of more potent analogs with enhanced bioactivities and improved drug-like properties of the underexplored class of briarane-type natural diterpenoids.
|
GUANG-HAO NIU; Wan-Chi Hsiao; Hong Zhuang; Hsiu-Wen Chen; Li-Guo Zheng; Zhi-Hong Wen; Ping-Jyun Sung; Mingzi Zhang; Lun Tsou
|
Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-06-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64803b57be16ad5c5797d870/original/enhancing-bioactivities-and-chemical-properties-of-a-marine-briarane-type-diterpenoid-with-late-stage-diversification.pdf
|
62bb0473be884b4f52f32728
|
10.26434/chemrxiv-2022-3jnwr-v2
|
Demonstrating the electron-proton transfer mechanism of aqueous phase 4-nitrophenol hydrogenation on supported metal catalyst using unbiased electrochemical cells
|
Heterogeneous thermocatalytic hydrogenation is widely believed to occur via co-adsorption of H2 and other reactants, but in aqueous phase an ionic or electrochemical mechanism was also proposed. Herein, we conduct 4-nitrophenol hydrogenation in an unbiased H-cell, where H2 and substrate are separately supplied into two chambers connected by a proton exchange membrane, in comparison with the same reaction in a single-cell in which H2 and 4-nitrophenol are co-fed. Based on the observation of the almost identical hydrogenation performance between the H-cell and the single cell, we conclude that co-adsorption of H2 and 4-nitrophenol is not a prerequisite for hydrogenation in aqueous phase in the tested pH range. Isotope experiments, scavenger test, DFT calculations and reaction kinetics suggest that a coupled electrochemical half-reaction mechanism for 4-nitrophenol hydrogenation in acidic aqueous phase is predominant. Importantly, while H2 oxidation primarily occurs on metal sites, 4-nitrophenol reduction occurs on both metal sites and conductive support, highlighting the non-innocent role of the support if the hydrogenation reaction follows the electron-proton transfer pathway.
|
Ning Yan; Hua An; Geng Sun; Max Hülsey; Philippe Sautet
|
Catalysis; Heterogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-06-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62bb0473be884b4f52f32728/original/demonstrating-the-electron-proton-transfer-mechanism-of-aqueous-phase-4-nitrophenol-hydrogenation-on-supported-metal-catalyst-using-unbiased-electrochemical-cells.pdf
|
6285f2a4809e326f96950acc
|
10.26434/chemrxiv-2022-tq7p9-v2
|
Effect of Bacillus and Pseudomonas biofilms on the corrosion behavior of AISI 304 stainless steel
|
In this research work, the corrosion tendency of stainless steel (SS 304) caused by the Pseudomonas aeruginosa ZK (PA-ZK) and Bacillus subtilis S1X (BS-S1X) bacterial strains is investigated. The topographical features of the biofilms and SS304 substrate achieved after 14 days of incubation at 37 °C were examined by scanning electron microscopy (SEM). Fourier Transform Infrared Spectroscopic (FTIR) analysis of the extracellular polymer substance (EPS) was also carried out to estimate the chemical composition of the biofilm. Electrochemical Impedance Spectroscopy (EIS) and Tafel Polarization test methods were applied to understand the in-situ corrosion tendency of the SS304 in the presence of PA-ZK and BS-S1X strains. Compared to the biofilm produced by the PA-ZK, the EPS in the BS-S1X containing bacteria was porous and non-uniform as revealed in the SEM analysis. The improved hydrophobicity and uniformity of the PA-ZK containing biofilm retarded the corrosion of the underlying SS304 sample. Appreciably large resistance of the PA-ZK biofilm (~ 6.04 kΩ-cm2) and hindered charge transport (11.12 kΩ-cm2) were evident from the EIS analysis. In support of these results, a large cathodic Tafel slope (0.2 V/decade) and low corrosion rate (1.69 µA/cm2) were corroborated by the inhibitive properties of the PA-ZK containing biofilm. However, the formation of porous biofilm and non-homogeneity of the EPS layer produced by the BS-S1X bacteria facilitated localized corrosion. Also, low charge transfer resistance, a high corrosion rate and pitting of the surface under BS-S1X biofilm were comparable to the surface features of SS304 obtained after exposure to a controlled medium. These results highlighted the poor corrosion inhibitive properties of the BS-S1X biofilm compared to the PK-ZK bacterial strain.
|
Hafiz Zeeshan Wadood; Aruliah Rajasekar; Ameeq Farooq; Kashif Mairaj Deen
|
Materials Science; Biocompatible Materials; Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2022-05-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6285f2a4809e326f96950acc/original/effect-of-bacillus-and-pseudomonas-biofilms-on-the-corrosion-behavior-of-aisi-304-stainless-steel.pdf
|
60c7558ff96a0056de2888c4
|
10.26434/chemrxiv.14128298.v1
|
Polariton Induced Conical Intersection and Berry Phase
|
We investigate the Polariton induced conical intersection (PICI) created from coupling a diatomicmolecule with the quantized photon mode inside an optical cavity, and the corresponding BerryPhase effects. We use the rigorous Pauli-Fierz Hamiltonian to describe the quantum light-matterinteractions between a LiF molecule and the cavity, and exact quantum propagation to investigatethe polariton quantum dynamics. The molecular rotations relative to the cavity polarization directionplay a role as the tuning mode of the PICI, resulting in an effective CI even within a diatomic molecule.To clearly demonstrate the dynamical effects of the Berry phase, we construct two additional modelsthat have the same Born-Oppenheimer surface, but the effects of the geometric phase are removed.We find that when the initial wavefunction is placed in the lower polaritonic surface, the Berryphase causes aπphase-shift in the wavefunction after the encirclement around the CI, indicatedfrom the nuclear probability distribution. On the other hand, when the initial wavefunction is placedin the upper polaritonic surface, the geometric phase significantly influences the couplings betweenpolaritonic states and therefore, the population dynamics between them. These BP effects are furtherdemonstrated through the photo-fragment angular distribution. PICI created from the quantizedradiation field has the promise to open up new possibilities to modulate photochemical reactivities.
|
Marwa Farag; Arkajit Mandal; Pengfei Huo
|
Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-03-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7558ff96a0056de2888c4/original/polariton-induced-conical-intersection-and-berry-phase.pdf
|
67c7297381d2151a020d97a4
|
10.26434/chemrxiv-2025-5m37d
|
Detection and Analysis of Reactive Oxygen Species (ROS): Buffer Components Are Not Bystanders
|
Reactive oxygen species (ROS) play critical roles in pathophysiological processes. Therefore, there are widespread interests in determining ROS concentrations under various conditions. However, “the application and interpretation of these measurements are fraught with challenges and limitations,” as indicated by a recent consensus paper in Nature Metabolism. These challenges and limitations are partially due to the large number of factors that could impact experimental outcome, making most side-by-side comparisons difficult. In an effort to address some seemingly idiosyncratic fluctuations in our own experiments, we examined buffer effects on ROS concentration determination through kinetic and HPLC experiments. Specifically, we examined the effects of the following buffer compounds: HEPES, Tris, MES, citrate, ammonium acetate, and PBS and found that most organic buffer components can rapidly consume NaOCl (the second most abundant ROS) and/or directly interact with certain ROS probes such as a boronate for H2O2 determination, leading to substantial variations in experimental outcome. We use these examples to draw attention to the profound effects of buffer components on ROS concentration determination. We hope that the work described will stimulate additional studies in examining similar factors that impact ROS research. Because of their highly reactive nature, very few chemical entities are truly bystanders in ROS studies. Together with our recent finding of DMSO’s effect on ROS concentration determination, we hope the results described will lead to improved rigor in designing ROS experiments by considering factors that were previously considered as nothing but bystanders or benign.
|
Shubham Bansal; Muskan Gori; Joanna Afokai Quaye; Giovanni Gadda; Binghe Wang
|
Biological and Medicinal Chemistry; Organic Chemistry; Analytical Chemistry; Analytical Chemistry - General; Cell and Molecular Biology; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c7297381d2151a020d97a4/original/detection-and-analysis-of-reactive-oxygen-species-ros-buffer-components-are-not-bystanders.pdf
|
6384876e0949e1353158bcde
|
10.26434/chemrxiv-2022-hbgp0
|
Understanding Charge Recombination of TiO2 using Ultrafast mid-Infrared Spectroscopy: The Effect of Photogenerated Holes
|
We utilize mid-infrared probe to explore the mechanism for the dramatic charge recombination process of the photogenerated charges within the band gap of TiO2. Using the low-energy photons probes the free electrons in the conduction band of TiO2 and upon trapping to shallow-trap states. We found that > 70% of the photogenerated charges disappear from the conduction band in the first few nanoseconds, due to electron trapping or charge recombination. We compare the behavior of free electron dynamics within the bandgap of TiO2 and upon generating them across the interface with adsorbing organic dyes. This comparison shows that the main driving force of dramatic charge recombination of photogenerated charges is the presence of hole within the band-gap of TiO2 or close to the interface of TiO2. Once, the hole is far from the TiO2 surface, the electron trapping process is hindered and almost 100% of photogenerated charges can live up till nanoseconds. This paper allows for further understandings of the charge trapping and charge recombination processes in TiO2 and in other semiconductors.
|
Ahmed M. El-Zohry
|
Physical Chemistry; Energy; Photovoltaics; Chemical Kinetics; Photochemistry (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-11-30
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6384876e0949e1353158bcde/original/understanding-charge-recombination-of-ti-o2-using-ultrafast-mid-infrared-spectroscopy-the-effect-of-photogenerated-holes.pdf
|
6751f8165a82cea2fa1bb69b
|
10.26434/chemrxiv-2024-xss2j
|
Mapping the Distribution and Affinities of Ligand Interaction Sites on Human Serum Albumin
|
Ligands in many instances interact with a protein at multiple sites with a range of affinities. In the present study, ligand-protein interaction sites on Human Serum Albumin (HSA) are mapped using the site-identification by ligand competitive saturation (SILCS)-Biologics approach in conjunction with Hydrogen-Deuterium Exchange (HDX)-Mass Spectrometry (MS) experiments. Ligands studied include known HSA binders, Ibuprofen and Ketoprofen, and compounds Arginine, Alanine, Sucrose and Trehalose, excipients used in therapeutic formulations of protein-based drugs. In addition, the impact of excipient binding to HSA on its stability is investigated through temperature-ramp stability studies monitoring solution viscosity. For the studied ligands, interactions that correspond to known drug-binding sites (DS) are identified. These include previously identified Ibuprofen and Ketoprofen interaction sites as well as additional sites and, in the case of the excipients, the ligands are shown to also bind at previously unidentified lower affinity interaction sites, termed excipients sites (ES) with 20 or more sites identified for the studied compounds. HDX-MS titrations were used to determined dissociation constants for a subset of the interaction sites for Ibuprofen, Ketoprofen, Arginine, and Sucrose, which exhibited Kd values in the low micromolar to millimolar range in satisfactory agreement with SILCS-Biologics predicted affinities, validating the computational approach to identify both high and low affinity interaction sites. The stability studies indicate the excipients to offer protection at low excipient-protein ratios up to 66 with destabilization occurring at ratios above 132 with the exception of Sucrose at the t0 timepoint, indicating that the more favorable affinities of Sucrose seen in the SILCS-Biologics and HDX-MS analyses contribute to protein stabilization. These results indicate that ligands can bind to large numbers of interaction sites on proteins, with those interactions having implications for the development of formulations for therapeutic proteins.
|
Asuka Orr; Agbo-oma Uwakweh; Xun Li; Ahmad Karanji; Stephen Hoag; Daniel Deredge; Alexander MacKerell
|
Theoretical and Computational Chemistry; Physical Chemistry; Biological and Medicinal Chemistry; Bioengineering and Biotechnology; Biophysics; Computational Chemistry and Modeling
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6751f8165a82cea2fa1bb69b/original/mapping-the-distribution-and-affinities-of-ligand-interaction-sites-on-human-serum-albumin.pdf
|
60c73ebdbb8c1afc0f3d9987
|
10.26434/chemrxiv.7087010.v1
|
Optoregulated Drug Release from an Engineered Living Hydrogel
|
A living hydrogel has been developed with metabolically and optogenetically engineered E. coli encapsulated within an agarose-based hydrogel matrix to produce and release deoxyviolacein in response to blue light irradiation. Localized, tunable and prolonged drug release have been demonstrated.<br />
|
Shrikrishnan Sankaran; Judith Becker; Christoph Wittmann; Aránzazu del Campo
|
Biological Materials; Controlled-Release Systems; Bioengineering and Biotechnology; Chemical Biology; Drug Discovery and Drug Delivery Systems; Microbiology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-09-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73ebdbb8c1afc0f3d9987/original/optoregulated-drug-release-from-an-engineered-living-hydrogel.pdf
|
60c74661469df41f1ef4363a
|
10.26434/chemrxiv.11306867.v1
|
Primary Evaluation of Potential Small Molecule Inhibitors of the Astacin Metalloproteinase Ovastacin, A Novel Drug Target in Female Infertility Treatment
|
<p>Despite huge progress in
hormonal therapy and improved in vitro fertilization methods, the
success rates in infertility treatment are still limited. A recently
discovered mechanism revealed the interplay between the plasma protein
fetuin-B and the cortical granule-based proteinase ovastacin as novel
key-mechanism in the regulation of fertilization. Upon sperm-egg fusion,
cleavage of a distinct zona pellucida component by ovastacin destroys
the sperm receptor, enhances zona robustness and eventually provides a
definitive block against polyspermy. An untimely onset of this zona
hardening prior to fertilization would consequently result in
infertility. Physiologically, this process is controlled by fetuin-B, an
endogenous ovastacin inhibitor. Here we aimed at the discovery of small
molecular inhibitors of ovastacin that could mimic the effect of
fetuin-B. Hence, these compounds could be useful lead structures for the
development of specific ovastacin inhibitors that can be utilized in
infertility treatment or in vitro fertilization.</p>
|
Hagen Körschgen; Christian Jäger; Kathrin Tan; Mirko Buchholz; Walter Stöcker; Daniel Ramsbeck
|
Chemical Biology; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-12-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74661469df41f1ef4363a/original/primary-evaluation-of-potential-small-molecule-inhibitors-of-the-astacin-metalloproteinase-ovastacin-a-novel-drug-target-in-female-infertility-treatment.pdf
|
60c74e6a0f50db39ac3971fe
|
10.26434/chemrxiv.12752006.v1
|
Vacancy Engineered Polymeric Carbon Nitride Nanosheets for Enhanced Photoredox Catalytic Efficiency
|
Polymeric carbon nitrides (PCNs) have emerged as promising heterogeneous photocatalysts for organic transformations as they are metal-free, inexpensive, and possess suitable bandgaps, and excellent chemical- and photo-stability. However, current application of PCNs in organic synthesis is rather limited to several well-established materials, which limits the scope of reaction patterns and efficiency. We herein report the synthesis and fabrication of two new PCN nanosheets by incorporating nanostructure construction, element doping, and vacancy engineering into one hybrid platform. The heteroatom doped PCN nanosheets with vacancies feature highly porous structures with extremely large substrate-catalyst interface areas, enhanced charge separation, and improved lipophilicity. The generated heterogeneous catalysts demonstrate impressive photoredox catalytic performances in a variety of organic transformations (e.g., defluoroborylation, [2+2] cycloaddition, C-N, C-S, and C-O cross couplings), providing efficiencies comparable to reported optimized homogeneous catalysts and exceeding those with commonly utilized PCNs.
|
Qiong Liu; Wengang Xu; Hui Cao; Jing Li; Qi Zhou; Weijian Tao; Haiming Zhu; Xingzhong Cao; Linxin Zhong; Jiong Lu; Xinwen Peng; Jie Wu
|
Heterogeneous Catalysis; Photocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-08-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e6a0f50db39ac3971fe/original/vacancy-engineered-polymeric-carbon-nitride-nanosheets-for-enhanced-photoredox-catalytic-efficiency.pdf
|
626671c388636c48051e91dd
|
10.26434/chemrxiv-2022-t783k
|
IUPAC Specification for the FAIR Management of
Spectroscopic Data in Chemistry (IUPAC FAIRSpec)
- Guiding Principles
|
A set of guiding principles for the development of a standard for FAIR management of spectroscopic data are outlined and discussed. The principles form the basis for future recommendations of IUPAC Project 2019-031-1-024 specifying a detailed data model and metadata schema for describing the contents of an "IUPAC FAIRData Collection" and the organization of digital objects within that collection. Foremost among the recommendations will be a specification for an "IUPAC FAIRData Finding Aid" that describes the collection in such a way as to optimize the findability, accessibility, interoperability, and reusability of its contents. Results of an analysis of data provided by an American Chemical Society Publications pilot study are discussed in relation to potential workflows that might be used in implementing the "IUPAC FAIRSpec" standard based on these principles.
|
Robert Hanson; Damien Jeannerat; Mark Archibald; Ian Bruno; Stuart Chalk; Antony Davies; Robert Lancashire; Jeffrey Lang; Henry Rzepa
|
Theoretical and Computational Chemistry; Organic Chemistry; Organometallic Chemistry; Natural Products; Organic Synthesis and Reactions; Chemoinformatics - Computational Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-04-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626671c388636c48051e91dd/original/iupac-specification-for-the-fair-management-of-spectroscopic-data-in-chemistry-iupac-fair-spec-guiding-principles.pdf
|
632b4d11cf3829850aacfa82
|
10.26434/chemrxiv-2022-xwbst
|
Encoding Hierarchical 3D Architecture through Inverse Design of Programmable Bonds
|
The ability to fabricate materials and devices by-design at small scales, largely based in advances in lithographic and additive manufacturing methods, has led to the tremendous technological progress of the last decades. However, the growing need to structure 3D nanoscale matter for emergent functions, according to design and in a massively parallel manner, requires new means of material fabrication. Here, we demonstrate the concept and experimental realization of the encoded assembly of nanoparticles into prescribed, hierarchically ordered 3D organizations using DNA programmable bonds. Our information-constrained inverse design approach allows for encoding of targeted 3D hierarchical architectures with programmable bonds through identification of repeating mesoscale motifs and their elemental blocks, nanoscale voxels, that can also carry encoded nano-cargo. Using intrinsic symmetries of mesoscale motifs in targeted 3D architectures, we reduce the amount of information required for encoding bonds and incorporate this into the inverse design assembly strategy. As examples of this approach, we assemble spatially ordered, low-dimensional arrays with coupled plasmonic and photonic scales, a nanoscale analog of face-perovskite lattice, and a hierarchically organized lattice of spiral motifs. Detailed x-ray scattering and electron microcopy methods confirm the correspondence between the designed and realized architectures. The presented approach paves the road for establishing a by-design assembly platform for the fabrication of 3D architectures from diverse types of nanocomponents.
|
Jason S. Kahn; Brian Minevich; Aaron Michelson; Hamed Emamy; Kim Kisslinger; Shuting Xiang; Sanat K. Kumar; Oleg Gang
|
Materials Science; Nanoscience; Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-09-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632b4d11cf3829850aacfa82/original/encoding-hierarchical-3d-architecture-through-inverse-design-of-programmable-bonds.pdf
|
675f3131f9980725cf2c6a19
|
10.26434/chemrxiv-2024-58b3h
|
Advanced computation of enthalpies for a range of hydroformylation reactions with a predictive power to match experiments
|
While hydroformylation is a central homogeneous catalytic industrial processes, we find a relatively large (17 kcal/mol) scatter of DFT reaction enthalpies with a range of widely-employed DFT methods, unexpected in organic chemistry. Thus, we obtained gold standard hydroformylation enthalpies for a large variety of substrates exploiting the local natural orbital method. The corresponding hydroformylation enthalpies of ethylene and propylene agree with the experiments within a few tenth of a kcal/mol. This predictive power enabled the study of nuanced trends in the hydroformylation for a wide range of aliphatic and aromatic substrates as a function of chain elongation, branching, and substituent effects.
|
Tamara Papp; Peter Nagy; Tamas Kegl
|
Theoretical and Computational Chemistry; Organometallic Chemistry; Chemical Engineering and Industrial Chemistry; Computational Chemistry and Modeling; Theory - Computational; Main Group Chemistry (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675f3131f9980725cf2c6a19/original/advanced-computation-of-enthalpies-for-a-range-of-hydroformylation-reactions-with-a-predictive-power-to-match-experiments.pdf
|
67c72bb381d2151a020e3eea
|
10.26434/chemrxiv-2025-532p4
|
High-resolution electron-multi-ion coincidence set-up for gas-phase experiments in the tender and hard X-ray range
|
The MUSTACHE setup (MUlti-STep photofragmentation studies by Auger electron - ion Coincidences using High Energy photons) is a high-resolution electron-multi-ion coincidence system optimized for gas-phase experiments in the tender (~2-10 keV) and hard (>5 keV) X-ray range. The system integrates a high-resolution hemispherical electron analyzer with a Wiley-McLaren-type ion time-of-flight (TOF) spectrometer, enabling coincidence measurements of Auger electrons and high-energy photoelectrons. Designed to overcome challenges in high-energy electron detection while maintaining excellent energy resolution, the setup covers a broad kinetic energy range up to 5 keV. The ion TOF spectrometer provides high-resolution ion mass and momentum analysis, essential for studying light and fast ions generated by deep-core ionization. System capabilities are demonstrated through test measurements on benchmark atomic and molecular systems, such as argon, nitrogen, and carbon disulfide. These measurements demonstrate energy-resolved high-kinetic-energy photoelectron-ion coincidences and momentum-resolved multi-ion coincidences following deep-core ionization and Coulomb explosion. MUSTACHE enables investigations into deep-core ionization, Auger cascade processes and Coulomb explosion dynamics in isolated gas-phase species, offering insights into fundamental ionization and fragmentation processes. These results confirm the MUSTACHE setup as a powerful tool for high-resolution electron-ion coincidence spectroscopy, extending advanced coincidence techniques into the hard X-ray regime and providing unprecedented opportunities for studying high-energy X-ray induced phenomena.
|
Edwin Kukk; Regis Vacheresse; Iyas Ismail; Tatiana Marchenko; Renaud Guillemin; Maria Novella Piancastelli; Marc Simon; Oksana TRAVNIKOVA
|
Physical Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2025-03-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c72bb381d2151a020e3eea/original/high-resolution-electron-multi-ion-coincidence-set-up-for-gas-phase-experiments-in-the-tender-and-hard-x-ray-range.pdf
|
66100aff21291e5d1d266497
|
10.26434/chemrxiv-2024-s0s5d
|
Local structure and dynamics in MPt(CN)6 Prussian blue analogues
|
We use a combination of X-ray pair distribution function (PDF) measurements, lattice dynamical calculations, and ab initio density functional theory (DFT) calculations to study local structure and dynamics in various MPt(CN)6 Prussian blue analogues. In order to link directly the local distortions captured by the PDF with the lattice dynamics of this family, we develop and apply a new `interaction-space' PDF refinement approach. This approach yields effective harmonic force constants, from which the (experiment-derived) low-energy phonon dispersion relations can be approximated. Calculation of the corresponding Gr¨neisen parameters allows us to identify the key modes responsible for negative thermal expansion (NTE) as arising from correlated tilts of coordination octahedra. We compare our results against the phonon dispersion relations determined using DFT calculations, which identify the same NTE mechanism.
|
Elodie Harbourne; Helena Barker; Quentin Guéroult; John Cattermull; Liam Nagle-Cocco; Nikolaj Roth; John Evans; David Keen; Andrew Goodwin
|
Physical Chemistry; Inorganic Chemistry; Physical and Chemical Properties; Materials Chemistry; Crystallography – Inorganic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-04-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66100aff21291e5d1d266497/original/local-structure-and-dynamics-in-m-pt-cn-6-prussian-blue-analogues.pdf
|
6541530fa8b423585aaab725
|
10.26434/chemrxiv-2023-v4hx2
|
Synthesis of 15N-Pyridines and Higher Mass Isotopologs via Zincke Imine Intermediates
|
Methods to incorporate stable radioisotopes are integral to pharmaceutical and agrochemical development. However, despite the prevalence of pyridines in candidate compounds, methods to incorporate 15N-atoms within their structures are limited. Here, we present a general approach to pyridine 15N-labeling that proceeds via ring-opening to NTf-Zincke imines and then ring-closure with commercially available 15NH4Cl salts. This process functions on a range of substituted pyridines, from simple building block-type compounds to late-stage labeling of complex pharmaceuticals, and 15N-incorporation is >95% in most cases. The reactivity of the Zincke imine intermediates also enables deuteration of the pyridine C3- and C5-positions, resulting in higher mass isotopologs required for LCMS analysis of biological fluids during drug development.
|
Hillary M. H. Nguyen; David C. Thomas; Marie A. Hart; Kaila R. Steenback; Jeffrey N. Levy; Andrew McNally
|
Biological and Medicinal Chemistry; Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-11-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6541530fa8b423585aaab725/original/synthesis-of-15n-pyridines-and-higher-mass-isotopologs-via-zincke-imine-intermediates.pdf
|
60c74867bb8c1a85fa3dac66
|
10.26434/chemrxiv.11904915.v1
|
Correction Terms for Calculating Binding Free Energy Using Rates from Nonequilibrium Simulations
|
<div>The free energy of a process is the fundamental quantity that determines its spontaneity or propensity at a given temperature. Binding free energy of a drug candidate to its biomolecular target is used as an objective quantity in drug design. Binding kinetics -- rates of association (k<sub>on</sub>) and dissociation (k<sub>off</sub>) -- have also demonstrated utility for their ability to predict efficacy and in some cases have been shown to be more predictive than the binding free energy alone. Although challenging, some methods exist to calculate binding kinetics from molecular simulations. While the kinetics of the binding process are related to the free energy by the log of their ratio, it is not straightforward to account for common, practical details pertaining to the calculation of rates in molecular simulations, such as the finite simulation volume or the particular definition of the ``bound" and ``unbound" states. Here we derive a set of correction terms that can be applied to calculations of binding free energies using rates observed in simulations. One term accounts for the particular definitions of the bound and unbound states. The second term accounts for residual electrostatic interactions that might still be present between the molecules, which is especially useful if one or both of the molecules carry an explicit charge. The third term accounts for the volume of the unbound state in the simulation box, which is useful to keep the simulated volume as small as possible during rate calculations. We apply these correction terms to revisit the calculation of binding free energies from rate constants for a host-guest system that was part of a blind prediction challenge, where significant deviations were observed between free energies calculated with rate ratios and those calculated from alchemical perturbation. The correction terms combine to significantly decrease the error with respect to computational benchmarks, from 3.4 to 0.76 kcal/mol.</div>
|
Robert Hall; Tom Dixon; Alex Dickson
|
Computational Chemistry and Modeling; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-02-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74867bb8c1a85fa3dac66/original/correction-terms-for-calculating-binding-free-energy-using-rates-from-nonequilibrium-simulations.pdf
|
66f3fe23cec5d6c142272d31
|
10.26434/chemrxiv-2024-0c0lk
|
100-Gram Batch Production of Graphene Using High-Power Rapid Joule Heating Method
|
Graphene has a vast market demand in the industrial field, but the high cost and complexity of traditional production methods limit its application. The newly developed flash Joule heating method based on capacitor discharge presents a cost-effective production alternative for graphene, but the batch yield is still limited in gram-scale. This study presents a rapid Joule heating (RJH) method based on direct current power discharge to enable large-scale graphene production. Utilizing a high-power RJH system, we can rapidly heat 100 grams of carbon black to 3000°C within minutes, promoting its graphitization transformation, thus achieving a substantial increase in graphene production efficiency. Detailed characterizations confirm the successful synthesis of high-quality turbostratic rapid graphene (RG), with production energy consumption of only ~5 kWh kg-1 (0.5 $ kg-1). Furthermore, by adding boron oxide and melamine as additives, direct mass production of boron, nitrogen, and nitrogen-boron co-doped RGs can be carried out. Doping modifies the local structure of RG, thereby enhancing its hydrophobicity and electrical conductivity. This work is expected to accelerate the process of low-cost bulk production of graphene and its industrial applications.
|
Dan-Na Wu; Jian Sheng; Hai-Gang Lu; Si-Dian Li; Yan Li
|
Materials Science; Nanoscience; Carbon-based Materials; Multilayers; Nanostructured Materials - Materials; Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-09-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f3fe23cec5d6c142272d31/original/100-gram-batch-production-of-graphene-using-high-power-rapid-joule-heating-method.pdf
|
6520405345aaa5fdbb709f2f
|
10.26434/chemrxiv-2023-m2n4r
|
hplc-py: A Python Package For Rapid Peak Quantification in Complex Chromatograms
|
High-Performance Liquid Chromatography (HPLC) and Gas Chromatography are analytical techniques which allow for the quantitative characterization of the chemical components of mixtures . Technological advancements in sample preparation and mechanical automation have allowed HPLC to become a high-throughput tool which poses new challenges for reproducible and rapid analysis of the resulting chromatograms. Here we present hplc-py, a Python package that permits rapid and reliable quantitation of component signals within a chromatogram for pipelined workflows. This is achieved by a signal detection and quantitation algorithm which i) identifies windows of time which contain peaks and ii) infers the parameters of a mixture of amplitude-weighted skew-normal distributions which sum to reconstruct the observed signal. This approach is particularly effective at deconvolving highly overlapping signals, allowing for precise absolute quantitation of chemical constituents with similar chromatographic retention times.
|
Griffin Chure; Jonas Cremer
|
Analytical Chemistry; Separation Science
|
CC BY 4.0
|
CHEMRXIV
|
2023-10-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6520405345aaa5fdbb709f2f/original/hplc-py-a-python-package-for-rapid-peak-quantification-in-complex-chromatograms.pdf
|
6426eefa16782ec9e62299d1
|
10.26434/chemrxiv-2023-b5pqp
|
Optically distinguishable electronic spin isomers of a stable organic diradical
|
Herein, we demonstrate a model of electronic spin isomers, the electronic counterpart of nuclear spin isomers, by employing a through-space conjugated stable organic diradical. We investigated a benzotriazinyl radical dimer linked via triptycene skeleton. The diradical has a small singlet–triplet energy gap of -3.0 kJ/mol, indicating ca. 1:1 coexistence of the two spin states at room temperature. The diradical at room temperature shows characteristic near-IR absorption bands around 500–900 nm, which is absent for the corresponding mono-radical subunit. Variable temperature measurement revealed that the absorbance of the NIR band depends on the abundance of the singlet state, and we assigned the NIR band as the singlet-specific absorption band. It enables photoexciting one of the two spin states coexisting in thermal equilibrium. Ultrafast transient spectroscopy disclosed that the two spin-states independently follow qualitatively different excited-state dynamics. Namely, the singlet excited state undergoes intramolecular symmetry-breaking charge transfer, and the triplet excited state goes exciton fusion to form a monomer-like excited state. These results demonstrate optically distinguishable spin isomers.
|
Daiki Shimizu; Hikaru Sotome; Hiroshi Miyasaka; Kenji Matsuda
|
Organic Chemistry; Photochemistry (Org.); Physical Organic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6426eefa16782ec9e62299d1/original/optically-distinguishable-electronic-spin-isomers-of-a-stable-organic-diradical.pdf
|
60c74cb04c89194569ad36b6
|
10.26434/chemrxiv.12516880.v1
|
How Plausible Is Getting Ferromagnetic Interactions by Coupling Blatter’s Radical via Its Fused Benzene Ring?
|
In an effort to obtain superior magnetic properties, all the possible isomers of di-Blatter diradical coupled through its fused benzene ring are investigated employing numerous density and wave function-based<i> </i>methods. It reveals that the energetically stable and also experimentally reported diradicals are anti-ferromagnetic in nature due to dominant coexisting exchange interactions between the strongly localized micro-magnetic radical centers. However, due to strong steric hindrance in certain cases, the exchange interaction switches from anti-ferromagnetic to weak ferromagnetic interactions. Moreover, we propose the modified version of <i>spin alternation</i> rule, called here as <i>zonal spin alternation</i> rule, which can be applied successfully to predict exchange interactions in such diradicals.<br />
|
Rishu Khurana; Ashima Bajaj; Md. Ehesan Ali
|
Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-06-23
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74cb04c89194569ad36b6/original/how-plausible-is-getting-ferromagnetic-interactions-by-coupling-blatter-s-radical-via-its-fused-benzene-ring.pdf
|
60c73fddbdbb8943eaa3809d
|
10.26434/chemrxiv.7138088.v2
|
Carbon Dioxide-Mediated C(sp2)–H Arylation of Primary and Secondary Benzylamines
|
Carbon-carbon bond formation by transition
metal-catalyzed C–H activation has become an important strategy to fabricate
new bonds in a rapid fashion. Despite the pharmacological importance of <i>ortho</i>-arylbenzylamines, however,
effective <i>ortho</i>-C–C bond formation
from C–H bond activation of free primary and secondary benzylamines using Pd<sup>II</sup>
remains an outstanding challenge. Presented herein is a new strategy for
constructing <i>ortho</i>-arylated primary
and secondary benzylamines mediated by carbon dioxide (CO<sub>2</sub>). The use
of CO<sub>2</sub> is critical to allowing this transformation to proceed under milder
conditions than previously reported, and that are necessary to furnish free
amine products that can be directly used or elaborated without the need for
deprotection. In cases where diarylation is possible, a chelate effect is
demonstrated to facilitate selective monoarylation.
|
Mohit Kapoor; Pratibha Chand-Thakuri; Michael Young
|
Bond Activation; Catalysis; Kinetics and Mechanism - Organometallic Reactions; Reaction (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-11-30
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73fddbdbb8943eaa3809d/original/carbon-dioxide-mediated-c-sp2-h-arylation-of-primary-and-secondary-benzylamines.pdf
|
60c740e4f96a00a5c2286371
|
10.26434/chemrxiv.7863176.v1
|
Epitaxial Dimers and Auger-Assisted De-Trapping in PbS Quantum Dot Solids
|
Electronic trap states limit the overall power conversion efficiency of
quantum dot (QD) solar cells by inhibiting charge carrier transport and
reducing the open-circuit voltage. Here, we explore the dynamic interaction of
charge carriers between band edge states and sub-band trap states using
broadband transient absorption spectroscopy. In monodisperse arrays of 4-5 nm
diameter PbS QDs, we observe an optically active trap state ~100-200 meV below
the band edge that occurs at a frequency of 1 in ~2500 QDs. Uncoupled QD solids
with oleic acid ligands show trap-to-ground-state recombination that resembles
Auger recombination. In electronically coupled QD solids, we observe
entropically-driven uphill thermalization of trapped charge carriers from the
trap state to the band edge <i>via</i> two
distinct mechanisms: Auger-assisted charge transfer (~35 ps) and thermally
activated hopping (~500 ps). Photophysical characterization combined with
atomistic simulations and high-resolution transmission electron microscopy
suggest that these states arise from epitaxially fused pairs of QDs – rather
than electron or hole traps at the QD surface – offering new strategies for
improving the efficiency of QD solar cells.
|
Rachel H. Gilmore; Yun Liu; Wenbi Shcherbakov-Wu; Nabeel Dahod; Elizabeth Lee; Mark Weidman; Huashan Li; Joel Jean; Vladimir Bulovic; Adam Willard; Jeffrey C. Grossman; William Tisdale
|
Nanostructured Materials - Materials; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-03-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740e4f96a00a5c2286371/original/epitaxial-dimers-and-auger-assisted-de-trapping-in-pb-s-quantum-dot-solids.pdf
|
66d9029c51558a15ef13a00a
|
10.26434/chemrxiv-2024-lmcql
|
Fracture Dynamics in Silicon Anode Solid-State Batteries
|
Solid-state batteries (SSBs) with silicon anodes could enable improved safety and energy density compared to lithium-ion batteries. However, degradation arising from the massive volumetric changes of silicon anodes during cycling are not well understood in solid-state systems. Here, we use operando X-ray computed microtomography to reveal micro-to-macro-scale chemo-mechanical degradation processes of silicon anodes in SSBs. Mud-type channel cracks driven by biaxial tensile stress form across the electrode during delithiation. We also find detrimental cracks at the silicon/solid electrolyte interface that form due to local reaction competition between neighboring domains of different sizes. Continuum phase-field damage modeling quantifies stress-driven channel cracking and shows that the lithiated silicon stress state is critical for determining the extent of interfacial fracture. This work reveals novel mechanisms that govern SSBs compared to conventional lithium-ion batteries and provides guidelines for engineering chemo-mechanically resilient electrodes for high-energy batteries.
|
D. Lars Nelson; Stephanie Sandoval; Jaechan Pyo; Donald Bistri; Talia Thomas; Kelsey Cavallaro; John Lewis; Abhinav Iyer; Pavel Shevchenko; Claudio Di Leo; Matthew McDowell
|
Materials Science; Energy; Energy Storage
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-09-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d9029c51558a15ef13a00a/original/fracture-dynamics-in-silicon-anode-solid-state-batteries.pdf
|
660bc8fe66c138172976b32d
|
10.26434/chemrxiv-2024-q2308
|
Electric-field Assisted Spatioselective Deposition of MIL-101(Cr)PEDOT to Enhance Electrical Conductivity and Humidity Sensing Performance
|
Poly(3,4-ethylenedioxythiophene)-functionalized (PEDOT) MIL-101(Cr) nanoparticles were deposited via drop-casting onto interdigitated electrodes (IDEs). The application of an alternating potential during drop-casting allowed precise spatioselective deposition of the nanoparticles in the interelectrode gaps, generating percolating nanoparticle chains aligned between the finger electrodes. The resulting conductivities of the aligned and chained samples were up to 4 orders of magnitude higher than that of unaligned samples prepared via regular drop-casting. The performance of the unaligned and aligned samples for resistive humidity sensing was investigated, whereby the aligned samples showed a conductivity gain of 230 times at a relative humidity of 90% versus 10%, whereas the unaligned samples showed a lower gain of 40 times at relative humidity 90% versus 10%. Further, the aligned samples could also be utilized as capacitive humidity sensors, showing a change of sensitivity at different frequencies for the aligned sample, whereas unaligned samples show a resistive behavior unsuitable for capacitive sensing. This work demonstrates that simple drop-casting when carried out in conjunction with an applied alternating potential exerts dielectrophoretic control allowing for precise spatioselective deposition, thus leading to higher sample conductivity and enhanced performances for humidity sensing.
|
Youven Benseghir; Min Ying Tsang; Flora Schöfbeck; Daniel Hetey; Michael Reithofer; Hidetsugu Shiozawa; Jia Min Chin
|
Physical Chemistry; Inorganic Chemistry; Supramolecular Chemistry (Inorg.); Physical and Chemical Processes; Physical and Chemical Properties; Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2024-04-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/660bc8fe66c138172976b32d/original/electric-field-assisted-spatioselective-deposition-of-mil-101-cr-pedot-to-enhance-electrical-conductivity-and-humidity-sensing-performance.pdf
|
61fd19c221686745ac6b3494
|
10.26434/chemrxiv-2022-b8mxp
|
A Sweet Introduction to the Mathematical Analysis of Time-Resolved Spectra and Complex Kinetic Mechanisms: The Chameleon Reaction Revisited
|
We present a detailed yet easy-to-follow discussion of the mathematical treatment of time-resolved spectroscopic data in a model-based approach. This is accompanied and complemented by an example of a colourful and pedagogically rich chemical reaction: the permanganate oxidation of sugars in basic aqueous media (often known as the chameleon reaction). Our sweet approach allows both students and lecturers to tackle the problem of a model-based analysis of time-resolved data in a simple manner and one step at the time, while also exercising programming and data analysis skills---fundamental for present and future chemists of all levels.
|
Ricardo Fernández-Terán; Estefanía Sucre-Rosales; Lorenzo Echevarria; Florencio Hernández
|
Physical Chemistry; Chemical Education; Chemical Kinetics; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-02-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61fd19c221686745ac6b3494/original/a-sweet-introduction-to-the-mathematical-analysis-of-time-resolved-spectra-and-complex-kinetic-mechanisms-the-chameleon-reaction-revisited.pdf
|
6763dfdafa469535b9119d85
|
10.26434/chemrxiv-2024-7v4l7
|
Heteronuclear Parahydrogen-Induced Hyperpolarization via Side Arm Hydrogenation
|
Nuclear spin hyperpolarization dramatically enhances the sensitivity of nuclear magnetic resonance spectroscopy and imaging. Hyperpolarization of biomolecules (e.g., pyruvate) is of particular interest as it allows one to follow their metabolism, providing a diagnostic tool for various pathologies, including cancer. In this regard, the hyperpolarization of 13C nuclei is especially beneficial due to its relatively long hyperpolarization lifetime and the absence of a background signal. Parahydrogen-induced polarization (PHIP) is arguably the most affordable hyperpolarization technique. PHIP exploits the pairwise addition of parahydrogen to an unsaturated substrate. This sets limitations on the range of compounds amenable to direct PHIP hyperpolarization. The range of molecules that can be hyperpolarized with PHIP significantly expanded in 2015 when PHIP by means of side arm hydrogenation (PHIP-SAH) was introduced. Here, parahydrogen is added to an unsaturated alcoholic moiety of an ester followed by polarization transfer to carboxylate 13C nuclei with a subsequent cleavage of the side arm. In this review, the recent advances in PHIP-SAH are discussed, including the synthetic methodology to produce isotopically labeled precursors, peculiarities of pairwise addition of parahydrogen to PHIP-SAH precursors, polarization transfer, cleavage of the side arm, purification of hyperpolarized solution, and, finally, in vitro and in vivo applications.
|
Oleg G. Salnikov; Nikita V. Chukanov; Andrey N. Pravdivtsev; Dudari B. Burueva; Sergey V. Sviyazov; Jan-Bernd Hövener; Igor V. Koptyug
|
Physical Chemistry; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-23
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6763dfdafa469535b9119d85/original/heteronuclear-parahydrogen-induced-hyperpolarization-via-side-arm-hydrogenation.pdf
|
60c74fc24c89198191ad3c6a
|
10.26434/chemrxiv.12925802.v1
|
Origin Invariant Optical Rotation in the Length Dipole Gauge without London Atomic Orbitals
|
<div>
<div>
<div>
<p>We present an approach to perform origin-invariant optical rotation calculations in
the length dipole gauge without recourse to London atomic orbitals, called LG(OI).
The LG(OI) approach works with any approximate wave function or density functional method, but here we focus on the implementation with the coupled cluster (CC)
with single and double excitations method because of the lack of production-level alternatives. Preliminary numerical tests show the efficacy of the LG(OI) procedure,
and indicate that conventional CC-LG calculations with the origin in the center of
mass of a molecule may still carry significant origin dependence.
</p>
</div>
</div>
</div>
|
Marco Caricato
|
Computational Chemistry and Modeling; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-09-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fc24c89198191ad3c6a/original/origin-invariant-optical-rotation-in-the-length-dipole-gauge-without-london-atomic-orbitals.pdf
|
60c74dd9bdbb892e90a39a8f
|
10.26434/chemrxiv.12587336.v2
|
SARS-CoV-2 Nucleocapsid Assembly Inhibitors: Repurposing Antiviral and Antimicrobial Drugs Targeting Nucleocapsid-RNA Interaction
|
<p></p><p>SARS-CoV-2 pandemic has become a
serious concern due to high transmission of this virus and unavailability of
any definitive drugs yet in clinics. While novel antivirals are under
investigation stage, scientists are also rigorously trying to use drug repurposing
as an option to fight against this highly infectious novel coronavirus. Several
drugs are under regular use for other diseases that are getting screened for
their usability against SARS-CoV2. In this study we have targeted SARS-CoV-2
nucleocapsid assembly to shortlist FDA approved drugs that could be tested for
inhibition of SARS-CoV-2 virus particles inside the host cell. We could
shortlist five antiviral and anti-microbial drugs. These showed good fit in
docking studies inside the RNA binding cleft of the nucleocapsid protein. Also,
these drugs have lipophilic properties suggesting that they have the potential
to enter the host cells. We propose that these shortlisted drugs could
potentially compete out binding of viral RNA to nucleocapsid and thus inhibit
successful virus assembly leading to poor virus progeny levels. </p><br /><p></p>
|
Debica Mukherjee; UPASANA RAY
|
Chemical Biology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-07-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dd9bdbb892e90a39a8f/original/sars-co-v-2-nucleocapsid-assembly-inhibitors-repurposing-antiviral-and-antimicrobial-drugs-targeting-nucleocapsid-rna-interaction.pdf
|
6578cfa9bec7913d27755da7
|
10.26434/chemrxiv-2023-2vnw6
|
Optimization of Microbial a Fuel Cell with Linear Sweep Voltammetry and Microfluidics
|
A microbial fuel cell with a pure-culture Geobacter sulfurreducens electroactive biofilm was used for performance optimization by making rapid changes to experimental parameters in microchannels while monitoring their effect using linear sweep voltammetry. A systematic investigation of polarization behavior and evaluation of system resistivity provided important figures of merit and mechanistic insights on the effects of flow rates, concentrations, and temperature after reaching maturity. After individual parameters were optimized, a synergistic effect was observed by applying optimal parameters together, resulting in improved current and maximum power densities, compared to stable values at unoptimized conditions. Continued acclimation for just two days under these conditions resulted in further improvements to anode area-normalized current and power maxima (10.49±0.23 A m-2 and 2.48±0.27 W m-2), which are among the highest reported in the literature for a microfluidic MFC. In keeping with other accepted normalization protocol using the area separating anode and cathode chambers, the outputs were recalculated as 64 A m-2 and 15 W m-2.
|
Jayesh Sonawane; Jesse Greener
|
Biological and Medicinal Chemistry; Analytical Chemistry; Energy; Electrochemical Analysis; Bioengineering and Biotechnology; Fuel Cells
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-12-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6578cfa9bec7913d27755da7/original/optimization-of-microbial-a-fuel-cell-with-linear-sweep-voltammetry-and-microfluidics.pdf
|
6742b3735a82cea2fa99b77e
|
10.26434/chemrxiv-2024-g0drf-v2
|
A DFT analysis for synthesizing vitamin A
|
Vitamin A deficiency (VAD) is a major nutritional concern in lower-income countries. It is responsible for thousands of deaths in those countries every year. Thus, finding the optimal route for vitamin A synthesis is essential, especially for the countries that are influenced by VAD. Three mechanisms of synthesizing Vitamin A have been evaluated by Density Functional Theory (DFT) calculations. This experiment investigated the BASF C15 + C5 Wittig approach, the Rhône-Poulenc C15 + C5 Julia approach, and the Kuraray C10 + C10 approach. The electronic energy, highest occupied molecular orbital energy, and dipole moments were calculated using the B3LYP functional and the 3-21g basis set. The energy profiles of these synthesis routes were compared to determine the most energetically favorable method. The Julia approach has the lowest energy change, indicating its higher efficiency in terms of energy compared to the Wittig and Kuraray methods. It is shown that other factors such as scalability and raw material availability should also be considered in industrial applications.
|
Tianyou Huang; Jesus Valdiviezo
|
Theoretical and Computational Chemistry; Computational Chemistry and Modeling
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-11-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6742b3735a82cea2fa99b77e/original/a-dft-analysis-for-synthesizing-vitamin-a.pdf
|
67db20c081d2151a020a4699
|
10.26434/chemrxiv-2025-36d35
|
Mapping proton-coupled electron transfer with real space dimensions
|
Both electron transfer (ET) and proton transfer (PT) are common steps in energy conversion. Coupling of these two transfer events alleviates the energy demand relative to either individual process, but introduces a fundamentally new process—proton-coupled electron transfer (PCET)—with its own demands for theoretical description. Conceptualization of PCET usually involves a square scheme representing, ET, PT and PCET, each generating state of different energy. While intuitive, these square schemes do not offer detailed chemical insight—such as the identity and contribution of nuclear motions to PCET. Herein, we present a computational approach that maps these square schemes onto real space coordinates (Å), from which corresponding potential energy surfaces can be generated. This mapping involves the identification of PT and ET coordinates. Using the relative orientations of these coordinates, we propose a new criterion for ‘concerted’ proton-electron transfer, as well as disambiguate the concepts of concerted and coupled proton and electron transfer.
|
Adam Srut; Martin Diefenbach; Marvin L. Kronenberger; Benjamin J. Lear; Vera Krewald
|
Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling
|
CC BY 4.0
|
CHEMRXIV
|
2025-03-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67db20c081d2151a020a4699/original/mapping-proton-coupled-electron-transfer-with-real-space-dimensions.pdf
|
60c7549b0f50db5cbd397d55
|
10.26434/chemrxiv.13692772.v1
|
Prebiotic Photoredox Synthesis from Carbon Dioxide and Sulfite
|
Carbon dioxide (CO2) is the major carbonaceous component of many planetary atmospheres including the Earth throughout its history, and prebiological chemistry that reduces this C1 feedstock to organics has accordingly been sought. Carbon fixation chemistry utilizing hydrogen as stoichiometric reductant tends to require high pressures
and temperatures, and yields of products of potential use to nascent biology are low1 . Here we demonstrate efficient ultraviolet (UV) photoredox chemistry between CO2 and sulfite
(SO3
2–) that generates organics and sulfate (SO4
2– ). The chemistry is initiated by electron
photodetachment from SO3
2– giving sulfite radicals and hydrated electrons, which reduce CO2 to its radical anion. By subjecting individual products and putative intermediates to the reaction conditions and analyzing the resultant mixtures, a network of ensuing reactions that can rationalize the products was revealed. In this way it was further discovered that citrate, malate, succinate, and tartrate can be generated by irradiation of
glycolate in the presence of SO3
2– . The simplicity of this carboxysulfitic chemistry and the widespread occurrence and abundance of its feedstocks suggest that it could have readily taken place on the early Earth as well as on the surfaces of many rocky planets. The environmental availability of the carboxylate products on Earth could have driven the development of central carbon metabolism before the advent of biological CO2 fixation.
|
Ziwei Liu; Long-Fei Wu; Corinna Kufner; Dimitar D. Sasselov; Woodward Fischer; John Sutherland
|
Photochemistry (Org.); Geochemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-02-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7549b0f50db5cbd397d55/original/prebiotic-photoredox-synthesis-from-carbon-dioxide-and-sulfite.pdf
|
61116bab45805d6574841b6f
|
10.26434/chemrxiv-2021-h9v9p
|
A Bioinspired Threonine-based Antifreeze Protein Mimic with Potent Ice Recrystallization Inhibition Activity
|
Ice growth mitigation is a pervasive challenge for multiple industries. In nature, ice-binding proteins (IBPs) demonstrate potent ice-growth prevention through ice recrystallization inhibition (IRI). However, IBPs are expensive, difficult to produce in large quantities, and exhibit minimal resilience to non-physiological environmental stressors, such as elevated pH. For these reasons, researchers have turned to polymeric bioinspired mimics. To-date, however, no mimic has rivaled the ability of native IBPs to display IRI activity at ultra-low nanomolar concentrations. In this work, we study the IRI activity of peptides and polypeptides inspired by common ice-binding residues of IBPs to inform the synthesis and characterization of a potent bioinspired polymer mimic. We show first that the threonine polypeptide (pThr) displays the best IRI activity in phosphate-buffered saline (PBS). Second, we use pThr as a molecular model to synthesize and test a new bioinspired polymer mimic, poly(2-hydroxypropyl methacrylamide) (pHPMA). We show that pHPMA exhibits potent IRI activity in neutral PBS at nanomolar concentrations. These results substantiate that pHPMA outperforms poly(vinyl alcohol) (PVA), the current top performing IBP mimic in the field, in terms of effectiveness at mitigating ice crystal growth at concentrations akin to native IBPs.
|
Elizabeth Delesky; Luis Garcia; Aparna Lobo; Jaqueline Wallat; Garret Miyake; Wil Srubar III
|
Organic Chemistry; Materials Science; Organic Compounds and Functional Groups; Biological Materials; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-08-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61116bab45805d6574841b6f/original/a-bioinspired-threonine-based-antifreeze-protein-mimic-with-potent-ice-recrystallization-inhibition-activity.pdf
|
6585468ce9ebbb4db97bbb94
|
10.26434/chemrxiv-2023-278n2-v3
|
Homo- to Co-Polyester Conversion in the Absence of Reagents Fa-cilitated by a Dual Catalytic Process Involving Hydrogen Borrowing
|
A ruthenium-catalyzed hydrogen transfer ester metathesis (HTEM) is reported that allows for the isomerization of a linear polyester such as polycaprolactone (PCL) without the need for any stoichiometric reagent, forming a novel type of co-polyester containing additional hexylene adipate (HA) repeating units. Mechanistic investigations show that the formation of the chemically modified polyester relies on a two-fold catalytic reaction; a HTEM via a hydrogen borrowing process and a concomitant transesterification catalyzed by the base co-catalyst. Evidence is provided that the hydrogen transfer ester me-tathesis proceeds via a reversible aldehyde formation. The described HTEM represents an unprecedented catalyzed hydrogen borrowing process within polymers – and bears significant importance regarding a dynamic post-synthetic modification of polyesters.
|
Frederik Rummel; Afiq Anuar ; Yu Qiang; Frerk-Ulfert Wehmeyer; Matthias Rohmer; Matthias Vogt; Frederik Haase; Wolfgang Binder; Kay Saalwächter; Thomas Thurn-Albrecht; Robert Langer
|
Catalysis; Polymer Science; Homogeneous Catalysis
|
CC BY 4.0
|
CHEMRXIV
|
2023-12-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6585468ce9ebbb4db97bbb94/original/homo-to-co-polyester-conversion-in-the-absence-of-reagents-fa-cilitated-by-a-dual-catalytic-process-involving-hydrogen-borrowing.pdf
|
64d4fd57dfabaf06ff0d4ef7
|
10.26434/chemrxiv-2023-km9t7
|
Enantioselective Synthesis of C-O Axially Chiral Diaryl Ethers via NHC-Catalyzed Atroposelective Desymmetrization
|
Axially chiral diaryl ethers, a distinguished class of atropisomers possessing unique dual C-O axis, hold immense potential for diverse research domains. In contrast to the catalytic enantioselective synthesis of conventional single axis bearing atropisomers, the atroposelective synthesis of axially chiral ethers containing flexible C-O axis remains a significant challenge. Herein, we demonstrate the first N-heterocyclic carbene (NHC)-catalyzed synthesis of axially chiral diaryl ethers via atroposelective esterification of dialdehyde-containing diaryl ethers. Mechanistically, the reaction proceeds via NHC-catalyzed desymmetrization strategy to afford the corresponding axially chiral diaryl ether atropisomers in good yields and high enantioselectivities under mild conditions. The derivatization of the synthesized product expands the utility of present strategy via access to a library of C-O axially chiral compounds. The temperature dependency and preliminary investigations on the racemization barrier of C-O bonds are also presented.
|
A T Biju; Sayan Shee; Sowmya Ranganathappa; Mahesh Gadhave; Romin Gogoi
|
Organic Chemistry; Catalysis; Stereochemistry; Homogeneous Catalysis; Organocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-08-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64d4fd57dfabaf06ff0d4ef7/original/enantioselective-synthesis-of-c-o-axially-chiral-diaryl-ethers-via-nhc-catalyzed-atroposelective-desymmetrization.pdf
|
60c74dbeee301c2939c7a374
|
10.26434/chemrxiv.12659948.v1
|
Palladium-Catalyzed [3+2] Cycloaddition via Two-Fold 1,3-C(sp3)−H Activation
|
<div>Cycloaddition reactions provide an expeditious route to construct ring systems in a highly convergent and stereoselective manner. For a typical cycloaddition reaction to occur, however, the installation of multiple reactive functional groups (π-bonds, leaving group, etc.) are required within the substrates, compromising the overall efficiency or scope of the cycloaddition reaction. Here, we report a palladium-catalyzed [3+2] reaction that utilizes C(sp<sup>3</sup>)–H activation to generate the three-carbon unit for formal cycloaddition with maleimides. We implemented a strategy where the initial C(sp<sup>3</sup>)–H activation/olefin insertion would trigger a relayed, second remote C(sp<sup>3</sup>)–H activation to complete a formal [3+2] cycloaddition. The diastereoselectivity profile of this reaction resembles that of a typical pericyclic cycloaddition reaction in that the relationships between multiple stereocenters are exquisitely controlled in a single reaction. The key to success was the use of weakly coordinating amides as the directing group, as undesired Heck or alkylation pathways were preferred with other types of directing groups. The use of the pyridine-3-sulfonic acid ligands is critical to enable C(sp<sup>3</sup>)–H activation directed by this weak coordination. The method is compatible with a wide range of amide substrates, including lactams, which lead to novel spiro-bicyclic products. The [3+2] product is also shown to undergo a reductive desymmetrization process to access chiral cyclopentane bearing multiple stereocenters with excellent enantioselectivity.</div>
|
Hojoon Park; jin-quan yu
|
Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-07-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dbeee301c2939c7a374/original/palladium-catalyzed-3-2-cycloaddition-via-two-fold-1-3-c-sp3-h-activation.pdf
|
60c753d9842e659817db401d
|
10.26434/chemrxiv.13562342.v1
|
Site-Fixed Hydroboration of Alkenes under Metal-Free Conditions: Scope and Mechanistic Studies
|
An unprecedented and general metal-free hydroboration of alkenes with BBr3 as the
boration reagent in the presence of iPr2NEt is reported. The addition of iPr2NEt not only suppresses
alkene oligomerization and bromoboration side reactions, but also provides a proton source for
hydroboration. More importantly, the site-fixed installation of a boryl group at the original position
of the internal double-bond is easily achieved using our strategy as compared with traditional
transition-metal-catalyzed hydroboration processes. Preliminary studies on the mechanism revealed
a distinct reaction pathway that involves radical species and may operate through frustrated-Lewispair-type single-electron transfer.
|
Sida Li; Chenyang Hu; Xin Cui; Liu Leo Liu; Lipeng Wu
|
Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-01-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753d9842e659817db401d/original/site-fixed-hydroboration-of-alkenes-under-metal-free-conditions-scope-and-mechanistic-studies.pdf
|
645cb08ffb40f6b3ee651520
|
10.26434/chemrxiv-2023-x39xt
|
Kinetics-Constrained Neural Ordinary Differential Equations: Artificial Neural Network Models tailored for Small Data to boost Kinetic Model Development
|
Artificial neural networks (ANNs) are powerful tools for solving a wide range of tasks in fundamental and applied science. However, training and building reliable ANN models requires a lot of data which so far hinders their wider application in kinetic modelling where typically only small (experimental) datasets are available. In the present work we propose a method to design ANN models for kinetic modelling that can be trained even with small data sets as are typically available. The key idea is to constrain the architecture of the ANN models by integrating kinetic and thermodynamic knowledge leading to what we call Kinetics-Constrained Neural Ordinary Differential Equations (KCNODE). The feasibility and effectiveness of the approach is first demonstrated in a numerical experiment using the catalytic hydrogenation of CO2 to methane as example. Next, we demonstrate the approach for real experimental data of a more complex reaction, the hydrogenation of CO2 to higher hydrocarbons (CO2-FT). Finally, the ANN trained for CO2-FT is used to derive an improved mechanistic model for the reverse water gas shift reaction which is a key reaction in the CO2-FT reaction network. This last step exemplifies how the opportunity to obtain reliable ANN models from small data opens new ways to approach kinetic model development.
|
Aleksandr Fedorov; Anna Perechodjuk; David Linke
|
Theoretical and Computational Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry; Machine Learning; Reaction Engineering; Heterogeneous Catalysis
|
CC BY 4.0
|
CHEMRXIV
|
2023-05-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/645cb08ffb40f6b3ee651520/original/kinetics-constrained-neural-ordinary-differential-equations-artificial-neural-network-models-tailored-for-small-data-to-boost-kinetic-model-development.pdf
|
618e88a39960f39a35a973aa
|
10.26434/chemrxiv-2021-v22fb
|
Predicted Melt Curve and Liquid Shear Viscosity of RDX up to 30 GPa
|
Recent grain scale simulations of HMX and TATB have shown that predictions for hot spot formation in high explosives are particularly sensitive to accurate determinations of the pressure-dependent melt curve and the shear viscosity of the liquid phase. These physics terms are poorly constrained beyond ambient pressure for the explosive RDX. We adopt an all-atom modeling approach using molecular dynamics (MD) simulations to predict the melt curve of RDX near to detonation conditions (30 GPa) and determine the shear viscosity of the liquid as a function of temperature and pressure above the melt curve. Phase-coexistence simulations were used to determine the melt curve, which is predicted to vary by almost 1100 K as the pressure increases from 0 GPa to 30 GPa. Equilibrium MD simulations and the Green-Kubo formalism were used to obtain the pressure-temperature dependent shear viscosity. The shear viscosity of RDX is predicted to be of similar magnitude to the viscosity of TATB at low GPa-range pressures, and to be roughly an order of magnitude lower than the viscosity of HMX. The temperature dependence of the shear viscosity is Arrhenius at a given pressure, and the exponential pre-factor and activation term exhibit a strong, yet complicated, pressure dependence. An empirical pressure-temperature dependent function for RDX shear viscosity is developed that simultaneously captures a wide range of MD predictions while taking an analytic form that extrapolates smoothly beyond the fitted regime. The relative strength of the pressure and temperature dependencies of these two physics terms is found to be of similar magnitude for RDX, HMX, and TATB, which motivates incorporating these results in future RDX grain scale modeling.
|
Matthew Kroonblawd; H. Keo Springer
|
Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Computational Chemistry and Modeling; Thermodynamics (Physical Chem.); Transport phenomena (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-11-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/618e88a39960f39a35a973aa/original/predicted-melt-curve-and-liquid-shear-viscosity-of-rdx-up-to-30-g-pa.pdf
|
652020e1bda59ceb9a0066bc
|
10.26434/chemrxiv-2023-gwm1s-v2
|
HydraScreen: A Generalizable Structure-Based Deep Learning Approach to Drug Discovery
|
We propose HydraScreen, a deep-learning framework for safe and robust accelerated drug discovery. HydraScreen utilizes a state-of-the-art 3D convolutional neural network, designed for the effective representation of molecular structures and interactions in protein-ligand binding. We design an end-to-end pipeline for high-throughput screening and lead optimization, targeting applications in structure-based drug design. We assess our approach using established public benchmarks based on the CASF 2016 core set, achieving top-tier results in affinity and pose prediction (Pearson's r = 0.86, RMSE = 1.15, Top-1 = 0.95). We introduce a novel approach for interaction profiling, aimed at detecting potential biases within both the model and datasets. This approach not only enhances interpretability but also reinforces the impartiality of our methodology. Finally, we demonstrate HydraScreen's ability to generalize effectively across novel proteins and ligands through a temporal split. We also provide insights into potential avenues for future development aimed at enhancing the robustness of machine learning scoring functions. HydraScreen, accessible at https://hydrascreen.ro5.ai, provides a user-friendly GUI and a public API, facilitating easy-access assessment of protein–ligand complexes.
|
Alvaro Prat; Hisham Abdel Aty; Gintautas Kamuntavicius; Tanya Paquet; Povilas Norvaisas; Piero Gasparotto; Roy Tal
|
Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Machine Learning; Chemoinformatics - Computational Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-10-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652020e1bda59ceb9a0066bc/original/hydra-screen-a-generalizable-structure-based-deep-learning-approach-to-drug-discovery.pdf
|
6516dab5a69febde9eec90cf
|
10.26434/chemrxiv-2023-rgc7x
|
Palladium-Catalyzed, Highly Regio-, Stereo-, and Enantioselective Anti-Carboxylation of Unactivated Internal Allenes
|
Presented herein is the first report of a directing group-controlled, palladium-catalyzed, regio-, stereo-, and enantioselective anti-carboxylation of unactivated, internal allenes enabled via the synergistic interplay of rationally designed bidentate directing groups, palladium catalyst, and multifunctional acetate ligand. The corresponding trans allyl ester was obtained in excellent yields with exclusive delta-regioselectivity and anti-carboxypalladation stereocontrol. The pair of palladium catalysts coordinated with the bidentate directing group control regio-, and stereo- and enantioselectivity in the desired transformation. The potential of this concept has been demonstrated by the development of the first example of a chiral version of this transformation by using axial-to-central chirality transfer with high yields and good enantioselectivities. Several control experiments were conducted to validate the ligand-assisted nucleopalladation process and the rationale behind the racemization of chiral allenes. Detailed investigations, including kinetic studies, order studies, and DFT studies, were performed to elucidate the mechanism of this transformation, indicating that the anti-carboxypalladation step was the rate-limiting as well as the stereo- and enantio-determining step.
|
Prajyot Jayadev Nagtilak; Manoj V. Mane; Deveen Rajeshbhai Hirapara; Akshat Jain; Manmohan Kapur
|
Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Catalysis; Kinetics and Mechanism - Organometallic Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-10-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6516dab5a69febde9eec90cf/original/palladium-catalyzed-highly-regio-stereo-and-enantioselective-anti-carboxylation-of-unactivated-internal-allenes.pdf
|
63bb15b753a45a74fd532113
|
10.26434/chemrxiv-2023-f182x
|
Large Scale Docking in the Cloud
|
Molecular docking is a pragmatic approach to exploit protein structure for new ligand discovery, but the growing size of available chemical space is increasingly challenging to screen on in-house computer clusters. We have therefore developed AWS-DOCK, a protocol for running UCSF DOCK in the AWS cloud. Our approach leverages the low cost and scalability of cloud resources combined with a low-molecule-cost docking engine to screen billions of molecules efficiently. We benchmarked our system by screening 50 million HAC 22 molecules against the DRD4 receptor. We saw up to 3-fold variations in cost between AWS availability zones. Docking 4.5 billion lead-like molecules, a 7-week calculation on our 1000-core lab cluster, runs in less than a week in AWS for around $25,000, less than the cost of two new nodes. The cloud docking protocol is described in easy-to-follow steps and may be sufficiently general to be used for other docking programs. All the tools to enable AWS-DOCK are available free to everyone, while DOCK 3.8 is free for academic research.
|
John Irwin; Benjamin Tingle
|
Theoretical and Computational Chemistry; Computational Chemistry and Modeling
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-01-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63bb15b753a45a74fd532113/original/large-scale-docking-in-the-cloud.pdf
|
60c753ed469df403bef44e65
|
10.26434/chemrxiv.13578203.v1
|
A Drug Repurposing Approach to Identify Therapeutics by Screening Medicines for Malaria Ventures Exploiting SARS-CoV-2 Main Protease
|
<p>COVID-19 pandemic makes the human-kind
standstill and results in high morbidity and mortality cases worldwide. Still,
there are no approved antiviral drugs with proven efficacy nor any therapeutic
vaccines to combat the disease as per the current date. In the
present study, SARS-CoV-2 main protease (Mpro) has been taken as a potential
drug target considering its crucial role in virus propagation. We have used 400 diverse bioactive inhibitors with proven antibacterial and antiviral
properties for screening against Mpro target. Our screening result identifies ten
compounds with higher binding affinity than N3 (used as a reference compound to
validate the experiment). All the compounds possess desire physicochemical
properties. Later on, in-depth docking and superimposition of selected complexes
confirm that only three compounds (MMV1782211, MMV1782220 and MMV1578574) are actively interacting with the catalytic domain of
Mpro. </p>
<p>Furthermore,
the selected three molecules complexed with Mpro and N3-Mpro as control are
subjected to molecular dynamics simulation study (root means square deviation, root mean
square fluctuation, hydrogen bonding, solvent-accessible area and radius of
gyration). MMV1782211-Mpro
complex shows a strong and stable interaction as compared to others.
The MM/PBSA free energy calculation shows the highest binding
free energy of –115.8 kJ/mol for MMV1782211 compound also cross-confirms our
molecular docking study. Therefore,
our <i>in silico</i> findings become very
interesting towards developing alternative medicine against SARS-CoV-2 Mpro
target. So, we can expect prompt actions in this direction to combat the
COVID-19.</p>
|
Rashmi Tyagi; Anubrata Paul; V. Samuel Raj; Krishna Kumar Ojha; Manoj Kumar Yadav
|
Bioengineering and Biotechnology; Bioinformatics and Computational Biology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-02-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753ed469df403bef44e65/original/a-drug-repurposing-approach-to-identify-therapeutics-by-screening-medicines-for-malaria-ventures-exploiting-sars-co-v-2-main-protease.pdf
|
60c73d91469df4b8fcf42728
|
10.26434/chemrxiv.5877868.v1
|
Decarboxylative sp3 C–N Coupling via Dual Copper/Photoredox Catalysis
|
<p>Over the last three decades, significant progress has been made in the development of methods to construct <i>sp<sup>2</sup></i> C–N bonds using palladium, copper, or nickel catalysis. However, the incorporation of alkyl substrates to form <i>sp<sup>3</sup></i> C–N bonds remains one of the major challenges in the field of cross-coupling chemistry. Here, we demonstrate that the synergistic combination of copper catalysis and photoredox catalysis can provide a general platform to address this long-standing challenge. This novel cross-coupling system employs naturally abundant alkyl carboxylic acids and commercially available <i>N</i>-nucleophiles as coupling partners, and is applicable to a wide variety of primary, secondary, and tertiary alkyl carboxylic acids (via in situ iodonium activation). At the same time, a vast array of <i>N</i>-nucleophiles, including <i>N</i>-heterocycles, amides, sulfonamides, and anilines, can undergo C–N coupling to provide <i>N</i>-alkyl products in good to excellent efficiency at room temperature and in short order (5 minutes to 1 hour). We have also demonstrated that this C–N coupling protocol can be applied to substrates bearing multiple amines with high regioselectivity, as well as complex drug molecules, enabling the rapid construction of molecular complexity and the late stage functionalization of bioactive pharmaceuticals.</p>
|
David W. C. MacMillan; Yufan Liang; Xiaheng Zhang
|
Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Photochemistry (Org.); Homogeneous Catalysis; Photocatalysis; Redox Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-02-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d91469df4b8fcf42728/original/decarboxylative-sp3-c-n-coupling-via-dual-copper-photoredox-catalysis.pdf
|
679cb853fa469535b98e1921
|
10.26434/chemrxiv-2024-prw8k-v2
|
Robotic arms for benchtop hyperpolarization-enhanced NMR experiments
|
Optimization of nuclear spin hyperpolarization experiments often requires varying one system parameter at a time (or several parameters in a nontrivial manner) as well as multiple repetitions of signal measurements. Use of automated robotic systems can significantly streamline this optimization process, accelerating data acquisition and improving reproducibility in the long term. In this work we show an exemplary system built on open-source components and demonstrate several benchtop and ultralow-field NMR experiments employing photo-CIDNP and SABRE-derived hyperpolarization. This work illustrates that open-source platforms employing benchtop NMR and robotic systems built in a modular manner with remote operation allow the implementation of various unconventional experiments in a reproducible manner.
|
Kirill Sheberstov; Erik Van Dyke; Jingyan Xu; Raphael Kircher; Liubov Chuchkova; Yinan Hu; Sulaiman Alvi; Dmitry Budker; Danila Barskiy
|
Physical Chemistry; Analytical Chemistry; Chemical Education; Analytical Apparatus; Spectroscopy (Physical Chem.); Robotics
|
CC BY NC 4.0
|
CHEMRXIV
|
2025-02-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/679cb853fa469535b98e1921/original/robotic-arms-for-benchtop-hyperpolarization-enhanced-nmr-experiments.pdf
|
657c90f09138d23161bb4ee8
|
10.26434/chemrxiv-2023-9nqnw
|
Decarboxylative C N coupling of 2,2-difluorobicyclo[1.1.1]pentane (BCP-F2) building blocks
|
Described herein is our effort towards achieving the decarboxylative functionalization of 2,2-difluorobicyclo[1.1.1]pentane (BCP-F2) building blocks. When compared with the non-fluorinated bicyclo[1.1.1]pentane (BCP) analogues, we discovered divergent reactivities. This is the first successful decarboxylative coupling of BCP-F2 building blocks reported via photoredox mechanism.
|
Xiaoshen Ma; Joanna Chen; Bryce Gaskins
|
Organic Chemistry; Catalysis; Photocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-12-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/657c90f09138d23161bb4ee8/original/decarboxylative-c-n-coupling-of-2-2-difluorobicyclo-1-1-1-pentane-bcp-f2-building-blocks.pdf
|
67c31ca26dde43c9080375c3
|
10.26434/chemrxiv-2025-l90hb
|
A solvent selection framework for porous organic polymers
|
The relationship between solvent, morphology, and properties is crucial for developing functional materials. However, selecting suitable solvents for novel systems remains a significant challenge due to the lack of prior knowledge to guide solvent selections. In this work, we present a solvent selection toolkit for functional porous organic polymers. We have developed an interpretable machine-learning algorithm, MLoc, for the fast prediction of Hansen solubility parameters (HSPs) of novel target materials. This workflow is accessible to non-specialists, operates at negligible computing costs and relies simply on ultraviolet and visible (UV/Vis) absorbance data that can be measured using a standard laboratory setup. We demonstrate successful tuning of both morphology and carbon capture performance for target polymers using MLoc. We describe our vision for MLoc’s broader application in the sustainable development of functional materials, without the need for extensive screening, i.e., in a low data regime. Using MLoc, we report the first HSP database for porous organic polymers, which will serve as a valuable resource for future data-driven research.
|
Xue Fang; Ulzhalgas Karatayeva; John D. Worth; Merve Gumussoy Girgin; Safa A. Al Siyabi; Dauren Mukhanov; Ella M. Gale; Natalie Fey; Charl F. J. Faul
|
Theoretical and Computational Chemistry; Polymer Science; Organic Polymers; Machine Learning; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c31ca26dde43c9080375c3/original/a-solvent-selection-framework-for-porous-organic-polymers.pdf
|
644a614c80f4b75b532edb21
|
10.26434/chemrxiv-2023-t82zv
|
DNA-based Signaling Networks for Transient Colloidal Co-Assemblies
|
Programmable chemical circuits inspired by the signaling networks in living cells are a promising approach for the development of adaptive and autonomous self-assembling molecular systems and material functions. Progress has been made at the molecular level, but connecting molecular control circuits to self-assembling larger elements such as colloids that enable real-space studies and access to functional materials is sparse and can suffer from kinetic traps, flocculation, or difficult system integration protocols. Here we report a toehold-mediated DNA strand displacement reaction network capable of autonomously directing two different microgels into transient and self-regulating co-assemblies. The microgels are functionalized with DNA and become elemental components of the network. The flexibility of the circuit design allows the installation of delay phases or accelerators by chaining additional circuit modules upstream or downstream of the core circuit. The design provides an adaptable and robust route to regulate other building blocks for advanced biomimetic functions.
|
Charu Sharma; Avik Samanta; Ricarda Schmidt; Andreas Walther
|
Biological and Medicinal Chemistry; Materials Science; Nanoscience; Aggregates and Assemblies; Nanostructured Materials - Nanoscience; Bioengineering and Biotechnology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/644a614c80f4b75b532edb21/original/dna-based-signaling-networks-for-transient-colloidal-co-assemblies.pdf
|
660cf5fa418a5379b0f21063
|
10.26434/chemrxiv-2024-twml7-v2
|
Electronically Tunable Non-Fullerene Acceptor Based Ka-Band Phase Shifter
|
This communication introduces a Ka-band phase shifter that leverages a blend of the donor polymer PM6 and non-fullerene acceptor (NFA) Y7 organic materials. The design integrates a coplanar waveguide (CPW) with a spin-coated thin film of PM6:Y7 blend, characterized by its dielectric nonlinearity and light sensitivity. An applied electric field between the CPW signal and ground electrodes governs the phase shift mechanism, effectively modulating the permittivity of the blend. Our study reveals a significant differential phase shift of up to 28 degree at 38 GHz across the waveguide's 1000 um. Additionally, we explore the dynamic interplay between illumination and temperature on the performance of the phase shifter, providing insights into its operational versatility. The findings underscore the substantial potential of NFA-based phase shifters in millimeter-wave applications and adaptive communication systems, such as active antennas, marking a significant stride in developing organic material-based electronic components for self powered next-generation technologies.
|
suraj Manikandan; Jens Andreasen
|
Materials Science; Energy; Photovoltaics; Power
|
CC BY 4.0
|
CHEMRXIV
|
2024-12-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/660cf5fa418a5379b0f21063/original/electronically-tunable-non-fullerene-acceptor-based-ka-band-phase-shifter.pdf
|
678e6504fa469535b9ce4201
|
10.26434/chemrxiv-2025-fvz0q
|
Enantioselective Redox-Neutral Coupling of Allenylic Alcohols through Divergent Cooperative Catalysis
|
The past two decades have witnessed a magnificent growth of cooperative catalysis, where two substrates usually of complimentary polarity are activated independently by two different catalysts, before the reactive intermediates converge into the desired product. Different variants of cooperative catalysis have emerged since the inception of this concept and led to the discovery of innumerable transformations, which are difficult or impossible to achieve under a single catalyst. In this paper, we introduce the concept of divergent cooperative catalysis, which is fundamentally different from traditional modes of cooperative catalysis. Here, the reaction takes place with a single substrate, which is converted to two transient intermediates of complimentary polarity under the influence of two different catalysts. The combination of these two polarity-matched inter-mediates gives the desired product. Due to the use of a single substrate, the reactions under divergent cooperative catalysis are expected to minimize the complications associated with traditional cooperative catalysis. The proof of this concept is demonstrated by an enantioselective redox-neutral coupling of branched allenylic alcohols, cooperatively catalyzed by iridium and Lewis acid. In the Lewis acid-catalytic cycle, racemic allenylic alcohol is transformed into an alpha,beta-unsaturated enol (cross dienol) through Meyer-Schuster-type 1,3-hydroxy transposition. On the other hand, in an independent process, catalyzed by a combination of an Ir(I)/(phosphoramidite,olefin) complex and Lewis acidic Sc(OTf)3, allenylic alcohol is believed to produce an η2-Ir(I)-bound allenylic carbocation intermediate, which is intercepted by the in situ generated cross dienol. Overall, starting from stable and easily accessible branched allenylic alcohols, the process combines Lewis acid-catalyzed 1,3-hydroxy transposition with Ir-catalyzed enantioselective allenylic substitution to furnish alpha′-allenylic alpha,beta-unsaturated ketones, without using preformed carbon nucleophiles, in moderate to good yields generally with excellent enantioselectivities (up to >99.9:0.1 er). Detailed experimental and DFT studies helped shed light on the mechanism of the reaction, which revealed the initially formed bis-allenylic ether to be a substrate reservoir.
|
Aditya Chakrabarty; Ritwika Chatterjee; Santanu Mukherjee
|
Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Stereochemistry; Homogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678e6504fa469535b9ce4201/original/enantioselective-redox-neutral-coupling-of-allenylic-alcohols-through-divergent-cooperative-catalysis.pdf
|
64c6099a9ed5166e93b7cfb6
|
10.26434/chemrxiv-2023-kd4f3
|
Catalytic, Dearomative 2,3-Difluorination of Indoles
|
Indolines, characterized by their diverse biological activities and structural significance, have garnered considerable attention in the realms of natural product synthesis and drug discovery. Concurrently, the incorporation of fluorine atoms into organic molecules has emerged as a powerful strategy to enhance their pharmacological properties. Herein, we report a robust and diastereoselective approach for the synthesis of 2,3-difluorinated indolines through the iodine(I/III)-catalyzed dearomatization of readily available indoles. The protocol operates under mild conditions, displaying excellent functional group tolerance and remarkable diastereoselectivity. By employing this developed protocol, vicinal-difluorinated analogues of indole-containing drugs can be efficiently accessed. Theoretical calculations have shed light on the underlying reaction mechanism, proposing the formation of a β-fluorine-substituted carbocation intermediate. It is postulated that the observed high diastereoselectivity can be attributed to the dipole-dipole interactions facilitated by the C-F bond. Crystallographic analysis has revealed the profound impact of fluorine atom introduction on the conformational preferences of the indoline core. Given the unique structural characteristics and pharmacological significance of 2,3-difluorinated indolines, we anticipate their widespread application in medicinal chemistry and drug discovery endeavors.
|
Fang-Hai Tu; Shuang Lin; Ya-Jie Tang; Li-Cai Liu; Qingjiang Li; Honggen Wang
|
Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Stereochemistry; Homogeneous Catalysis
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-07-31
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64c6099a9ed5166e93b7cfb6/original/catalytic-dearomative-2-3-difluorination-of-indoles.pdf
|
6655a628418a5379b0782c70
|
10.26434/chemrxiv-2024-4s29q
|
Effect of Filler Surface Chemistry on the Multifunctional Properties of GNP Epoxy Nanocomposites
|
Plasma reactors can be used to surface functionalise industrial scale (tonnes/annum) quantities of graphene nanoplatelets (GNPs). When used as fillers in polymer nanocomposites, surface functionalisation of GNPs can modify the chemical interactions at the filler-matrix interphase. In this work baseline (PG-10), plasma fluorinated (PG-CF), and aminated (PG-NH) GNPs were used to manufacture GNP epoxy nanocomposites, and their multifunctional properties tested. We find that the high aspect ratio and homogeneous dispersion of PG-NH enables a ~75% increase in filler modulus and reduces the thermal conductivity. While the high density of low lateral size particulates in PG-CF nanocomposites, reduces the filler modulus by ~50%, and increases the thermal conductivity. We link filler surface chemistry, to the dispersion and morphology of flakes in the matrix, and the resultant nanocomposite multifunctional properties. Demonstrating that surface functionalisation can be carried out in a scalable manner to improve filler-matrix property transfer in GNP epoxy nanocomposites.
|
Vicente Orts Mercadillo; Happiness Ijije; Pietro Steiner; Kai Chio Chan; Mufeng Liu; Ian A. Kinloch; Mark Bissett
|
Physical Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Interfaces; Physical and Chemical Properties
|
CC BY 4.0
|
CHEMRXIV
|
2024-05-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6655a628418a5379b0782c70/original/effect-of-filler-surface-chemistry-on-the-multifunctional-properties-of-gnp-epoxy-nanocomposites.pdf
|
66f15736cec5d6c142f0c9f0
|
10.26434/chemrxiv-2024-tphl1
|
Neural Network-Driven Exploration of Solvophilic Block Size Effects in Polymerization-Induced Self-Assembly: From 2D To 3D Comprehensive Pseudo-Phase Diagram
|
We explore the application of artificial intelligence (AI) to predict the morphology of poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) diblock copolymer nano-objects prepared via polymerization-induced self-assembly (PISA) in aqueous media. Traditional studies typically map copolymer morphology using two-dimensional (2D) pseudo-phase diagrams, plotting variables such as the mean degree of polymerization (Xn) of the solvophobic block against the copolymer concentration (also known as the solids content). In contrast, our approach utilizes deep neural networks (DNNs) trained on literature data to generate detailed three-dimensional (3D) morphology maps. These maps include the molecular weight of the solvophilic block, providing a comprehensive volumetric view that reveals more complex relationships and transitional morphologies. This advanced modeling not only deepens our understanding of how PGMA molecular weight influences copolymer morphology but also significantly reduces the need for extensive experimental trials. Consequently, it simplifies the creation of accurate pseudo-phase diagrams across a broad range of aqueous PISA formulations. Experimental validation confirms the accuracy of our models, demonstrating the potential of AI to make predictive modeling more accessible to chemists and paving the way for future research on other PISA formulations.
|
Erika Paola Fonseca Parra; jihad Oumerri; Ana Arteni Andrea; Jean-Luc Six; Steven Peter Armes; khalid ferji
|
Materials Science; Polymer Science; Nanoscience; Polymerization (Polymers); Polymer morphology; Nanostructured Materials - Nanoscience
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-09-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f15736cec5d6c142f0c9f0/original/neural-network-driven-exploration-of-solvophilic-block-size-effects-in-polymerization-induced-self-assembly-from-2d-to-3d-comprehensive-pseudo-phase-diagram.pdf
|
64f4775179853bbd78ff18e1
|
10.26434/chemrxiv-2023-vbzxw
|
Stereoselective C−B and C−H Bonds Functionalization of polyBorylated Alkenes
|
Alkenes are fundamental functional groups which feature in various materials and bioactive molecules; however, efficient divergent strategies for their stereodefined synthesis are difficult. In this regard, numerous synthetic methodologies have been developed to construct carbon–carbon bonds with regio- and stereoselectivity, enabling the predictable and efficient synthesis of stereodefined alkenes. In fact, an appealing alternative approach for accessing challenging stereodefined alkenes molecular frameworks could involve the sequential selective activation and cross-coupling of strong bonds instead of conventional C–C bond formation. In this study, we introduce a programmed site- and stereoselective strategies that capitalizes on the versatile reactivity of readily accessible polymetalloid alkenes, through a tandem cross-coupling reaction, which is catalyzed by an organometallic Rh-complex to produce complex molecular scaffolds. By merging selective C–B and remote C–H bond functionalization, we achieve the generation of polyfunctional C(sp2)-nucleophilic species intermediates. These species can be further modified by selective coupling reactions with various C-based electrophiles, enabling the formation of C(sp2)–C(sp3) bond for the generation of even more complex molecular architectures using the readily available starting polyborylated-alkenes.
|
Narendra K. Vaishanv; Nadim Eghbarieh; Rahul A. Jagtap; Ahmad Masarwa
|
Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-09-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64f4775179853bbd78ff18e1/original/stereoselective-c-b-and-c-h-bonds-functionalization-of-poly-borylated-alkenes.pdf
|
674d8a425a82cea2fab2dfdd
|
10.26434/chemrxiv-2024-dgqn7-v2
|
Fewer, but better: on the benefits of surfactant-free colloidal syntheses of nanomaterials
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Colloidal syntheses are common bottom-up synthetic approaches to obtain various nanomaterials, e.g. gold nanoparticles, where a precursor, e.g. HAuCl4, is reduced in presence of reducing agents in a solvent. It is often claimed, and almost dogmatically believed, that stabilizers, capping agents, ligands, surfactants or other additives, must be added to ensure the stability of the colloids. Although there is almost a systematic use of such chemicals in the literature, a range of surfactant-free, or additive-free, colloidal syntheses have been reported. In those syntheses, the solvent plays the role of source of reducing agents and/or stabilizers. Recently, the use of alkaline solutions of low viscosity mono-alcohols, such as ethanol, has been shown to lead to stable surfactant-free colloids for various metal nanoparticles. Here, with the example of gold nanoparticles obtained at room temperature, it is shown that adding commonly reported stabilizers, such as trisodium citrate, PVP, SDS, poly(NIPAM), CTAB, or chemicals such as hydroquinone, actually does not lead to any advantages compared to the surfactant-free colloidal synthesis performed in alkaline mixture of water and 20 v.% ethanol. The results stress the potential of surfactant-free approaches compared to more conventional surfactant- and additives- assisted strategies to develop greener research studies and syntheses.
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Marton Varga; Jonathan Quinson
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Inorganic Chemistry; Nanoscience; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Materials Chemistry
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CC BY NC 4.0
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CHEMRXIV
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2024-12-03
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674d8a425a82cea2fab2dfdd/original/fewer-but-better-on-the-benefits-of-surfactant-free-colloidal-syntheses-of-nanomaterials.pdf
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6553bf236e0ec7777ff1d61e
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10.26434/chemrxiv-2023-tgdm9-v2
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Probing the dynamics of the local structure of Na in NaNO3-promoted, MgO-based CO2 sorbents via X-ray absorption spectroscopy
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This work provides insight into the local structure of Na in MgO-based CO2 sorbents that are promoted with NaNO3. To this end, we use X-ray absorption spectroscopy (XAS) at the Na K-edge to interrogate the local structure of Na during CO2 capture (MgO + CO2 ↔ MgCO3). The analysis of Na K-edge XAS data shows that the local environment of Na is altered upon MgO carbonation when compared to NaNO3 in the as-prepared sorbent. We attribute the changes observed in the carbonated sorbent to an alteration in the local structure of Na at the NaNO3/MgCO3 interfaces and/or in the vicinity of [Mg2+···CO32–] ionic pairs that are trapped in the cooled down NaNO3 melt. The changes observed are reversible, i.e. the local environment of NaNO3 was restored after a regeneration treatment to decompose MgCO3 to MgO. The ex situ Na K-edge XAS experiments were complemented by ex situ magic-angle spinning 23Na nuclear magnetic resonance (MAS 23Na NMR), Mg K-edge XAS and X-ray powder diffraction (XRD). These additional experiments support our interpretation of the Na K-edge XAS data. Furthermore, we develop in situ Na (and Mg) K-edge XAS experiments during the carbonation of the sorbent (NaNO3 is molten at the conditions of the in situ experiments). These in situ Na K-edge XANES spectra of molten NaNO3 open new opportunities to investigate the atomic scale structure of CO2-sorbents modified with Na-based molten salts using XAS.
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Margarita Rekhtina; Aram Bugaev; Matthew T. Dunstan; Dal Pozzo Alessandro ; Manouchehr Nadjafi; Camelia Borca; Thomas Huthwelker; Paula Abdala; Christoph Müller
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Materials Science
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CC BY NC ND 4.0
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CHEMRXIV
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2023-11-15
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6553bf236e0ec7777ff1d61e/original/probing-the-dynamics-of-the-local-structure-of-na-in-na-no3-promoted-mg-o-based-co2-sorbents-via-x-ray-absorption-spectroscopy.pdf
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