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60c73e10ee301c78dbc7867d
|
10.26434/chemrxiv.6281264.v1
|
On the Lack of Beneficial Role of Rh Towards C-C Bond Cleavage During Low Temperature Ethanol Electrooxidation on Pt-Rh Nanoalloys
|
Numerous reports in scientific literature claim the increased activity of Rh-containing systems towards C-C bond scission in electrocatalytic oxidation of ethanol at ambient temperatures. Due to the claimed C-C bond breaking ability, Rh-containing systems are intensively investigated and widely recognized as the most promising candidates as anode materials for ethanol-feed low temperature fuel cells. This study aims at verifying the claim of beneficial role of Rh towards C-C bond scission during low temperature ethanol electrooxidation on Pt-Rh nanoparticles. We determined that the surface-normalized amounts of CO<sub>2 </sub>produced during ethanol oxidation are comparable on Pt, Rh and Pt-Rh nanoalloys, and smaller than CO<sub>2</sub> amounts obtained on exactly the same electrode from oxidation of monolayer of adsorbed CO. The whole amount of CO<sub>2</sub> detected during ethanol oxidation, regardless of Rh presence, or lack of thereof, seems to come exclusively from oxidation of submonolayer of CO<sub>ads</sub> produced during dissociative adsorption of ethanol at low electrode potential, and its subsequent oxidation at sufficiently high electrode potential. Our work suggest that Rh-containing alloys are not more active towards C-C bond scission than pure Pt, and on both metals the mechanism of oxidation of ethanol to CO<sub>2</sub> proceeds via the submonolayer of CO<sub>ads</sub>, which limits the quantity of CO<sub>2</sub> produced from ethanol at room temperature to negligible amount. The higher activity of Rh-containing materials towards C-C bond scission claimed in literature was determined to be due to overinterpretation of selectivity data.<br />To characterized the samples we used techniques like XPS, TEM, and cyclic voltammetry. For drove a conclusions we compere amount of CO<sub>2</sub> detected in DEMS during ethanol oxidation reaction and so called CO stripping experiment. <br /><br />
|
Justyna Piwowar; Adam Lewera
|
Alloys; Nanostructured Materials - Nanoscience; Electrocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-05-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e10ee301c78dbc7867d/original/on-the-lack-of-beneficial-role-of-rh-towards-c-c-bond-cleavage-during-low-temperature-ethanol-electrooxidation-on-pt-rh-nanoalloys.pdf
|
60c74243469df480d5f42f71
|
10.26434/chemrxiv.8247152.v1
|
Autoionization Dynamics of (2P1/2)ns/d States in Krypton Probed by Noncollinear Wave Mixing with Attosecond Extreme Ultraviolet and Few-Cycle Near Infrared Pulses
|
The autoionization dynamics of the (<sup>2</sup>P<sub>1/2</sub>)ns/d Rydberg states in krypton are investigated using wave-mixing signals generated with subfemtosecond XUV pulses and noncollinear, few-cycle NIR pulses. Despite quantum beat oscillations from the XUV-induced coherence, these wave-mixing spectra allow for the simultaneous evaluation of autoionization lifetimes from a series of Rydberg states. Experimentally measured lifetimes for the wave-mixing signals emitting from the (<sup>2</sup>P<sub>1/2</sub>)6d/8s, 7d/9s, and 8d/10s resonances compare favorably with lifetimes for the (<sup>2</sup>P<sub>1/2</sub>)6d, 7d, and 8d Rydberg states determined from spectral linewidths. Analysis of the quantum beats reveals that the enhancement of wave-mixing pathways leads to reporter state-dependent decays in the wave-mixing signals. The results demonstrate the promise of wave-mixing spectroscopies with subfemtosecond XUV pulses to provide valuable insights into processes governed by electronic dynamics.<br />
|
Ashley Fidler; Hugo Marroux; Erika Warrick; Etienne Bloch; Wei Cao; Stephen Leone; Daniel Neumark
|
Optics; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-06-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74243469df480d5f42f71/original/autoionization-dynamics-of-2p1-2-ns-d-states-in-krypton-probed-by-noncollinear-wave-mixing-with-attosecond-extreme-ultraviolet-and-few-cycle-near-infrared-pulses.pdf
|
6306494b1945ad421de55c7f
|
10.26434/chemrxiv-2022-00gls
|
Decarbonization of the Chemical Industry through Electrification: Barriers and Opportunities
|
The chemical industry is a major source of economic productivity and employment globally and
among the top 3 industrial sources of greenhouse gas (GHG) emissions, along with steel and cement. As
global demand for chemical products continues to grow, there is an urgency to develop and deploy
sustainable chemical production pathways and re-consider continued investment in current emissionintensive
production technologies. This Perspective describes the challenges and opportunities to
decarbonize the chemical industry via electrification powered by the low-emission electric power sector,
both in the near-term and long-term, and discusses four technological pathways ranging from the more
mature direct substitution of heat with electricity and use of hydrogen to technologically less mature, yet
potentially more selective approaches based on electrochemistry and plasma. Finally, we highlight the key
elements of integrating an electrified industrial process with the power sector to leverage process flexibility
to reduce energy costs of chemical production and provide valuable power grid support services. Unlocking such plant-to-grid coordination and the four electrification pathways has significant potential to facilitate
rapid and deep decarbonization of the chemical industry sector.
|
Dharik Mallapragada; Yury Dvorkin; Miguel Modestino; Daniel Esposito; Wilson Smith; Bri-Mathias Hodge; Michael Harold; Vincent Donnelly; Alice Nuz; Casey Bloomquist; Kyri Baker; Lars Grabow; Yushan Yan; Nav Nihdi Rajput; Ryan Hartman; Elizabeth Biddinger; Eray Aydil; Andre Taylor
|
Energy; Chemical Engineering and Industrial Chemistry; Industrial Manufacturing; Process Control; Power
|
CC BY 4.0
|
CHEMRXIV
|
2022-08-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6306494b1945ad421de55c7f/original/decarbonization-of-the-chemical-industry-through-electrification-barriers-and-opportunities.pdf
|
62d9cbe358198723b14b1135
|
10.26434/chemrxiv-2022-dbc0n
|
The Source of Proton in the Noyori−Ikariya Reaction
|
The study of the mechanism of the Noyori‒Ikariya asymmetric transfer hydrogenation of ketones spans nearly three decades of investigations. Whereas the early part of the catalytic cycle being the hydride transfer is now well-understood, the late part being the proton transfer is still ambiguous. Specifically, the source of the proton can be the N‒H functionality of the catalyst and/or the O‒H functionality of the reagent/solvent leading to two conceptually different catalytic cycles or even their combination. For three popular reagents/solvents typically used in the method, namely propan-2-ol, 5:2 HCO2H‒NEt3 and water, the source of the proton is presently either unknown, or the evidence is presented partially by only one approach ‒ experimental or computational. This work eliminates this ambiguity by means of various state-of-the-art molecular dynamics simulation methods (ab initio, quantum mechanics/molecular mechanics and path integral to include quantum tunneling effects). Here we show that the source of proton in propan-2-ol is catalyst’s N‒H functionality, whereas in more acidic water, binary 5:2 HCO2H‒NEt3 or neat formic acid the source of proton is reagent/solvent. Thus, depending on the source of reagent/solvent the catalyst’s ligand can be either chemically non-innocent or chemically innocent in the Noyori‒Ikariya reaction, which opens new opportunities for the outer-sphere homogeneous catalysts design.
|
Nikolay V. Tkachenko; Pavel Rublev; Pavel A. Dub
|
Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Homogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-07-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62d9cbe358198723b14b1135/original/the-source-of-proton-in-the-noyori-ikariya-reaction.pdf
|
60c754db567dfef4fdec6151
|
10.26434/chemrxiv.13775182.v1
|
Dynamical Cooperativity of Ligand-Residue Interactions Evaluated with the Fragment Molecular Orbital Method
|
By the splendid advance in computation power realized with Fugaku supercomputer, it has become
possible to perform ab initio fragment molecular orbital (FMO) calculations for thousands of
dynamical structures of a protein-ligand complex in a parallelized way. We have thus carried out the
electron-correlated FMO calculations for a complex of the 3C-like (3CL) main protease (Mpro) of the
new coronavirus (SARS-CoV-2) and its inhibitor N3 incorporating the structural fluctuations sampled
by classical molecular dynamics (MD) simulation in hydrated condition. Along with a statistical
evaluation of inter-fragment interaction energies (IFIEs) between the N3 ligand and surrounding
amino-acid residues for a thousand of dynamical structure samples, we have applied in this study a
novel approach based on the principal component analysis (PCA) and the singular value
decomposition (SVD) to the analysis of IFIE data in order to extract the dynamically cooperative
interactions between the ligand and residues. We have found that the relative importance of each
residue is modified via the structural fluctuations and that the ligand is bound in the pharmacophore
in a dynamical manner through collective interactions formed by multiple residues, thus providing a
new insight into structure-based drug discovery
|
Shigenori Tanaka; Shusuke Tokutomi; Ryo Hatada,; Koji Okuwaki; Kazuki Akisawa; Kaori Fukuzawa; Yuto Komeiji; Yoshio Okiyama; Yuji Mochizuki
|
Biophysical Chemistry; Quantum Mechanics
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-02-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c754db567dfef4fdec6151/original/dynamical-cooperativity-of-ligand-residue-interactions-evaluated-with-the-fragment-molecular-orbital-method.pdf
|
638a772292f084b6bd248b36
|
10.26434/chemrxiv-2022-88t32
|
Data-driven discovery of organic electronic materials enabled by hybrid top-down/bottom-up design
|
The high-throughput molecular exploration and screening of organic electronic materials often starts with either a 'top-down' mining of existing repositories, or the 'bottom-up' assembly of fragments based on predetermined rules and known synthetic templates. In both instances, the datasets used are often produced on a case-by-case basis, and require the high-quality computation of electronic properties and extensive user input: curation in the top-down approach, and the construction of a fragment library and introduction of rules for linking them in the bottom-up approach. Both approaches are time-consuming and require significant computational resources. Here, we generate a top-down set of 117K synthesized molecules containing their optimized structures, associated electronic and topological properties and chemical composition, and use these structures as a vast library of molecular building blocks for bottom-up fragment-based materials design. A tool is developed to automate the coupling of these building block units based on their available C(sp2/sp)-H bonds, thus providing a fundamental link between the two philosophies of dataset construction. Statistical models are trained on this dataset and a subset of the resulting hybrid top-down/bottom-up compounds, which enable on-the-fly prediction of key ground state (frontier molecular orbital gaps) and excited state (S1 and T1 energies) properties from molecular geometries with high accuracy across all known p-block organic compound space.
With access to ab initio-quality optical properties in hand, it is possible to apply this bottom-up pipeline using existing compounds as molecular building blocks to any materials design campaign. To illustrate this, we construct and screen over a million molecular candidates for efficient intramolecular singlet fission, the leading candidates of which provide insight into the structural features that may promote this multiexciton-generating process.
|
J. Terence Blaskovits; Ruben Laplaza; Sergi Vela; Clémence Corminboeuf
|
Theoretical and Computational Chemistry; Materials Science; Optical Materials; Computational Chemistry and Modeling; Machine Learning; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-12-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/638a772292f084b6bd248b36/original/data-driven-discovery-of-organic-electronic-materials-enabled-by-hybrid-top-down-bottom-up-design.pdf
|
67d9b12c81d2151a02e19564
|
10.26434/chemrxiv-2025-qfdlq-v2
|
Metal-Free Catalytic Cross-Coupling of Esters and Boranes
|
Over the last 50 years, palladium-catalyzed cross-coupling has become ubiquitous in chemical synthesis from laboratory to commercial scale. Due to the great importance of these reactions, extensive research efforts have been devoted to improving the sustainability, cost, and diversity of the catalysts and coupling partners. Herein, we report the rational design and experimental validation of a metal-free catalyst for cross-coupling of formate esters with organoboranes, forming aldehydes under mild, additive-free conditions. The novel mechanism establishes a model for direct C(acyl)–C(sp2) bond formation, a motif previously inaccessible via metal-free or radical-free cross-coupling pathways. Overall, this boron/nitrogen-based system is found to even outperform the efficacy of state-of-the-art nickel catalysts for ester cross-coupling, demonstrating the utility of main-group catalysts in efficiently activating challenging bonds.
|
Gabriella Morin; Christina McCabe; Douglas Turnbull; Victoria Pham-Tran; Marc-André Légaré
|
Inorganic Chemistry; Catalysis; Organometallic Chemistry; Frustrated Lewis Pairs; Homogeneous Catalysis; Bond Activation
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d9b12c81d2151a02e19564/original/metal-free-catalytic-cross-coupling-of-esters-and-boranes.pdf
|
674adbc55a82cea2fa81a76f
|
10.26434/chemrxiv-2024-mxppn
|
Unlocking the Potential of Tris(pentafluorophenyl)borane in Reductive Desulfurization of Thioamides with Silane
|
Selective conversion of a functional group to a high-value product, namely defunctionalization, is an important procedure in synthetic chemistry. Herein, we report the first transition metal-free desulfurization of thioamides under relatively mild reaction conditions. The catalytic reaction proceeds with the selective cleavage of the C=S bonds of thioamides to furnish the corresponding amines in good to excellent yields with B(C6F5)3 and PhSiH3. The protocol is simple, does not require any additives, and encompasses a broad substrate scope with chemoselective reduction of vulnerable functional groups. To understand the mechanism, several control studies and detailed computational calculations were performed.
|
Arup Mukherjee; Hemanta K. Kisan; Pinaki Nad
|
Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674adbc55a82cea2fa81a76f/original/unlocking-the-potential-of-tris-pentafluorophenyl-borane-in-reductive-desulfurization-of-thioamides-with-silane.pdf
|
6218ba9b5f1d9af700a75b0e
|
10.26434/chemrxiv-2022-0dn37
|
Homochiral β-CF3, -SCF3 and -OCF3 secondary alcohols: catalytic stereoconvergent synthesis, bioactivity and flexible crystals
|
An optimized catalytic protocol for enantio- and diastereoselective reduction of racemic α-CF3, α-SCF3 and α-OCF3 aryl ketones is described. The reaction involves a dynamic kinetic resolution (DKR) based on ruthenium catalyzed Noyori–Ikariya asymmetric transfer hydrogenation for simultaneous construction of two contiguous stereogenic centers. A range of previously inaccessible fluorinated secondary alcohols was prepared in excellent stereomeric purity (up to above 99.9% ee, up to above 99.9:0.1 dr) and in high isolated yield (up to 99%). The origin of DKR (exceptional stereoselectivity and racemization mechanism) is rationalized by density functional theory calculations. Pharmaceutically relevant further transformations of the products are demonstrated including incorporation into heat shock protein 90 inhibitor with in vitro anti-cancer activity. Moreover, needle-shaped crystals of representative stereopure products are mechanically responsive: either elastically or plastically flexible, opening the door to novel class of functional materials based on chiral molecular crystals.
|
Andrej Emanuel Cotman; Pavel A. Dub; Maša Sterle; Matic Lozinšek; Jaka Dernovšek; Živa Zajec; Tihomir Tomašič; Dominique Cahard
|
Biological and Medicinal Chemistry; Organic Chemistry; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-02-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6218ba9b5f1d9af700a75b0e/original/homochiral-cf3-scf3-and-ocf3-secondary-alcohols-catalytic-stereoconvergent-synthesis-bioactivity-and-flexible-crystals.pdf
|
60c752ee0f50dba4c5397a9d
|
10.26434/chemrxiv.13369043.v1
|
Collagen Pentablock Copolymers Form Smectic Liquid Crystals as Precursors for Mussel Byssus Fabrication
|
Protein-based biological materials are important role models for the design and fabrication of next generation advanced polymers. Marine mussels (Mytilus spp.) fabricate hierarchically structured collagenous fibers known as byssal threads via bottom-up supramolecular assembly of fluid protein precursors. The high degree of structural organization in byssal threads is intimately linked to their exceptional toughness and self-healing capacity. Here, we investigated the hypothesis that multidomain collagen precursor proteins, known as preCols, are stored in secretory vesicles as a colloidal liquid crystal (LC) phase prior to thread self-assembly. Using advanced electron microscopy methods, including scanning TEM and FIB-SEM, we visualized the detailed smectic preCol LC nanostructure in 3D, including various LC defects, confirming this hypothesis and providing quantitative insights into the mesophase structure. In light of these findings, we performed an in-depth comparative analysis of preCol protein sequences from multiple Mytilid species revealing that the smectic organization arises from an evolutionarily conserved ABCBA penta-block co-polymer-like primary structure based on demarcations in hydropathy and charge distribution, as well as terminal pH-responsive domains<br />that trigger fiber formation. These distilled supramolecular assembly principles provide inspiration and strategies for sustainable assembly of nanostructured polymeric materials for<br />potential applications in engineering and biomedical applications.
|
Franziska Jehle; Tobias Priemel; Michael Strauss; Peter Fratzl; Luca Bertinetti; Matthew Harrington
|
Biological Materials; Fibers; Liquid Crystals; Materials Processing; Biopolymers
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-12-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752ee0f50dba4c5397a9d/original/collagen-pentablock-copolymers-form-smectic-liquid-crystals-as-precursors-for-mussel-byssus-fabrication.pdf
|
657af05d9138d23161a00065
|
10.26434/chemrxiv-2023-tzf48-v3
|
Ni0(cod)(dq) (COD: 1,5-cycloctadiene; DQ: duroquinone) complex as a catalyst precursor for oligothiophene and polythiophene synthesis
|
Nickel-catalyzed syntheses of oligothiophene and polythiophene were carried out with Ni(cod)(dq) (COD: 1,5-cycloctadiene; DQ: duroquinone) as a catalyst precursor. Studies on ligand exchange of Ni(cod)(dq) revealed that a high temperature was necessary to replace COD and DQ with PPh3 and N-heterocyclic carbene IPr. A coupling reaction of a meta-lated 3-hexylthiophene with 2-chloro-3-hexylthiophene employing Ni(cod)(dq) with IPr proceeded with a remarkably re-duced amount of homocoupling byproduct. Polymerization of 2-chloro-3-hexylthiophene with Ni(cod)(dq)/DPPP also re-sulted to reduce the regioregularity defect.
|
Naoki Noda; Seiha Yamaoka; Ukyo Ogi; Masaki Horie; Kentaro Okano; Atsunori Mori
|
Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis; Transition Metal Complexes (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-12-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/657af05d9138d23161a00065/original/ni0-cod-dq-cod-1-5-cycloctadiene-dq-duroquinone-complex-as-a-catalyst-precursor-for-oligothiophene-and-polythiophene-synthesis.pdf
|
60c74a7e469df4de2bf43d50
|
10.26434/chemrxiv.9864071.v2
|
Arene Dearomatization via a Catalytic N-Centered Radical Cascade Reaction
|
<p>This photocatalysis methodology leverages <i>N-</i>centered radicals, from easily
prepared γ,δ-unsaturated <i>N</i>-arylsulfonyl enamides, to initiate a carboamination/dearomatization cascade reaction that generates
stereodefined <a>1,4-cyclohexadiene-fused sultams</a>. This
unique reactivity serves as a general platform for arene dearomatization and
the fused heterocyclic products are viewed as valuable building blocks for drug
discovery programs. </p>
|
Rory McAtee; Efrey Noten; Corey Stephenson
|
Organic Synthesis and Reactions; Photocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-04-23
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74a7e469df4de2bf43d50/original/arene-dearomatization-via-a-catalytic-n-centered-radical-cascade-reaction.pdf
|
65e0577fe9ebbb4db98bbd44
|
10.26434/chemrxiv-2024-8md2k
|
Tailoring Parameters for QM/MM Simulations: Accurate Modeling of Adsorption and Catalysis in Zirconium-Based Metal-Organic Frameworks
|
Quantum mechanics/molecular mechanics (QM/MM) simulations offer an efficient way to model reactions occurring in complex environments. This study introduces a specialized set of charge and Lennard-Jones parameters tailored for electrostatically embedded QM/MM calculations, aiming to accurately model both adsorption processes and catalytic reactions in zirconium-based metal-organic frameworks (Zr-MOFs). To validate our approach, we compare adsorption energies derived from QM/MM simulations against experimental results and Monte Carlo simulation outcomes. The developed parameters showcase the ability of QM/MM simulations to represent long-range electrostatic and van der Waals interactions faithfully. This capability is evidenced by the prediction of adsorption energies with a low root mean square error of 1.1 kcal/mol across a wide range of adsorbates. The practical applicability of our QM/MM model is further illustrated through the study of glucose isomerization and epimerization reactions catalyzed by two structurally distinct Zr-MOF catalysts, UiO-66 and MOF-808. Our QM/MM calculations closely align with experimental activation energies. Importantly, the parameter set introduced here is shown to be compatible with the widely used universal force field (UFF). Moreover, we thoroughly explore how the size of the cluster model and the choice of density functional theory (DFT) methodologies influence the simulation outcomes. This work provides an accurate and computationally efficient framework for modeling complex catalytic reactions within Zr-MOFs, contributing valuable insights into their mechanistic behaviors and facilitating further advancements in this dynamic area of research.
|
Yu-Chi Kao; Yi-Ming Wang; Jyun-Yi Yeh; Shih-Cheng Li; Kevin C.-W. Wu; Li-Chiang Lin; Yi-Pei Li
|
Theoretical and Computational Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry; Computational Chemistry and Modeling
|
CC BY 4.0
|
CHEMRXIV
|
2024-03-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e0577fe9ebbb4db98bbd44/original/tailoring-parameters-for-qm-mm-simulations-accurate-modeling-of-adsorption-and-catalysis-in-zirconium-based-metal-organic-frameworks.pdf
|
67b9fdc46dde43c90802985a
|
10.26434/chemrxiv-2025-16j7d
|
Unraveling the Mn2+ Substitution Effect on the Structural, Magnetic, and Heating Properties of MnxFe3-xO4 Magnetic Nanoparticles
|
Composition is a key parameter to effectively tune the magnetic anisotropy of magnetic nanoparticles, which in turn can modulate their structural-magnetic properties and, thus,their final applications. The Mn2+ content of manganese ferrite nanoparticles (MnxFe3-xO4) deeply impacts their structure, magnetism, and, thus, their capacity as nanoheaters. To properly unveil how Mn2+ content influences these parameters, it is essential to synthesize monodisperse MNPs with similar sizes and shapes. Herein we report the synthesis of a wide range of MnxFe3-xO4 with x = 0.14 to 1.40, with similar polyhedral morphologies and sizes (13 to 15 nm) to exclude the crucial role that size and shape play. We demonstrate that high Mn2+ levels (x ≥ 0.70) lead to structural changes and the appearance of strain defects reflected in their poor saturation magnetization (Ms) values but, without modification of the final crystallite size. For the rest of the samples (in the range of x = 0.0 up to 0.70), average Ms values remain nearly constant despite Mn2+ levels, but the coercive field (Hc) varies significantly, indicating the critical role of composition in driving the transition of the particles towards soft magnets behaviors. As MNPs were synthesized in organic solvents, they were transferred into water using a polymer coating. Even when this step is often overlooked, water transference results in cations leaching, promoting vacancies and changes in the local ferrite structure. These changes had a minor impact on Ms values, suggesting that leaching probably affects the cations located closer to the surface. The magnetic heating capabilities were evaluated by calorimetry and AC magnetometry, finding that the heating capacity increased as the Mn2+ content increased (x ≤ 0.60). Lastly, selected MNPs (x = 0.07 and 0.60) were incubated with MIA PaCa-2 cell line for 24 h, showing an absence of cell cytotoxicity together with a high internalization rate independent of the compositions used. Our detailed analysis provides a better understanding of the effect of composition on the efficiency of heat generation and straightforward guidance for the optimized composition needed to modulate structural-magnetic properties depending on the final applications.
|
Susel Del Sol Fernandez; Oscar F. Odio; Giuseppina Tommasini; Francisco J. Terán; Jesus G. Ovejero; Javier Rubín; Maria Moros
|
Physical Chemistry; Materials Science; Nanoscience; Magnetic Materials; Nanostructured Materials - Nanoscience
|
CC BY 4.0
|
CHEMRXIV
|
2025-02-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67b9fdc46dde43c90802985a/original/unraveling-the-mn2-substitution-effect-on-the-structural-magnetic-and-heating-properties-of-mnx-fe3-x-o4-magnetic-nanoparticles.pdf
|
639938c3836ceb147c80c442
|
10.26434/chemrxiv-2022-v2zhp
|
Post-Synthetic Cyano-Ferrate(II) Functionalization of the Metal–Organic Framework, NU-1000
|
Starting with ferrocyanide ions in acidic aqueous solution, cyano-ferrate(II) species are post-synthetically grafted to the nodes of a mesoporous zirconium-based MOF, NU-1000. As indicated by single-crystal X-ray crystallography, grafting occurs by substitution of cyanide ligands by node-based hydroxo and oxo ligands, rather than by substitution of node aqua ligands by cyanide ligands as bridges between Fe(II) and Zr(IV). The installed moieties yield a broad absorption band that is tentatively ascribed to iron-to-zirconium charge-transfer. Consistent with Fe(III/II) redox activity, a modest fraction of the installed iron complexes are directly electrochemically addressable.
|
Chung-Wei Kung; Ken-ichi Otake; Riki J. Drout; Subhadip Goswami; Omar K. Farha; Joseph T. Hupp
|
Inorganic Chemistry; Coordination Chemistry (Inorg.); Electrochemistry; Materials Chemistry; Crystallography – Inorganic
|
CC BY 4.0
|
CHEMRXIV
|
2022-12-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/639938c3836ceb147c80c442/original/post-synthetic-cyano-ferrate-ii-functionalization-of-the-metal-organic-framework-nu-1000.pdf
|
64bfc3b9b053dad33adb28ad
|
10.26434/chemrxiv-2023-m4f0c
|
A Water-Stable Boronate Ester Cage
|
The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backwards hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is only feasible under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after encapsulation of ruthenium catalysts.
|
Philipp H. Kirchner; Louis Schramm; Svetlana Ivanova; Kazutaka Shoyama; Frank Würthner; Florian Beuerle
|
Organic Chemistry; Nanoscience; Supramolecular Chemistry (Org.); Nanostructured Materials - Nanoscience; Materials Chemistry
|
CC BY NC ND 4.0
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CHEMRXIV
|
2023-07-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64bfc3b9b053dad33adb28ad/original/a-water-stable-boronate-ester-cage.pdf
|
671bdf8b98c8527d9e61c74e
|
10.26434/chemrxiv-2024-l8p2v
|
Absorbents For Ammonia Capture and Storage: Structure and Composition for Stability, Capacity, and Transport
|
Metal halides such as MgCl2 have a high capacity for ammonia absorption and can be used in place of a condenser to efficiently separate ammonia from reactor effluent in the Haber-Bosch process. Although these salts are effective at capturing and storing ammonia, they show reduced working capacity in their pure form with repeated cycling due to slowed uptake and release with particle agglomeration and heat transfer limitations. To stabilize ammonia uptake performance, MgCl2 salt crystals were supported on aluminum fibers. Incorporating aluminum fibers into pure MgCl2 was found to reduce sample charging during electron microscopy and increase bed thermal conductivity. By using a 40 wt.% MgCl2-Al absorbent mixture, ammonia storage capacity was increased 33%, and the absorbent bed thermal conductivity increased by two orders of magnitude over our previously reported absorbent (40 wt.% MgCl2-SiO2). Higher stability of the aluminum-supported MgCl2 was attributed to sorbent surface area stabilized by the aluminum fibers, which guided recrystallization events to maintain small crystals that adhered to the metal surface; thermal conductivity of the metal fibers also suppressed temperature overshoot or undershoot during ammonia uptake or release, respectively.
|
Chinomso Onuoha; William Straub; Tejas Nivarty; Mahdi Malmali; Paul Dauenhauer; Alon McCormick
|
Energy; Chemical Engineering and Industrial Chemistry; Reaction Engineering; Transport Phenomena (Chem. Eng.); Energy Storage; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-10-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671bdf8b98c8527d9e61c74e/original/absorbents-for-ammonia-capture-and-storage-structure-and-composition-for-stability-capacity-and-transport.pdf
|
63efa0919da0bc6b33156884
|
10.26434/chemrxiv-2023-9nv85
|
Orbitrap mass spectrometry and high-field asymmetric waveform ion mobility spectrometry (FAIMS) enable the in-depth analysis of human serum proteoforms
|
Blood serum and plasma are arguably the most commonly analyzed clinical samples, with dozens of proteins serving as validated biomarkers for various human diseases. Top-down proteomics may provide additional insights into disease etiopathogenesis since this approach focuses on protein forms, or proteoforms, originally circulating in blood, potentially providing access to information about relevant post-translational modifications, truncation, single amino acid substitutions and many other sources of protein variation. However, the vast majority of proteomic studies on serum and plasma are carried out using peptide-centric, bottom-up approaches which cannot recapitulate the original proteoform content of samples. Lengthy sample preparation and the need for extensive prefractionation to mitigate proteoform dynamic range issues are likely factors preventing clinical laboratories from routinely performing top-down experiments. In this study, we describe a straightforward protocol for intact proteoform sample preparation based on depletion of albumin and immunoglobulins followed by simplified fractionation of remaining serum proteins via polyacrylamide gel electrophoresis. After molecular weight-based fractionation, we supplemented the traditional liquid chromatography tandem mass spectrometry (LC-MS2) data acquisition with high-field asymmetric waveform ion mobility spectrometry (FAIMS), which served as an additional separation dimension to further simplify serum proteoforms mixtures. This LC-FAIMS-MS2 method led to the identification of over 1,000 serum proteoforms <30 kDa using a reduced number of experiments, more than doubling the number of proteoforms identified in previous studies.
|
Jake Kline; Michael Belford; Cornelia Boeser; Romain Huguet; Ryan Fellers; Joseph Greer; Sylvester Greer; David Horn; Kenneth Durbin; Jean-Jacques Dunyach; Nagib Ahsan; Luca Fornelli
|
Analytical Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-02-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63efa0919da0bc6b33156884/original/orbitrap-mass-spectrometry-and-high-field-asymmetric-waveform-ion-mobility-spectrometry-faims-enable-the-in-depth-analysis-of-human-serum-proteoforms.pdf
|
643910de08c86922fff5e364
|
10.26434/chemrxiv-2023-rpdcg
|
Enhancing water sensing via aggregation-induced emission (AIE) and solvatofluorochromic studies using two new dansyl derivatives containing a disulfide bound: Pollutant metal ions detection and preparation of water-soluble fluorescent polymeric particles
|
Polarity-sensitive dansyl derivatives L1 and L2 were synthesized, and their ability to sense pollutant metal ions was investigated. All compounds were highly sensitive towards Cu2+ and Hg2+ metal ions, while L2 could detect and quantify Hg2+ concentrations as low as 2.5 µM. Both L1 and L2 exhibit positive solvatofluorochromic behaviour, modulated in the presence of water, which in turn results in fluorescence enhancement via aggregation-induced emission (AIE). Seeking stability and water solubility, luminescent L1-based polystyrene-block-polybutadiene-block-polystyrene (SBS) microparticles (size: 520 ± 76 nm) were successfully prepared while maintaining the fluorescence emission of fluorophore L1 (22%). This work shows the dansyl-derivative's multiple properties and promising applications in biomedicine and environmental fields.
|
Frederico Duarte; Georgi Dobrikov; Atanas Kurutos; Hugo M Santos; Javier Fernández-Lodeiro; Jose Luis Capelo-Martínez; Elisabete Oliveira; Carlos Lodeiro
|
Inorganic Chemistry; Sensors; Spectroscopy (Inorg.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643910de08c86922fff5e364/original/enhancing-water-sensing-via-aggregation-induced-emission-aie-and-solvatofluorochromic-studies-using-two-new-dansyl-derivatives-containing-a-disulfide-bound-pollutant-metal-ions-detection-and-preparation-of-water-soluble-fluorescent-polymeric-particles.pdf
|
6727de9cf9980725cffc7a03
|
10.26434/chemrxiv-2024-lld8n-v3
|
Hypothesis of Concerted Reactivity of Singlet Non-Covalent Radical Dimers
|
This work explores the intriguing domain of Frustrated Radical Pairs (FRPs) and their potential to form non-covalent dimers, termed Entangled Radical Pairs (ERPs), which exhibit unique singlet ground states and potential concerted reactivity, differing from traditional stepwise reactions. A few recent publications showed that in certain cases when two radicals cannot form a covalent bond, they unexpectedly form a non-covalent dimer with a singlet ground state. This potentially opens a new elusive route of FRPs’ reactivity, in which both radicals react simultaneously as one molecule. Here, we review several published articles, in which such reactivity probably took place, but was overlooked. The idea presented in this proposal suggests a path towards many interesting reactions, such as low-temperature metal-free dehydrogenation of aliphatic hydrocarbons and others. Additionally, an alternative mechanism for the reactivity of Frustrated Lewis Pairs (FLPs) based on the ERP framework is proposed. Lastly, the implications of the ERP model on the general theory of chemical bond formation are contemplated, suggesting a revision of the traditional views on hybridization and electron entanglement. The manuscript calls for further experimental and theoretical investigations to substantiate the presented hypotheses, aiming to unlock new pathways in radical chemistry and beyond.
|
Gregory Molev
|
Physical Chemistry; Organic Chemistry; Inorganic Chemistry; Bonding; Frustrated Lewis Pairs; Kinetics and Mechanism - Inorganic Reactions
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-11-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6727de9cf9980725cffc7a03/original/hypothesis-of-concerted-reactivity-of-singlet-non-covalent-radical-dimers.pdf
|
656eec9ccf8b3c3cd7d1c34c
|
10.26434/chemrxiv-2023-qxn0j-v2
|
Droplet size dependency and spatial heterogeneity of lipid oxidation in whey protein isolate-stabilized emulsions
|
Spatiotemporal assessment of lipid and protein oxidation is key for understanding quality deterioration in emulsified food products containing polyunsaturated fatty acids. In this work, we first mechanistically validated the use of the lipid oxidation-sensitive fluorophore BODIPY 665/676 as a semi-quantitative marker for local peroxyl radical formation. Next, we assessed the impact of microfluidic and colloid mill emulsification on local protein and lipid oxidation kinetics in whey protein isolate (WPI)-stabilized emulsions. For that purpose, we also used BODIPY 581/591 C11 and CAMPO-AFDye 647 as colocalisation markers for lipid and protein oxidation. The polydisperse emulsions showed an inverse relation between droplet size and lipid oxidation rate. Further, we observed less protein and lipid oxidation occurring in similar sized droplets in monodisperse emulsions. This observation was linked to more heterogeneous protein packing at the droplet surface during colloid mill emulsification, resulting in larger inter-droplet heterogeneity in both protein and lipid oxidation. Our findings indicate the critical roles of emulsification methods and droplet sizes in understanding and managing lipid oxidation.
|
Suyeon Yang; Sten ten Klooster; Khoa Nguyen; Marie Hennebelle; Claire Berton-Carabin; Karin Schroën; John van Duynhoven; Johannes Hohlbein
|
Agriculture and Food Chemistry; Food
|
CC BY 4.0
|
CHEMRXIV
|
2023-12-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/656eec9ccf8b3c3cd7d1c34c/original/droplet-size-dependency-and-spatial-heterogeneity-of-lipid-oxidation-in-whey-protein-isolate-stabilized-emulsions.pdf
|
61d6e71f828c2f203ed8a2bf
|
10.26434/chemrxiv-2022-63b91
|
Molecular Inhibition for Selective CO2 Conversion
|
Electrochemical CO2 reduction presents a sustainable route to the production of chemicals and fuels. Achieving a narrow product distribution with copper catalysts is challenging and conventional material modifications offer limited control over selectivity. Here, we show that the mild cathodic potentials required to reach high currents in an alkaline gas-fed flow cell permits retention of a surface-bound thiol (4-mercaptopyridine), enabling molecule-directed selective formate generation at high reaction rates. Combined experimental and computational results showed that formate production is favoured due to the inhibition of a CO producing pathway caused by destabilising interactions with the anchored molecule. The immobilisation of molecules to inhibit specific carbon-based products therefore offers a novel approach to rationally tune the selectivity of heterogeneous catalysts.
|
Charles Creissen; José Guillermo Rivera de la Cruz; Dilan Karapinar; Dario Taverna; Moritz Schreiber; Marc Fontecave
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Physical Chemistry; Catalysis; Electrocatalysis; Heterogeneous Catalysis; Electrochemistry - Mechanisms, Theory & Study; Materials Chemistry
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CC BY 4.0
|
CHEMRXIV
|
2022-01-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d6e71f828c2f203ed8a2bf/original/molecular-inhibition-for-selective-co2-conversion.pdf
|
6541576648dad23120cb4af0
|
10.26434/chemrxiv-2023-g2v34
|
Compounds from Morchella esculenta as Potential Inhibitors of RNA-Binding Protein La in Ovarian Cancer: A Molecular Modeling and Quantum Mechanics Approach
|
Ovarian cancer (OC) is implicated in most gynecological cancer-related deaths. Currently, the primary treatments for OC are surgery and chemotherapy using platinum-based drugs to induce remission. However, OC recurs in 70-80% of patients within two years, which usually results in the death of most OC patients. La protein is significantly expressed in various malignant tumors, including OC. Previous studies reported that OC patients have significantly higher levels of La protein expression in their serum than healthy individuals, which is related to the poor response to platinum-based chemotherapy. Inhibiting La protein could control the expression of the potential downstream genes involved in promoting proliferation and chemotherapy resistance to OC, which could serve as a therapeutic intervention in treating OC. Extract from Morchella esculenta (morel mushroom) has been reported to contain anti-cancer properties, but no study has reported the interaction of its bioactive compounds with La protein in OC. This study examines the interaction of La protein with some bioactive compounds of Morchella esculenta, as well as their pharmacokinetics and thermochemical properties using structural bioinformatics and advanced theoretical chemistry techniques. Molecular modeling techniques incorporating molecular docking, free energy calculation, MD simulation, drug-likeness, and quantum chemical calculations, including the global hybrid and long-range corrected density functional theory approximations, were employed in this study. Thus, the results identify hits compounds from morchella esculanta, which could serve as a starting for the development of novel LA protein inhibitors for OC therapeutics.
|
Gbenga Dairo; Matthew Ward; Mette Soendergaard; John Determan
|
Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems; Quantum Computing
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CC BY NC 4.0
|
CHEMRXIV
|
2023-11-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6541576648dad23120cb4af0/original/compounds-from-morchella-esculenta-as-potential-inhibitors-of-rna-binding-protein-la-in-ovarian-cancer-a-molecular-modeling-and-quantum-mechanics-approach.pdf
|
62e951a2a05ea1625890a616
|
10.26434/chemrxiv-2021-8wm8v-v2
|
Elucidating the Dynamics of Polymer Transport through Nanopores using Asymmetric Salt Concentrations
|
While notable progress has been made in recent years both experimentally and theoretically in understanding the highly complex dynamics of polymer capture and transport through nanopores, there remains significant disagreement between experimental observation and theoretical prediction that needs to be resolved. Asymmetric salt concentrations, where the concentrations of ions on each side of the membrane are different, can be used to enhance capture rates and prolong translocation times of electrophoretically driven polymers translocating through a nanopore from the low salt concentration reservoir, which are both attractive features for single-molecule analysis. However, since asymmetric salt concentrations affect the electrophoretic pull inside and outside the pore differently, it also offers a useful control parameter to elucidate the otherwise inseparable physics of the capture and translocation process. In this work, we attempt to paint a complete picture of the dynamics of polymer capture and translocation in both symmetric and asymmetric salt concentration conditions by reporting the dependence of multiple translocation metrics on voltage, polymer length, and salt concentration gradient. Using asymmetric salt concentration conditions, we experimentally observe the predictions of tension propagation theory, and infer the significant impact of the electric field outside the pore in capturing polymers and in altering polymer conformations prior to translocation.
|
Martin Charron; Lucas Philipp; Liqun He; Vincent Tabard-Cossa
|
Polymer Science; Nanoscience; Biopolymers; Nanodevices; Nanofluidics
|
CC BY NC 4.0
|
CHEMRXIV
|
2022-08-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62e951a2a05ea1625890a616/original/elucidating-the-dynamics-of-polymer-transport-through-nanopores-using-asymmetric-salt-concentrations.pdf
|
60c7530d337d6c1a29e287f0
|
10.26434/chemrxiv.12745193.v2
|
pH and Anion Effects on Cu-Phosphate Interfaces for CO Electroreduction
|
Herein,
we have investigated the interfacial properties of Cu(111) and Cu(100) in
phosphate buffer solutions at different pH conditions and in presence of CO. Ab
initio molecular simulations of the Cu-electrolyte interface were combined with
voltammetric experiments carried out on Cu(100) and Cu(111) single-crystalline
electrodes. We show that the adsorption strength of phosphate species on the
different Cu facets affects the potential range at which CO poisons the
surface. The properties of the Cu-electrolyte interface controls the potential
range for CO reduction on Cu.
|
Paula Sebastián Pascual; Amanda Schramm Petersen; Alexander Bagger; Jan Rossmeisl; María Escudero-Escribano
|
Electrochemistry - Mechanisms, Theory & Study
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-12-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7530d337d6c1a29e287f0/original/p-h-and-anion-effects-on-cu-phosphate-interfaces-for-co-electroreduction.pdf
|
64466bb9df78ec5015501e11
|
10.26434/chemrxiv-2023-5ml1l
|
Elucidating the reaction pathway of glucose electrooxidation to its valuable products: the Influence of mass transport and electrode potential on the product distribution
|
Converting glucose electrochemically to its valuable derivatives, gluconic and glucaric acid, is a promising process for the utilization of renewable carbon sources. Understanding the reaction pathway to form glucaric acid from glucose is key in performing the process efficiently. In this study we investigate the influence of mass transport as well as electrode potential on the product distribution in glucose, gluconic acid and glucuronic acid oxidation on a gold disk in an RDE-setup. We find glucose and glucuronic acid to be easily oxidized, while the oxidation of gluconic acid is kinetically limited. Combining DFT calculations and the experimental results, we show that on gold, the oxidation of aldehyde groups proceeds readily while the oxidation of hydroxyl groups is challenging and occurs indiscriminately on C-atoms in glucose and its derivatives. Additionally, the DFT calculation present a reaction pathway which can explain the absence of glucuronic acid in the conducted experiments.
|
Matthias Arenz; Nicolas Schlegel; Alexander Bagger; Jan Rossmeisl
|
Physical Chemistry; Catalysis; Electrocatalysis; Electrochemistry - Mechanisms, Theory & Study; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64466bb9df78ec5015501e11/original/elucidating-the-reaction-pathway-of-glucose-electrooxidation-to-its-valuable-products-the-influence-of-mass-transport-and-electrode-potential-on-the-product-distribution.pdf
|
60c74846842e658e88db2b61
|
10.26434/chemrxiv.11874735.v1
|
Seeing is Believing: Experimental Spin States from Machine Learning Model Structure Predictions
|
<p>Determination of ground-state spins of open-shell transition metal complexes is critical to understanding catalytic and materials properties but also challenging with approximate electronic structure methods. As an alternative approach, we demonstrate how structure alone can be used to guide assignment of ground-state spin from experimentally determined crystal structures of transition metal complexes. We first identify the limits of distance-based heuristics from distributions of metal–ligand bond lengths of over 2,000 unique mononuclear Fe(II)/Fe(III) transition metal complexes. To overcome these limits, we employ artificial neural networks (ANNs) to predict spin-state-dependent metal–ligand bond lengths and classify experimental ground state spins based on agreement of experimental structures with the ANN predictions. Although the ANN is trained on hybrid density functional theory data, we exploit the method-insensitivity of geometric properties to enable assignment of ground states for the majority (ca. 80-90%) of structures. We demonstrate the utility of the ANN by data-mining the literature for spin-crossover (SCO) complexes, which have experimentally-observed temperature-dependent geometric structure changes, by correctly assigning almost all (> 95%) spin states in the 46 Fe(II) SCO complex set. This approach represents a promising complement to more conventional energy-based spin-state assignment from electronic structure theory at the low cost of a machine learning model. </p>
|
Michael Taylor; Tzuhsiung Yang; Sean Lin; Aditya Nandy; Jon Paul Janet; Chenru Duan; Heather Kulik
|
Organometallic Compounds; Computational Chemistry and Modeling; Machine Learning; Theory - Organometallic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-02-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74846842e658e88db2b61/original/seeing-is-believing-experimental-spin-states-from-machine-learning-model-structure-predictions.pdf
|
66b3e5985101a2ffa87427f9
|
10.26434/chemrxiv-2024-8xc0d
|
Gabriel Synthesis of Aminomethyl-Bicyclo[1.1.0]butanes
|
The reaction of iodo-bicyclo[1.1.1]pentanes with potassium phthalimide yields phthalimide-substituted bicyclo[1.1.0]butanes (BCBs), which upon hydrazinolysis afford the corresponding aminomethyl-BCB products.
|
Manivel Pitchai; Nanjundaswamy K.C.; Sankar Ulaganathan; Mohammad Javeed; Pavan Srinivas; Sourav Roy; Sarah Traeger; James Mignone; Elizabeth Jurica; Kumar Pabbisetty; Muthalagu Vetrichelvan; Anuradha Gupta; Arvind Mathur; Michael Mandler
|
Biological and Medicinal Chemistry; Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions
|
CC BY 4.0
|
CHEMRXIV
|
2024-08-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b3e5985101a2ffa87427f9/original/gabriel-synthesis-of-aminomethyl-bicyclo-1-1-0-butanes.pdf
|
6684345f01103d79c5cdd501
|
10.26434/chemrxiv-2024-xj5bw
|
Discovery and Application of a Lysine 5-Hydroxylase for
Bioorthogonal Chemistry
|
The selective functionalization of unactivated C(sp3)–H bonds remains an ongoing challenge in synthetic organic chemistry. In this context, biocatalysis provides an attractive strategy to perform such chemistry under mild reaction conditions. We now report the discovery of K5H, the first enzyme that catalyzes the one-step conversion of free L-lysine into enantiopure (2S, 5R)-5-hydroxylysine (5-Hyl), producing a β-amino alcohol motif on the lysine side-chain. As chiral β-amino alcohols are versatile synthetic motifs found in natural products, pharmaceuticals, ligands, and other complex molecules, we demonstrate that this noncanonical amino acid can be incorporated into several pharmaceutically-relevant peptides in place of lysine through a tandem one-pot biocatalytic cascade using in vitro transcription/translation. Indeed, we show that the introduction of a single hydroxyl group adjacent to the ε-amine on lysine serves as a selective handle for downstream bioorthogonal chemistry such as heterocyclization, ligation to various payloads, and formation of branched peptides. Taken together, the discovery and characterization of K5H provides a modular genetically-encoded platform to tune the structure and properties of diverse bioactive peptides via biocatalytic transformations of unactivated C(sp3)–H bonds.
|
Elizabeth Stone; Andrew Whitten; Nicole Angelisanti; Elijah Kissman; Douglas Millar; Adriana Vargas-Figueroa; Michelle Chang
|
Biological and Medicinal Chemistry; Organic Chemistry; Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-07-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6684345f01103d79c5cdd501/original/discovery-and-application-of-a-lysine-5-hydroxylase-for-bioorthogonal-chemistry.pdf
|
645c8ab9a32ceeff2d7299e0
|
10.26434/chemrxiv-2023-g32v5
|
Eco-friendly fabrication of boron nitride aerogels for multifunctional applications
|
Over the years, researchers have begun to spend more time looking at the applications of aerogels in the semiconductor industry, especially for boron nitride aerogels, which have a few more superior properties than carbon aerogels. However, the production method of boron nitride aerogels is far less looked at, and still needs more research to find a more eco-friendly fabrication method, which is a gap in research that needs to be explored. Thus, in this research paper, several different boron nitride aerogels are made using different materials, and the type of boron nitride aerogel with the best heat resistant property and structure is determined.
|
Samuel Wang
|
Chemical Engineering and Industrial Chemistry; Thermodynamics (Chem. Eng.)
|
CC BY 4.0
|
CHEMRXIV
|
2023-05-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/645c8ab9a32ceeff2d7299e0/original/eco-friendly-fabrication-of-boron-nitride-aerogels-for-multifunctional-applications.pdf
|
67bdda626dde43c9086c7d41
|
10.26434/chemrxiv-2025-67h0z
|
Stepwise Spin-State Switching with Symmetry Breaking and ON/OFF Photo-switching in Iron(II) Complex
|
In recent world advancement and the quest for smart multi-functional material, stimuli-responsive molecular bistable systems offer unique opportunities to explore their applicability in molecular switches, data storage, and sensing technologies. Multi-stimuli responsive stepwise Spin Crossover (SCO) systems stand tall in this area. While the effects of external stimuli, particularly thermal variations and photoirradiation on the magneto-structural properties of SCO systems have been extensively studied, the area of pressure-modulated stepwise spin crossover and its associated magneto-structural changes remains lesser explored. Herein, we report a mononuclear iron(II) complex containing tetradentate macrocyclic ligand with -diimine-based bidentate coligand, [Fe(L)(bik*)](BPh4)2 (1) (L = N,N'-di-iso-propyl-2,11-diaza[3,3](2,6)pyridinophane and bik* = bis(1-ethyl-1H-imidazol-2-yl)ketone)) undergoing a reversible stepwise thermo-induced spin-state switching with the presence of three spin-states HS, LS, and an ordered HS-LS with the exciting re-entrant symmetry breaking during the spin-state switching process. The influence of external pressure on the structure and magnetic response is thoroughly studied, where the pressure-induced modification in the intermolecular interactions leads to enhanced cooperativity and a hysteretic stepwise spin state switching. The versatility of the systems is further explored where 1 displays a reversible ON/OFF photo-switching between a photo-induced paramagnetic metastable HS and diamagnetic LS states under light irradiations at low temperatures along with light-induced excited spin state trapping (LIESST).
|
Sakshi Mehta; Sujit Kamilya; Sounak Ghosh; Debopam Sarkar; Yanling Li; Rodrigue Lescouëzec; Mathieu Rouzières; Jiří Pechoušek; Pradip Kumar Mondal; Irshad Kariyattuparamb Abbas; Boby Joseph; Subrata Ghosh; Abhishake Mondal
|
Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism; Materials Chemistry; Crystallography – Inorganic
|
CC BY 4.0
|
CHEMRXIV
|
2025-02-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bdda626dde43c9086c7d41/original/stepwise-spin-state-switching-with-symmetry-breaking-and-on-off-photo-switching-in-iron-ii-complex.pdf
|
67d1f95781d2151a022a9462
|
10.26434/chemrxiv-2024-zkz7v-v3
|
Nuclear quantum effects and the Grotthuss mechanism dictate the pH of liquid water
|
Water’s ability to autoionize into hydronium (H3O+) and hydroxide (OH−) ions dictates the acidity or basicity of aqueous solutions, influencing the reaction pathways of many chemical and biochemical processes. In this study, we determine the molecular mechanism of the autoionization process by leveraging both the computational efficiency of a deep neural network potential trained on highly accurate data calculated within density-corrected density functional theory and the ability of enhanced sampling techniques to ensure a comprehensive exploration of the underlying multidimensional free- energy landscape. By properly accounting for nuclear quantum effects, our simulations provide an accurate estimate of autoionization constant of liquid water (pKw = 13.71 ± 0.16), offering a realistic molecular-level picture of the autoionization process and emphasizing its quantum-mechanical nature. Importantly, our simulations highlight the central role played by the Grotthuss mechanism in stabilizing solvent-separated ion pair configurations, revealing its profound impact on acid-base equilibria in aqueous environments.
|
Saswata Dasgupta; Giuseppe Cassone; Francesco Paesani
|
Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Physical and Chemical Processes; Solution Chemistry; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d1f95781d2151a022a9462/original/nuclear-quantum-effects-and-the-grotthuss-mechanism-dictate-the-p-h-of-liquid-water.pdf
|
642f8213a41dec1a569c95ce
|
10.26434/chemrxiv-2023-6xg1d
|
Chemical Shrinkage Characterization during Curing through Three-Dimensional Digital Image Correlation
|
Chemical shrinkage in thermosetting polymers drives residual stress development and induces residual
deformation in composite materials. Accurate characterization of chemical shrinkage during curing is
therefore vital to minimize residual stresses through process modeling and optimize composite
performance. This work introduces a novel methodology to measure the pre- and post-gelation chemical
shrinkage of an epoxy resin using three-dimensional digital image correlation (3D-DIC). Differential
scanning calorimetry (DSC) is employed to calculate reaction kinetics and correlate chemical shrinkage
with the degree of cure. Rheology experiments are conducted to quantify gelation and validate post-gelation.
3D-DIC post-gelation results show excellent agreement with rheology. Pre-gelation results show the effect
of the in-situ curing in the proximity of constraints on the global strain behavior. This work introduced an innovative approach to characterize the chemical shrinkage of thermosets during curing, which will enable
accurate residual stress prediction for enhancing thermoset composite performance and provide insight into
the in-situ polymer behavior during processing.
|
Kalima Bukenya; Sagar Shah; Alessandro Sabato; Marianna Maiaru
|
Organic Chemistry; Materials Science; Polymer Science; Composites; Materials Processing; Polymerization (Polymers)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/642f8213a41dec1a569c95ce/original/chemical-shrinkage-characterization-during-curing-through-three-dimensional-digital-image-correlation.pdf
|
64135465dab08ad68f38c399
|
10.26434/chemrxiv-2023-3wsw3
|
Monitoring mAb proteoforms in mouse plasma using an automated immunocapture combined with top-down and middle-down mass spectrometry
|
Monoclonal antibodies (mAbs) have established themselves as the leading biopharmaceutical therapeutic modality. Once the developability of a mAb drug candidate has been assessed, an important step is to check its in vivo stability through pharmacokinetics (PK) studies. The gold standard is ligand-binding assay (LBA) and LC–MS (Liquid Chromatography- Mass Spectrometry) performed at the peptide level (bottom-up approach). However, these analytical techniques do not allow to address the different mAb proteoforms that can arise from biotransformation. In recent years, top-down and middle-down mass spectrometry approaches have gained popularity to characterize proteins at the proteoform level but are not yet widely used for PK studies. We propose here a workflow based on an automated immunocapture followed by top-down and middle-down LC-MS/MS approaches to characterize mAb proteoforms spiked in mouse plasma. We demonstrate the applicability of our workflow on a large concentration range using pembrolizumab as a model. We also compare the performance of two state-of-the-art Orbitrap platforms (Tribrid Eclipse and Exploris 480) for these studies. The added value of our workflow for an accurate and sensitive characterization of mAb proteoforms in mouse plasma is highlighted.
|
Jonathan DHENIN; Valérie Lafont; Mathieu Dupré; Alain Krick; Christine Mauriac; Julia Chamot-Rooke
|
Analytical Chemistry; Biochemical Analysis; Mass Spectrometry; Separation Science
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-03-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64135465dab08ad68f38c399/original/monitoring-m-ab-proteoforms-in-mouse-plasma-using-an-automated-immunocapture-combined-with-top-down-and-middle-down-mass-spectrometry.pdf
|
60c746ca4c89193b3cad2bcf
|
10.26434/chemrxiv.11409525.v1
|
SEA Ligation Is Accelerated at Mildly Acidic pH. Application to the Formation of Difficult Peptide Junctions
|
The bis(2-sulfanylethyl)amido (SEA)-mediated ligation has been introduced in 2010 as a novel chemoselective peptide bond forming reaction. SEA ligation is a useful reaction for protein total synthesis that is complementary to the native chemical ligation (NCL). In particular, SEA ligation proceeds efficiently in a wide range of pH, from neutral pH to pH 3-4. Thus, the pH can be chosen to optimize the solubility of the peptide segments or final product. It can be also chosen to facilitate the formation of difficult junctions, since the rate of SEA ligation increases significantly by decreasing the pH from 7.2 to 4.0. Here we describe a protocol for SEA ligation at pH 5.5 in the presence of 4-mercaptophenylacetic acid (MPAA) or at pH 4.0 in the presence of a newly developed diselenol catalyst. The protocols describe the formation of a valyl-cysteinyl peptide bond between two model peptides.<br />
|
Marine Cargoet; Vincent Diemer; Laurent Raibaut; Elizabeth Lissy; Benoît Snella; Vangelis Agouridas; Oleg Melnyk
|
Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Organocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-12-23
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746ca4c89193b3cad2bcf/original/sea-ligation-is-accelerated-at-mildly-acidic-p-h-application-to-the-formation-of-difficult-peptide-junctions.pdf
|
60c75562842e654f73db4312
|
10.26434/chemrxiv.14098652.v1
|
Tuning the Spin-Crossover Properties of the [(Cp1-R)2Mn] Metallocenes
|
<p>
In this work, we present a computational study
using density functional theory (DFT) on how the single
functionalization
of the cyclopentadienyl ligand in<br />
[(Cp<sup>1-R</sup>)<sub>2</sub>Mn]
systems can be used to tune the spin-crossover properties in such
systems. Using the OLYP functional, accurate values for the
transition temperature (<i>T</i><sub>1/2</sub>)
can be obtained, and our DFT methodology can be used to explore the
effect that different substituents have on tuning such quantity. In
particular, we show that the electronic structure of the [(Cp<sup>1-R</sup>)<sub>2</sub>Mn]
can be tuned via the R group, allowing for a fine-tuning degree of
the <i>T</i><sub>1/2</sub>
that expands between 0 and 400 K. Our results allow for a rational
design of new manganocene based systems with tailored SCO properties.</p>
|
Florian Matz; Jordi Cirera
|
Organometallic Compounds; Computational Chemistry and Modeling; Transition Metal Complexes (Organomet.)
|
CC BY 4.0
|
CHEMRXIV
|
2021-02-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75562842e654f73db4312/original/tuning-the-spin-crossover-properties-of-the-cp1-r-2mn-metallocenes.pdf
|
65414000c573f893f18683e8
|
10.26434/chemrxiv-2023-125r5
|
Synthesis and Chemistry of 5,6,7,8-Tetrahydro-4H-Pyrazolo[1,5-a] [1,4]Diazepine-2-Carboxylates.
|
5,6,7,8-tetrahydro-4H-pyrazolo[1,5-a] diazepine carboxylates are valuable scaffolds for drug design and medicinal chemistry. In this paper we disclose a short scalable synthesis and chemical reactivity patterns of the pyrazolo-diazepine pharmacophore. Commercial and cheaply available Methyl pyrazole 3,5-dicarboxylate was alkylated with 3-bromo-N-Boc propyl amine and the resulting derivative underwent concomitant cyclization upon deprotection of the Boc protecting group to yield the pyrazolo-diazepine skeleton. Selective reduction of the lactam was accomplished cleanly using borane and the resulting amine was pro-tected using a tert-butyloxycarbonyl protecting group. The free N-terminal of the diazepine underwent smooth Buchwald and Chan arylations among various standard chemistry applications examined on this pharmacophore.
|
Anwar Hussain; Jason Kingsbury; Yu Kawamata; Maya Natarajan
|
Organic Chemistry; Organic Synthesis and Reactions
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-11-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65414000c573f893f18683e8/original/synthesis-and-chemistry-of-5-6-7-8-tetrahydro-4h-pyrazolo-1-5-a-1-4-diazepine-2-carboxylates.pdf
|
65b045a166c13817291e637c
|
10.26434/chemrxiv-2024-fvbdh
|
Controlling Rates and Reversibilities of Elimination Reactions of Hydroxybenzylammoniums by Tuning Dearomatization Energies
|
Hydroxybenzylammonium compounds can undergo a reversible 1,4- or 1,6-elimination to afford quinone methide intermediates after release of the amine. These molecules are useful for the reversible conjugation of payloads to amines in proteins and peptides. We hypothesized that aromaticity could be used to alter the rate of reversibility as a distinct driving force. We describe the use of density functional theory (DFT) calculations to determine the effect of aromaticity on the rate of release of the amine from hydroxybenzylammonium compounds. Namely, altering the aromatic scaffold to lower the energy of dearomatization reduces the kinetic barrier and prevents the reversibility of the amine elimination. We consequently synthesized a small library of polycyclic hydroxybenzylammoniums, which resulted in a range of release half-lives from 18 minutes to 350 hours. The novel mechanistic insight provided in this study significantly expands the range of release rates amenable to hydroxybenzylammonium-containing compounds. This work is useful for the field of traceless, self-immolative linkers as it provides another way to affect the rate of payload release.
|
Zihuan Fu; Joseph Treacy; Brock Hosier; Kendall Houk; Heather Maynard
|
Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-02-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65b045a166c13817291e637c/original/controlling-rates-and-reversibilities-of-elimination-reactions-of-hydroxybenzylammoniums-by-tuning-dearomatization-energies.pdf
|
6437014308c86922ffdc4898
|
10.26434/chemrxiv-2023-jnq5d
|
Multimodal investigation of electronic transport in PTMA: Impact on organic radical battery performance
|
Organic radical batteries (ORBs) represent a viable pathway to a more sustainable energy storage technology compared to conventional Li-ion batteries. For further materials and cell development towards competitive energy and power densities, a deeper understanding of electron transport and conductivity in organic radical polymer cathodes is required. Such electron transport is characterised by electron hopping processes, which depend on the presence of closely spaced hopping sites. Using a combination of electrochemical, electron paramagnetic resonance (EPR) spectroscopic, and theoretical molecular dynamics (MD) as well as density functional theory (DFT) modelling techniques, we explored how compositional characteristics of cross-linked poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) polymers govern electron hopping and rationalise their impact on ORB performance. Electrochemistry and EPR spectroscopy not only show a correlation between capacity and the total number of radicals in an ORB using a PTMA cathode, but also indicates that the state-of-health degrades about twice as fast if the amount of radical is reduced by 15%. The presence of up to 3% free monomer radicals did not improve fast charging capabilities. Pulsed EPR indicated that these radicals readily dissolve into the electrolyte but a direct effect on battery degradation could not be shown. However, a qualitative impact cannot be excluded either. The work further illustrates that nitroxide units have a high affinity to the carbon black conductive additive, indicating the possibility of its participation in electron hopping. At the same time, the polymers attempt to adopt a compact conformation to increase radical–radical contact. Hence, a kinetic competition exists, which might gradually be altered towards a thermodynamically more stable configuration by repeated cycling, yet further investigations are required for its characterisation.
|
Davis Thomas Daniel; Steffen Oevermann; Souvik Mitra; Katharina Rudolf; Andreas Heuer; Rüdiger-A. Eichel; Martin Winter; Diddo Diddens; Gunther Brunklaus; Josef Granwehr
|
Physical Chemistry; Materials Science; Energy; Electrochemistry - Mechanisms, Theory & Study; Physical and Chemical Properties; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6437014308c86922ffdc4898/original/multimodal-investigation-of-electronic-transport-in-ptma-impact-on-organic-radical-battery-performance.pdf
|
60c749f8702a9b7f6f18b1f8
|
10.26434/chemrxiv.12133203.v1
|
Pyridine Bridging Diphenylamine-Carbazole with Linking Topology as Rational Hole Transporter for Perovskite Solar Cells Fabrication
|
<p>Developing cost-effective
and rational hole transporting materials is critical for fabricating high-performance
perovskite solar cells (PSCs) and to promote their commercial endeavor. We have
designed and developed pyridine (core) bridging diphenylamine-substituted
carbazole (arm) small molecules, named as <b>2,6PyDANCBZ
</b>and <b>3,5PyDANCBZ</b>. The linking
topology of core and arm on their photophysical, thermal, semiconducting and
photovoltaic properties were probed systematically. We found that the <b>2,6PyDANCBZ </b>shows higher mobility and
conductivity along with uniform film-forming ability as compared to <b>3,5PyDANCBZ</b>. The PSCs fabricated with <b>2,6PyDANCBZ </b>supersede the performance delivered
by Spiro-OMeTAD, and importantly also gave improved long-term stability. Our
findings put forward small molecules based on core-arm linking topology for
cost-effective hole selective layers designing.</p>
|
Peng Huang; Manju -; Samrana Kazim; Gangala Sivakumar; Manuel Salado; Rajneesh Misra; Shahzada Ahmad
|
Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials; Optical Materials; Thin Films
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-04-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749f8702a9b7f6f18b1f8/original/pyridine-bridging-diphenylamine-carbazole-with-linking-topology-as-rational-hole-transporter-for-perovskite-solar-cells-fabrication.pdf
|
66650bf4e7ccf7753a556e6f
|
10.26434/chemrxiv-2024-zr8zv
|
Hypershifted Spin Spectroscopy with Dynamic Nuclear Polarization at 1.4 K
|
Dynamic nuclear polarization (DNP) is a nuclear magnetic resonance (NMR) hyperpolarization technique that mediates polarization transfer from unpaired electrons to nearby nuclear spins, which then relay the polarization to more remote nuclear spins in the bulk via spin diffusion. Despite widespread applications of DNP, the role of these nearby nuclear spins has never been properly characterized because they were hitherto believed to be unobservable or ‘hidden’ due to severe shifts or line broadening due to strong electron-nuclear couplings, i.e., their NMR resonances are ‘hypershifted’ beyond detection limit. By using DNP on a frozen glycerol-water mixture (‘DNP juice’) doped with TEMPOL at 1.4 K, we employed a newly introduced technique known as SPIn Diffusion Enhanced Saturation Transfer (SPIDEST), to indirectly reveals the spectrum of these hypershifted spins. Then, we performed direct two-pulse echo experiment, and we report here the results of the first direct observation of these hypershifted 1H nuclear spins under actual DNP conditions. The inhomogeneously broadened 1H NMR lines span a range of 10 MHz and can be directly observed by acquiring a series of frequency-stepped NMR spectra. Experiments repeated with deuterated TEMPOL proves that the hypershifted 1H signals indeed originate from methyl and methylene protons that are covalently attached to TEMPOL. In addition to characterizing the relaxation times (T1 and T2) of these nearby nuclei, we show that their polarization can be transferred to the bulk via spin diffusion using 2D NMR, i.e., the transport is not impeded by a spin diffusion barrier, as has been widely believed so far. This work presents a new form of spectroscopy that directly characterizes the nearby nuclei that we like to refer to as “hypershifted” nuclei. This could lead to the design of more efficient DNP polarizing agents and to a better understanding of the role of the molecular structures of paramagnetic agents.
|
Zhenfeng Pang; Kirill Sheberstov; Bogdan A. Rodin; Jake Lumsden; Utsab Banerjee; Daniel Abergel; Geoffrey Bodenhausen; Kong Ooi Tan
|
Physical Chemistry; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-06-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66650bf4e7ccf7753a556e6f/original/hypershifted-spin-spectroscopy-with-dynamic-nuclear-polarization-at-1-4-k.pdf
|
633f69f0cf382942acc06ca5
|
10.26434/chemrxiv-2022-0rszc
|
App-Free Method for Visualization of Polymers in 3D and Augmented Reality
|
The rise of virtual and online education in recent years has led to the development and popularization of many online tools, notably 3D models and augmented reality (AR), for visualizing various structures in chemical sciences. The majority of the developed tools focus on either small molecules or biological systems, as information regarding their structure can be easily accessed from online databases or obtained through relatively quick theoretical calculations. As such, due to a lack of crystallographic and theoretical data available for non-biological macromolecules, there is a noticeable lack of accessible online tools for the visualization of polymers in 3D. Herein, using a few sample polymers, we showcase a workflow for the generation of 3D models using molecular dynamics and Blender. The 3D structures can then be hosted on p3d.in, where AR models can be generated automatically. Furthermore, the hosted 3D models can then be shared via quick response (QR) codes and used in various settings without the need to download any applications.
|
Hootan Roshandel; Matthew Shammami; Shiyun Lin; Yin-Pok Wong; Paula Diaconescu
|
Polymer Science; Chemical Education; Polymer chains; Polymer morphology
|
CC BY 4.0
|
CHEMRXIV
|
2022-10-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/633f69f0cf382942acc06ca5/original/app-free-method-for-visualization-of-polymers-in-3d-and-augmented-reality.pdf
|
60c73d0dbdbb894e96a37bed
|
10.26434/chemrxiv.5368474.v1
|
Two Mechanisms Determine Quantum Dot Blinking
|
<p>Many potential applications of quantum dots (QDs) can only be realized once the luminescence from single nanocrystals is understood. These applications include the development of quantum logic devices, single photon sources, long-life LEDs, and single molecule biolabels. At the singlenanocrystal level, random fluctuations in the QD photo-luminescence (PL) occur, a phenomenon termed blinking. There are two competing models to explain this blinking: Auger recombination and surface trap induced recombination. Here we use lifetime scaling on core-shell NCs with close to unity quantum yield to demonstrate that both types of blinking occur in the same QDs.</p>
<p><br /></p><p>We prove that Auger-blinking can yield exponential on/off times in contrast to earlier work. The surface passivation strategy determines which blinking mechanism dominates. This study unifies earlier studies on blinking mechanisms and provides direct evidence that stable single QDs can be engineered for optoelectronic applications.</p>
|
Gangcheng Yuan; Daniel E. Gomez; Nicholas Kirkwood; KLAUS BOLDT; Paul Mulvaney
|
Plasmonic and Photonic Structures and Devices
|
CC BY NC 4.0
|
CHEMRXIV
|
2018-05-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d0dbdbb894e96a37bed/original/two-mechanisms-determine-quantum-dot-blinking.pdf
|
65133b9eade1178b242ba036
|
10.26434/chemrxiv-2023-pzwp3
|
From light to hydrogen: the complete life cycle of free charges in organic photocatalytic nanoparticles
|
The blend of polymeric donor PM6 and non-fullerene acceptor Y6 is high performing as both an active layer in organic photovoltaics and as a nanoparticulate photocatalyst for the renewable production of hydrogen gas. Despite the high performance of PM6:Y6 blends, many aspects of the photophysics of this material remain unclear. Here we present a detailed spectroscopic analysis of bulk heterojunction PM6:Y6 nanoparticles for photocatalytic hydrogen evolution over 11 orders of magnitude in time, ranging from tens of femtoseconds to hundreds of microseconds. We find that the excitation of Y6 primarily results in the formation of charges first in Y6 domains, followed by diffusion of Y6 holes to PM6 domains. Upon excitation of PM6, charges are generated through two mechanisms: (1) energy transfer to Y6 followed by exciton dissociation and back hole transfer to PM6, and (2) electron transfer to Y6 facilitated by an interfacial charge-transfer state. We use kinetic modelling to confirm these mechanisms and determine the rates of formation and recombination of charges. We also investigate the PM6:Y6 nanoparticles under photocatalytic conditions, and show that the Pt co-catalyst can accept both Y6 electrons and Y6 holes on relatively fast (<100 ps) timescales, and that the sacrificial electron donor ascorbic acid scavenges holes from both components on picosecond and microsecond timescales. The results highlight the critical importance of rapid free polaron formation in Y6 domains, and point towards harnessing this property of the Y-series and other non-fullerene acceptors to develop industrially viable organic hydrogen-evolution photocatalysts.
|
Jessica de la Perrelle; Rohan Hudson; Andrew Dolan; Sanjib Jana; Xun Pan; Mats Andersson; Howe-Siang Tan; Trevor Smith; David Huang; Tak W. Kee
|
Physical Chemistry; Catalysis; Energy; Heterogeneous Catalysis; Chemical Kinetics; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-09-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65133b9eade1178b242ba036/original/from-light-to-hydrogen-the-complete-life-cycle-of-free-charges-in-organic-photocatalytic-nanoparticles.pdf
|
60c742ac337d6c9abde26aa5
|
10.26434/chemrxiv.8345516.v1
|
Boron-Nitrogen Doped Dihydroindeno[1,2-b]fluorene Derivatives as Acceptors in Organic Solar Cells
|
The electrophilic borylation of 2,5-diarylpyrazines
results in the formation of boron-nitrogen doped dihydroindeno[1,2-<i>b</i>]fluorene which can be synthesized via
mildly air-sensitive techniques and the end products handled readily under
atmosphereic conditions. Through transmetallation via diarylzinc reagents a series
of derivatives were sythesized which show broad absorption profiles that
highlight the versatility of this backbone to be used in organic solar cell
devices. These compounds can be synthesized in large yields, in alow number of
steps and functionalized at many stages along the way providing a large depth
of possibilities. Exploratory device paramaters were studied and show PCE of
2%.
|
Matthew Morgan; Maryam Nazari; Thomas Pickl; J. Mikko Rautiainen; Heikki M. Tuononen; Warren Piers; Gregory C. Welch; Benjamin
S. Gelfand
|
Main Group Chemistry (Inorg.); Theory - Computational; Photovoltaics
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-07-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c742ac337d6c9abde26aa5/original/boron-nitrogen-doped-dihydroindeno-1-2-b-fluorene-derivatives-as-acceptors-in-organic-solar-cells.pdf
|
65e60104e9ebbb4db9e39fcc
|
10.26434/chemrxiv-2023-nj817-v2
|
Impacts of Supercapacitor Electrode Structure on Electrochemical CO2 Capture
|
Supercapacitors are emerging as energy-efficient and robust devices for electrochemical CO2 capture. However, the impacts of electrode structure and charging protocols on CO2 capture performance, including the stability and CO2 selectivity over O2, remain unclear. Therefore, this study develops structure-property-performance correlations for supercapacitor electrodes at different charging conditions. We find that electrodes with large surface areas and low oxygen functionalization generally perform best, while a combination of micro- and meso-pores is important to achieve fast CO2 capture rates. With these structural features and tunable charging protocols, YP80F activated carbon electrodes show the best CO2 capture performance with a CO2 capture rate of 350 mmolCO2 kg–1 h–1 and a low electrical energy consumption of 18 kJ molCO2–1 at 300 A kg–1 under CO2, together with a long lifetime over 12000 cycles at 150 A kg–1 under CO2 and excellent CO2 selectivity over N2 and O2. Operated in a “positive charging mode”, the system achieves excellent electrochemical reversibility with Coulombic efficiencies over 99.8% in the presence of approximately 15% O2, alongside stable cycling performance over 1000 cycles. This study paves the way for improved supercapacitor electrodes and charging protocols for electrochemical CO2 capture.
|
Zhen Xu; Grace Mapstone; Zeke Coady; Mengnan Wang; Tristan Spreng; Xinyu Liu; Alexander Forse
|
Materials Science; Energy; Chemical Engineering and Industrial Chemistry; Carbon-based Materials; Energy Storage
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-03-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e60104e9ebbb4db9e39fcc/original/impacts-of-supercapacitor-electrode-structure-on-electrochemical-co2-capture.pdf
|
64cba01869bfb8925a49e4bd
|
10.26434/chemrxiv-2023-gmgk6-v2
|
Rapid chemical screening of microplastics and nanoplastics by thermal desorption and pyrolysis mass spectrometry with unsupervised fuzzy clustering
|
The transport and chemical identification of microplastics and nanoplastics (MNPs) are critical to the concerns over plastic accumulation in the environment. Chemically and physically transient MNP species present unique challenges for isolation and analysis due to many factors such as their size, color, surface properties, morphology, and potential for chemical change. These factors contribute to the eventual environmental and toxicological impact of MNPs. As analytical methods and instrumentation continue to be developed for this application, analytical test materials will play an important role. Here, a direct mass spectrometry screening method was developed to rapidly characterize manufactured and weathered MNPs, complementing lengthy pyrolysis-gas chromatography mass spectrometry analyses. The chromatography-free measurements took advantage of Kendrick mass defect analysis, in-source collision induced dissociation, and advancements in machine learning approaches for data analysis of the complex mass spectra. In this study, we applied Gaussian mixture models and fuzzy c-means clustering for the unsupervised analysis of MNP sample spectra, incorporating clustering stability and information criterion measurements to determine latent dimensionality. These models provided insight into the composition of mixed and weathered MNP samples. The multiparametric data acquisition and machine learning approach presented improved confidence in polymer identification and differentiation.
|
Thomas P Forbes; John M Pettibone; Eric Windsor; Joseph M Conny; Robert A Fletcher
|
Theoretical and Computational Chemistry; Analytical Chemistry; Environmental Analysis; Mass Spectrometry; Machine Learning; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-08-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64cba01869bfb8925a49e4bd/original/rapid-chemical-screening-of-microplastics-and-nanoplastics-by-thermal-desorption-and-pyrolysis-mass-spectrometry-with-unsupervised-fuzzy-clustering.pdf
|
60c75885ee301c0601c7b74d
|
10.26434/chemrxiv.14555532.v1
|
Unavoidable Failure of Point Charge Descriptions of Electronic Density Changes for Out-of-Plane Distortions
|
<div>Population analyses based on point charge approximations accurately estimating the equilibrium dipole moment will systematically fail when predicting infrared intensities of out-of-plane vibrations of planar molecules, whereas models based on both charges and dipoles will always succeed. It is not a matter of how the model is devised, but on its number of degrees of freedom. Population analyses based on point charges are very limited in terms of the amount of meaningful chemical information they provide, whereas models employing both atomic charges and atomic dipoles should be preferred for molecular distortions. A good model should be able to correctly describe not only static, equilibrium structures but also distorted geometries in order to correctly assess information from vibrating molecules. The limitations of point charge models also hold for distortions much larger than those encountered vibrationally.</div>
|
Wagner Richter; Leonardo
J. Duarte; Roy E. Bruns
|
Computational Chemistry and Modeling; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-05-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75885ee301c0601c7b74d/original/unavoidable-failure-of-point-charge-descriptions-of-electronic-density-changes-for-out-of-plane-distortions.pdf
|
6275f39d59f0d63470871d80
|
10.26434/chemrxiv-2022-nk6h3
|
Principles of Alternating Access in LeuT-fold Transporters: Commonalities and Divergences
|
Found in all domains of life, transporters belonging to the LeuT-fold class mediate the import and exchange of hydrophilic and charged compounds such as amino acids, metals, and sugar molecules. Nearly two decades of investigations on the eponymous bacterial transporter LeuT have yielded a library of high-resolution snapshots of its conformational cycle linked by solution-state experimental data obtained from multiple techniques. In parallel, its topology has been observed in symporters and antiporters characterized by a spectrum of substrate specificities and coupled to gradients of distinct ions. Here we review and compare mechanistic models of transport for LeuT, its well-studied homologs as well as functionally distant members of the fold, emphasizing the commonalities and divergences in alternating access and the corresponding energy landscapes. Our integrated summary illustrates how fold conservation, a hallmark of the LeuT-fold, coincides with divergent choreographies of alternating access that nevertheless capitalize on recurrent structural motifs.
|
Diego del Alamo; Jens Meiler; Hassane Mchaourab
|
Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Biophysics
|
CC BY NC 4.0
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CHEMRXIV
|
2022-05-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6275f39d59f0d63470871d80/original/principles-of-alternating-access-in-leu-t-fold-transporters-commonalities-and-divergences.pdf
|
64c02642ae3d1a7b0d58cf17
|
10.26434/chemrxiv-2023-gbspt
|
Self-Supported Heterogeneous Dirhodium(II) Catalyst for Nitrene and Carbene Transfer Reactions
|
The bimetallic rhodium(II) paddlewheel (Rh2A4) complex is one of the most reactive classes of rhodium catalysts, well-renowned for the most demanding carbene- and nitrene-transfer reactions. In view of its importance in modern synthetic chemistry, we herein report a facile approach for preparing a self-supported and reusable dirhodium(II) polymer-based heterogeneous catalyst through a reductive ligation protocol. The catalyst displays good reactivity for inter- and intramo-lecular nitrene- and carbene-insertions of various olefins, and can also engage in C–H insertion of hydrocarbon deriva-tives, all under ambient conditions. The increased catalyst reusability is expected to empower the use of these precious metal catalysts at industrial scales.
|
Michael Young; Vanaparthi Satheesh; Indunil Alahakoon; Kendra Shrestha; Livina Iheme; Michal Marszewski
|
Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Heterogeneous Catalysis; Transition Metal Complexes (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-07-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64c02642ae3d1a7b0d58cf17/original/self-supported-heterogeneous-dirhodium-ii-catalyst-for-nitrene-and-carbene-transfer-reactions.pdf
|
60c742ec567dfe5d05ec3fc7
|
10.26434/chemrxiv.8847962.v1
|
Dealkenylative Thiylation of C(sp3)–C(sp2) Bonds
|
Carbon–carbon bond
fragmentations are useful methods for the functionalization of molecules. The
value of such cleavage events is maximized when paired with a subsequent bond
formation. Herein we report a protocol for the cleavage of a C(sp<sup>3</sup>)–C(sp<sup>2</sup>)
bond, followed by the formation of a new C(sp<sup>3</sup>)–S bond. This
reaction is performed in non-anhydrous solvent and open to the air, employs
common starting materials, and can be used to rapidly diversify natural
products. We have also subjected the thiylated products to various synthetic
transformations, demonstrating their utility as synthetic intermediates.
|
Andrew Smaligo; Ohyun Kwon
|
Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-07-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c742ec567dfe5d05ec3fc7/original/dealkenylative-thiylation-of-c-sp3-c-sp2-bonds.pdf
|
60c7440f702a9bee5f18a735
|
10.26434/chemrxiv.9736049.v1
|
Carbon-Heteroatom Cross-Coupling via an Electronically Excited Nickel (II) Complex
|
<div>While carbon-heteroatom cross coupling reactions have been extensively studied, many methods are specific and</div><div>limited to a set of substrates or functional groups. Reported here is a method that allows for C-O, C-N and C-S cross coupling reactions under one general methodology. We propose that an energy transfer pathway, in which an iridium photosensitizer produces an excited nickel (II) complex, is responsible for the key reductive elimination step that couples aryl halides to 1° and 2° alcohols, anilines, thiophenols, carbamates and sulfonamides.</div>
|
Randolph Escobar; Jeffrey Johannes
|
Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-08-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7440f702a9bee5f18a735/original/carbon-heteroatom-cross-coupling-via-an-electronically-excited-nickel-ii-complex.pdf
|
62613a4111b14642a72aeb94
|
10.26434/chemrxiv-2022-sdm9c
|
Detection and correction of delocalization errors for electron- and hole-polarons using density-corrected DFT
|
Modeling of polaron defects is an important aspect of computational materials science but the description of unpaired spins in density functional theory (DFT) suffers from delocalization error. To diagnose and correct the over-delocalization of unpaired spins, we report an implementation of density-corrected (DC-)DFT and its analytic energy gradient. In this approach, an exchange-correlation functional is evaluated using a Hartree-Fock density rather than the DFT density, to incorporate correlation while avoiding self-interaction error. Results for an electron-polaron in TiO2 and a hole-polaron in Al-doped silica demonstrate that geometry optimization with semilocal functionals drives significant structural distortion including elongation of several bonds, such that subsequent single-point calculations with hybrid functionals fail to afford a localized defect even when hybrid functional optimizations do localize the polaron. This has significant implications for the traditional workflow in computational materials science. DC-DFT calculations provide a mechanism to detect situations where delocalization error is likely to affect the results.
|
Bhaskar Rana; Marc Coons; John Herbert
|
Theoretical and Computational Chemistry; Materials Science; Optical Materials; Computational Chemistry and Modeling; Theory - Computational
|
CC BY 4.0
|
CHEMRXIV
|
2022-04-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62613a4111b14642a72aeb94/original/detection-and-correction-of-delocalization-errors-for-electron-and-hole-polarons-using-density-corrected-dft.pdf
|
6276e5f56b12b65d5c69b9ae
|
10.26434/chemrxiv-2022-2fh88
|
Life Cycle Assessment of CO2 emission from Multigeneration of Water-Electricity-Ammonia Scheme using Sunlight in arid/semi-arid region and Seawater through Pipeline
|
Water, electricity, and ammonia (artificial fertilizer) are essential for human welfare. The self-sufficient and
sustainable productions of them from renewable resources are indispensable for social security and the future
society. In this study, we proposed the Water-Electricity-Ammonia (WEA) scheme that produces electricity,
freshwater, and ammonia and supplies them at a certain ratio. We investigated the life cycle CO2 (LCCO2) emission
from the case of inland cities in arid/semi-arid regions that obtain the three products (electricity, water, and
ammonia) generated by photovoltaic (PV) and seawater obtained through a pipeline connecting the ocean and the
cities. This study unraveled the necessary condition to reduce LCCO2 emission: the allocation ratio of PV electricity
for the three productions and the geographical conditions of inland cities. To reduce LCCO2 emission, allocating
PV power to seawater desalination is suitable if the city is in a lowland area, and ammonia synthesis is preferable if
the city is in a highland area. Note that the WEA scheme applied to most inland cities, even in extreme geographical
conditions, reduces LCCO2 emissions compared to conventional production methods by optimizing the PV
allocation of electricity, freshwater, and ammonia production.
|
Takaya Ogawa; Yoko Imamura; Masaki Yoshida; Keiichi N. Ishihara; Ryuichi Fukuhara; Maisa'a W. Shammout; Mohammad R. Shatanawi; Eiji Yamasue
|
Earth, Space, and Environmental Chemistry; Environmental Science
|
CC BY 4.0
|
CHEMRXIV
|
2022-05-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6276e5f56b12b65d5c69b9ae/original/life-cycle-assessment-of-co2-emission-from-multigeneration-of-water-electricity-ammonia-scheme-using-sunlight-in-arid-semi-arid-region-and-seawater-through-pipeline.pdf
|
61523e2a4853d2007db4f959
|
10.26434/chemrxiv-2021-pw9fj
|
Indacenodipyrene Containing Small Molecules and Ladder Polymers
|
A series of s-indaceno[1,2,3-cd:5,6,7-c'd']dipyrene-containing small molecule and ladder polymers were prepared using a palladium catalyzed arylation reaction. Precursor polymers and their resulting ladder polymers with molecular weights up to 13 kDa were prepared. The rigid, planar materials possessed highest occupied molecular orbital (HOMO) energies of -5.39 to -5.23 eV, lowest unoccupied molecular orbitals (LUMO) energies of -2.42 eV to -2.98 eV, and optical gaps of 1.68 to 2.03 eV. Organic field effect transistors were prepared with derivatives giving hole mobilities up to 2.5 X 10-5 cm2V-1s-1.
|
Ain Uddin; Kyle Plunkett
|
Organic Chemistry; Polymer Science; Organic Synthesis and Reactions; Conducting polymers; Organic Polymers; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-09-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61523e2a4853d2007db4f959/original/indacenodipyrene-containing-small-molecules-and-ladder-polymers.pdf
|
60c749690f50db631c3968e7
|
10.26434/chemrxiv.11695482.v2
|
Simulation-Based Evaluation of Zeolite Adsorbents for the Removal of Emerging Contaminants
|
<p>A number of experimental studies have evaluated the potential of
hydrophobic high-silica zeolites for the adsorptive removal of emerging organic
contaminants, such as pharmaceuticals and personal care products, from water.
Despite the widespread use of molecular modelling techniques in various other fields
of zeolite science, the adsorption of pharmaceuticals and related pollutants
has hardly been studied computationally. In this work, inexpensive molecular
simulations using a literature force field (DREIDING) were performed to study
the interaction of 21 emerging contaminants with two all-silica zeolites,
mordenite (MOR topology) and zeolite Y (FAU topology). The selection of adsorbents
and adsorbates was based on a previous experimental investigation of organic
contaminant removal using high-silica zeolites (Rossner et al., <i>Water Res.</i>
<b>2009</b>, <i>43</i>, 3787–3796). An analysis of the lowest-energy configurations revealed a good correspondence
between calculated interaction energies and experimentally measured removal
efficiencies (strong interaction – high removal), despite a number of inherent
simplifications. This indicates that such simulations could be used as a
screening tool to identify promising zeolites for adsorption-based pollutant
removal prior to experimental investigations. To illustrate the predictive
capabilities of the method, additional calculations were performed for
acetaminophen adsorption in 11 other zeolite frameworks, as neither mordenite
nor zeolite Y remove this pharmaceutical efficiently. Furthermore, the
lowest-energy configurations were analysed for selected adsorbent-adsorbate
combinations in order to explain the observed differences in affinity.</p>
|
Michael Fischer
|
Catalysts; Environmental Science; Wastes; Theory - Inorganic; Computational Chemistry and Modeling; Water Purification
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-03-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749690f50db631c3968e7/original/simulation-based-evaluation-of-zeolite-adsorbents-for-the-removal-of-emerging-contaminants.pdf
|
6240d38d61c5aaac2b7a97a5
|
10.26434/chemrxiv-2022-5f2cv-v2
|
Pyrimidine-2-amines increase susceptibility of methicillin-resistant Staphylococcus aureus to penicillin G
|
β-lactamase (penicillinase) renders early β-lactams like penicillin G useless against methicillin-resistant Staphylococcus aureus (MRSA). Antimicrobial discovery is difficult, and resistance exists against most treatment options. Enhancing β-lactams against MRSA would revive their clinical utility. Moreillon and others have demonstrated that penicillin G is as potent against a β-lactamase gene knockout strain, as vancomycin is against wild-type MRSA. Yet, direct β-lactamase inhibitors like sulbactam and clavulanate gave rise to penicillin G resistance. Instead, 50 μM pyrimidine-2-amines (P2A) reduce the minimum inhibitory concentration (MIC) of penicillin G against MRSA strains by up to 64-fold by reducing β-lactamase expression. PBP2a prevented oxacillin enhancement, demonstrating the advantage of penicillin G over penicillinase-insensitive β-lactams. P2As modulate an unknown global regulator, but not established antimicrobial-enhancement targets Stk1 and VraS. P2As are a practical implementation of Moreillon’s principle of suppressing β-lactamase activity to make penicillin G useful against MRSA, without employing direct enzyme inhibitors.
|
Payton Thomas; Margaret Deming; Aurijit Sarkar
|
Biological and Medicinal Chemistry; Chemical Biology; Drug Discovery and Drug Delivery Systems; Microbiology
|
CC BY 4.0
|
CHEMRXIV
|
2022-03-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6240d38d61c5aaac2b7a97a5/original/pyrimidine-2-amines-increase-susceptibility-of-methicillin-resistant-staphylococcus-aureus-to-penicillin-g.pdf
|
627d72a9d55550eb59987981
|
10.26434/chemrxiv-2022-ttpst
|
Influence of UV-A radiation on the Selected Nutrient Composition and Volatile Profiling of Whole Milk: Safety and Quality Evaluation
|
Aflatoxin (AF), a mycotoxin produced by several genera of fungi, is an important concern in milk-based products due to its toxicity and health consequences. The present study evaluates whether UV-A irradiation can preserve the composition of whole milk (WM) while degradaing these toxins. In addition, this study also investigates the expression of p53 proteins which can be correlated with carcinogenocity. UV-A irradiation experiments were conducted using a near collimated beam system operating at 365 nm. AFs at known concentrations were spiked in WM and irradiated at quantifiable UV doses based on the average volumetric intensity. The impact of ultraviolet light (UV-A) irradiation on volatile compounds, certain amino acids, and oxidative products were evaluated. No significant reduction in amino acids was observed except tryptophan, p<0.05. At 838 mJ/cm2 no significant lipid peroxidation was observed, p<0.05. The volatile profiling showed that alcohols, the key contributor of oxidized flavor was not significantly affected by the UV-A irradiation. Western blotting was used to assess the effect of UV-A irradiated WM on protein expression in HepG2 cells. Because the targeted gene p53 was not considerably altered, we can affirm that UV-A irradiated WM may be safe and not cytotoxic. Herein, the substantial breakdown of AF in WM by UV-A as well as no accumulation of toxic components from protein, lipid, and FAA degradation was observed. This study conclusively proves the performance of the UV-A LED system in degrading AF in WM below the levels recommended by Food and Drug Administration without compromising the product's quality or safety.
|
Anjali Kurup; Ankit Patras; Rishipal Bansode; Brahmaiah Pendyala; Ramasamy Ravi; Matthew Vergne
|
Agriculture and Food Chemistry; Food
|
CC BY 4.0
|
CHEMRXIV
|
2022-05-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/627d72a9d55550eb59987981/original/influence-of-uv-a-radiation-on-the-selected-nutrient-composition-and-volatile-profiling-of-whole-milk-safety-and-quality-evaluation.pdf
|
67856cf7fa469535b9da93f1
|
10.26434/chemrxiv-2025-b7qp7
|
Non-Covalent Molecular Interaction Rules to Define Internal Dimer Coordinates for Quantum Mechanical Potential Energy Scans
|
Non-covalent interactions (NCI) dominate the properties of condensed phase systems. Towards a detailed understanding of NCI quantum mechanical (QM) methods allow for accurate estimates of interaction energies and geometries, allowing for the contributions of different types of NCI to condensed phase properties to be understood. In addition, such information can be used for the optimization of empirical force fields including the specific contribution of electrostatic versus van der Waals interactions. However, to date the relative orientation of monomers defining molecular interactions of dimers are often based on full geometry optimizations of all degrees of freedom or extracted from known experimental structures of biological molecules. In such cases the spatial relationship of the monomers often lead to multiple atoms in each monomer making significant contributions to the interactions occurring in the dimer confounding understanding of the contributions of specific atoms or functional groups. To overcome this a workflow is presented that allows for systematic control of the interaction orientation between monomers to be performed through the use of molecular interaction rules (MIR) in an extendable tool that can be applied to a broad range of chemical space. Using the “MIR workflow” allows a user to perform automation of the determination of well-defined monomer interaction orientations in dimers using Z-matrices allowing for potential energy scans (PES) to be performed on combinatorial pairs of the monomers. In addition, compiled monomer and dimer geometries and PES data are stored in an extendable database. Illustration of the utility of the workflow is performed based on a collection of 89 monomers encompassing a variety of functional group classes from which 10616 interaction dimers are automatically generated. PES between all dimers were calculated at the QM HF/6-31G*, MP2/6-31G*, and 𝟂b97x-d3/6-31G* model chemistries. In addition, analysis of the benzene dimer in three interaction orientations, a hydrogen bond interaction between azetidinone and N-methylacetamide, and the interaction of pyridine with acetone in the Burgi-Dunitz orientation are presented including results with the aug-cc-pVDZ basis set. Results show the impact of different QM model chemistries on minimum interaction energies and distances over a large ensemble of intermolecular interactions with emphasis on the contributions of dispersion.
|
Suliman Sharif; Anmol Kumar; Alex MacKerell
|
Theoretical and Computational Chemistry; Computational Chemistry and Modeling
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67856cf7fa469535b9da93f1/original/non-covalent-molecular-interaction-rules-to-define-internal-dimer-coordinates-for-quantum-mechanical-potential-energy-scans.pdf
|
634d70c44b0af316e9c8983e
|
10.26434/chemrxiv-2022-8f3fk
|
Fluorine-Rich Oxyfluoride Spinel Li1.25Ni0.625Mn1.125O3F Utilizing Redox-Active Ni and Mn for High Capacity and Improved Cyclability
|
Extending the accessible capacity and cyclability is of central interest for cathode materials for Li-ion batteries. Here, we report the successful synthesis of a new spinel Li1.25Ni0.625Mn1.125O3F (Fd3 ̅m) with significant cation disorder characterised by combined refinement of X-ray and neutron diffraction data. Li1.25Ni0.625Mn1.125O3F utilizes redox reactions of both Ni and Mn, accessing capacities of 225 (i.e., 1.46 Li+ capacity) and 285 mAh g-1 (i.e., 1.85 Li+ capacity) at 25 °C and 40 °C, respectively, through intercalation of additional Li+ into the lattice. Moreover, compared to lithium transition metal disordered rocksalt or spinel-like oxyfluorides previously reported, Li1.25Ni0.625Mn1.125O3F shows significantly improved cycling stability. Ex situ compositional, structural and spectroscopic analysis of samples at different states of charge/discharge confirm a single-phase intercalation reaction and high structural integrity over cycling.
|
Hong Cai; Ruiyong Chen; Mounib Bahri; Cara Hawkins; Manel Sonni; Luke Daniels; Jungwoo Lim; Jae Evans; Marco Zanella; Leanne Jones; Troy Manning; Tim Veal; Laurence Hardwick; Matthew Dyer; Nigel Browning; John Claridge; Matthew Rosseinsky
|
Inorganic Chemistry; Energy; Solid State Chemistry; Energy Storage; Materials Chemistry; Crystallography – Inorganic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-10-18
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/634d70c44b0af316e9c8983e/original/fluorine-rich-oxyfluoride-spinel-li1-25ni0-625mn1-125o3f-utilizing-redox-active-ni-and-mn-for-high-capacity-and-improved-cyclability.pdf
|
65141301ade1178b2436ca64
|
10.26434/chemrxiv-2023-xpc2f
|
Fe-Electrocatalytic Deoxygenative Giese Reaction
|
A redox-neutral Fe-electrocatalytic deoxygenative Giese reaction is reported. Hydroxyl groups are among the most abundant functional groups. The advancement of efficient conversion reactions holds significant importance in medicinal and process chemistry. In this report, we present a redox-neutral Giese reaction via anodic oxidation to generate phosphonium ions and cathodic reduction to yield low-valent Fe catalysts. This reaction constitutes a ground-breaking account of a redox-neutral reaction utilizing Fe-catalyst and electrochemistry. It will facilitate the exploration of diverse novel reactions employing this redox cycle in the future.
|
Longhui Yu; Shangzhao Li; Hiroshige Ogawa; Hugh Nakamura
|
Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions
|
CC BY 4.0
|
CHEMRXIV
|
2023-09-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65141301ade1178b2436ca64/original/fe-electrocatalytic-deoxygenative-giese-reaction.pdf
|
63638fadcf6de905102dbc68
|
10.26434/chemrxiv-2022-wv6gc
|
NMR in operando Monitoring of Mechanochemically Accelerated Sublimations
|
Solid-solid interactions in co-crystals lead to alternations of the physico-chemical properties of the mixture compared to its single components. Herein, we report a setup that makes use of mechanochemistry to promote these interactions and is coupled with the analytical power of nuclear magnetic resonance (NMR) to in operando monitor the resulting variation. The system is applied to the analysis of optically active species responding to cases of self-disproportionation of enantiomers (SDE) by sublimation. The fundamentals behind the observed phenomenon led to an advanced concept of enantiomers recognition based on selective sublimation.
|
Carsten Bolm; Francesco Puccetti; Sanel Suljić; Torsten Rinesch
|
Organic Chemistry; Organic Synthesis and Reactions
|
CC BY 4.0
|
CHEMRXIV
|
2022-11-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63638fadcf6de905102dbc68/original/nmr-in-operando-monitoring-of-mechanochemically-accelerated-sublimations.pdf
|
6672902e5101a2ffa8ee372d
|
10.26434/chemrxiv-2024-7qtm0
|
Generality-Oriented Amination of Aryl Halides by Light-Induced Mn(II) Catalysis
|
In this paper, we report for the first time light-induced Mn(II)-catalyzed C-N coupling reactions of aryl halides with amine nucleophiles under the same reaction conditions (same catalyst, same ligand, same solvent, same base, same temperature) without an exogenous photocatalyst. The current single manganese catalyst system has a dual role of light harvesting and organometallic catalysis, showcasing an excellent substrate range in C-N coupling reactions (5 different nitrogen sources, >90 examples, up to 94% yield). Mechanistic studies indicate that a Mn(I)/Mn(III) catalytic cycle may be involved in the reaction.
|
Geyang Song; Jiameng Song; Qi Li; Tengfei Kang; Jianyang Dong; Gang Li; Huaming Sun; Juan Fan; Chao Wang; Dong Xue
|
Organic Chemistry; Catalysis; Organometallic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-06-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6672902e5101a2ffa8ee372d/original/generality-oriented-amination-of-aryl-halides-by-light-induced-mn-ii-catalysis.pdf
|
65def0af9138d23161383023
|
10.26434/chemrxiv-2024-zvrvh
|
Accessing Chemically Recyclable Polyamides with Tunable
Properties via Geminal Dimethyl Substitution
|
The development of new chemically recyclable polymers could serve as a means of reducing the plastic pollution and alleviating global energy crisis and monomer design strategy has driven the innovation in this field. In this contribution, α-dimethyl substituted caprolactam (α-DMCL) and γ-dimethyl substituted caprolactam (γ-DMCL) were prepared to evaluate the substitution position effect on chemical recyclability and material performance in polycaprolactam (PCL) system. The introduction of geminal dimethyl substitution to ε-caprolactam (CL) at α and γ position endowed the resulting polyamides P(α-DMCL) and P(γ-DMCL) with distinct thermal and mechanical properties. Remarkably, thermal depolymerization of P(γ-DMCL) in presence of potassium caprolactamate (CL-K) could be carried out at 200 °C and converted to γ-DMCL in 91% yield. The recovered γ-DMCL was capable of repolymerization to P(γ-DMCL) without a decrease in reactivity, demonstrating the proof-of-concept recyclability of P(γ-DMCL).
|
Jia-Hao Chen; Yi-Min Tu; Jia-Rong Yao; Xiang-Ting Tang; Yun-Yun Xia; Zhongzheng Cai; Qi Zhang; Jian-Bo Zhu
|
Polymer Science
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-03-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65def0af9138d23161383023/original/accessing-chemically-recyclable-polyamides-with-tunable-properties-via-geminal-dimethyl-substitution.pdf
|
624f326685d81418ed012332
|
10.26434/chemrxiv-2022-9v3nw
|
Imaging nitrogen fixation at lithium solid electrolyte interphases via cryo-electron microscopy
|
Electrifying ammonia synthesis will be vital to the decarbonization of the chemical industry, as the Haber-Bosch process contributes significantly to global carbon emissions. A lithium-mediated pathway is among the most promising ambient-condition electrochemical ammonia synthesis methods. However, the role of metallic lithium and its passivation layer, the solid electrolyte interphase (SEI), remains unresolved. Here, we apply a multiscale approach that leverages the powerful cryogenic transmission electron microscopy (cryo-TEM) technique to reveal new insights that were previously inaccessible with conventional methods. We discover that the proton donor (e.g. ethanol) governs lithium reactivity toward nitrogen fixation. Without ethanol, the SEI passivates lithium metal, rendering it inactive for ammonia production. Ethanol disrupts this passivation layer, enabling continuous reactivity at the lithium surface. As a result, metallic lithium is consumed via reactions with nitrogen, proton donor, and other electrolyte components. This reactivity across the SEI is vital to device-level performance of lithium-mediated ammonia synthesis.
|
Katherine Steinberg; Xintong Yuan; Nikifar Lazouski; Channing K. Klein; Karthish Manthiram; Yuzhang Li
|
Materials Science; Catalysis; Energy; Electrocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-04-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/624f326685d81418ed012332/original/imaging-nitrogen-fixation-at-lithium-solid-electrolyte-interphases-via-cryo-electron-microscopy.pdf
|
654b394a2c3c11ed71f38266
|
10.26434/chemrxiv-2023-t7r63
|
Interpreting Chemisorption Strength with AutoML-based Feature Deletion Experiments
|
The chemisorption energy of reactants on a catalyst surface, E_ads, is among the most informative characters of understanding and pinpointing the optimal catalyst. The intrinsic complexity of catalyst surfaces and chemisorption reactions presents significant difficulties in identifying the pivotal physical quantities determining Eads. In response to this, the study proposes a novel methodology, the feature deletion experiment, based on Automatic Machine Learning (AutoML) for knowledge extraction from a high-throughput density functional theory (DFT) database. The study reveals that, for binary alloy surfaces, the local adsorption site geometric information is the primary physical quantity determining E_ads, compared to the electronic and physiochemical properties of the catalyst alloys. By integrating the feature deletion experiment with instance-wise variable selection (INVASE), a neural network-based explainable AI (XAI) tool, we established the best-performing feature set containing 21 intrinsic, non-DFT computed properties, achieving an MAE of 0.23 eV across a periodic table-wide chemical space involving more than 1,600 types of alloys surfaces and 8,400 chemisorption reactions. This study demonstrates the stability, consistency, and potential of AutoML-based feature deletion experiment in developing concise, predictive, and theoretically meaningful models for complex chemical problems with minimal human intervention.
|
Zhuo Li; Changquan Zhao; Haikun Wang; Yanqing Ding; Yechao Chen; Philippe Schwaller; Ke Yang; Cheng Hua; Yulian He
|
Catalysis; Heterogeneous Catalysis
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CC BY NC 4.0
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CHEMRXIV
|
2023-11-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/654b394a2c3c11ed71f38266/original/interpreting-chemisorption-strength-with-auto-ml-based-feature-deletion-experiments.pdf
|
60c7477ff96a0070bd286f23
|
10.26434/chemrxiv.11674041.v1
|
Ring-Opening Metathesis Polymerization Derived Hierarchically Porous Carbon-Foams
|
Monolithic open macroporous
carbons of 80-85 % porosity are obtained from pyrolyzing oxidized high
internal phase templated poly(dicyclopentadiene) foams. The macropores
void diameters of the resulting carbon foams can be ajusted between 87
and 2.5 mikrometer simply by changing the surfactant amount used in the
preparation of the precursor foams. The resulting porous carbon
materials are charcterized by a carbon content >97%, an electronic
conductivity of up to 2800 S/m, a Young's modulus of up to 2.1 GPa and a
specific surface area of up to 1200 m<sup>2</sup>/g. <br />
|
Sebastijan Kovačič; Nadejda B. Matsko; Katharina Gruber; Stefan Koller; Christian Slugovc
|
Carbon-based Materials; Polymer scaffolds
|
CC BY NC 4.0
|
CHEMRXIV
|
2020-01-23
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7477ff96a0070bd286f23/original/ring-opening-metathesis-polymerization-derived-hierarchically-porous-carbon-foams.pdf
|
65bbefebe9ebbb4db9760587
|
10.26434/chemrxiv-2024-2nmh4-v2
|
Selecting Reducing Agents for Native Mass Spectrometry
|
In protein science, reducing agents are often added in cases where the protein, its cofactors, or its ligands are sensitive to oxidative stress. Although many native mass spectrometry (MS) workflows would benefit from maintaining reducing conditions throughout the analysis, there is a lack of consensus regarding the compatibility of reducing agents with that approach. This study systematically examines the effects of dithiothreitol (DTT), β-mercaptoethanol (βME), and tris(2-carboxyethyl)phosphine (TCEP) on the native mass spectra of protein standards. The selection and concentration of the reducing agents affected both the extent of nonspecific adduction and the charge-state distribution of the analyte. For a protein without disulfide bonds, increasing concentrations of DTT or βME resulted in shifts to higher charge states, whereas increasing concentrations of TCEP resulted in shifts to lower charge states. Based on these trends and additional properties of the reducing agents, we propose that DTT and βME are mild supercharging agents and that TCEP is a potent charge-reducing agent. The selection and concentration of the reducing agents, as well as the sample pH, also affected the extent of disulfide bond reduction, and for βME, the extent of covalent adduction by that molecule to cysteine. These results offer insights into the compatibility of reducing agents with the goal of obtaining high-quality native mass spectra. Based on our results, we present recommendations for the use of reducing agents in native MS experiments.
|
Theresa A. Gozzo; Christopher J. Weir; May A. Constabel; Matthew F. Bush
|
Biological and Medicinal Chemistry; Analytical Chemistry; Mass Spectrometry; Biophysics
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-02-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65bbefebe9ebbb4db9760587/original/selecting-reducing-agents-for-native-mass-spectrometry.pdf
|
60c755c7ee301cc218c7b225
|
10.26434/chemrxiv.14114306.v2
|
Spatial Separation of Plasmonic Hot Electron Generation and a Hydrodehalogenation Reaction Center Using a DNA Wire
|
<p>Using hot charge carriers far from
a plasmonic nanoparticle surface is very attractive for many applications in
catalysis and nanomedicine, and will lead to a better understanding of
plasmon-induced processes, such as hot charge carrier or heat driven chemical
reactions. Herein we show that DNA is able to transfer hot electrons generated by
a silver nanoparticle over several nanometers to drive a chemical reaction in a
molecule non-adsorbed on the surface. For this we use 8-bromo-adenosine introduced
in different positions within a double stranded DNA oligonucleotide. The DNA is
also used to assemble the nanoparticles into superlattices enabling the use of
surface enhanced Raman scattering to track the decomposition reaction. To prove
the DNA mediated transfer, the probe molecule was insulated from the charge carriers
source, which hindered the reaction. The results indicate that DNA can provide
an attractive platform to study the transfer of hot electrons, leading to the
future development of more advanced plasmonic catalysts. </p>
|
Sergio Kogikoski Junior; Anushree Dutta; Ilko Bald
|
Biophysical Chemistry; Chemical Kinetics; Interfaces; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-03-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755c7ee301cc218c7b225/original/spatial-separation-of-plasmonic-hot-electron-generation-and-a-hydrodehalogenation-reaction-center-using-a-dna-wire.pdf
|
63eca27efcfb27a31fd23d79
|
10.26434/chemrxiv-2023-p40nn
|
The Weyl Semimetals MIrTe4 (M = Nb, Ta) as Efficient Catalysts for Dye-sensitized Hydrogen Evolution
|
The prevalent global energy crisis calls for searching viable pathways for generating green hydrogen as an alternative energy resource. Dye-sensitized photocatalytic water splitting is a feasible solution to produce green hydrogen. However, identifying suitable catalysts has been one of the bottlenecks in driving dye-sensitized photocatalysis efficiently. In this work, we report a new class of electrocatalysts based on the layered Weyl semimetals MIrTe4 (M = Nb, Ta) for the Eosin Y (EY)-sensitized hydrogen evolution reaction (HER) under visible light illumination. NbIrTe4 and TaIrTe4 exhibit HER activities of ~ 18000 and ~ 14000 mol.g-1, respectively after 10h of irradiation with visible light. Time-dependent UV-Vis spectroscopy and high-pressure liquid chromatography coupled with mass spectroscopy analysis shed light on the reaction dynamics and enable deeper understanding of the observed trend in hydrogen evolution rates for MIrTe4 materials. MIrTe4 (M = Nb, Ta) semimetals outperform related catalysts including transition metal dichalcogenides and other Weyl semimetals in terms of HER activity using EY as photosensitizer and triethanolamine as the sacrificial agent. We hypothesize that the topology-related band inversion in MIrTe4 Weyl semimetals promotes a high density of metal d-states near the Fermi level, driving their high catalytic performance. This study introduces a new class of layered Weyl semimetals as efficient catalysts, and provides perspectives for designing topology-enhanced catalysts.
|
Manisha Samanta; Hengxin Tan; Sourav Laha; Hugo Alejandro Vignolo Gonzlez; Lars Grunenberg; Sebastian Bette; Viola Duppel; Binghai Yan; Bettina V. Lotsch
|
Catalysis; Heterogeneous Catalysis; Photocatalysis; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-02-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63eca27efcfb27a31fd23d79/original/the-weyl-semimetals-m-ir-te4-m-nb-ta-as-efficient-catalysts-for-dye-sensitized-hydrogen-evolution.pdf
|
6234cda921e2d068f6a87459
|
10.26434/chemrxiv-2022-l5f5h
|
Total Synthesis of (–)-Voacinol and (–)-Voacandimine C
|
We describe the first total synthesis of complex aspidosperma alkaloids (–)-voacinol and (–)-voacandimine C via a late-stage C7-methylenation strategy inspired by a biogenetic hypothesis. We envisioned rapid access to these natural alkaloids from a common, symmetrical precursor assembled by methylenation of a D-ring-oxidized variant of the structurally related natural product (–)-deoxoapodine. Chemoselective N9-oxidation of a pentacyclic deoxoapodine precursor enabled the synthesis of the corresponding hexacyclic C8-aminonitrile. Stereocontrolled methylenation of a C8-enamine derivative of deoxoapodine, accessed by ionization of the C8-aminonitrile, afforded a symmetrical dodecacyclic bisaminonitrile as a versatile precursor to these bisindole alkaloids. Final-stage, biosynthesis-inspired, controlled reductive opening of the oxolane substructures of this dodecacyclic intermediate provided a unified approach to (–)-voacinol and (–)-voacandimine C, while direct reduction of the same intermediate afforded the structurally related (–)-methylenebisdeoxoapodine.
|
Kristen Flynn; In-Soo Myeong; Taylor Pinto; Mohammad Movassaghi
|
Organic Chemistry; Natural Products; Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-03-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6234cda921e2d068f6a87459/original/total-synthesis-of-voacinol-and-voacandimine-c.pdf
|
62f0f2c4e78f702bba338367
|
10.26434/chemrxiv-2022-3wlhw
|
Nickel N-Heterocyclic Carbene Catalysts for Ester Carbonylation
|
Millions of tons of “acetyls” such as acetic acid and acetic anhydride are produced each year. These basic building blocks of chemical industry are elaborated into esters, amides, and eventually polymer materials, pharmaceuticals, and other consumer products. The vast majority of acetyls are produced industrially using homogeneous catalysis, but exclusively using scarce and expensive precious metal catalysts (principally rhodium and iridium complexes). We report here that nickel catalysts supported by N-heterocyclic carbene ligands mediate the carbonylation of methyl esters, selectively producing anhydrides with high activity at low catalyst loading. Carbene supporting ligands with aryl substituents, which can be added as air-stable imidazolium salts, dramatically improve carbonylation performance relative to prior nickel catalysts supported by tertiary phosphine ligands, raising hopes for industrial application of base metal carbonylation catalysts.
|
Changho Yoo; Xin Yi See; Shrabanti Bhattacharya; Drew Cunningham; Steven Perri; Nathan West; Dawn Mason; Chris Meade; Jeffrey Cowden; Phillip Turner; Randall Kilgore; Christopher Osborne; Javier Grajeda; Alexander Miller
|
Inorganic Chemistry; Catalysis; Organometallic Chemistry; Catalysis; Kinetics and Mechanism - Organometallic Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-08-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62f0f2c4e78f702bba338367/original/nickel-n-heterocyclic-carbene-catalysts-for-ester-carbonylation.pdf
|
65a7727a9138d231611a2bc8
|
10.26434/chemrxiv-2024-kpz68-v2
|
Tris-Azo Triangular Paraphenylenes: Synthesis and Reversible Interconversion into Radial π-Conjugated Macrocycles
|
We report the synthesis of cycloparaphenylene derivatives featuring tris-azo groups. The smaller derivative, [3]cycloazobenzene ([3]CAB-0), adopts a triangular all-cis form and exhibits thermally and photochemically stable characteristics due to significant ring strain, as well as symmetric Kagome-patterned crystal packing. In contrast, the as-synthesized [3]cycloazobenzene with three biphenylene bridges ([3]CAB-1) adopts a similar triangular all-cis form; however, it undergoes photoinduced isomerization, leading to a mixture of cis and trans forms at a photostationary state. Interestingly, the addition of an excess of acid selectively leads to the formation of the all-trans form. DFT calculations reveal that the interconversion from a triangular to a circular shape correlates with an increase in HOMO and a decrease in LUMO, characteristics intrinsic to radial π-conjugated systems.
|
Tomohito Ide; Wei-Ci Huang; Masaki Horie
|
Organic Chemistry; Organic Compounds and Functional Groups; Photochemistry (Org.); Materials Chemistry; Crystallography – Organic
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-01-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a7727a9138d231611a2bc8/original/tris-azo-triangular-paraphenylenes-synthesis-and-reversible-interconversion-into-radial-conjugated-macrocycles.pdf
|
64dd7ac269bfb8925a0cdd35
|
10.26434/chemrxiv-2023-s8fkr
|
C–H Alkylation of Cubanes via Polar Effect-Assisted Photocatalytic Generation of Cubyl Radicals
|
A method for C–H alkylation of cubanes is described herein. A hydrogen atom–transfer catalyst enables direct abstraction of a hydrogen atom from the C–H bond of cubanes, followed by conjugate addition of the generated cubyl radicals to various Michael acceptors. Synthetic applications of the developed functionalization method are also described.
|
Shota Nagasawa; Masaki Hosaka; Yoshiharu Iwabuchi
|
Organic Chemistry; Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-08-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64dd7ac269bfb8925a0cdd35/original/c-h-alkylation-of-cubanes-via-polar-effect-assisted-photocatalytic-generation-of-cubyl-radicals.pdf
|
647296a44f8b1884b762df1a
|
10.26434/chemrxiv-2023-3vbn6
|
High-Throughput Electrochemical Characterization of Aqueous Organic Redox Flow Battery Active Material
|
The development of redox-active organics for flow batteries providing long duration energy storage requires an accurate understanding of molecular lifetimes. Herein we report the development of a high-throughput setup for the cycling of redox flow batteries. Using common negolyte redox-active aqueous organics, we benchmark capacity fade rates and compare variations in measured cycling behavior of identical volumetrically unbalanced compositionally symmetric cells. We propose figures of merit for consideration when cycling sets of identical cells, and compare three common electrochemical cycling protocols typically used in battery cycling: constant current, constant current constant voltage, and constant voltage. Redox-active organics exhibiting either high or low capacity fade rates are employed in the cell cycling protocol comparison, with results shown from over 50 flow cells.
|
Eric Fell; Michael Aziz
|
Energy; Energy Storage
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-05-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/647296a44f8b1884b762df1a/original/high-throughput-electrochemical-characterization-of-aqueous-organic-redox-flow-battery-active-material.pdf
|
655c7a3edbd7c8b54bb26209
|
10.26434/chemrxiv-2023-hg9z8
|
Upcycling of low value end-of-life cathode material into next generation cathode materials
|
The increase in the use of electric vehicles (EVs) will ultimately lead to an increase in the number of end-of-life lithium-ion batteries (LIBs) that need to be recycled. A particular challenge concerns how to deal with low value cathodes, such as LiMn2O4 (LMO). To this end, this paper investigates recycling cathode material from an end-of-life Gen 1 Nissan Leaf (2011 model, 40,000 miles) which contains a mixture of spinel (LMO) and a Ni-rich layered oxide (LO). Citric acid was employed to selectively leach LMO into solution while leaving the remaining LO as a solid. The citric acid also acts as a delamination agent to remove the remaining LO from the Al current collector. The LMO was then recovered from solution and upcycled to form new cathode materials. Ni-doping of the solution allowed the synthesis of the high voltage cathode LiMn1.5Ni0.5O4 (LMNO) which is attracting commercial interest. Disordered rocksalt compounds Li4Mn2O5 and Li2MnO2.25F were also synthesised and gave a high specific discharge capacities of 293 and 279 mAh g-1 respectively. This work demonstrates a method to upcycle end-of-life cathode material into next generation cathode materials.
|
Rosie Madge; Abbey Jarvis; Wilgner Lima da Silva; Laura L. Driscoll; Paul A. Anderson; Peter R. Slater
|
Energy; Energy Storage; Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2023-11-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655c7a3edbd7c8b54bb26209/original/upcycling-of-low-value-end-of-life-cathode-material-into-next-generation-cathode-materials.pdf
|
63a5bfd816e9a8dae53298a6
|
10.26434/chemrxiv-2022-47jh9
|
GRAPHENE OXIDE BASED TRANSPARENT RESINS FOR ACCURATE 3D PRINTING OF CONDUCTIVE MATERIALS
|
Digital Light Processing (DLP) allows the fast realization of 3D objects with high spatial resolution. However, DLP is limited to highly transparent resins, and therefore not well suited for printing electrically conductive materials. Manufacturing conductive materials would significantly broaden the spectrum of applications of the DLP technology. But conductive metal or carbon based fillers absorb and scatter light; inhibiting thereby photopolymerization, and lowering 3D printing resolution. In this work, UV transparent liquid crystal graphene oxide (GO) is used as precursor for generating in-situ conductive particles. The GO materials are added to a photopolymerizable resin via an original solvent exchange process. By contrast to earlier contributions, the absence of drying during the all process allows the GO material to be transferred as monolayers to limit UV scattering. The absence of UV scattering and absorption allows for fast and high-resolution 3D printing. The chosen resin sustain high temperature to enable an in-situ efficient thermal reduction of GO into reduced graphene oxide rGO which is electrically conductive. The rGO particles form percolated networks with conductivities up to 1.2·10-2 S·m-1. The present method appears therefore as a way to reconcile the DLP technology with the manufacturing of 3D electrically conductive objects.
|
David Tilve-Martinez; Wilfrid Neri; Dylan Horaud; Nicolas Vukadinovic; Benoit Berton; Jinkai Yuan; Philippe Poulin
|
Materials Science; Nanoscience; Carbon-based Materials; Composites; Nanostructured Materials - Materials
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-12-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63a5bfd816e9a8dae53298a6/original/graphene-oxide-based-transparent-resins-for-accurate-3d-printing-of-conductive-materials.pdf
|
666a775112188379d8fbbf87
|
10.26434/chemrxiv-2024-g418f
|
Revealing the limits of energy recovery in forward-bias bipolar membranes
|
The ability for bipolar membranes (BPMs) to interconvert voltage and pH makes them attractive materials for use in energy conversion and storage. Reverse-biased BPMs, which use electrical voltage to dissociate water into acid and base, have become increasingly well-studied. However, forward-biased BPMs (FB-BPMs), in which voltage is extracted from pH gradients through recombination, are poorly understood. In this work, physics-based modeling elucidates how complex coupling of transport and kinetics dictates the performance of FB-BPMs in electrochemical devices. Simulations reveal that the open-circuit potential (OCP) of FB-BPMs is dictated by the balance of ion recombination and crossover, where recombination of buffering counter-ions attenuates OCP. Uptake of ionic impurities and fixed-charge neutralization limit achievable current densities by reducing the fraction of fixed-charge sites that mediate recombination. The model highlights the importance and nuances of selective ion management in mitigating energy losses and provides insight into the engineering of FB-BPMs for energy applications.
|
Justin Bui; Eric Lees; Andrew Liu; Wei Lun Toh; Priyamvada Goyal; Francisco Javier Galang; Yogesh Surendranath; Alexis Bell; Adam Weber
|
Theoretical and Computational Chemistry; Energy; Chemical Engineering and Industrial Chemistry; Computational Chemistry and Modeling; Transport Phenomena (Chem. Eng.); Energy Storage
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-06-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666a775112188379d8fbbf87/original/revealing-the-limits-of-energy-recovery-in-forward-bias-bipolar-membranes.pdf
|
66d913cecec5d6c1422ac831
|
10.26434/chemrxiv-2024-z3dlp-v2
|
Structure Sensitivity and Catalyst Restructuring for CO2 Electro-reduction on Copper
|
Cu is the most promising metal catalyst for CO2 electroreduction (CO2RR) to multi-carbon products, but the structure sensitivity of the reaction and the stability versus restructuring of the catalyst surface under reaction conditions are still controversial. Here, atomic scale simulations of surface energies and reaction pathway kinetics supported by experimental evidence unveil that CO2RR does not take place on perfect planar Cu(111) and Cu(100) surfaces but rather on steps or kinks defects, and that these planar surfaces tend to restructure in reaction conditions to the active stepped surfaces. By combining basin hopping global sampling and grand canonical density functional theory, we show that the extremely low CO coverage on (111) and (100) surfaces, originating from sluggish CO2 conversion and unfavorable CO binding, limits the ability of these surfaces to reduce CO2 to multi-carbon products. Steps and kinks at surfaces, despite the lack of decrease in C-C coupling barriers on these sites, exhibit a significant increase in activity arising from beneficial CO2 activation and higher CO coverage. Notably, the square motifs adjacent to defects, not the defects themselves, are the active sites for CO2RR via synergistic effect. In addition, the strong binding of CO on defective sites acts as a thermodynamic driving force for the restructuring of planar surfaces to active stepped terminations under reactive conditions. We evaluate these mechanisms against experiments of CO2RR on UHV-prepared ultraclean Cu surfaces. Overall, our findings highlight the structural sensitivity in steering CO2RR and elucidate the origin of in situ restructuring of Cu catalysts during the reaction. We furthermore feature that the active sites for CO2RR are created under reaction conditions.
|
Dongfang Cheng; Khanh-Ly C. Nguyen; Vaidish Sumaria; Ziyang Wei; Zisheng Zhang; Winston Gee; Yichen Li; Carlos G. Morales-Guio; Markus Heyde; Beatriz Roldan Cuenya; Anastassia N. Alexandrova; Philippe Sautet
|
Theoretical and Computational Chemistry; Physical Chemistry; Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-09-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d913cecec5d6c1422ac831/original/structure-sensitivity-and-catalyst-restructuring-for-co2-electro-reduction-on-copper.pdf
|
60c74fbc842e652ca3db38e1
|
10.26434/chemrxiv.12936218.v1
|
The Effect of N-Heterocyclic Carbene Units on the Absorption Spectra of Fe(II) Complexes: A Challenge for Theory
|
<div>The absorption spectra of five Fe(II) homoleptic and heteroleptic complexes containing strong sigma-donating N-heterocyclic carbene (NHC) and polypyridyl ligands have been theoretically characterized using a tuned range-separation functional.</div><div>From a benchmark comparison of the obtained results against other functionals and a multiconfigurational reference, it is concluded that none of the methods is completely satisfactory to describe the absorption spectra.</div><div>Using a compromised choice of 20\% exact exchange, the electronic excited states underlying the absorption spectra are analyzed.</div><div>The low-lying energy band of all the compounds shows predominant metal-to-ligand charge transfer (MLCT) character while the triplet excited states have metal-centered (MC) nature, which becomes more pronounced with increasing the number of NHC-donor groups. Excited MC states with partial charge transfer to the NHC-donor groups are higher in energy than comparable states without these contributions. The presence of the low-lying MC states prevents the formation of long-lived MLCT states.</div>
|
Olga S. Bokareva; Omar Baig; Mohamed Al-Marri; Oliver Kühn; Leticia Gonzalez
|
Computational Chemistry and Modeling
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-09-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fbc842e652ca3db38e1/original/the-effect-of-n-heterocyclic-carbene-units-on-the-absorption-spectra-of-fe-ii-complexes-a-challenge-for-theory.pdf
|
677ae8756dde43c90867a896
|
10.26434/chemrxiv-2025-rbqj6
|
Asemaa, Ma’iingan, and the Seventh Fire’s instructions for assessing sustainability
|
From environmental impact statements to regulatory impact assessments, there are a variety of
analyses in the United States that measure sustainability to inform federal, state, and/or local
decision-making. Without procedures to ensure meaningful inclusion of Indigenous Knowledge
and respect for Indigenous sovereignty, we find that many assessments currently jeopardize the
discovery and development of truly sustainable solutions. Specifically, we evaluate how 17
different kinds of assessments (mis)align with Anishinaabe Gikendaasowin (Knowledge) on
Asemaa, Ma’iingan, and the Seventh Fire prophecy – teachings that guide sustainable relationships
between Physical, Plant, Animal, and Human Worlds. Our analysis is rooted in Anishinology and
Two-Eyed Seeing, practices that together guide our approach to bridging Anishinaabe
Gikendaasowin and Western scientific Knowledge and elucidate a more robust understanding of
sustainability. “Sustainability” stands at a crossroads; ultimately, this analysis provides guidance
for improving assessment protocols to ensure that current sustainability efforts do not repeat
injustices of the past.
|
Margaret O'Connell; Kathleen Smith; Mike Wiggins Jr.; Marvin DeFoe Shingwe Bines, Neme Clan; James Rasmussen; Esteban Chiriboga; Michael Waasegiizhig Price; Kimberly R. Marion Suiseeya; Jennifer Dunn
|
Earth, Space, and Environmental Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677ae8756dde43c90867a896/original/asemaa-ma-iingan-and-the-seventh-fire-s-instructions-for-assessing-sustainability.pdf
|
60c753740f50db23df397b89
|
10.26434/chemrxiv.13491543.v1
|
AutoGraph: Autonomous Graph Based Clustering of Small-Molecule Conformations
|
<div>
<div>
<div>
<p>While accurately modeling the conformational ensemble is required for predicting
properties of flexible molecules, the optimal method of obtaining the conformational
ensemble seems as varied as their applications. Ensemble structures have been modeled
by generation, refinement, and clustering of conformations with a sufficient number of
samples. We present a conformational clustering algorithm intended to automate the
conformational clustering step through the Louvain algorithm, which requires minimal
hyperparameters and importantly no predefined number of clusters or threshold values. The conformational graphs produced by this method for O-succinyl-L-homoserine,
oxidized nicotinamide adenine dinucleotide, and 200 representative metabolites each
preserved the geometric/energetic correlation expected for points on the potential energy surface. Clustering based on these graphs provide partitions informed by the
potential energy surface. Automating conformational clustering in a workflow with
AutoGraph may mitigate human biases introduced by guess-and-check over hyperparameter selection while allowing flexibility to the result by not imposing predefined
criteria other than optimizing the model’s loss function. Associated codes are available
at https://github.com/TanemuraKiyoto/AutoGraph .
</p>
</div>
</div>
</div>
|
Kiyoto Tanemura; Susanta Das; Kenneth M. Merz Jr.
|
Computational Chemistry and Modeling
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-12-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753740f50db23df397b89/original/auto-graph-autonomous-graph-based-clustering-of-small-molecule-conformations.pdf
|
64e5cb573fdae147faa5d451
|
10.26434/chemrxiv-2023-3xrkp
|
Photocrosslinked and pH-switchable Soft Polymer Nanocapsules from Polyglycidyl Ethers
|
Soft polymer nanocapsules and microgels, which can adapt their shape and at the same time sequester and release molecular payloads in response to an external trigger, are a challenging complement to vesicular structures like polymersomes. In this work we report the synthesis of such capsules by photocrosslinking of coumarin-substituted polyglycidyl ethers, which we prepared by Williamson etherification of epichlorohydrin (ECH) repeating units with 7-hydroxycoumarin in copolymers with tert-butyl glycidyl ether (tBGE). To control capsule size, we employed the prepolymers in an o/w miniemulsion, where they formed a gel layer at the interface upon irradiation at 365 nm by [2π+2π] photodimerization of the coumarin groups. Upon irradiation at 245 nm, the reaction could be reversed and the gel wall could be repeatedly disintegrated and rebuilt. We further demonstrated (i) reversible hydrophilization of the gels by hydrolysis of the lactone rings in coumarin dimers as a mechanism to manipulate the permeability of the capsules, and (ii) binding functional molecules as amides. Together with the possibility to hydrolyze the tert-butyl ether group we demonstrate a remarkable versatility of such nanogels for their use as a carrier system.
|
Stefan Engel; Pascal M. Jeschenko; Marcel van Dongen; Jonas C. Rose; Dominic Schäfer; Michael Bruns; Sonja Herres-Pawlis; Helmut Keul; Martin Möller
|
Polymer Science; Nanoscience; Drug delivery systems; Hydrogels; Nanostructured Materials - Nanoscience; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-08-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e5cb573fdae147faa5d451/original/photocrosslinked-and-p-h-switchable-soft-polymer-nanocapsules-from-polyglycidyl-ethers.pdf
|
631d6315bc257b12b8e255f1
|
10.26434/chemrxiv-2022-kh0jk
|
Harnessing Deep Reinforcement Learning to Construct Time-Dependent Optimal Fields for Quantum Control Dynamics
|
We present an efficient deep reinforcement learning (DRL) approach to automatically construct time-dependent optimal control fields that enable desired transitions in reduced-dimensional chemical systems. Our DRL approach gives impressive performance in autonomously and efficiently constructing optimal control fields, even for cases that are difficult to converge with existing gradient-based approaches. We provide a detailed description of the algorithms and hyperparameters as well as performance metrics for our DRL-based approach. Our results demonstrate that DRL can be employed as an effective artificial intelligence approach to efficiently and autonomously design control fields in continuous quantum dynamical chemical systems.
|
Yuanqi Gao; Xian Wang; Nanpeng Yu; Bryan Wong
|
Theoretical and Computational Chemistry; Physical Chemistry; Energy; Theory - Computational; Artificial Intelligence; Quantum Mechanics
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-09-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631d6315bc257b12b8e255f1/original/harnessing-deep-reinforcement-learning-to-construct-time-dependent-optimal-fields-for-quantum-control-dynamics.pdf
|
60c73e13f96a009859285e66
|
10.26434/chemrxiv.6294941.v1
|
Effect of High Salt Concentration on Ion Clustering and Transport in Polymer Solid Electrolytes: a Molecular Dynamics Study of PEO-LiTFSI
|
<div>
<div>
<div>
<p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li-
bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the
conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically
relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling
rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1.
Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the
salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in
the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p>
</div>
</div>
</div>
|
Nicola Molinari; Jonathan P. Mailoa; Boris Kozinsky
|
Polyelectrolytes - Polymers; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-05-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e13f96a009859285e66/original/effect-of-high-salt-concentration-on-ion-clustering-and-transport-in-polymer-solid-electrolytes-a-molecular-dynamics-study-of-peo-li-tfsi.pdf
|
60c742ac567dfea4a1ec3f7f
|
10.26434/chemrxiv.8335262.v1
|
High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters
|
<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br /></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>
|
Aurelio A. Rossinelli; Henar Rojo; Aniket S. Mule; Marianne Aellen; Ario Cocina; Eva De Leo; Robin Schäublin; David J. Norris
|
Core-Shell Materials; Nanostructured Materials - Materials; Optical Materials; Nanodevices; Plasmonic and Photonic Structures and Devices
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-07-01
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c742ac567dfea4a1ec3f7f/original/high-temperature-synthesis-of-cd-se-based-core-shell-core-shell-shell-and-core-graded-shell-nanoplatelets-for-stable-and-efficient-narrowband-emitters.pdf
|
624daf6b3b5f99f91bd00213
|
10.26434/chemrxiv-2022-mkcw8
|
Designing Geometric Degrees of Freedom in ReO3-Type Coordination Polymers
|
Engineering the interplay of structural degrees of freedom that couple to external stimuli such as temperature and pressure is a powerful approach for material design. New structural degrees of freedom expand the potential of the concept, and coordination polymers as a chemically versatile material platform offer fascinating possibilities to adress this challenge. Here we introduce a new class of hierarchically organized, perovskite-like AB2X6 coordination polymers based on a [BX3]- ReO3-type host network ([Mn(C2N3)3]-), in which the spatial orientation of divalent A2+ cations with separated charge centers that bridge adjacent ReO3-cavities ([R3N(CH2)nNR3]2+) is introduced as a new geometric degree of freedom. Herringbone and head-to-tail order pattern of [R3N(CH2)nNR3]2+ cations are obtained by varying the separator length n and, together with distortions of the pseudocubic [BX3]- network, they determine the materials’ stimuli-responsive behavior such as counterintuitive large negative compressibility and uniaxial negative thermal expansion. This new family of coordination polymers highlights the chemists’ capabilities of designing matter on a molecular level to address macroscopic material functionality and underpins the opportunities of the design of structural degrees of freedom as a conceptual framework for rational material synthesis in the future.
|
Stefan Burger; Karina Hemmer; David C. Mayer; Pia Vervoorts; Dominik Daisenberger; Jan K. Zareba; Gregor Kieslich
|
Materials Science; Inorganic Chemistry; Hybrid Organic-Inorganic Materials; Solid State Chemistry; Supramolecular Chemistry (Inorg.); Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-04-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/624daf6b3b5f99f91bd00213/original/designing-geometric-degrees-of-freedom-in-re-o3-type-coordination-polymers.pdf
|
6711bd0d12ff75c3a1bf9180
|
10.26434/chemrxiv-2024-hxgnv
|
Teaching the concepts of Donnan potential and liquid-junction potential by evaluating homemade pH and ion-sensitive probes constructed using commercial ion-exchange membranes and reference electrodes
|
Transport of ions across semipermeable membranes, like ion-exchange membranes, and salt bridges, like porous frits, each results in electric potential differences that are sensed in most electrochemical experiments. While often neglected, these electric potential differences can significantly impact the interpretation of experimental results. To assist in comprehension of these concepts, a one-to-two-hours-long hands-on laboratory activity, intended for students in electroanalytical chemistry courses, was designed, implemented, and evaluated. This activity requires that students construct a simple two-compartment electrochemical cell from inexpensive and readily available disposable plastic cuvettes, commercially available polymeric ion-exchange membranes, two nominally identical reference electrodes placed in liquid electrolytes that wet each side of the membrane, and a voltmeter or a potentiostat to measure the open-circuit potential between the reference electrodes, i.e. the cell potential. Using commercially available reference electrodes, each consisting of a wire (e.g. Ag/AgCl) immersed in a fritted tube containing an aqueous electrolyte, measured open-circuit potentials report on the magnitude of both Donnan and liquid-junction electric potential differences. These electric potentials are sensitive to the composition of ions in each electrolyte, through interactions with the ion-exchange membrane and porous frits at the tip of each reference electrode. When a cation-exchange membrane separates aqueous solutions consisting of different concentrations of hydrochloric acid (HCl) or potassium hydroxide (KOH), the cell responds like a pH or pK probe, respectively, because the membrane interfaces are more sensitive to the activity of H+ and K+ over Cl– and OH–, respectively. Analogously, when an anion-exchange membrane is used, the cell responds like a pCl or pOH probe, respectively, because the membrane interfaces are more sensitive to the respective activity of Cl– and OH– over H+ and K+. When the solutions contain large concentrations of multiple types of ions, measured open-circuit potentials typically deviate from these Donnan-dominated effects and are instead dominated by a liquid-junction-like effect where electric potentials within and across ion-exchange membranes form due to differences in the permeabilities of the ions. When reference electrodes consist of wires immersed directly into the aqueous electrolytes that wet the membranes, and not in fritted tubes, measured open-circuit potentials also include contributions from the chemical potential of redox-active species that are present in the aqueous electrolytes. While this hands-on laboratory activity is suitable for most upper-level undergraduate students in physical science and engineering disciplines, the concepts of Donnan electric potential, liquid-junction electric potential, and species chemical potential are advanced enough to educate graduate students and senior researchers alike. Our activity also helps instructors teach a topic that is pertinent to the electrochemistry of many aqueous chemical systems using simple components and a straightforward setup.
|
William Gaieck; Anni Zhang; Ashley Sabatose; Madison Ngo; Eric Schwartz; William White; Simon Luo; Leanna Schulte; Yixian Wang; Shane Ardo
|
Analytical Chemistry; Polymer Science; Chemical Education; Electrochemical Analysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-10-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6711bd0d12ff75c3a1bf9180/original/teaching-the-concepts-of-donnan-potential-and-liquid-junction-potential-by-evaluating-homemade-p-h-and-ion-sensitive-probes-constructed-using-commercial-ion-exchange-membranes-and-reference-electrodes.pdf
|
60c73cc9ee301ce92fc78493
|
10.26434/chemrxiv.14770971.v1
|
Towards Chemotactic Supramolecular Nanoparticles: From Autonomous Surface Motion Following Specific Chemical Gradients to Multivalency-Controlled Disassembly
|
<p>Nature designs chemotactic supramolecular
structures that can selectively bind specific groups present on surfaces, autonomously
scan them moving along density gradients, and react once a critical
concentration is encountered. While such properties
are key in many biological functions, these also offer inspirations for
designing artificial systems capable of similar bioinspired autonomous
behaviors. One approach is to use soft molecular units that self-assemble in
aqueous solution generating nanoparticles (NPs) that display specific chemical
groups on their surface, enabling for multivalent interactions with
complementarily functionalized surfaces. However, a first challenge is to
explore the behavior of these assemblies at sufficiently high-resolution to
gain insights on the molecular factors controlling their behaviors. Here we
show that, coupling coarse-grained molecular models and advanced simulation
approaches, it is possible to study the (autonomous or driven) motion of
self-assembled NPs on a receptor-grafted surface at submolecular resolution. As
an example, we focus on self-assembled NPs composed of facially amphiphilic
oligomers. We observe how tuning the multivalent interactions between the NP
and the surface allows to control NP binding, its diffusion along chemical
surface gradients, and ultimately, the NP reactivity at determined surface
group densities. <i>In silico</i> experiments provide physical-chemical
insights on key molecular features in the self-assembling units which determine
the dynamic behavior and fate of the NPs on the surface: from adhesion, to
diffusion, and disassembly. This offers a privileged point of view into the
chemotactic properties of supramolecular assemblies, improving our knowledge on
how to design new types of materials with bioinspired autonomous behaviors.</p>
|
Chiara Lionello; Andrea Gardin; Annalisa Cardellini; Davide Bochicchio; Manisha Shivrayan; Ann Fernandez; S Thayumanavan; Giovanni M. Pavan
|
Aggregates and Assemblies; Controlled-Release Systems; Computational Chemistry and Modeling; Interfaces; Physical and Chemical Properties; Self-Assembly
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-06-14
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73cc9ee301ce92fc78493/original/towards-chemotactic-supramolecular-nanoparticles-from-autonomous-surface-motion-following-specific-chemical-gradients-to-multivalency-controlled-disassembly.pdf
|
679a12effa469535b94aabac
|
10.26434/chemrxiv-2025-8dbck
|
Nature-Inspired C-terminus Modification of Oligo-prolines to Stabilize PPII Helix
|
Oligomers of proline (oligo-Pro) are valuable models for studying the structural and thermodynamic properties of the all-trans polyproline II (PPII) helix. These peptides, in their rigid PPII form, serve as spectroscopic and molecular rulers. However, proline cis/trans isomerization can lead to the undesired all-cis PPI conformation in nonpolar solvents. In this study, we investigated mechanisms to stabilize the PPII structure by analyzing PPII regions in the Protein Data Bank (PDB) and observed a high prevalence of α-helices and β-turns at the C-termini of PPII helices. These motifs likely contribute to PPII stabilization through CO∙∙∙HN hydrogen bonding with the C-terminal carbonyl. To probe this, we synthesized oligo-Pro peptides of varying lengths, each capped with C-terminal β-turns. These peptides exhibited enhanced PPII stability, even in solvents that typically favor PPI. Our findings suggest that C-terminal hydrogen bonding promotes CO∙∙∙CO n → π* interactions within the peptide chain, playing a key role in stabilizing the PPII helix. These insights offer new strategies for designing stable PPII peptides and understanding the underlying mechanisms of PPII stabilization.
|
Paramesh Das; Amar Ghosh; Kalpita Baruah; Debashree Borah; Bani Sarma
|
Biological and Medicinal Chemistry; Biochemistry; Chemical Biology; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-31
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/679a12effa469535b94aabac/original/nature-inspired-c-terminus-modification-of-oligo-prolines-to-stabilize-ppii-helix.pdf
|
60c74ab2469df4ae80f43dc0
|
10.26434/chemrxiv.12234683.v1
|
Separation of Extracellular Vesicles by DNA-Directed Immunocapturing Followed by Enzymatic Release
|
Extracellular vesicles (EVs) have attracted great interest among researchers due to their role in cell-cell communication, disease diagnosis, and drug delivery. In spite of their potential in the medical field, there is no consensus on the best method for separating microvesicles from cell culture supernatant and complex biological fluids. Obtaining a good recovery yield and preserving physical characteristics is critical for the diagnostic and therapeutic use of EVs. The separation is made complex by the fact that blood and cell culture media, contain a large number of nanoparticles in the same size range. Methods that exploit immunoaffinity capture provide high purity samples and overcome the issues of currently used separation methods. However, the release of captured nanovesicles requires harsh conditions that hinder their use in certain types of downstream analysis. Herein, a novel capture and release approach for small extracellular vesicles (sEVs), based on DNAdirected immobilization of antiCD63 antibody is presented. The flexible DNAlinker increases the capture efficiency and allows releasing of EVs by exploiting the endonucleasic activity of DNAse I. This separation protocol works under mild conditions, enabling the release of intact vesicles that can be successfully analyzed by imaging techniques. In this article sEVs recovered from plasma were characterized by established techniques for EVs analysis including nanoparticle tracking and transmission electron microscopy.<br />
|
Dario Brambilla; Laura Sola; Elisa Chiodi; Natasa Zarovni; Diogo Fortunato; Mattia Criscuoli; Vincenza Dolo; Ilaria Giusti; Valentina Murdica; Riccardo Vago; Marcella Chiari
|
Separation Science
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-05-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ab2469df4ae80f43dc0/original/separation-of-extracellular-vesicles-by-dna-directed-immunocapturing-followed-by-enzymatic-release.pdf
|
6124b75e1d1cc2c6b2cb1eb1
|
10.26434/chemrxiv-2021-vnnnr
|
Detergent-free functionalisation of hybrid vesicles with membrane proteins using SMALPs
|
Hybrid vesicles (HVs) that consist of mixtures of block copolymers and lipids are robust biomimetics of liposomes, providing a valuable building block in bionanotechnology, catalysis and synthetic biology. However, functionalisation of HVs remains laborious and expensive, creating a significant current challenge in the field. Here, using a new approach of extraction with styrene-maleic acid lipid particles (SMALPs), we show that a membrane protein (cytochrome bo3) directly transfers into HVs with an efficiency of 73.9 ± 13.5% and without the requirement of any detergent, long incubation times or mechanical disruption. Interestingly, direct transfer of membrane proteins using this approach was not possible into liposomes. This suggests that the HVs are more amenable than liposomes to membrane protein incorporation from a SMALP system. Finally, we show that this transfer method is not limited to cytochrome bo3 and can also be performed with complex membrane protein mixtures.
|
Rosa Catania; Jonathan Machin; Michael Rappolt; Stephen P. Muench; Paul A. Beales; Lars J.C. Jeuken
|
Materials Science; Polymer Science; Nanoscience
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-08-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6124b75e1d1cc2c6b2cb1eb1/original/detergent-free-functionalisation-of-hybrid-vesicles-with-membrane-proteins-using-smal-ps.pdf
|
60c73e98bb8c1ac5783d9919
|
10.26434/chemrxiv.7037264.v1
|
Carbon Supports Mitigate Resistivity Limitations in Ni-Mo Alkaline Hydrogen Evolution Electrocatalysts
|
We have studied the composition and morphology of Ni-Mo alloys. These alloys consist of a Ni-rich core surrounded by Mo-rich oxide layer. The HER activity of Ni-Mo alloys was seen to be limited by interfacial resistance rather than kinetic and solution transport. Vulcan carbon, a conductive support mitigate the resistive limitations by providing conductive percolation networks.
|
Rituja Patil; Aayush Mantri; Stephen House; Judith C. Yang; James McKone
|
Alloys; Base Catalysis; Electrocatalysis; Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-09-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e98bb8c1ac5783d9919/original/carbon-supports-mitigate-resistivity-limitations-in-ni-mo-alkaline-hydrogen-evolution-electrocatalysts.pdf
|
64f3488379853bbd78ee80be
|
10.26434/chemrxiv-2023-fmpq9
|
TGA-FTIR Guided Ligand Evaluation for Iron Photocatalyzed Decarboxylative Giese Reactions
|
A general Fe photocatalyzed Giese reaction was developed using a unique analytical technique for synthetic organic chemistry: Thermal Gravimetric Analysis-Fourier Transform Infrared Spectroscopy (TGA-FTIR). The optimized Giese conditions proceed with low loadings of a simple Fe salt with a commercial amine ligand and obviates the need for the traditional large excess of one coupling partner to facilitate radical capture. This protocol enables the successful coupling of primary, secondary, and tertiary carboxylic acids with sterically hindered, cyclic, and acyclic electron-deficient acceptors. Additionally, methylation of acceptors proceeds smoothly at room temperature from commercial acetic acid. Protected amines, heterocycles, and electron-rich alkenes are well-tolerated, enabling functionalization of Osimertinib, a kinase inhibitor for non-small-cell lung carcinoma. Preliminary investigation of the reaction mechanism was consistent with formation of an Fe-carboxylate species followed by a light-promoted decarboxylation. TGA-FTIR was used to evaluate ligand trends for Fe carboxylates. Using 30-minute decomposition times a correlation was revealed between Fe carboxylate CO2 extrusion time and the yield attained with aliphatic amine ligands coordinated to Fe. Less substituted amine ligands gave greater yields of product and could eliminate the need for stoichiometric quantities of base and provide control for decarboxylation chemistry over hydrogen atom transfer chemistry.
|
Laura K.G. Ackerman-Biegasiewicz; Michael S. Crocker; Jung-Ying Lin; Reem Nsouli; Nathan D. McLaughlin
|
Organic Chemistry; Catalysis; Analytical Chemistry; Organic Synthesis and Reactions; Spectroscopy (Anal. Chem.); Photocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-09-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64f3488379853bbd78ee80be/original/tga-ftir-guided-ligand-evaluation-for-iron-photocatalyzed-decarboxylative-giese-reactions.pdf
|
60c74911469df4839ef43b44
|
10.26434/chemrxiv.12022779.v1
|
Photoinduced Intersystem Crossing in DNA Oxidative Lesions and Epigenetic Intermediates
|
The propensity of 5-formyluracil and 5-formylcytosine, i.e. oxidative lesions and epigenetic intermediates, in acting as intrinsic DNA photosensitizers is unraveled by using a combination of molecular modeling, simulation and spectroscopy. Exploration of potential energy surfaces and non-adiabatic dynamics confirm a higher intersystem crossing rate for 5-formyluracil, whereas the kinetic models evidence different equilibria in the excited states for both compounds
|
Antonio Francés-Monerris; Mauricio Lineros-Rosa; Miguel Angél Miranda; Virginie Lhiaubet-Vallet; Antonio Monari
|
Biophysical Chemistry; Photochemistry (Physical Chem.); Quantum Mechanics; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-03-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74911469df4839ef43b44/original/photoinduced-intersystem-crossing-in-dna-oxidative-lesions-and-epigenetic-intermediates.pdf
|
646d22f3b3dd6a65309f5119
|
10.26434/chemrxiv-2023-xl6w3
|
Challenging ChatGPT with Chemistry-Related Subjects
|
Tools based on large language models such as ChatGPT may revolutionize information retrieval and knowledge discovery, particularly with the vast amount of electronic material available. In this communication we evaluate how two versions of ChatGPT can answer complex questions on chemistry-related subjects in six topics. The tools are still insufficient to deal with subtleties of complex topics, especially as they do not have access to the whole of the scientific literature. However, the progress from ChatGPT-3 to ChatGPT-4 is an indicator that we shall soon have tools to assist scientists in surveys, reviews of the literature, and for teaching.
|
André Pimentel; Angela Wagener; Enio Frota da Silveira; Paulo Picciani; Benjamin Salles; Cristian Follmer; Oswaldo N. Oliveira Jr.
|
Chemical Education; Chemical Education - General
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-05-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646d22f3b3dd6a65309f5119/original/challenging-chat-gpt-with-chemistry-related-subjects.pdf
|
60c73e12ee301c54cdc78684
|
10.26434/chemrxiv.6297185.v1
|
Maxwell’s Equations versus Newton’s Third Law
|
The presented simulated data compares concentration gradients and electric fields with experimental and numerical data of others. This data is simulated for cases involving liquid junctions and electrolytic transport. The objective of presenting this data is to support a model and theory. This theory demonstrates the incompatibility between conventional electrostatics inherent in Maxwell's equations with conventional transport equations. <br />
|
Glyn Kennell; Richard Evitts
|
Electrochemistry - Mechanisms, Theory & Study; Solution Chemistry; Transport phenomena (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-05-22
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e12ee301c54cdc78684/original/maxwell-s-equations-versus-newton-s-third-law.pdf
|
670dcd0c12ff75c3a171f67f
|
10.26434/chemrxiv-2024-r2tc4-v2
|
Strong metal support interaction in Ru/V2O3 catalyst reduces reactant induced poisoning during succinic acid hydrogenation
|
Hydrogenation of carboxylic acids to lactones and alcohols is an important reaction. However, strong adsorption of carboxylic acid on the catalyst surface leads to poisoning of the active site, demands harsher reaction condition and use of organic solvents. In this study, we demonstrate that the strong metal support interaction (SMSI) and hydrogen spillover on Ru/V2O3 can counter the poisoning effect. The Ru/V2O3 catalysts reduced at 400 C formed a layer of V2O3 over Ru. The catalyst was able to hydrogenate succinic acid to gamma-butyrolactone (GBL) in 77 % yield in the presence of water at mild conditions of 150 C and 6 h. H2-D2 exchange experiment showed that for the Ru/V2O3 without SMSI the H2 dissociation was inhibited due to the adsorption of substrate over Ru surface, whereas catalysts with SMSI effect created a barrier between the substrate and the hydrogen dissociation sites. Spillover of dissociated H2 onto the V2O3 surface was found to enhance the catalytic activity. Thermodynamics calculations using density functional theory showed that transfer of a hydride from Ru and proton from V2O3 to the substrate have a lower reaction free energy compared to that of transfer of two hydrogen atoms from a bare ruthenium surface. Additionally, weaker adsorption of substrates and easier desorption of product from the Ru/V2O3 surface increased catalytic activity compared to that of bare ruthenium surface. We show that the general concept of using SMSI to mitigate poisoning can be applied to catalytic hydrogenation of substrates that adsorb on metal sites.
|
Yayati Naresh Palai; Eti Mahal; Biswarup Pathak; Atsushi Fukuoka; Abhijit Shrotri
|
Catalysis; Heterogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-10-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670dcd0c12ff75c3a171f67f/original/strong-metal-support-interaction-in-ru-v2o3-catalyst-reduces-reactant-induced-poisoning-during-succinic-acid-hydrogenation.pdf
|
629dfa2d4f43d6f21531924a
|
10.26434/chemrxiv-2022-pf8k0
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Degradable Vinyl Polymer Nanoparticles/Latexes by Aqueous Nitroxide-Mediated Polymerization-Induced Self-Assembly
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The synthesis of degradable vinyl polymer nanoparticles/latexes in aqueous dispersed media is receiving much attention, particularly for biomedical applications and plastic pollution control, as it can circumvent the severe limitations associated with emulsification of preformed degradable polymers. Polymerisation-induced self-assembly (PISA), which enables the in-situ formation of aqueous suspensions of diblock copolymer nano-objects of high solids content, has become a very popular polymerization process due to its many advantages in terms of simplicity, robustness, scalability and versatility. However, the preparation of degradable vinyl polymer nanoparticles by direct aqueous PISA has never been reported. This severely limits the use of PISA in biomedical and environmental applications. Herein, we report the first aqueous emulsion PISA able to generate degradable vinyl polymer nanoparticles. It relies on radical ring-opening polymerization-induced self-assembly (rROPISA) of traditional vinyl monomers (n-butyl acrylate or styrene) with dibenzo[c,e]oxepane-5-thione (DOT), a thionolactone that features high stability in protic solvents and favourable reactivity with many vinyl monomers, and is a precursor of labile thioester groups in the main chain. Stable aqueous suspensions of thioester-containing diblock copolymer nanoparticles were obtained with both vinyl monomers. Extensive degradation of the copolymers and the nanoparticles was successfully demonstrated under aminolytic or basic conditions. Given the success of the PISA process within the polymer community, this work has the potential to greatly expand its use in many areas, from nanomedicine (providing an extension to biocompatible vinyl polymers) to sustained materials in the context of the polymer circular economy.
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Maëlle Lages; Noémie Gil; Paul Galanopoulo; Julie Mougin; Catherine Lefay; Yohann Guillaneuf; Muriel Lansalot; Franck D'Agosto; Julien Nicolas
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Polymer Science; Polymerization (Polymers); Polymerization kinetics
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CC BY NC ND 4.0
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CHEMRXIV
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2022-06-07
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629dfa2d4f43d6f21531924a/original/degradable-vinyl-polymer-nanoparticles-latexes-by-aqueous-nitroxide-mediated-polymerization-induced-self-assembly.pdf
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623dd9d5ab0051be6298f3c4
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10.26434/chemrxiv-2022-pvn9f
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Halogen Bonding and Chalcogen Bonding Mediated Sensing
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Sigma-hole interactions, in particular halogen bonding (XB) and chalcogen bonding (ChB), have become indispensible tools in supramolecular chemistry, with wide-ranging applications in crystal engineering, catalysis and materials chemistry as well as anion recognition, transport and sensing. The latter has very rapidly developed in recent years and is becoming a mature research area in its own right. This can be attributed to the numerous advantages sigma-hole interactions imbue in sensor design, in particular high degrees of selectivity, sensitivity and the capability for sensing in aqueous media. Herein, we provide the first detailed overview of all developments in the field of XB and ChB mediated sensing, in particular the detection of anions but also neutral (gaseous) Lewis bases. This includes a wide range of optical colorimetric and luminescent sensors as well as an array of electrochemical sensors, most notably redox-active host systems. In addition, we discuss a range of other sensor designs, including capacitive sensors and chemiresistors, and provide a detailed overview and outlook for future fundamental developments in the field. Exemplified herein for the XB and ChB mediated sensing of anions, importantly the sensing concepts and methodologies described are generically applicable for the development of supramolecular receptors and sensors in general, including those for cations and neutral molecules employing a wide array of non-covalent interactions. As such we believe this review to be a useful guide to both the supramolecular and general chemistry community with interests in the fields of host-guest recognition and small molecule sensing. Moreover, we also highlight the need for a broader integration of supramolecular chemistry, analytical chemistry, synthetic chemistry and materials science in the development of the next generation of potent sensors.
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Robert Hein; Paul D. Beer
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Organic Chemistry; Inorganic Chemistry; Analytical Chemistry; Supramolecular Chemistry (Org.); Sensors; Supramolecular Chemistry (Inorg.)
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CC BY NC 4.0
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CHEMRXIV
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2022-03-29
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/623dd9d5ab0051be6298f3c4/original/halogen-bonding-and-chalcogen-bonding-mediated-sensing.pdf
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