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60c74463702a9b6cb018a819 | 10.26434/chemrxiv.9784625.v1 | Dual Electrocatalysis Enables Enantioselective Hydrocyanation of Conjugated Alkenes | Chiral nitriles and their derivatives are prevalent in pharmaceuticals and bioactive compounds. Enantioselective alkene hydrocyanation represents a convenient and efficient approach for synthesizing these molecules. However, a generally applicable method featuring a broad substrate scope and high functional group tolerance remains elusive. Here, we address this long-standing synthetic problem using an electrocatalytic strategy. Electrochemistry allows for the seamless combination of two classic radical reactions—cobalt-mediated hydrogen-atom transfer and copper-promoted radical cyanation—to accomplish highly enantioselective hydrocyanation without the need for stoichiometric oxidant. We harness electrochemistry’s unique feature of precise potential control to optimize the chemoselectivity of challenging substrates. Computational analysis sheds light on the origin of enantioinduction, for which the chiral catalyst imparts a combination of attractive and repulsive non-covalent interactions that direct the enantio-determining C–CN bond formation. This discovery demonstrates the power of electrochemistry in accessing new chemical space and providing solutions to pertinent challenges in synthetic chemistry. | Lu Song; Niankai Fu; Brian G. Ernst; Wai-Hang Lee; Michael O. Frederick; Robert A. DiStasio Jr.; Song Lin | Organic Synthesis and Reactions; Stereochemistry; Electrocatalysis; Redox Catalysis; Catalysis; Electrochemistry - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74463702a9b6cb018a819/original/dual-electrocatalysis-enables-enantioselective-hydrocyanation-of-conjugated-alkenes.pdf |
60e70ef1609d0dd44cd8b31a | 10.26434/chemrxiv-2021-f74dt | Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate via a Preorganized Secondary Coordination Sphere | Enzymes exert control over the reactivity of metal centers with precise tuning of the secondary coordination sphere of active sites. One particularly elegant illustration of this principle is in the controlled delivery of proton and electron equivalents in order to activate abundant but kinetically inert oxidants such as O2 for oxidative chemistry. Chemists have drawn inspiration from biology in designing molecular systems where the secondary coordination sphere can shuttle protons or electrons to substrates. However, a biomimetic activation of O2 requires the transfer of both protons and elec-trons, and molecular systems where ancillary ligands are designed to provide both of these equivalents are comparative-ly rare. Here we report the use of a dihydrazonopyrrole (DHP) ligand complexed to Fe to perform exactly such a biomi-metic activation of O2. In the presence of O2, this complex directly generates a high spin Fe(III)-hydroperoxo intermediate which features a DHP• ligand radical via ligand-based transfer of an H-atom. This system displays oxidative reactivity and ultimately releases hydrogen peroxide, providing insight on how secondary coordination sphere interactions influence the evolution of oxidizing intermediates in Fe-mediated aerobic oxidations. | Kate Jesse; Sophie Anferov; Kelsey Collins; Juan Valdez-Moreira; Alexander Filatov; John Anderson | Inorganic Chemistry; Bioinorganic Chemistry; Ligands (Inorg.); Small Molecule Activation (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-07-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60e70ef1609d0dd44cd8b31a/original/direct-aerobic-generation-of-a-ferric-hydroperoxo-intermediate-via-a-preorganized-secondary-coordination-sphere.pdf |
60c74560842e659d82db2609 | 10.26434/chemrxiv.10007627.v1 | Understanding Chemical Selectivity Through Well Selected Excited States | All calculations performed using ORCA 4.0, B3LYP (Gaussian version) + def2-tzvp/cc-pvtz level<br /> | Frédéric Guégan; Thomas Pigeon; Frank de Proft; Vincent Tognetti; Laurent Joubert; Henry Chermette; Paul W. Ayers; Dominique Luneau; Christophe Morell | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74560842e659d82db2609/original/understanding-chemical-selectivity-through-well-selected-excited-states.pdf |
60c73e180f50dbba383955df | 10.26434/chemrxiv.6670739.v1 | Fine-Tuning Electronic Properties of Luminescent Pt(II) Complexes via Vertex-Differentiated Coordination of Sterically Invariant Carborane-Based Ligands | We report the synthesis of two isomeric Pt(II) complexes ligated by doubly deprotonated 1,1′-bis(<i>o</i>-carborane) (<b>bc</b>). This work provides a potential route to fine-tune the electronic properties of luminescent metal complexes by virtue of vertex-differentiated coordination chemistry of carborane-based ligands. | Kent O. Kirlikovali; Jonathan C. Axtell; Kierstyn Anderson; Peter I. Djurovich; Arnold L. Rheingold; Alexander Spokoyny | Organic Synthesis and Reactions; Photochemistry (Org.); Organometallic Compounds; Theory - Computational; Ligand Design | CC BY NC ND 4.0 | CHEMRXIV | 2018-06-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e180f50dbba383955df/original/fine-tuning-electronic-properties-of-luminescent-pt-ii-complexes-via-vertex-differentiated-coordination-of-sterically-invariant-carborane-based-ligands.pdf |
67623e3f6dde43c90879c894 | 10.26434/chemrxiv-2024-rqq9s | Downsizing Lactams via Rh-Catalyzed C–C Activation | Ring-contraction reactions are valuable transformations to access harder-to-synthesize smaller-sized rings from more available larger-sized precursors. Herein, we report an unprecedented lactam downsizing strategy by taking advantage of removable directing groups (DGs) and Rh-catalyzed C–C activation. A mild method for DG installation to common lactam substrates is developed
by employing silylated amines and Ti catalysts, and the resulting amidine moiety can be converted back to lactams via acid mediated hydrolysis. The ring-contraction reaction exhibits a broad substrate scope, excellent functional group tolerance, and high selectivity for yielding γ-lactams, facilitating “6-to-5”, “7-to-5”, and “8-to-5” ring contractions. Additionally, through careful selection of DGs and ligands, preliminary results on selective “7-to-6” ring contraction has been obtained. Finally, density functional theory (DFT) calculations reveal the origin of the product selectivity. | Rui Zhang; Kangmin Wen; Guangbin Dong | Organic Chemistry; Organometallic Chemistry; Organic Synthesis and Reactions; Bond Activation | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67623e3f6dde43c90879c894/original/downsizing-lactams-via-rh-catalyzed-c-c-activation.pdf |
642e91700784a63aee9fbff0 | 10.26434/chemrxiv-2023-vxngn | Substrate driven Spin Crossover in a Fe(II) scorpionate complex. | A new spin crossover complex based on a heteroscorpionate ligand was synthesized and characterized. Thin films were grown by sublimation in ultra-high vacuum on highly oriented pyrolytic graphite (HOPG) and on gold single crystal Au (111), and spectroscopically characterized through X-ray absorption and by X-ray photoemission. Temperature-dependent experiments on sub-nanometric deposits demonstrated that the thermally induced spin-crossover is preserved at a sub-monolayer (0.7 ML) coverage on HOPG, while deposits with similar thickness lose the switching behaviour on Au(111) surface. The system was unresponsive to light stimuli at low temperature indepently of the used substrate. | Margaux Pénicaud; Edoardo Martinez; Giulia Serrano; Brunetto Cortigiani; Lorenzo Squillantini; Juan González-Estefan; Emilio Velez-Fort; Mathieu Duttine; Mathieu Gonidec; Patrick Rosa; Matteo Mannini; Lorenzo Poggini | Physical Chemistry; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2023-04-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/642e91700784a63aee9fbff0/original/substrate-driven-spin-crossover-in-a-fe-ii-scorpionate-complex.pdf |
651a4aa4a69febde9e1116d7 | 10.26434/chemrxiv-2023-6tz43 | “On-the-fly” Crystal: How to reliably and automatically characterize and construct potential energy surfaces | In this work, the Crystal code, developed previously by the authors to find “holes” as well as legitimate transition states in existing potential energy surface (PES) functions [JPC Lett. 11, 6468 (2020)], is retooled to perform on-the-fly “direct dynamics”-type PES explorations, as well as automatic construction of new PES functions. In all of these contexts, the chief advantage of Crystal over other methods is its ability to globally map the PES, thereby determining the most relevant regions of configuration space quickly and reliably—even when the dimensionality is rather large. Here, Crystal is used to generate a uniformly-spaced grid of density functional theory (DFT) or ab initio points, truncated over the relevant regions, which can then be used to either: (a) hone in precisely on PES features such as minima and transition states, or; (b) create a new PES function automatically, via interpolation. Proof of concept is demonstrated via application to three molecular systems: water (H2O), methane (CH4), and methylene imine (CH2NH). | Mahdi Aarabi; Ankit Pandey; Bill Poirier | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC 4.0 | CHEMRXIV | 2023-10-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651a4aa4a69febde9e1116d7/original/on-the-fly-crystal-how-to-reliably-and-automatically-characterize-and-construct-potential-energy-surfaces.pdf |
60c751ad702a9b48fd18bfc1 | 10.26434/chemrxiv.13200197.v1 | Bias Free Multiobjective Active Learning for Materials Design and Discovery | <div>The design rules for materials are clear for applications with a single objective. For most applications, however, there are often multiple, sometimes competing objectives where there is no single best material, and the design rules change to finding the set of Pareto optimal materials. </div><div>In this work, we introduce an active learning algorithm that directly uses the Pareto dominance relation to compute the set of Pareto optimal materials with desirable accuracy. <br /></div><div>We apply our algorithm to de novo polymer design with a prohibitively large search space.</div><div>Using molecular simulations, we compute key descriptors for dispersant applications and reduce the number of materials that need to be evaluated to reconstruct the Pareto front with a desired confidence by over 98% compared to random search.</div><div>This work showcases how simulation and machine learning techniques can be coupled to discover materials within a design space that would be intractable using conventional screening approaches.</div> | Kevin Maik Jablonka; Giriprasad Melpatti Jothiappan; Shefang Wang; Berend Smit; Brian Yoo | Polymers; Computational Chemistry and Modeling; Theory - Computational; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c751ad702a9b48fd18bfc1/original/bias-free-multiobjective-active-learning-for-materials-design-and-discovery.pdf |
63b73f0a1f240347f717acc1 | 10.26434/chemrxiv-2022-rctz4-v2 | 193 nm ultraviolet photodissociation for the characterization of singly charged proteoforms generated by MALDI | MALDI imaging allows for the near-cellular profiling of proteoforms directly from microbial, plant, and mammalian samples. Despite detecting hundreds of proteoforms, identification of unknowns with only intact mass information remains a distinct challenge, even with high mass resolving power and mass accuracy. To this end many supplementary methods have been used to create experimental databases for accurate mass matching, including bulk or spatially re-solved bottom-up and/or top-down proteomics. Herein we describe the application of 193 nm ultraviolet photodissociation (UVPD) for fragmentation of quadrupole isolated singly charged ubiquitin (m/z 8565) by MALDI-UVPD on an UHMR HF Orbitrap. This platform permitted the high-resolution accurate mass measurement of not just terminal fragments, but also large internal fragments. The outlined workflow demonstrates the feasibility of top-down analyses of isolated MALDI protein ions and the potential towards more comprehensive characterization of proteoforms in MALDI imaging applications. | Kevin Zemaitis; Mowei Zhou; William Kew; Ljiljana Paša-Tolić | Biological and Medicinal Chemistry; Analytical Chemistry; Analytical Chemistry - General; Analytical Apparatus; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63b73f0a1f240347f717acc1/original/193-nm-ultraviolet-photodissociation-for-the-characterization-of-singly-charged-proteoforms-generated-by-maldi.pdf |
6721291bf9980725cf4a3958 | 10.26434/chemrxiv-2024-mh4vk | Potassium Isopropyl(trimethylsilyl)amide and Potassium tert-Butyl(trimethylsilyl)amide:
Solvent-Dependent Solution Structures and Reactivities | Potassium isopropyl(trimethylsilyl)amide (KPTA) and potassium tertbutyl(trimethylsilyl)amide (KBTA) were prepared as stable 1.0 M stock solutions in Et3N or isolable crystalline solids. A combination of the Method of Continuous Variations and a heavy reliance on 29Si NMR spectroscopy revealed solventdependent dimers and monomers. DFT computations offered insights into the solvation. Weakly coordinating solvents such as toluene and triethylamine afford dimers. In THF, KPTA is dimeric whereas KBTA is dimeric at low THF concentration and monomeric in neat THF. Chronic and often poorly understood loss of the 29Si resonance made a broadly based, systematic study difficult and may have obscured deaggregation or ionization. Reactivity was probed using orthometalations by KBTA, which pressed the limits of its basicity and probably impacted the yields in some cases. | Jesse Spivey; David Collum | Organic Chemistry; Organometallic Chemistry; Organic Synthesis and Reactions; Ligands (Organomet.); Main Group Chemistry (Organomet.) | CC BY 4.0 | CHEMRXIV | 2024-11-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6721291bf9980725cf4a3958/original/potassium-isopropyl-trimethylsilyl-amide-and-potassium-tert-butyl-trimethylsilyl-amide-solvent-dependent-solution-structures-and-reactivities.pdf |
6716e35112ff75c3a11ff03e | 10.26434/chemrxiv-2024-6v9hk | Thermally immobilized cellulose acetate butyrate on silica particles as stationary phase for high-performance liquid chromatography | Reversed-phase liquid chromatography is the most widely used analytical technique nowadays. However, it generates a large volume of toxic organic residues and presents poor separations of small polar molecules in traditional stationary phases. In this work, cellulose acetate butyrate was synthesized and used as a reversed-phase coating for separating compounds using highly aqueous mobile phases, reducing organic solvent consumption and minimizing the supra-cited problems. Cellulose acetate butyrate presented a degree of substitution of 0.65 (±0.05) by 1H nuclear magnetic resonance, resulting in hydrophilic and hydrophobic groups in the polymer. The stationary phases were characterized physicochemically by infrared spectroscopy, indicating the polymer attachment on the silica surface with 180 m2 g-1 of surface area and 22 nm of mean pore size. The stationary phase was column-packed and chromatographically characterized by separating the Tanaka mixtures. These separations occurred in reversed-phase mode with hydrophobic and hydrophilic interactions related to the acetate/butyrate and hydroxyl groups from cellulose derivative. The stationary phase showed unique selectivity for separating small polar molecules with 90 % water in mobile phases. Cellulose acetate butyrate stationary phase can potentially separate polar compounds requiring high water contents, making reversed-phase liquid chromatography closer to the Principles of Green Chemistry. | Isabela Ambroso; Aline Silva; Allyson Santos; Rosana Assunção; Anizio Faria | Analytical Chemistry; Separation Science | CC BY NC 4.0 | CHEMRXIV | 2024-10-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6716e35112ff75c3a11ff03e/original/thermally-immobilized-cellulose-acetate-butyrate-on-silica-particles-as-stationary-phase-for-high-performance-liquid-chromatography.pdf |
60c749b7bb8c1a86593daead | 10.26434/chemrxiv.12100638.v1 | A Modular Programmable Inorganic Cluster Discovery Robot for the Discovery and Synthesis of Polyoxometalates | <p>The exploration of complex
multi-component chemical reactions leading to new clusters, where discovery
requires both molecular self-assembly and crystallization, is a major
challenge. This is because the systematic approach required for an experimental
search is limited when the number of parameters in a chemical space becomes too
large, restricting both exploration, and reproducibility. Herein, we present a
synthetic strategy to systematically search a very large set of potential
reactions, using an inexpensive, high-throughput platform; modular in terms of both hardware and
software, and capable of running multiple reactions with in-line analysis; for
the automation of inorganic and materials chemistry. The platform has been used
to explore several inorganic chemical spaces to discover new, and reproduce
known, tungsten-based, mixed transition-metal polyoxometalate clusters, giving
a digital code allowing the easy repeat synthesis of the clusters. Among the
many species identified in this work, most significantly is the discovery of a novel,
purely inorganic W<sub>24</sub>Fe<sup>III</sup>-superoxide cluster formed under
ambient conditions. The
Modular Wheel Platform (MWP) was then employed to undertake two chemical space
explorations producing compounds [1-4]: (C<sub>2</sub>H<sub>8</sub>N)<sub>10</sub>Na<sub>2</sub>[H<sub>6</sub>Fe(O<sub>2</sub>)W<sub>24</sub>O<sub>82</sub>(H<sub>2</sub>O)<sub>25</sub>] (1, {W<sub>24</sub>Fe}),
(C<sub>2</sub>H<sub>8</sub>N)<sub>72</sub>Na<sub>16</sub>[H<sub>16</sub>Co<sub>8</sub>W<sub>200</sub>O<sub>660</sub>(H<sub>2</sub>O)<sub>40</sub>]
(2, {W<sub>200</sub>Co<sub>8</sub>}), (C<sub>2</sub>H<sub>8</sub>N)<sub>72</sub>Na<sub>16</sub>[H<sub>16</sub>Ni<sub>8</sub>W<sub>200
</sub>O<sub>660-</sub>(H<sub>2</sub>O)<sub>40</sub>] (3, {W<sub>200</sub>Ni<sub>8</sub>}) and (C<sub>2</sub>H<sub>8</sub>N)<sub>14</sub>[H<sub>26</sub>W<sub>34</sub>V<sub>4</sub>O<sub>130</sub>]
(4,
{W<sub>34</sub>V<sub>4</sub>}), along with many other known species, for
example simple Keggin clusters and 1D {W<sub>11</sub>M<sup>2+</sup>} chains. <b></b></p> | Daniel Salley; Graham Keenan; De-Liang Long; Nicola Bell; Leroy Cronin | Coordination Chemistry (Inorg.); Reaction (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749b7bb8c1a86593daead/original/a-modular-programmable-inorganic-cluster-discovery-robot-for-the-discovery-and-synthesis-of-polyoxometalates.pdf |
6787b5316dde43c908ab197a | 10.26434/chemrxiv-2025-73g4m | Facile visible-light upcycling of diverse waste plastics using a single organocatalyst with minimal loadings | The escalating plastic waste crisis stems from limitations in conventional recycling methods, which are energy-intensive and produce lower-quality materials, leaving a substantial portion unrecycled. Here, we report a versatile organo-photocatalytic upcycling method employing an easily accessible phenothiazine derivative, PTH-3CN, to selectively depolymerize an unprecedented array of commodity polymers—including polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyurethanes (PU), polycarbonates (PC), and other vinyl polymers—into valuable small molecules with minimal catalyst loading (as low as 102 ppm). Operating under mild conditions with visible light and ambient air, this protocol requires no additional acids or metals and adapts effectively to mixed and post-consumer plastic waste. Mechanistic analysis reveals that PTH-3CN serves as a precatalyst, decomposing into active triarylamine species that drive efficient depolymerization likely through a consecutive photoinduced electron transfer mechanism. This approach offers a promising, scalable route for sustainable plastic upcycling with broad applicability. | Sijing Zhang; Jingxiang Wang; Dewen Su; Xiao Xiao | Organic Chemistry; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6787b5316dde43c908ab197a/original/facile-visible-light-upcycling-of-diverse-waste-plastics-using-a-single-organocatalyst-with-minimal-loadings.pdf |
631ccd8d5351a37cdff5be1b | 10.26434/chemrxiv-2022-6jzw9 | Modifying Ionogel Solid-Electrolytes for Complex Electrochemical Systems | The solution processability of ionogel solid electrolytes have recently garnered interest in the Li-ion battery community as a means to address the interface and fabrication issues commonly associated with most solid-electrolytes. However, the trapped ionic liquid (ILE) component has hindered the electrochemical performance. Herein, we present a process to tune the properties by replacing the ILE in a silica-based ionogel after fabrication with a liquid component befitting the desired application. Electrochemical cycling under various conditions showcases gels containing different liquid components incorporated into LiFePO4 (LFP)/gel/Li cells: high power (455 W kg-1) systems using carbonates, low temperature (-40 oC) using ethers, or high temperature (100 oC) using ionic liquids. Fabrication of additive manufactured (AM) cells utilizing the exchanged carbonate-based system is demonstrated in a planar LFP/Li4Ti5O12 (LTO) system, where a marked improvement over an ionogel is found in terms of rate capability, capacity, and cycle stability (118 vs 41 mAh g-1 at C/4). This process represents a promising route to create a separator-less cell, potentially in complex architectures, where the electrolyte properties can be facilely tuned to meet the required conditions for a wide range of battery chemistries while maintaining uniform electrolyte access throughout cast electrodes. | David Ashby; Jorge Cardenas; Austin Bhandarkar; Adam Cook; Albert Alec Talin | Energy; Energy Storage | CC BY 4.0 | CHEMRXIV | 2022-09-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631ccd8d5351a37cdff5be1b/original/modifying-ionogel-solid-electrolytes-for-complex-electrochemical-systems.pdf |
64dccfd94a3f7d0c0d437056 | 10.26434/chemrxiv-2023-qh6p6 | Crystallographic evidence for global aromaticity in the di-anion and tetra-anion of a cyclophane hydrocarbon | [2(4)]Paracyclophanetetraene is a classic example of a macrocyclic hydrocarbon that becomes globally aromatic on reduction to the di-anion, and switches to globally anti-aromatic in the tetra-anion. This redox activity makes it promising as an electrode material for batteries. Here, we report the solid-state structures of the di- and tetra-anions of this cyclophane, in several coordination environments. The changes in bond length on reduction yield insights into the global aromaticity of the di-anion (26 π electrons), and anti-aromaticity of the tetra-anion (28 π electrons), that were previously deduced from NMR spectra of species generated in situ. The experimental geometries of the aromatic di-anion and anti-aromatic tetra-anion from X-ray crystallographic data match well with gas-phase calculated structures, and reproduce the low symmetry expected in the anti-aromatic ring. Comparison of coordinated and naked anions confirms that metal coordination has little effect on the bond lengths. The UV-vis-NIR absorption spectra show a sharp intense peak at 878 nm for the di-anion, whereas the tetra-anion gives a broad spectrum typical of an anti-aromatic system. | Wojciech Stawski; Yikun Zhu; Zheng Wei; Marina Petrukhina; Harry Anderson | Organic Chemistry; Organic Compounds and Functional Groups; Physical Organic Chemistry; Crystallography – Organic | CC BY NC 4.0 | CHEMRXIV | 2023-08-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64dccfd94a3f7d0c0d437056/original/crystallographic-evidence-for-global-aromaticity-in-the-di-anion-and-tetra-anion-of-a-cyclophane-hydrocarbon.pdf |
62c6906b638326f4ea434b47 | 10.26434/chemrxiv-2022-x5hm9-v2 | Industrial potential of the enzymatic synthesis of nucleoside analogs: Existing challenges and perspectives | Nucleoside phosphorylases have progressed from an enzymatic curiosity to a viable synthetic tool. However, despite the recent advances in nucleoside phosphorylase-catalyzed nucleoside synthesis, the widespread application of these enzymes in industrial processes is still lacking. We attribute this gap to three key challenges, which are outlined in this short review. To address these persistent obstacles, we believe that biocatalytic nucleoside synthesis needs to embrace interdisciplinary partnerships with the fields of organic chemistry, process engineering and flow chemistry. | Sarah Westarp; Felix Kaspar; Peter Neubauer; Anke Kurreck | Organic Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry; Industrial Manufacturing; Pharmaceutical Industry; Biocatalysis | CC BY 4.0 | CHEMRXIV | 2022-07-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c6906b638326f4ea434b47/original/industrial-potential-of-the-enzymatic-synthesis-of-nucleoside-analogs-existing-challenges-and-perspectives.pdf |
64b62833ae3d1a7b0de69d62 | 10.26434/chemrxiv-2023-bkt80 | Inverse Design of Porous Materials: A Diffusion Model Approach | The success of diffusion models in the field of image processing has propelled the creation of software such as Dall-E, Midjourney and Stable Diffusion, which are tools used for text-to-image generations. Mapping this workflow onto materials discovery, a new diffusion model was developed for the generation of pure silica zeolite, marking it the first application of diffusion models to porous materials. Our model demonstrates the ability to generate novel crystalline porous materials that are not present in the training dataset, while exhibiting exceptional performance in inverse design tasks targeted on various chemical properties including the void fraction, Henry coefficient and heat of adsorption. Comparing our model with a Generative Adversarial Network (GAN) revealed that the diffusion model outperforms the GAN in terms of structure validity, exhibiting an over 2,000-fold improvement in performance. We firmly believe that diffusion models (along with other deep generative models) hold immense potential in revolutionizing the design of new materials, and anticipate the wide extension of our model to other classes of porous materials. | Junkil Park; Aseem Partap Singh Gill; Seyed Mohamad Moosavi; JIHAN KIM | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Machine Learning; Artificial Intelligence | CC BY 4.0 | CHEMRXIV | 2023-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b62833ae3d1a7b0de69d62/original/inverse-design-of-porous-materials-a-diffusion-model-approach.pdf |
673499eaf9980725cf0d05ad | 10.26434/chemrxiv-2024-9mt19-v2 | Microflow liquid chromatography coupled to multinozzle electrospray ionization for improved lipidomics coverage of 3D clear cell renal cell carcinoma | In most bioanalytical laboratories, high resolution mass spectrometry (HRMS) systems with electrospray ionization (ESI) are hyphenated to liquid chromatography platforms. The latter typically operate under analytical flow (AF; 0.2-1 mL/min) regimes. Hence, AF/ESI-HRMS methods prioritize detection of analytes of higher abundances or ionizability and tend to suffer from matrix effects or ion suppression. A far higher sensitivity can be obtained with electrospray at nanoflow (10- 1000 nL/min) thanks to a better ionization efficiency and significant decrease of matrix effects. Both advantages are crucial to reliably access low-abundant compounds or weakly ionizable analytes. This work presents a microflow (μF) chromatographic set-up coupled to a novel microfabricated multinozzle electrospray (mnESI) emitter with 5 nozzles spraying at 600 nL/min per nozzle for untargeted HRMS lipidomic profiling. With a runtime of 19 minutes, similar to our established analytical flow (AF/ESI) lipidomics platform, μF/mnESI produced a 16-fold median increase across 69 deuterated lipid standards. The performance of this new configuration was also evaluated in the context of the profiling of 3D clear cell renal cell carcinoma (ccRCC) model exposed to a multidrug combination therapy. The processing of the acquired data resulted in 1270 (μF/mnESI) vs. 752 (AF/ESI) MS2-annotated lipids. Among those, 762 achieved <10% variation on pooled QC samples for μF/mnESI compared to only 361 for the AF method. In addition, the measurements of ccRCC samples confirmed the improvements in ionization efficiency and adduct patterns observed with standards, enabling to annotate 79 oxidized triglycerides, 38 cholesterol esters (only 5 and 4 detected in AF/ESI, respectively), as well as 12 sitosterol esters, not yet reported in mammalian cell cultures. | Sergey Girel; Mathieu Galmiche; Mathis Fiault; Valentin Mieville; Patrycja Nowak-Sliwinska; Serge Rudaz; Isabel Meister | Biological and Medicinal Chemistry; Analytical Chemistry; Mass Spectrometry; Separation Science; Cell and Molecular Biology | CC BY 4.0 | CHEMRXIV | 2024-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673499eaf9980725cf0d05ad/original/microflow-liquid-chromatography-coupled-to-multinozzle-electrospray-ionization-for-improved-lipidomics-coverage-of-3d-clear-cell-renal-cell-carcinoma.pdf |
60c7562d4c8919fb33ad47e7 | 10.26434/chemrxiv.14204453.v1 | Multicomponent Cyclopolymerization of Alkynes, Isocyanides and Isocyanates Toward Heterocyclic Polymers | <p>Multicomponent cyclopolymerization
(MCCP) based on isocyanides, among the tremendous synthetic methodologies, is a
powerful tool for the preparation of functional heterocyclic polymers like poly(maleimide)s
(PMDs), which should be further developed. In this work, an atom-economic and catalyst-free
MCCP of activated alkynes, diisocyanides and diisocyanates was fully explored. The
PMDs with high weight-average molecular weights (<i>M</i><sub>w</sub> up to 29
000) were facilely produced in satisfactory yields (up to 85%). The resultant
polymers showed excellent solubility, high thermal stability, and good
film-forming ability, and their thin films possessed high refraction indices
(RI) in a range of 1.613 to 1.708 at 632.8 nm. Therefore, this work not only
supplements the isocyanide-based multicomponent cyclopolymerizations but also enriches
the family of polymerization reactions based on triple-bond building blocks. </p> | Xiaoheng Wang; Baixue Li; Jianwen Peng; Bingnan Wang; Anjun Qin; Ben Zhong Tang | Polymerization (Polymers) | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7562d4c8919fb33ad47e7/original/multicomponent-cyclopolymerization-of-alkynes-isocyanides-and-isocyanates-toward-heterocyclic-polymers.pdf |
63e9f986fcfb27a31fb36767 | 10.26434/chemrxiv-2023-xq148 | Rhodanine-Based Chromophores: Fast Access to Capable Photoswitches and Application in Light-Induced Apoptosis | Molecular photoswitches are highly desirable in all chemistry-related areas of research. They provide effective outside control over geometric and electronic changes at the nanoscale using an easy to control and waste-free stimulus. However, simple and effective access to such molecular tools is typically not granted and elaborate syntheses and substitution schemes are needed in order to obtain efficient photoswitching properties. Here we present a series of rhodanine-based photoswitches that are prepared in one simple synthetic step without requiring elaborate purification. Photoswitching is induced by UV and visible light in both switching directions and thermal stabilities of the metastable states are high. An additional benefit is the hydrogen bonding capacity of the rhodanine fragment, which enables applications in supramolecular or medicinal chemistry. We further show that the known rhodanine-based inhibitor SMI-16a is a photoswitchable apoptosis inducer. The activity of SMI-16a can be switched ON or OFF by reversible photoisomerization between the inactive E and the active Z isomer. Rhodanine-based photoswitches therefore represent an easy to access and highly valuable molecular toolbox for implementing light responsiveness to functional molecular systems. | Laura Köttner; Friederike Wolff; Peter Mayer; Esther Zanin; Henry Dube | Physical Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Photochemistry (Org.); Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63e9f986fcfb27a31fb36767/original/rhodanine-based-chromophores-fast-access-to-capable-photoswitches-and-application-in-light-induced-apoptosis.pdf |
60c7453d469df42d95f43495 | 10.26434/chemrxiv.9992081.v1 | HIV Capsid Inhibitor Capacity of Different Isomers of Di-Pyridine Benzene and Its Alkyl and Halide Derivatives | HIV-1 Capsid-A inhibitor capacity of different isomers of di-pyridine benzene and its alkyl and halide derivatives are studied systematically. It is found that p-di-pyridine o-ethyl benzene has very good inhibition constant. It is a small, cost effective organic compound and very promising as a HIV drug. It is a molecular docking based study.<br /> | Nilanjana Biswas; Sangita Ghosh; Arijit Bag | Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems; Computational Chemistry and Modeling; Theory - Computational; Quantum Computing; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7453d469df42d95f43495/original/hiv-capsid-inhibitor-capacity-of-different-isomers-of-di-pyridine-benzene-and-its-alkyl-and-halide-derivatives.pdf |
61d41bbb1e13eb16a00f8e6b | 10.26434/chemrxiv-2022-x5x7d | Must be the wave function single-valued? Ring vs. periodic boundary conditions, spinors and double rotations | This is a lecture notes for undergraduate students. We try to tackle the single valuedness of spatial and double valuedness of spin functions. Also, we adress the need of spinors to accommodate spin functions with some parallelism to the need of axial vectors (or antisymmetric traceless tensors) to accommodate angular momentum. Finally, we revisit the Dirac and Weyl tricks on the non-equivalence of a 2 pi and a 4 pi rotation related the topology of rotation and unitary groups. | Josep Planelles | Theoretical and Computational Chemistry; Physical Chemistry; Chemical Education; Quantum Mechanics | CC BY NC 4.0 | CHEMRXIV | 2022-01-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d41bbb1e13eb16a00f8e6b/original/must-be-the-wave-function-single-valued-ring-vs-periodic-boundary-conditions-spinors-and-double-rotations.pdf |
65ae4819e9ebbb4db9b6a10e | 10.26434/chemrxiv-2024-42v2r | Universal Approach to Direct Spatiotemporal Dynamic in-situ Optical Visualization of On-Catalyst Water Splitting Electrochemical Processes | Electrochemical reactions are the unrivaled backbone of next generation energy storage, energy conversion and healthcare devices. However, the in-situ real-time visualization of electrochemical reactions, which can shed light on various critical unknown insights on the electrochemical processes, still remains the bottleneck for fully exploiting their intrinsic potential. In this work, for the first time, a universal approach to the direct spatiotemporal-dynamic in-situ optical visualization of pH based as well as specific byproduct based electrochemical reactions is performed. As a highly relevant and impactful example, the in-operando optical visualization of on-catalyst water splitting processes is performed under neutral water/seawater conditions. pH based visualization are performed using a water-soluble fluorescent pH probe HPTS (8-hydroxypyrene-1,3,6-trisulfonicacid), known for its exceptional optical capability of detecting even the tiniest environment pH changes, thus allowing the unprecedented “spatiotemporal” real-time visualization at the cathode and anode. The successful experimental investigations embarked here, allowed us to reach several yet unveiled deeper insights into the spatiotemporal water splitting processes and their practical modulation for potentially improving the applicability and efficiency of water splitting devices. As a result, we were able to unprecedentedly reveal that at a critical cathode-to-anode distance, a continuous bulk-electrolyte “self-neutralization” phenomenon can be achieved during the water splitting process, leading to the practical realization of enhanced additive-free neutral water splitting. Furthermore, we experimentally unveiled that at increasing electrolyte flow rates, a swift and severe inhibition of the concomitantly forming acidic and basic ‘fronts’, developed at anode and cathode compartments is observed, thus acting as a continuous on-catalysts “buffering” mechanism that allows for a remarkably enhanced water splitting process. Furthermore, to demonstrate the universal applicability of this elegant strategy which is not limited to pH changes, the technique was extended to visualization of specific electrochemical process by the use of reaction product-specific fluorophore. For the purpose, N-(4-butanoic acid) dansylsulfonamide (BADS) fluorophore was successfully explored to in-situ visualize the formation of hypochlorite/ chlorine at the anode during electrolysis of sea water. Thus, a unique experimental tool that allow real-time spatiotemporal visualization and simultaneous mechanistic investigation of complex electrochemical processes in developed that can be universally extended to various fields of research. | Gaurav Bahuguna; Fernando Patolsky | Materials Science; Analytical Chemistry; Energy; Catalysts; Electrochemical Analysis; Spectroscopy (Anal. Chem.) | CC BY 4.0 | CHEMRXIV | 2024-01-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65ae4819e9ebbb4db9b6a10e/original/universal-approach-to-direct-spatiotemporal-dynamic-in-situ-optical-visualization-of-on-catalyst-water-splitting-electrochemical-processes.pdf |
6363eae71db0bd4deb4563d5 | 10.26434/chemrxiv-2022-f362k | Concentration-dependent characteristics of a complex coacervate | In this work, we have comprehensively and systematically investigated the influence of the initial concentration of oppositely charged polyelectrolyte solutions on the interaction strength, interfacial tension and local structure of the coacervate phase generated at charge stoichiometry in a PDADMAC/PANa model system. We have shown for the first time that the concentration has a direct and significant impact on the complexation strength between the two polyelectrolytes, leading to lighter coacervates with constant mass yield and increasing network mesh and decreasing liquid-liquid interfacial tensions until a critical concentration where oppositely charged chains no longer interact, generating the so-called self-supressed coacervate single phase (SSCV). An effect that is due the free counterions present in the solution, whose concentration increases with that of the PE polyelectrolytes and gradually screens the electrostatic complexation. These characteristics will certainly have an impact on the capacity of these coacervates, objects of great scientific and technical interest today, to be efficiently stabilized, to encapsulate active principles and to serve as bioreactors. | Hongwei Li; Lionel Porcar; Ahmed Bentaleb; Christophe Schatz; Jean-Paul Chapel | Polymer Science; Polyelectrolytes - Polymers | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6363eae71db0bd4deb4563d5/original/concentration-dependent-characteristics-of-a-complex-coacervate.pdf |
66001d9666c1381729b56ea7 | 10.26434/chemrxiv-2024-r4bzn-v2 | Catalyst-free photochemical fluorination of C-H bonds of aromatic carbonyl compounds | A wide range of organic molecules can participate in hydrogen atom transfer (HAT) processes as both HAT-donors and photo-HAT-acceptors simultaneously. Therefore, it opens the possibilities to exclude catalysts for C-H functionalization in such cases. This is the underlying idea of the presented catalyst-free C-H bond fluorination approach. We demonstrated that broad range of aryl alkyl ketones can be efficiently fluorinated with Selectfluor-based reagents at benzylic position under UV-A irradiation without any added catalyst. The selectivity of mono- and difluorination can be controlled by con-trolling the excess of fluorinating reagent. Additionally, we propose an analogue of Selectfluor reagent - F-TEDA-TFSI with much greater solubility in acetonitrile which makes our protocol solvent-economical. By the same manner benzaldehydes can be transformed to corresponding benzoyl fluorides with almost quantitative yields. The protocol was successfully applied in late-stage fluorination of complex molecules Tonalide and Tolperisone. Kinetic measurements demonstrated zero-order kinetics which indicates that light flux is the limiting factor. A tentative mechanism was proposed based on the selectivity of fluorination of primary, secondary, and tertiary benzylic C-H bonds. | Nikita Chernovskii; Pavel Zaikin | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66001d9666c1381729b56ea7/original/catalyst-free-photochemical-fluorination-of-c-h-bonds-of-aromatic-carbonyl-compounds.pdf |
60c749c7567dfe01acec4c51 | 10.26434/chemrxiv.12103341.v1 | Monte Carlo Study of a Liquid-Liquid Phase Transition Using a Modified Gibbs Ensemble | <div>The carbon disulfide-methanol liquid-liquid critical point is studied using a Monte</div><div>Carlo simulation of classical Stockmayer particles. A low energy configuration for the segregated</div><div>two component system is determined using standard Monte Carlo methods then a modified</div><div>Gibbs ensemble is employed to study the effect of transferring particles from one phase to</div><div>another. Rather than use the model for the entropy of mixing in the Gibbs ensemble, which is</div><div>of the regular solution type, a semi-quasi-chemical model is used which involves an interaction</div><div>energy. We are able to simulate the mixing of the two components as the temperature approaches</div><div>the critical temperature from below. Further, a method is given whereby the simulation results</div><div>can be used to predict the critical temperature.</div> | Douglas Barlow | Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749c7567dfe01acec4c51/original/monte-carlo-study-of-a-liquid-liquid-phase-transition-using-a-modified-gibbs-ensemble.pdf |
60c74646337d6ccc88e27128 | 10.26434/chemrxiv.11295029.v1 | Interfacial Charge Transfer Processes in 2D and 3D Semiconducting Hybrid Perovskites: Azobenzene as Photoswitchable Ligand | <p>In the vast majority of studies on semiconductor particles one uses ligands, respectively capping agents, which bind to the external surfaces of the particles and cover it with an electrically insulating shell. Since transport of charge carrier and/ or energy across interfaces is desirable for a large number of applications, the use of pi-conjugated ligands becomes more and more interesting. Among those, compounds which show stimuli-responsive properties, particularly molecular switches are fascinating, as one hopes to be able to adjust the properties of the interfaces by demand. However, how the properties of such special ligands get influenced by the presence of a semiconductor and vice-versa is under debate. Here, ammonium-modified azobenzene compounds were selected as prototypes for molecular switches and organic-inorganic hybrid perovskites on the semiconductor side. The class of ammonium-lead-halide phases as prototypes is special, because in addition to surface functionalization of 3D crystals, organic compounds can be truly incorporated into the crystal as 2D phases yielding, for example, layered Ruddelsden-Popper phases. We present photoswitchable azobenzene ligands with varying head group lengths for the synthesis of 2D and 3D hybrid perovskite phases. Energy transfer mechanisms are influenced by the length of the molecular spacer moiety, which determines the distance between the pi-system to the semiconductor surfaces. We find huge differences in the photoswitching behaviour between the free, surface coordinated versus ligands integrated inside perovskite layers. Photoswitching of azobenzene ligands incorporated to 2D phases is nearly quenched, while the same mechanism for coordinating ligands is greatly improved, compared to the free ligands. The improvement originates from an energy transfer from the perovskite to the azobenzene, which is strongly distance dependent. This study provides evidence for the photoswitching behaviour of azobenzene as ligand for hybrid perovskites and the dependence of the head group between a chromophore and the perovskite phase.</p> | Nicole Fillafer; Tobias Seewald; Lukas Schmidt-Mende; Sebastian Polarz | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74646337d6ccc88e27128/original/interfacial-charge-transfer-processes-in-2d-and-3d-semiconducting-hybrid-perovskites-azobenzene-as-photoswitchable-ligand.pdf |
6163fabdf718dfa34edaaaa1 | 10.26434/chemrxiv-2021-h59n1-v2 | Raman Tweezers for Tire and Road Wear Micro- and Nanoparticles analysis | Tire and Road Wear Particles (TRWP) are non-exhaust particulate matter generated by road transport means during the mechanical abrasion of tires, brakes and roads. TRWP accumulate on the roadsides and are transported into the aquatic ecosystem during stormwater runoffs. Due to their size (sub-millimetric) and rubber content (elastomers), TRWP are considered microplastics (MPs). While the amount of the MPs polluting the water ecosystem with sizes from ~ 5 μm to more than 100 μm is known, the fraction of smaller particles is unknown due to the technological gap in the detection and analysis of < 5 μm MPs. Here we show that Raman Tweezers, a combination of optical tweezers and Raman spectroscopy, can be used to trap and chemically analyze individual TWRPs in a liquid environment, down to the sub-micrometric scale. Using tire particles mechanically grinded from aged car tires in water solutions, we show that it is possible to optically trap individual sub-micron particles, in a so-called 2D trapping configuration, and acquire their Raman spectrum in few tens of seconds. The analysis is then extended to samples collected from a brake test platform, where we highlight the presence of sub-micrometric agglomerates of rubber and brake debris, thanks to the presence of additional spectral features other than carbon. Our results show the potential of Raman Tweezers in environmental pollution analysis and highlight the formation of nanosized TRWP during wear. | Gillibert Raymond; Alessandro Magazzù; Agnese Callegari; David Brente Ciriza; Foti Antonino; Maria Grazia Donato; Onofrio M. Maragò; Giovanni Volpe; Marc Lamy de La Chapelle; Fabienne Lagarde; Pietro Giuseppe Gucciardi | Analytical Chemistry; Nanoscience; Environmental Analysis; Spectroscopy (Anal. Chem.); Nanostructured Materials - Nanoscience | CC BY NC 4.0 | CHEMRXIV | 2021-10-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6163fabdf718dfa34edaaaa1/original/raman-tweezers-for-tire-and-road-wear-micro-and-nanoparticles-analysis.pdf |
60c747d0bb8c1a63b43dab5c | 10.26434/chemrxiv.11800257.v1 | Synthesis, Characterisation and Cytotoxic Activity Evaluation of New Metalsalen Complexes Based on the 1,2-bicyclo[2.2.2]octane Bridge | Diaminobicyclo[2.2.2]octane was used as starting material for the preparation, in solution or in a ball-mill, of a salen ligand. Five metal salen complexes were prepared in high yield and their cytotoxic activities were evaluated against HCT116 cell lines. Original manganese salen complex displayed the highest activity with a potency 16 fold higher than the one of cisplatin, demonstrating the benefit of the bridging backbone, compared to other salen systems. An alternative preparation route for this complex by mechanochemistry was also performed.<br /> | Pierre Milbeo; François Quintin; Laure Moulat; Claude Didierjean; Jean Martinez; Xavier Bantreil; Monique Calmès; Frédéric Lamaty | Bioorganometallic Chemistry; Coordination Chemistry (Organomet.); Ligands (Organomet.); Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c747d0bb8c1a63b43dab5c/original/synthesis-characterisation-and-cytotoxic-activity-evaluation-of-new-metalsalen-complexes-based-on-the-1-2-bicyclo-2-2-2-octane-bridge.pdf |
626b4332368ab64701913771 | 10.26434/chemrxiv-2022-g3gvz | Conditional 𝛽-VAE for De Novo Molecular Generation | Deep learning has significantly advanced and accelerated de novo molecular generation. Generative networks, namely Variational Autoencoders (VAEs) can not only randomly generate new molecules but also alter molecular structures to optimize specific chemical properties which are pivotal for drug-discovery. While VAEs have been proposed and researched in the past for pharmaceutical applications, they possess deficiencies that limit their ability to both optimize properties and decode syntactically valid molecules. We present a recurrent, conditional 𝛽-VAE that disentangles the latent space to enhance post hoc molecule optimization. We create a mutual information driven training protocol and data augmentations to both increase molecular validity and promote longer sequence generation. We demonstrate the efficacy of our framework on the ZINC-250k dataset, achieving SOTA unconstrained optimization results on the penalized LogP (pLogP) and QED scores, while also matching current SOTA results for validity, novelty, and uniqueness scores for random generation. We match the current SOTA on QED for top-3 molecules at 0.948, while setting a new SOTA for pLogP optimization at 104.29, 90.12, 69.68 and demonstrating improved results on the constrained optimization task. | Ryan Richards; Austen Groener | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems | CC BY NC 4.0 | CHEMRXIV | 2022-05-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626b4332368ab64701913771/original/conditional-vae-for-de-novo-molecular-generation.pdf |
60c7552d4c891925b9ad4635 | 10.26434/chemrxiv.14049719.v1 | The Role of Hydrogen Bonding in the Dehydration of Bioalcohols in Hydrophobic Pervaporation Membranes | <p>The dehydration of bioalcohols is considered one of
the major factors contributing to the cost of biofuel production. In this
study, liquid phase separation of water from methanol and ethanol in a
siliceous MFI pervaporation membrane was studied by performing concentration
gradient driven molecular dynamic (CGD-MD) simulations. CGD-MD simulations work
by imposing a higher concentration in the feed side and a lower concentration
in the permeate side of the membrane. This creates a concentration gradient
across the membrane that facilitates the diffusion of molecules from the feed
to the permeate side, mimicking the experimental pervaporation membrane set up.
Fluxes of methanol, ethanol and water were calculated in single component
permeation simulations and in equimolar methanol-water and ethanol-water
mixture separation simulations. It was found that water formed hydrogen bonding
with the silanol (Si-OH) groups on the external surface of the MFI and did not
enter the membrane in the single component permeation simulation. While this
may suggest that MFI can be used to effectively dehydrate bioalcohols, our
simulations showed that water permeated through the MFI membrane when it was in
a mixture with either methanol or ethanol. Furthermore, in the alcohol-water
mixture simulations, the fluxes of methanol and ethanol were significantly
lower than that of expected based on their single component fluxes. A detailed
analysis of hydrogen bonding in the alcohol-water mixture separation
simulations revealed that water preferred making hydrogen bonds with methanol
and ethanol rather than with the silanol groups. This resulted in drifting of
water molecules along with permeating alcohol molecules in to the MFI membrane
in mixture simulations, while slowing the permeation of methanol and ethanol
fluxes. </p> | Rafael M. Madero-Castro; Sofía Calero; A. Ozgur Yazaydin | Nanostructured Materials - Materials; Computational Chemistry and Modeling; Transport Phenomena (Chem. Eng.); Fuels - Energy Science | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7552d4c891925b9ad4635/original/the-role-of-hydrogen-bonding-in-the-dehydration-of-bioalcohols-in-hydrophobic-pervaporation-membranes.pdf |
67c58edf81d2151a02dd2ccb | 10.26434/chemrxiv-2025-4dncx | Controlled aggregation of pyrene-based supramolecular nanostructures for light-driven switchable H2 or H2O2 production | Self-assembled organic chromophores form nanostructures in solutions, with their molecular packing determining the optoelectronic properties and photocatalytic activity. Here we report an organic dye molecule, 1,3,6,8-tetrakis(4-ethynylbenzoic acid)pyrene (TEBAPy), that exhibits two aggregate states in aqueous conditions: nanofibers or nanoparticles depending on the charge-screening conditions. The nanofibers promote sacrificial photocatalytic hydrogen production (H2, 84 mmol g–1 h–1) while the nanoparticles produce hydrogen peroxide (H2O2, 71 mmol g–1 h–1). Using a combination of structural and photophysical characterizations, we show that the photocatalytic activity is determined by the nature of the formed self-assembled aggregate, demonstrating the potential of supramolecular nanostructures to tune their activity and switch their reactivity. We show clear correlation between the presence of fibrous nanostructures and photocatalytic H2 evolution, with spectroscopy showing mixing of excitonic states that enables efficient charge separation over multiple chromophore units. In the nanoparticular aggregates, on the contrary, the excitation is localized and leads to excimer formation that is involved in H2O2 production. The results demonstrate that the molecular packing of a single chromophore in self-assembled organic nanostructures can not only optimize solar fuel production but also enable multiple and switchable photocatalytic functions. | Marianna Barbieri; Matilde Doardo; Ilaria Fortunati; Anna Fortunato; Elisabetta Collini; Francesca Arcudi; Luka Đorđević | Catalysis; Nanoscience; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Photocatalysis; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2025-03-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c58edf81d2151a02dd2ccb/original/controlled-aggregation-of-pyrene-based-supramolecular-nanostructures-for-light-driven-switchable-h2-or-h2o2-production.pdf |
66f5229f51558a15ef2a4373 | 10.26434/chemrxiv-2023-qf6rb-v3 | Structural and mechanistic insights into Main protease (Mpro) dimer interface destabilization inhibitor: Unveiling new therapeutic avenues against SARS-CoV-2 | SARS-CoV-2 variants recurrence has emphasized the imperative prerequisite for effective antivirals. The main protease (Mpro) of SARS-CoV-2 is crucial for viral replication, making it one of the prime and promising antiviral target. Mpro features several druggable sites, including active site and allosteric sites near the dimerization interface that regulate its catalytic activity. This study has identified six highly efficacious antiviral SARS-CoV-2 compounds (WIN-62577, KT185, bexarotene, ledipasvir, diacerein, and simepervir) using structure-based virtual screening of compound libraries against Mpro. Using SPR and ITC, the binding of selected inhibitory compounds to target Mpro was validated. FRET-based protease assay demonstrated that the identified molecules effectively inhibit Mpro with IC50 values in the range from 0.08 to 7.31 μM. Additionally, in-vitro cell-based antiviral assays showed high efficacy with EC50 values in the range of 1.8 to 18.92 μM. Crystal structure of Mpro-minocycline complex detailed the possible inhibition mechanism of minocycline, an FDA-approved antibiotic. Minocycline binds to an allosteric site, revealing residues critical for the loss of protease activity due to destabilization of molecular interactions at the dimeric interface, which are crucial for Mpro proteolytic activity. The study suggests that the binding of minocycline to the allosteric site may play a role in Mpro dimer destabilization and directs the rational design of minocycline derivatives as antiviral drugs. | Ankur Singh; Kuldeep jangid; Sanketkumar Nehul; Preeti Dhaka; Ruchi Rani; Akshay Pareek; Gaurav Sharma; Pravindra Kumar; Shailly Tomar | Biological and Medicinal Chemistry; Biochemistry; Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f5229f51558a15ef2a4373/original/structural-and-mechanistic-insights-into-main-protease-mpro-dimer-interface-destabilization-inhibitor-unveiling-new-therapeutic-avenues-against-sars-co-v-2.pdf |
60c74ff3337d6ccca3e281ff | 10.26434/chemrxiv.12966890.v1 | Band Positioning in Boron Nitride and Metal-Free Photocatalysts via Photoelectron- and UV-Vis Diffuse Reflectance Spectroscopy | <p>New photocatalysts, particularly porous ones such as porous boron nitride, have emerged that exhibit complex structures and for which, there is limited knowledge of the electronic structure. Gaining insight into their complete band structure on the absolute energy scale will help assessing their suitability for a given photocatalytic reaction. To address this, we rationalise key concepts of band positioning alignment for both porous and non-porous semiconductors on the absolute energy scale. The approach employs a range of techniques generally accessible to many research groups. It involves a combination of spectroscopic techniques, namely X-ray photoelectron spectroscopy to determine the work function and valence band offset, and UV-Vis diffuse reflectance spectroscopy to measure the band gap. We apply this to present the complete band structure of boron nitride, in both porous and non-porous forms. We validate our methodology by comparing the experimentally obtained band structure for graphitic carbon nitride and amorphous boron, both amorphous semiconductors with a known band structure. We show how this can help predict possible photocatalytic reactions and demonstrate this in the context of CO2 photoreduction. With porous materials, such as porous BN, garnering increasing interest for photocatalytic applications, shedding light on their band structures could pave the way towards a methodical tuning and optimization of the photochemistry of these materials. </p> | Ravi Shankar; Anna Hankin; Gwilherm Kerherve; Camille Petit | Catalysts | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ff3337d6ccca3e281ff/original/band-positioning-in-boron-nitride-and-metal-free-photocatalysts-via-photoelectron-and-uv-vis-diffuse-reflectance-spectroscopy.pdf |
637507ed56c6f42d397034ad | 10.26434/chemrxiv-2022-94pg8 | A Unified Approach to the Aminoallylation of Carbonyl Compounds Through Cu-Catalyzed Enantioselective Reductive Coupling of Allenamides | Herein, we report the development of a highly enantioselective aminoallylation reaction of both aldehyde and ketone electrophiles through the Cu-catalyzed reductive coupling of N-substituted allenes (allenamides). Through optimization of the allenamide to avoid an on-cycle rearrangement, high enantioselectivities could be obtained for a variety of ketone and aldehyde electrophiles in up to >99% ee and >98:2 anti:syn diastereoselectivities. Use of the acyclic allenamides described in this report selectively generated anti-diastereomers in contrast to cyclic allenamides that were previously shown to favor the syn form. Rationale for this change in diastereoselectivity and synthetic applications are also presented. | Raphael Klake; Stephen Collins; Joshua Sieber | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/637507ed56c6f42d397034ad/original/a-unified-approach-to-the-aminoallylation-of-carbonyl-compounds-through-cu-catalyzed-enantioselective-reductive-coupling-of-allenamides.pdf |
65d192369138d231615dd2d9 | 10.26434/chemrxiv-2024-rw2rr | Towards Understanding Trans-Cleavage of Natural and Synthetic Nucleic Acids by Cas12a for Sensitive CRISPR Biosensing | CRISPR/Cas systems have been widely utilized for the development of biosensing platforms for precision molecular diagnostics. Their remarkable biosensing performance critically depends on the efficiency of sequence-independent trans-cleavage in type V and VI Cas effectors. Cas12a, a typical example of type V Cas effector exhibits varying trans-cleavage efficiency on different types of nucleic acids, and also in response to different nucleobase sequences. However, the underlying mechanism of Cas12a’s trans-cleavage characteristic remains unclear. To explore this mechanism, we introduced Xeno nucleic acids (XNA) as potential trans-cleavage substrates of Cas12a. XNAs are chemically modified nucleic acid analogues, which originate from chemical modifications of nucleobases, sugar moieties, and the backbone. We observed a progressive decrease in trans-cleavage rates by Cas12a across different types of XNAs, in the following sequence: nucleobase-modified XNA > sugar moiety-modified XNA > backbone-modified XNA. In addition, more complex chemical modifications on either of the three above locations led to the lowering of the trans-cleavage rate of Cas12a. These findings elucidate the mechanism behind Cas12a’ trans-cleavage characteristic, which is attributed to varying molecular complexity of the sugar moieties and nucleobases. Based on these findings, we also developed a colorimetric CRISPR/Cas12a biosensing system utilizing XNA for the detection of circulating tumor DNA (ctDNA), with a limit of detection of 10 pM and a 4 logs detection range from 10 pM to 100 nM. These results indicate that XNA can serve as a novel Cas12a trans-cleavage target for sensitive biosensing applications. | Fei Deng; Rui Sang ; Yi Li ; Danting Yang ; Wei Deng ; Ewa Goldys | Analytical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d192369138d231615dd2d9/original/towards-understanding-trans-cleavage-of-natural-and-synthetic-nucleic-acids-by-cas12a-for-sensitive-crispr-biosensing.pdf |
60c74952567dfe224fec4b9e | 10.26434/chemrxiv.11538708.v2 | Rational Enzyme Design Without Structural Knowledge: A Sequence-Based Approach for Efficient Generation of Glycosylation Catalysts | <p>We present an enzyme engineering
approach based solely on amino-acids sequence to convert glycoside hydrolases
into transglycosylases. We demonstrate its effectiveness on enzymes form five
different glycoside hydrolase families, synthesizing various oligosaccharides
containing different α-/β-pyranosides or furanosides in one-step with high
yields.</p> | David Teze; Zhao, Jiao; Mathias Wiemann; Zubaida Gulshan Kazi; Rossana Lupo; Mette Errebo Rønne; Göran Carlström; Jens Øllgaard Duus; Yves-Henri Sanejouand; Michael J. O’Donohue; Eva Nordberg Karlsson; Régis Fauré; Henrik Stålbrand; Birte Svensson | Biocatalysis | CC BY 4.0 | CHEMRXIV | 2020-03-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74952567dfe224fec4b9e/original/rational-enzyme-design-without-structural-knowledge-a-sequence-based-approach-for-efficient-generation-of-glycosylation-catalysts.pdf |
60c74c42702a9ba48418b60b | 10.26434/chemrxiv.12448970.v1 | Dual Nickel/Palladium-Catalyzed Reductive Cross-Coupling Reactions Between Two Phenol Derivatives | Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance and low cost of phenols. Here, we report a dual nickel/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2’disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allow for straightforward late-stage functionalization, illustrated with examples such as Ezetimibe and tyrosine. NMR spectroscopy and DFT calculations indicate that the nickel catalyst is responsible for activating the aryl triflate, while the palladium catalyst preferentially reacts with the aryl tosylate. | Baojian Xiong; Yue Li; Yin Wei; Søren Kramer; Zhong Lian | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74c42702a9ba48418b60b/original/dual-nickel-palladium-catalyzed-reductive-cross-coupling-reactions-between-two-phenol-derivatives.pdf |
65cf665e66c1381729ca26ea | 10.26434/chemrxiv-2024-5mmvj | Enhancing LC×LC separations through Multi-Task Bayesian Optimization | Method development in comprehensive two-dimensional liquid chromatography (LC×LC) is a challenging process. The interdependencies between the two dimensions and the possibility of incorporating complex gradient profiles, such as multi-segmented gradients or shifting gradients, make trial-and-error method development time-consuming and highly dependent on user experience. Retention modeling and Bayesian optimization (BO) have been proposed as solutions to mitigate these issues. However, both approaches have their strengths and weaknesses. On one hand, retention modeling depends on effective peak tracking and accurate retention time and width predictions, becoming increasingly challenging for complex samples and advanced gradient assemblies. On the other hand, Bayesian optimization may require many experiments when dealing with many adjustable parameters, as in LC×LC. Therefore, in this work, we investigate the use of multi-task Bayesian optimization (MTBO), a method that can combine information from both retention modeling and experimental measurements. The algorithm was first tested and compared with BO using a synthetic retention modeling test case, where it was shown that MTBO finds better optima with fewer method-development iterations than conventional BO. Next, the algorithm was tested on the optimization of a method for a pesticide sample and we found that the algorithm was able to improve upon the initial scanning experiments. Multi-task Bayesian optimization is a promising technique in situations where modeling retention is challenging, and the high number of adjustable parameters and/or limited optimization budget makes traditional Bayesian optimization impractical. | Jim Boelrijk; Stef R.A. Molenaar; Tijmen S. Bos; Tina A. Dahlseid; Bernd Ensing; Dwight R. Stoll; Patrick Forré; Bob W.J. Pirok | Analytical Chemistry; Chemoinformatics; Mass Spectrometry; Separation Science | CC BY NC 4.0 | CHEMRXIV | 2024-02-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65cf665e66c1381729ca26ea/original/enhancing-lc-lc-separations-through-multi-task-bayesian-optimization.pdf |
675c9d777be152b1d0e8683c | 10.26434/chemrxiv-2024-110m5 | Autocatalytic-Amplificative Detection of Ethylene | Amplified sensing systems offer the potential for high sensitivity; however, the vast majority of molecular strategies involve stoichiometric detection and signal transduction, including numerous recent examples of systems inspired by transition metal catalyzed reactions. Allosteric catalysis via activation of latent precatalysts by a target analyte represents an attractive strategy for detecting low concentration species. Analyte amplification represents another attractive approach, akin to PCR-based assays. Here we report the development of an autocatalytic detection system based on ethylene activation of latent Ru-based olefin metathesis precatalysts. Signal transduction is amplified both by catalytic ring closing metathesis of profluorescent substrates and ethylene propagation to activate additional units of latent catalyst. High sensitivity is observed as a result of this dual-mode Amplified Detection of Ethylene (ADE). Detection of endogenous ethylene from fruit and oxidation-decomposition of polyunsaturated fatty acids via lipid peroxides is demonstrated. | Autumn Giger; Jaiden Voldrich; Brian Michel | Catalysis; Analytical Chemistry; Organometallic Chemistry; Environmental Analysis; Kinetics and Mechanism - Organometallic Reactions; Ligands (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675c9d777be152b1d0e8683c/original/autocatalytic-amplificative-detection-of-ethylene.pdf |
60c7523c337d6c8d9ae286cd | 10.26434/chemrxiv.13270553.v1 | Hopping Conductance in Molecular Wires Exhibits a Large HeavyAtom Kinetic Isotope Effect | We report a large kinetic isotope effect (KIE) for intramolecular charge transport through pi-conjugated oligophenylene imine (OPI) molecules > 4 nm in length connected to Au electrodes. 13C and 15N heavy-atom substitution on the imine bonds produces a normalized conductance KIE of ~2.7 per labeled atom in OPI wires, far larger than typical heavy-atom KIEs reported for chemical reactions. In contrast, isotopic labeling of the imine bonds for short OPI wires < 4 nm does not produce a conductance KIE, consistent with a direct tunneling mechanism expected for short molecules. Temperature dependent measurements on a long (> 4 nm) 15N-substituted OPI wire and its unlabeled isotopologue reveal that conductance is activated. The conductance results for long wires are thus consistent with multi-step polaron transport and we propose that the exceptionally large conductance KIEs imply a thermally-assisted, through-barrier polaron tunneling mechanism. In general, the observation of large heavy-atom conductance KIEs opens up considerable opportunities for exploring microscopic conduction mechanisms in pi-conjugated molecules. <br /> | Quyen nguyen; C. Daniel Frisbie | Thin Films; Self-Assembly; Surface; Transport phenomena (Physical Chem.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7523c337d6c8d9ae286cd/original/hopping-conductance-in-molecular-wires-exhibits-a-large-heavy-atom-kinetic-isotope-effect.pdf |
63e26c1af1da89c683811b71 | 10.26434/chemrxiv-2023-9n8zn | Poly(styrene sulfonate) coated gold nanoparticles display virucidal antiviral activity | Viruses are pathogens capable of causing serious global health problems. Designing and developing interventions against viruses is of paramount importance. By mimicking sulfonated cell surface polymers it is possible to design materials that interact with viruses and inhibit infection. These materials typically have a reversible, non-destructive, virustatic mechanism. A virucidal, destroy on contact, mechanism is advantageous for many applications. We show that by attaching virustatic polymers to a nanoparticle core it is possible to alter their mode of action to virucidal. Here we attach poly(styrene sulfonate)(PSS) to gold nanoparticles. The virustatic antiviral properties of PSS are well known, however, this is the first ime a virucidal mechanism has been achieved. Here we synthesise Thiol-terminated PSS using RAFT polymerisation. This thiol-terminated PSS was then used to synthesise PSS coated AuNPs via reduction of gold salts. These PSS coated AuNPs were then studied for their toxicity, antiviral properties and mode of action. We found that they were non-toxic, broad-spectrum and had a virucidal mode of action. Designing non-toxic virucidal materials is a significant challenge and a simple approach to accessing this advantageous mode of action is urgently needed. This strategy should be applicable to other virustatic polymers, greatly increasing their applicability. | Lorraine Bhebhe; Luke Jones; Elana Super; Samuel Jones | Biological and Medicinal Chemistry; Polymer Science; Nanoscience; Nanostructured Materials - Nanoscience; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63e26c1af1da89c683811b71/original/poly-styrene-sulfonate-coated-gold-nanoparticles-display-virucidal-antiviral-activity.pdf |
6688d56ac9c6a5c07a6b6c68 | 10.26434/chemrxiv-2024-x36vm-v2 | Application of Deconvolution in Path Integral Simulations | In path integral molecular dynamics (PIMD) simulations, additional vibrations appear beyond the physical vibrations. In harmonic approximation, the frequencies of these internal modes can be determined from the physical frequencies. We show that this formal effect of the path integral simulations on the vibrations can be considered as a convolution if we use the square of the frequency as an independent variable. This convolution can be represented as a matrix multiplication. The potential of the formalism is demonstrated in two applications. We present an alternative method to determine the power spectrum of thermostats used in PIMD simulations. We also show that in simple anharmonic model systems, the physical frequencies can be obtained from ring polymer molecular dynamics simulations by deconvolution. | Ádám Madarász; Gergely Laczkó | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6688d56ac9c6a5c07a6b6c68/original/application-of-deconvolution-in-path-integral-simulations.pdf |
655677246e0ec7777f175636 | 10.26434/chemrxiv-2023-xz19l | Lessons Learnt in Photocatalysis - the Influence of Solvent Polarity and the Photostability of the Photocatalyst | The yields obtained in a photocatalysis reaction are frequently dependent on the choice of solvent. Yet, the intrinsic optoelectronic properties of photocatalysts (PCs) that form the basis for the thermodynamic driving force of the photocatalysis are often acquired in a solvent different to that used in the photocatalytic reaction, despite these crucial parameters being solvent dependent. Herein, we report the detailed computational modelling and optoelectronic characterization of eight popular PCs, encompassing transition metal complexes and organic compounds, in four commonly used solvents of varying polarity. Significant variation of up to 270 mV in the experimental ground-state and excited-state redox potentials is noted as a function of solvent polarity, while experimental triplet energies are found to be dependent on solvent (up to 110 meV) when the excited state is charge transfer, rather than locally excited, in nature. A range of photocatalytic electron and energy transfer reactions were investigated using a subset of the PCs and solvents to verify the impact of the changes in optoelectronic properties on the yields of the reactions. For the photoredox reactions, the yields are not correlated with solvent polarity. Instead, when the PC could promote the formation of the target product, we observed photodegradation for all PCs across all solvents, something that is rarely investigated in the literature. This, therefore, makes it difficult to ascertain whether the parent PC and/or the photodegraded product is responsible for the photochemistry, or indeed, whether photodegradation is actually detrimental to the reaction yield. Conversely, the PCs were found to be photostable for energy transfer reactions; however, yields were not correlated to the triplet energies of the PCs, highlighting that triplet energies alone are not a suitable descriptor to discriminate the performance between PCs in photoinduced energy transfer processes. | Megan Bryden; Francis Millward; Oliver Lee; Lauren Cork; Malte Gather; Andreas Steffen; Eli Zysman-Colman | Catalysis; Photocatalysis | CC BY 4.0 | CHEMRXIV | 2023-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655677246e0ec7777f175636/original/lessons-learnt-in-photocatalysis-the-influence-of-solvent-polarity-and-the-photostability-of-the-photocatalyst.pdf |
63cb4b871125960ea974af2a | 10.26434/chemrxiv-2023-58g0x | High-Resolution Photoelectron Spectroscopy of Vibrationally Excited Vinoxide Anions | High-resolution photoelectron spectra of vibrationally pre-excited vinoxide anions (CH2CHO‒) are reported using the recently developed IR-cryo-SEVI technique. This method is combined with a newly developed implementation of vibrational perturbation theory that can readily identify relevant anharmonic couplings among nearly degenerate vibrational states. IR-cryo-SEVI spectra are obtained by resonant infrared excitation of vinoxide anions via the fundamental C-O (𝜈4, 1570 cm−1) or isolated C-H (𝜈3, 2546 cm−1) stretching vibrations prior to photodetachment. Excitation of the 𝜈4 mode leads to a well-resolved photoelectron spectrum that is in excellent agreement with a harmonic Franck-Condon simulation. Excitation of the higher energy 𝜈3 mode results in a more complicated spectrum that requires consideration of the calculated anharmonic resonances in both the anion and neutral. From this analysis, information about the zeroth-order states that contribute to the nominal 𝜈3 wavefunction in the anion is obtained. In the neutral, we observe anharmonic splitting of the 𝜈3 fundamental into a polyad feature with peaks at 2737(22), 2835(18) and 2910(12) cm−1, for which only the center frequency has been previously reported. Overall, nine out of the twelve fundamental frequencies of the vinoxy radical are extracted from the IR-cryo-SEVI and ground state cryo-SEVI spectra, most of which are consistent with previous measurements. However, we provide a new estimate of the 𝜈5 (CH2 scissoring) fundamental frequency at 1395(11) cm−1 and attribute the large difference with previously reported values to a Fermi resonance with the 2𝜈11 overtone (CH2 wagging). | Jascha A. Lau; Martin DeWitt; Mark A. Boyer; Mark C. Babin; Tonia Solomis; Max Grellmann; Knut R. Asmis; Anne B. McCoy; Daniel M. Neumark | Physical Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63cb4b871125960ea974af2a/original/high-resolution-photoelectron-spectroscopy-of-vibrationally-excited-vinoxide-anions.pdf |
658c0d5766c138172924e247 | 10.26434/chemrxiv-2023-fdkf2-v2 | Acyl phosphates as chemically fueled building blocks for self-sustaining protocells. | Lipids can spontaneously assemble into vesicle-forming membranes. Such vesicles serve as compartments for even the simplest living systems. Vesicles have been extensively studied for constructing synthetic cells or as models for protocells—the cells hypothesized to have existed before life. These compartments exist almost always close to equilibrium. Life, however, exists out of equilibrium. In this work, we studied vesicle-based compartments regulated by a non-equilibrium chemical reaction network that converts activating agents. Specifically, we use activating agents to condense carboxylates and phosphate esters into acylphosphate-based lipids that form vesicles. These vesicles can only be sustained when condensing agents are present, and without them, they decay. We demonstrate that the chemical reaction network can operate on prebiotic activating agents, opening the door to prebiotically plausible, self-sustainable protocells that compete for resources. In future work, such protocells should be endowed with a genotype, for example, based on self-replicating RNA structures that affect the protocell behavior to enable Darwinian evolution in a prebiotically plausible chemical system. | Oleksii Zozulia; Christine Kriebisch; Brigitte Kriebisch; Héctor Soria Carrera; Kingu Rici Ryadi; Juliana Steck; Job Boekhoven | Organic Chemistry; Combinatorial Chemistry; Supramolecular Chemistry (Org.) | CC BY 4.0 | CHEMRXIV | 2023-12-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/658c0d5766c138172924e247/original/acyl-phosphates-as-chemically-fueled-building-blocks-for-self-sustaining-protocells.pdf |
657b7a949138d23161a90e22 | 10.26434/chemrxiv-2023-3d0zf | Amplified Photomodulation of a Bis(dithienylethene)-Substituted Phosphine | Phosphine ligands play a crucial role in homogeneous catalysis, allowing to fine-tune the catalytic activity of various metals by modifying their structure. An ultimate challenge in this field is to reach controlled modulation of catalysis in situ, for which the development of phosphines capable of photoswitching between states with differential electronic properties has been proposed. To magnify this light-induced behavior, in this work we describe a novel phosphine ligand incorporating two dithienylethene photoswitchable moieties tethered to the same phosphorus atom. Double photoisomerization was observed for this ligand, which remains unhindered upon gold(I) complexation. As a result, the preparation of a fully ring-closed phosphine isomer was accomplished, for which amplified variation of phosphorus electron density was verified both experimentally and by computational calculations. Accordingly, the presented molecular design based on multiphotochromic phosphines could open new ways for preparing enhanced photoswitchable catalytic systems. | Anastasiia Sherstiuk; Marc Villabona; Agustí Lledós; Jordi Hernando; Rosa María Sebastián; Evamarie Hey-Hawkins | Organic Chemistry; Inorganic Chemistry; Photochemistry (Org.); Ligands (Inorg.); Transition Metal Complexes (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-12-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/657b7a949138d23161a90e22/original/amplified-photomodulation-of-a-bis-dithienylethene-substituted-phosphine.pdf |
6527e15845aaa5fdbbd8e7ee | 10.26434/chemrxiv-2023-0701v | Nanoporous Materials as Carriers of Hydrogen Peroxide Vapour: a New Bio-Decontamination Technology | High-level bio-decontamination, which involves reducing microorganisms by 99.9999%, is essential in preventing Hospital Acquired Infections and controlling pandemics. This study demonstrates that nanoporous materials, which can retain molecules within their pores, and subsequently release them, can be used in high level bio-decontamination. H2O2 vapor is a golden-standard in high level bio-decontamination. This work demonstrates that various nanoporous materials, particularly mesoporous silicas, can be utilized to store and release H2O2 in the vapor phase. H2O2 concentrations of over 2500 ppm were achieved by desorbing it from the carrier material at low temperatures of 60-80 °C. Generation of H2O2-vapor by desorption from nanoporous materials is technically much simpler than vaporization of aqueous H2O2 solutions, which use flash vaporization processes occurring at 130-150 °C. This has important technical implications, highlighting the potential of nanoporous materials as carriers for H2O2 for high-level bio-decontamination. | Fadhil Musa; Raquel Nogueira; Margarida Beiral; Fernando Antunes; João Pires | Biological and Medicinal Chemistry; Materials Science; Environmental biology; Microbiology; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6527e15845aaa5fdbbd8e7ee/original/nanoporous-materials-as-carriers-of-hydrogen-peroxide-vapour-a-new-bio-decontamination-technology.pdf |
66f43548cec5d6c1422d10e9 | 10.26434/chemrxiv-2024-k0l35 | Convenient Lanthanum-Mediated Synthesis of Bulky tert-Alkyl Amines from Nitriles | Tert-alkyl amines can be conveniently prepared in one step from nitriles by a double addition of ethyl or propyl Grignard reagents mediated by commercially available lanthanum chloride-lithium chloride complex solution. The reaction operates on a variety of benzonitriles, with several heterocyclic nitriles and an alkyl nitrile also being suitable substrates. | Alex Speed; Emily Burke | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f43548cec5d6c1422d10e9/original/convenient-lanthanum-mediated-synthesis-of-bulky-tert-alkyl-amines-from-nitriles.pdf |
60c7596a842e65e1cedb49f8 | 10.26434/chemrxiv.14692026.v1 | Correlation Between Reduced Mass and Gibbs Energy Change of Reaction | <p>The correlation between the Gibbs free energy change of reaction and the
reduced mass was clarified. In the case of bond formation reactions, the computed
Gibbs energy change of reaction increased in the positive direction as the
reduced mass increased. In the case of dissociation equilibrium reactions, such
as the dissociation of tetrahedral carbonyl addition compound, the computed Gibbs
energy change of reaction also increased in the positive direction as the
reducing mass increased, but the extent of the change was smaller than in the
case of bond formation reactions. The results were in good agreement with those
derived from the relationship between yield and reduced mass, indicating that was
originated from the correlation between the Gibbs energy change and the reduced
mass.</p> | Masatoshi Kawashima | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7596a842e65e1cedb49f8/original/correlation-between-reduced-mass-and-gibbs-energy-change-of-reaction.pdf |
66f3d3d912ff75c3a166d408 | 10.26434/chemrxiv-2024-tz0fg | Acquiring and Transferring Comprehensive Catalyst Knowledge through Integrated High-Throughput Experimentation and Automatic Feature Engineering | Solid catalyst development has traditionally relied on trial-and-error approaches, limiting the broader application of valuable insights across different catalyst families. To overcome this fragmentation, we introduce a framework that integrates high-throughput experimentation (HTE) and automatic feature engineering (AFE) with active learning to acquire comprehensive catalyst knowledge. The framework is demonstrated for oxidative coupling of methane (OCM), where active learning is continued until the machine learning model achieves robustness for each of the BaO-, CaO-, La2O3-, TiO2-, and ZrO2-supported catalysts, with 333 catalysts newly tested. The resulting models are utilized to extract catalyst design rules, revealing key synergistic combinations in high-performing catalysts. Moreover, we propose a method for transferring knowledge between supports, showing that features refined on one support can improve predictions on others. This framework advances the understanding of catalyst design and promotes reliable machine learning. | Aya Fujiwara; Sunao Nakanowatari; Yohei Cho; Toshiaki Taniike | Materials Science; Catalysis; Catalysts | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f3d3d912ff75c3a166d408/original/acquiring-and-transferring-comprehensive-catalyst-knowledge-through-integrated-high-throughput-experimentation-and-automatic-feature-engineering.pdf |
60c74fc30f50db07d7397462 | 10.26434/chemrxiv.11516967.v4 | Memory of Chirality in Room Temperature Flow Electrochemical Reactor | <p>Chiral compounds have become of great interest to the pharmaceutical industry as they possess various biological activities. Concurrently, the concept of “memory of chirality” has been proven as a powerful tool in asymmetric synthesis, while flow chemistry has begun its rise as a new enabling technology to add to the ever increasing arsenal of techniques available to the modern day chemist. Here, we have employed a new simple electrochemical microreactor design to oxidise an L-proline derivative at room temperature in continuous flow. Compared to batch, organic electrosynthesis via microflow reactors are advantageous because they allow shorter reaction times, optimization and scale up, safer working environments, and high selectivities (e.g. reduce overoxidation). Flow electrochemical reactors also provide high surface-to-volume ratios and impart the possibility of excluding the supporting electrolyte due to a very short interelectrode distance. By the comparison of Hofer Moest type electrochemical oxidations at room temperature in batch and flow, we conclude that continuous flow electrolysis is superior to batch, producing a good yield and a higher enantiomeric excess. These results show that continuous flow has the potential to act as a new enabling technology for asymmetric synthesis to replace some aspects of conventional batch electrochemical processes. </p> | Tomas Hardwick; Rossana Cicala; Nisar Ahmed | Bioorganic Chemistry; Natural Products; Organic Synthesis and Reactions; Physical Organic Chemistry; Electrocatalysis; Heterogeneous Catalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fc30f50db07d7397462/original/memory-of-chirality-in-room-temperature-flow-electrochemical-reactor.pdf |
6411e4f0dab08ad68f291ec2 | 10.26434/chemrxiv-2023-6604r-v2 | Influence of temperature on the performance of carbon- and ATO-supported OER catalysts in a GDE setup | State-of-the-art industrial electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions are Ir-based. Considering the scarce supply of Ir, it is imperative to use the precious metal as efficiently as possible. In this work, we immobilized ultrasmall Ir and Ir0.4Ru0.6 nanoparticles on two different supports to maximize their dispersion. One high surface area carbon support serves as reference but has limited technological relevance due to its lack of stability. The other support, antimony-doped tin oxide (ATO), has been proposed in the literature as a possible better support for OER catalysts. Temperature-dependent measurements performed in a newly developed gas diffusion electrode (GDE) setup reveal that surprisingly the catalysts immobilized on commercial ATO performed worse than their carbon-immobilized counterparts. The measurements suggest that the ATO support deteriorates particularly fast at elevated temperatures. | Aline Bornet; Rebecca Pittkowski; Tobias Nielsen; Etienne Berner; Johanna Schroeder; Jonathan Quinson; Kirsten Jensen; Matthias Arenz | Catalysis; Nanoscience; Nanocatalysis - Catalysts & Materials; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6411e4f0dab08ad68f291ec2/original/influence-of-temperature-on-the-performance-of-carbon-and-ato-supported-oer-catalysts-in-a-gde-setup.pdf |
61a8e7ee704d0568f83d7c64 | 10.26434/chemrxiv-2021-z3wgm-v2 | Organocatalytic Discrimination of Non-Directing Aryl and Heteroaryl Groups: Enantioselective Synthesis of Bioactive Indole-Containing Triarylmethanes | Despite the enormous developments of asymmetric catalysis, the basis for asymmetric induction is largely limited to spatial interaction between substrate and catalyst. Consequently, asymmetric discrimination between two sterically similar groups remains a challenge. This is particularly formidable for enantiodifferentiation between aryl and heteroaryl groups without a directing group or electronic manipulation. Here we address this challenge by a robust organocatalytic system leading to excellent enantioselection between aryl and heteroaryl groups. With the versatile 2-indole imine methide as platform, an excellent combination of a superb chiral phosphoric acid and the optimal hydride source provided efficient access to a range of highly enantioenriched indole-containing triarylmethanes. Control experiments and kinetic studies provided important insights into the mechanism. DFT calculations also indicated that, while hydrogen bonding is important for activation, the key interaction for discrimination of the two aryl groups is mainly π-π stacking. Preliminary biological studies also demonstrated the great potential of these triarylmethanes for anticancer and antiviral drug development. | Qiaolin Yan; Meng Duan; Cien Chen; Zhiqin Deng; Mandi Wu; Peiyuan Yu; Ming-liang He; Guangyu Zhu; K. N. Houk; Jianwei Sun | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-12-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61a8e7ee704d0568f83d7c64/original/organocatalytic-discrimination-of-non-directing-aryl-and-heteroaryl-groups-enantioselective-synthesis-of-bioactive-indole-containing-triarylmethanes.pdf |
6590913a9138d23161d7f3ae | 10.26434/chemrxiv-2023-m016b-v2 | High-speed cryo-microscopy proves that ice-nucleating proteins of Pseudomonas syringae trigger freezing at hydrophobic interfaces | Ice-nucleating proteins (INpro) trigger the freezing of supercooled water droplets relevant to atmospheric, biological, and technological applications. Ice nucleation caused by INpro from the bacteria Pseudomonas syringae has been suggested to initiate at the bacterial membrane or at the air-water interface (AWI) of droplets. Here, we show direct evidence of this proposed mechanism. We monitored the freezing of droplets, between two hydrophobic glass slides, with a high-speed camera on a cryo-microscope. Onset nucleation sites of INpro from sterilized P. syringae (Snomax) were enriched at the AWI of the droplets. Removing cellular fragments by filtration or adding surfactants increased the frequency of nucleation events at the AWI. On the other hand, cultivated intact bacteria cells or lipid-free droplets nucleated ice without an affinity to the AWI. Overall, we provide visual evidence that INpro from P. syringae trigger freezing at hydrophobic interfaces, with important mechanistic implications for applications of INpro. | Paul Bieber; Nadine Borduas-Dedekind | Physical Chemistry; Analytical Chemistry; Earth, Space, and Environmental Chemistry; Atmospheric Chemistry; Microscopy; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2024-01-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6590913a9138d23161d7f3ae/original/high-speed-cryo-microscopy-proves-that-ice-nucleating-proteins-of-pseudomonas-syringae-trigger-freezing-at-hydrophobic-interfaces.pdf |
60c74456567dfe2680ec425a | 10.26434/chemrxiv.9775493.v1 | Sharing Data from Molecular Simulations | Given the need for modern researchers to produce open, reproducible scientific output, the lack of standards and best practices for sharing data and workflows used to produce and analyze molecular dynamics (MD) simulations have become an important issue in the field. There are now multiple well-established packages to perform molecular dynamics simulations, often highly tuned for exploiting specific classes of hardware, and each with strong communities surrounding them, but with very limited interoperability/transferability options. Thus, the choice of the software package often dictates the workflow for both simulation production and analysis. The level of detail in documenting the workflows and analysis code varies greatly in published work, hindering reproducibility of the reported results and the ability for other researchers to build on these studies. An increasing number of researchers are motivated to make their data available, but many challenges remain in order to effectively share and reuse simulation data. To discuss these and other issues related to best practices in the field in general, we organized a workshop in November 2018 ( <a href="https://bioexcel.eu/events/workshop-on-sharing-data-from-molecular-simulations/">https://bioexcel.eu/events/workshop-on-sharing-data-from-molecular-simulations/</a>). Here, we present a brief overview of this workshop and topics discussed. We hope this effort will spark further conversation in the MD community to pave the way towards more open, interoperable and reproducible outputs coming from research studies using MD simulations. | Mark J. Abraham; Rossen Apostolov; Jonathan Barnoud; Paul Bauer; Christian Blau; Alexandre M.J.J. Bonvin; matthieu chavent; John Chodera; Karmen Condic-Jurkic; Lucie Delemotte; Helmut Grubmüller; Rebecca J. Howard; E joseph jordan; Erik Lindahl; Samuli Ollila; Jana Selent; Daniel Smith; Phillip J. Stansfeld; Johanna Tiemann; Mikael Trellet; Christopher Woods; Artem Zhmurov | Bioinformatics and Computational Biology; Computational Chemistry and Modeling; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74456567dfe2680ec425a/original/sharing-data-from-molecular-simulations.pdf |
60c74ba6702a9b721718b4c4 | 10.26434/chemrxiv.12367505.v1 | Energy Level Engineering of Charge Selective Contact and Halide Perovskite by Modulating Band Offset: Mechanistic Insights | <p>Mixed cation
and anion based perovskites solar cells (FAPbI<sub>3</sub>)<sub>0.85</sub>(MAPbBr<sub>3</sub>)<sub>0.15</sub>
gave enhanced stability under outdoor conditions, however, it yielded limited power
conversion efficiency when SnO<sub>2</sub> and Spiro-OMeTAD were employed as electron
and hole transport layer (ETL/HTL). The inevitable interfacial recombination of
charge carriers at ETL/perovskite and perovskite/HTL interface diminished the
efficiency in planar (n-i-p) perovskite solar cells. Employing computational
approach for uni-dimensional device simulator, the effect of band offset on
charge recombination at both interfaces were investigated. We noted that it
acquired cliff structure when the conduction band minimum of the ETL is lower
than that of the perovskite, and thus maximizes interfacial recombination.
However, if the conduction band minimum of ETL is higher than perovskite, i.e.
spike structure is formed, which improve the performance of solar cell up to an
optimum value of conduction band offset allowing to reach performance of 25.21%,
with an open circuit voltage (<i>V</i><sub>oc</sub>) of 1231 mV, a current density
<i>J</i><sub>sc</sub> of 24.57 mA/cm<sup>2</sup> and a fill factor of 83.28%. Additionally,
we found that beyond the optimum offset value, large spike structure could decrease
the performance. With an optimized, energy level of Spiro-OMeTAD and the
thickness of mixed-perovskite layer performance of 26.56 % can be attained. Our
results demonstrate a detailed understanding about the energy level tuning between
the charge selective layers and perovskite and furthermore how the improvement
in PV performance can be achieved by adjusting the energy level offset.</p> | Yassine Raoui; Hamid Ez-Zahraouy; Samrana Kazim; Shahzada Ahmad | Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials; Optical Materials; Photosensitizers; Thin Films | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ba6702a9b721718b4c4/original/energy-level-engineering-of-charge-selective-contact-and-halide-perovskite-by-modulating-band-offset-mechanistic-insights.pdf |
64ff34a9b338ec988a4ad7d3 | 10.26434/chemrxiv-2023-fh1l7 | Extracellular Vesicles lysis: a guide for the release of biomarkers to be used in cancer diagnostics | In the medical field, extracellular vesicles (EVs) are gaining importance as they act as mediators between cells. These nanosized vesicles contain crucial biochemical information about their mother cells in the form of proteins, lipids, and nucleic acids. After they are released into the extracellular matrix, they enter the systemic circulation and can be found in all human biofluids. A lipid bilayer protects their contents, distinguishing between internal and external bioinformation. Since EVs reflect the state of the cell of origin, there is exponential attention as potential source of new circulating biomarkers for liquid biopsy. However, using EVs in clinical practice is still hindered by several issues, including the need for standardized, low-cost reagents and lysis protocols that can practically detect internal biomarkers of EVs. The process of lysis is an important step that can impact all subsequent analyses. To help researchers in this field, this article summarizes the most commonly used lysis reagents and protocols for characterizing the content of EVs. The goal of this review is to provide practical guidance for those new to this critical topic, helping them achieve their research objectives. Although the information contained into the blood-circulating vesicles are broad, e.g. nucleic acids, lipids, proteins, etc., the protocols to extract this information might be time-consuming, not applicable for on-site measurements. Herein we deeply investigated and discussed all the major chemical lysis, highlighting strengthen and limitation of each, aimed by the future possibility in realizing integrated portable sensing devices for cancer EVs. | Sabrina Romanò; Stefano Cinti | Analytical Chemistry; Biochemical Analysis; Electrochemical Analysis; High-throughput Screening | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ff34a9b338ec988a4ad7d3/original/extracellular-vesicles-lysis-a-guide-for-the-release-of-biomarkers-to-be-used-in-cancer-diagnostics.pdf |
60c7536a9abda2e87ef8dfaa | 10.26434/chemrxiv.13489608.v1 | Superphanes: Old Yet New Binding–Agents for Highly Selective Recognition of Fluoride by Size–Sieving Effect | <p>Superphanes, namely percyclophanes,
have been widely investigated for the sake of their aesthetically pleasing
structures with high symmetry, intriguing physical and chemical properties and
synthetic challenges. Nonetheless, the host–guest chemistry of superphanes
remains to be an unmet challenge. Herein, we delineate the design, preparation,
characterization, and host–guest chemistry of an unprecedented superphane <b>15</b>,
which was evidenced by mass spectroscopy, NMR spectroscopy, X–ray
crystallography, and DFT calculations. <b>15</b> features six bridges between
two benzene planes, up to 18 C<sub>sp</sub>–<b>H</b> hydrogen–bonding donors
well–distributed around the near–closed inner cavity in three dimensions. These allow <b>15</b> to exhibit exclusive selectivity towards F<sup>–</sup> against
Cl<sup>–</sup>, Br<sup>–</sup>, I<sup>–</sup>, N<sub>3</sub><sup>–</sup>, SCN<sup>–</sup>,
NO<sub>3</sub><sup>–</sup>, ClO<sub>4</sub><sup>–</sup>, SO<sub>4</sub><sup>2–</sup>
and HP<sub>2</sub>O<sub>7</sub><sup>3–</sup> due to the size–sieving effect.
This contribution opens up new opportunities for design and synthesis of new supramolecular hosts for anions of interest with high selectivity.<br /></p> | Qing He; Aimin Li; Shenglun Xiong; Wei Zhou; Huijuan Zhai; Yuanchu Liu | Organic Compounds and Functional Groups; Supramolecular Chemistry (Org.); Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7536a9abda2e87ef8dfaa/original/superphanes-old-yet-new-binding-agents-for-highly-selective-recognition-of-fluoride-by-size-sieving-effect.pdf |
649763bf1dcbb92a5e835e83 | 10.26434/chemrxiv-2023-0cdr1 | Revealing the interdiffusion equilibrium of lithium cations across a solid--electrolyte interface by T1 NMR relaxation | Fast charging of batteries is pivotal for a broader acceptance of electric mobility. While fast charging capabilities have been demonstrated for lithium titanate (Li4Ti5O12, LTO) anode materials, the underlying mechanisms are still poorly understood. Recently the interdiffusion of mobile lithium ions between a liquid electrolyte and LTO, facilitated by unpinning of polarons from surface defects, has been suggested as a potential factor influencing fast charging. This effect is explored further by systematically varying the concentration of the electrolyte salt in an aprotic electrolyte in contact with LTO, and acquiring Li-7 T1 NMR relaxation time constants as a measure for the bulk concentration of paramagnetic polarons. A systematic relation between electrolyte concentration and Li-7 T1 was found, with a qualitatively different behavior above and below about 5\;mM. In the high concentration region, the observed relation was consistent with the law of mass action for a biphasic equilibrium exchange of lithium ions between LTO and electrolyte. Upon contact of the two phases, there was a redistribution of lithium ions between anode and electrolyte, which can be understood analogously to osmotic pressure of mobile lithium ions. This is the first demonstration of such an equilibrium for a non-faradaic lithium exchange at a solid–-electrolyte interface, substantiating our previous hypothesis of a polaron-supported fast-charging mechanism. This study provides a basis for more quantitative (surface)-defect engineering, which is key to optimize battery fast-charging properties. | P. Philipp M. Schleker; Rüdiger-A. Eichel; Josef Granwehr | Physical Chemistry; Materials Science; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.) | CC BY NC 4.0 | CHEMRXIV | 2023-06-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/649763bf1dcbb92a5e835e83/original/revealing-the-interdiffusion-equilibrium-of-lithium-cations-across-a-solid-electrolyte-interface-by-t1-nmr-relaxation.pdf |
64aea4ba9ea64cc167e4519f | 10.26434/chemrxiv-2023-137mn | Liposomes and Lipid Droplets Display a Reversal of Charge-Induced Hydration Asymmetry | The unique properties of water are critical for life. Water molecules have been reported to hydrate cations and anions asymmetrically. We show here that this behavior extends to charged nanoscale interfaces. We investigated charge hydration asymmetry using nonlinear light scattering methods on lipid nanodroplets and liposomes in water made of negative, zwitterionic, and positive lipids. Nanodroplets covered with negatively charged lipids induce the strongest water ordering, while droplets covered with positively charged lipids induce the weakest water ordering. Surprisingly, this charge-induced hydration asymmetry is reversed around liposomes. This opposite behavior in charge hydration asymmetry is caused by a delicate balance of electrostatic and hydrogen bonding interactions: In nanodroplets, the electrostatic effects from negatively (positively) charged lipids and oil phase interfere constructively (destructively). Electrostatic contributions drive the asymmetric hydration of positively charged liposomes, whereas a destructive interference between electrostatic and hydrogen bonding contributions drives the asymmetric hydration of negatively charged liposomes. These findings highlight the importance of not only the charge state but also the specific distribution of neutral and charged lipids in cellular membranes. | Saranya Pullanchery; Nathan Dupertuis; Tereza Schönfeldová; Sylvie Roke | Physical Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Interfaces; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64aea4ba9ea64cc167e4519f/original/liposomes-and-lipid-droplets-display-a-reversal-of-charge-induced-hydration-asymmetry.pdf |
60c74780469df47b3ef43829 | 10.26434/chemrxiv.11688291.v1 | Highly Active Deficient Ternary Sulfide Photoanode for Photoelectrochemical Water Splitting | <div>The exploration of photoanode materials with high efficiency and stability is the </div><div>eternal pursuit for the realization of practically solar-driven photoelectrochemical </div><div>water splitting. Here we develop a novel deficient ternary metal sulfide (CdIn2S4) </div><div>as photoanode, and its PEC performance is significantly enhanced by introducing </div><div>surface S vacancies, achieving a photocurrent density of 5.73 mA cm-2 at 1.23 V vs. </div><div>RHE and 1 Sun and an applied bias photon-to-current efficiency of 2.49% at 0.477 </div><div>V vs. RHE, which, to the best of our knowledge, are the record-high values for a </div><div>single sulfide photon absorber to date. The experimental characterizations and </div><div>theoretical calculations highlight the enhanced effect of surface S vacancies on the </div><div>interfacial charge separation and transfer kinetics, and also demonstrate the </div><div>restrained surface states distribution and the transformation of active sites after </div><div>introducing surface S vacancies. This work may inspire more excellent work on </div><div>developing sulfide-based photoanodes. </div> | Haimei Wang; Yuguo Xia; Haiping Li; Xiang Wang; Yuan Yu; Xiuling Jiao; Dairong Chen | Nanocatalysis - Catalysts & Materials | CC BY NC ND 4.0 | CHEMRXIV | 2020-01-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74780469df47b3ef43829/original/highly-active-deficient-ternary-sulfide-photoanode-for-photoelectrochemical-water-splitting.pdf |
60c75266f96a005e932881d7 | 10.26434/chemrxiv.13293296.v1 | Aging Process of Polyamidoamine Dendrimers: Effect of pH and Shaking in the Fluorescence Emission and Aggregation-State | In the last years, it has been discovered and intensely studied the non-traditional intrinsic fluorescence of PAMAM dendrimers. Nevertheless, their aging process in aqueous suspension is scarcely studied, being unknown the causes of the observed changes in their fluorescence properties. Hence, this work aims to characterize the PAMAM dendrimers of generation 4.0 (DG4.0) and 4.5 (DG4.5) through the aging process at three different pH conditions, stored with or without shaking. We studied, up to 16 days, the UV-Vis absorption, the fluorescence emission, and the size of dendrimers/aggregates. In a different way than the already published work, we demonstrated that there is no chemical change in dendrimers through the aging process, even though changes in fluorescence emission were observed. Besides, we have put in evidence that changes in the agglomeration patterns of dendrimers would not be related to change in the fluorescence emission thought aging. Moreover, we demonstrated that DG4.5 formed large aggregates in water that need to be disrupted by shaking previous to an in vivo administration. <br /> | Igartua Daniela; David Ybarra; Dario Cabezas; Silvia del Valle Alonso; Fernando Alvira | Biophysical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75266f96a005e932881d7/original/aging-process-of-polyamidoamine-dendrimers-effect-of-p-h-and-shaking-in-the-fluorescence-emission-and-aggregation-state.pdf |
65c5675e66c13817293ea9e9 | 10.26434/chemrxiv-2024-qdqwv-v2 | Advancing Dynamic Polymer Mechanochemistry through Molecular Gears | Harnessing mechanical force to modulate material properties and enhance biomechanical functions is essential for advancing smart materials and bioengineering. Polymer mechanochemistry provides an emerging toolkit to unlock unconventional chemical transformations and modulate molecular structures via mechanical force. One of the key challenges is developing innovative force-sensing mechanisms for precise, in situ force detection and quantification. This study addresses this challenge by introducing mDPAC, a mechanosensitive molecular gear with dynamic and sensitive mechanochromic properties. Its unique mechanoresponsive mechanism is based on the simultaneous configurational variation of its phenazine and phenyl moieties, facilitated by a worm-gear structure. We affirm mDPAC's sensitive mechanochemical response and elucidate its force transduction mechanism through our experimental emission data and comprehensive DFT and MD simulations. The compatibility of mDPAC with hydrogels is particularly notable, highlighting its potential for applications in aqueous biological environments as a dynamic molecular force sensor and mapping tool. Moreover, mDPAC's multicolored mechanochromism enables direct force sensing, visual detection, and real-time quantification, paving the way for integrating molecular gears into bulk materials for precise and instantaneous mechanical force sensing. | Nnamdi Ofodum; Qingkai Qi; Richard Chandradat; Theodore Warfle; Xiaocun Lu | Physical Chemistry; Materials Science; Polymer Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c5675e66c13817293ea9e9/original/advancing-dynamic-polymer-mechanochemistry-through-molecular-gears.pdf |
65c751d1e9ebbb4db90cbd2d | 10.26434/chemrxiv-2024-h25d9 | Triple Nucleophilic Head-to-Tail Cascade Polycyclization of Diazodienals via Combination Catalysis: Direct Access to Cyclopentane Fused Aza-Polycycles with Six-Contiguous Stereocenters | Reported herein are the bench stable (2E,4E)-diazohexa-2,4-dienals (diazodienals) and their unprecedented polycy-clization with aldimine and arylamines enabled by Rh(II)/Brønsted acid relay catalysis. This scalable and atom-economical reaction provides direct access to the biologically important azatricyclo[6.2.1.04,11]undecane fused polycycles having six contiguous stereocenters. Mechanistic studies revealed that polycyclization proceeds through an unusual triple-nucleophilic cascade initiated by aldimine attack on remote Rh-carbenoid, 6-electrocyclization of aza-trienyl azomethine ylide, stereoselective aza-Michael addition via iminium activation and inverse electron-demand intramolecular aza Diels-Alder reaction. The secondary interactions play a crucial role in the preorganization of reactive intermediates for the pericyclic reactions and hence the overall efficiency of the polycyclization. | Haribabu Chennamsetti; Kuldeep Singh Rathore; Saikat Chatterjee; Pratap Kumar Mandal; Sreenivas Katukojvala | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c751d1e9ebbb4db90cbd2d/original/triple-nucleophilic-head-to-tail-cascade-polycyclization-of-diazodienals-via-combination-catalysis-direct-access-to-cyclopentane-fused-aza-polycycles-with-six-contiguous-stereocenters.pdf |
60c755199abda21039f8e296 | 10.26434/chemrxiv.14039825.v1 | Synchronized Reagent Delivery in Double Emulsions for Triggering Chemical Reactions and Gene Expression | Microfluidic methods to form single emulsion and double emulsion (DE) droplets have greatly enhanced the toolbox for high throughput screening for cell or enzyme engineering and drug discovery. However, remaining challenges in the supply of reagents into these enclosed nanoliter compartments limit the applicability of droplet microfluidics. Here, we introduce a strategy for on-demand delivery of reactants in DEs. We use lipid vesicles as transport carriers, which are co-encapsulated in double emulsions and release their cargo upon addition of an external trigger, here the anionic surfactant SDS. The reagent present inside the lipid vesicles stays isolated from the remaining content of the DE vessel until SDS enters the DE lumen and solubilizes the lipid bilayer. We demonstrate the versatility of the method with two critical applications, chosen as representative assays for high throughput screening. First, we trigger enzymatic reactions after releasing a reactant and second, we encapsulate bacteria and induce gene expression at a delayed time. The presented technique is compatible with the high throughput analysis of individual DE droplets using conventional flow cytometry as well as with microfluidic time-resolved studies. The possibility of delaying and controlling reagent delivery in current high throughput compartmentalization systems will significantly extend their range of applications e.g. for directed evolution, and further improve their compatibility with biological systems. | Ariane Stucki; Petra Jusková; Nicola Nuti; Steven Schmitt; Petra Dittrich | Analytical Apparatus; Bioengineering and Biotechnology; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755199abda21039f8e296/original/synchronized-reagent-delivery-in-double-emulsions-for-triggering-chemical-reactions-and-gene-expression.pdf |
674761ccf9980725cf375179 | 10.26434/chemrxiv-2024-stm40 | A Graph-Theoretic Framework for Analyzing and Designing Chemical Engineering Curricula | Topics and courses that compose chemical engineering curricula are interconnected in a complex manner. The organization/structure of chemical engineering curricula closely matches the practice of breaking down chemical processes into fundamental phenomena (e.g., thermo, balances, and transport) and unit operations (e.g., reactors, separators, and heat exchangers). Emergence of modern topics (e.g., sustainability and molecular engineering) and advances in pedagogy call for the analysis and potential re organization of curricula (e.g., use of case studies to foster integration of courses and include new topics/courses in a synergistic manner). In this work, we propose a graph theoretic abstraction to represent, analyze, and reorganize the structure of curricula. In this abstraction, nodes represent topics/concepts, edges represent connectivity/dependencies between topics, and courses can be interpreted as collections of topics that are tightly interconnected (also known as clusters or modules). The abstraction enables the use of algorithms and software tools of graph theory and optimization to formalize the visualization and evaluation of curricula (e.g., identify key topics) and to identify re-organization strategies (e.g., defining strategic modules/courses that maximize topic cohesiveness/connectivity). Additionally, the abstraction can help formalize and facilitate discussions between instructors that might have different priorities/perspectives on curriculum content and organization. We provide case studies that analyze real curricula at the University of Wisconsin-Madison to highlight the benefits of the proposed framework. | Blake Lopez; Yue Shao; Victor M. Zavala | Chemical Engineering and Industrial Chemistry; Chemical Education | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674761ccf9980725cf375179/original/a-graph-theoretic-framework-for-analyzing-and-designing-chemical-engineering-curricula.pdf |
6312239849042ae8a6c99be4 | 10.26434/chemrxiv-2022-njhrw | Performance Evaluation of In-source Ion Activation
Hardware for Collision-Induced Unfolding of Proteins and
Protein Complexes on a Drift Tube Ion Mobility-Mass
Spectrometer | Native ion mobility-mass spectrometry (IM-MS) has emerged as an information-rich technique for gas phase protein structure characterization; however, IM resolution is currently insufficient for the detection of subtle structural differences in large biomolecules. This challenge has spurred the development of collision-induced unfolding (CIU) which utilizes incremental gas phase activation to unfold a protein in order to expand the number of measurable descriptors available for native protein ions. Although CIU is now routinely used in native mass spectrometry studies, the interlaboratory reproducibility of CIU has not been established. Here we evaluate the reproducibility of the CIU data produced across three laboratories (University of Michigan, Texas A&M University, and Vanderbilt University). CIU data were collected for a variety of protein ions ranging from 8.6-66 kDa. Within the same laboratory, the CIU fingerprints were found to be repeatable with root mean square deviation (RMSD) values of less than 5%. Collision cross section (CCS) values of the CIU intermediates were consistent across the laboratories, with most features exhibiting an interlaboratory reproducibility of better than 1%. In contrast, the activation potentials required to induce protein CIU transitions varied between the three laboratories. To address these differences, three source assemblies were constructed with an updated ion activation hardware design utilizing higher mechanical tolerance specifications. The production-grade assemblies were found to produce highly consistent CIU data for intact antibodies, exhibiting high precision ion CCS and CIU transition values, thus opening the door to establishing databases of CIU fingerprints to support future biomolecular classification efforts. | Varun Gadkari; Brock Juliano; Christopher Mallis; Jody May; Ruwan Kurulugama; John Fjeldsted; John McLean; David Russell; Brandon Ruotolo | Analytical Chemistry; Mass Spectrometry; Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6312239849042ae8a6c99be4/original/performance-evaluation-of-in-source-ion-activation-hardware-for-collision-induced-unfolding-of-proteins-and-protein-complexes-on-a-drift-tube-ion-mobility-mass-spectrometer.pdf |
60c74643337d6c5764e27122 | 10.26434/chemrxiv.11288465.v1 | Data-Driven Many-Body Models for Molecular Fluids: CO2/H2O Mixtures as a Case Study | <div>
<div>
<div>
<p>In this study, we extend the scope of the many-body TTM-nrg and MB-nrg potential
energy functions (PEFs), originally introduced for halide ion–water and alkali-metal
ion–water interactions, to the modeling of carbon dioxide (CO<sub>2</sub>) and water (H<sub>2</sub>O)
mixtures as prototypical examples of molecular fluids. Both TTM-nrg and MB-nrg
PEFs are derived entirely from electronic structure data obtained at the coupled cluster level of theory and are, by construction, compatible with MB-pol, a many-body
PEF that has been shown to accurately reproduce the properties of water. Although
both TTM-nrg and MB-nrg PEFs adopt the same functional forms for describing permanent electrostatics, polarization, and dispersion, they differ in the representation
of short-range contributions, with the TTM-nrg PEFs relying on conventional Born-Mayer expressions and the MB-nrg PEFs employing multidimensional permutationally invariant polynomials. By providing a physically correct description of many-body effects at both short and long ranges, the MB-nrg PEFs are shown to quantitatively
represent the global potential energy surfaces of the CO<sub>2</sub>–CO<sub>2</sub> and CO<sub>2</sub>–H<sub>2</sub>O dimers
and the energetics of small clusters as well as to correctly reproduce various properties
in both gas and liquid phases. Building upon previous studies of aqueous systems, our
analysis provides further evidence for the accuracy and efficiency of the MB-nrg framework in representing molecular interactions in fluid mixtures at different temperature
and pressure conditions. </p>
</div>
</div>
</div> | Marc Riera; Eric Yeh; Paesani Lab | Computational Chemistry and Modeling; Physical and Chemical Properties; Quantum Mechanics; Statistical Mechanics; Structure; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74643337d6c5764e27122/original/data-driven-many-body-models-for-molecular-fluids-co2-h2o-mixtures-as-a-case-study.pdf |
60c75609337d6ccba7e28d65 | 10.26434/chemrxiv.14198357.v1 | Photocatalysis Goes Thinner Than a Hair: Carbon Nitride Thin Films as All-in-one Technology for Photocatalysis | Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of a dispersion in liquid medium, which is bound to certain technological limits of applicability. Herein, we present an innovative approach using carbon nitride thin films prepared via chemical vapor deposition (CVD) at different vessel walls and using them as batch and microfluidic photoreactors. This approach allows not only to fabricate technologically relevant and reusable devices, also photophysical properties of carbon nitride, such as singlet-triplet energy gap and lifetime of triplet excited states, are improved, when the material is assembled in thin films. These morphological changes are employed to maximize performance of the materials in photocatalytic reactions, in which the carbon nitride thin films show at least one orders of magnitude higher activity per area unit compared to photocatalysis using suspended particles.<br /> | Stefano Mazzanti; Giovanni Manfredi; Alex J. Barker; Markus Antonietti; Aleksandr Savateev; Paolo Giusto | Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75609337d6ccba7e28d65/original/photocatalysis-goes-thinner-than-a-hair-carbon-nitride-thin-films-as-all-in-one-technology-for-photocatalysis.pdf |
663adb4f418a5379b0b51462 | 10.26434/chemrxiv-2024-53kdz | Molecular Origin of Viscoelasticity and Influence of Methylation in Mesophase Pitch | The viscoelastic and thermomechanical properties of pitches are responsible for their melt- spinning behavior, a critical step for manufacturing high-performance pitch-based carbon fibers. Here, we systematically explore the impact of methyl group modifications on the viscoelastic and thermal properties of mesophase pitches. We employ a range of atomistic modeling approaches, including Density Functional Theory (DFT), Density Functional Tight Binding (DFTB), and Classical Molecular Mechanics (MM), to provide detailed insights into the molecular interactions and structural changes. Our results revealed the molecular mechanisms that promote layered structures leading to the anisotropic nature of the viscoelastic behavior of mesophase pitch. Furthermore, we propose a modified molecular representation of naphthalene-based mesophase pitch based on the analysis of x-ray diffraction measurements. This study provides fundamental insights into the molecular structures of mesophase pitch and the role of methyl groups controlling its viscosity, which offer valuable insights into mesophase-based carbon fiber production. | Gang Seob Jung; Pilsun Yoo; Matthew Ryder; Frederic Vautard; Aparna Annamraju; Stephan Irle; Nidia Gallego; Edgar Lara-Curzio | Theoretical and Computational Chemistry; Chemical Engineering and Industrial Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC 4.0 | CHEMRXIV | 2024-05-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/663adb4f418a5379b0b51462/original/molecular-origin-of-viscoelasticity-and-influence-of-methylation-in-mesophase-pitch.pdf |
60c74d21bdbb898cbea39928 | 10.26434/chemrxiv.12589529.v1 | Quantitative Prediction of Selectivity in Iridium-Catalysed Hydrogen Isotope Exchange Reactions | A pallette of commonly used directing groups, including various pharmaceutically relevant nitrogen-containing heterocycles,
are quantitatively ranked based on the results of intermolecular hydrogen isotope exchange competition reactions using
two iridium complexes: [Ir(COD)(IMes)(PPh3)][BArF24] and [IrCl(COD)(IMes)]. The directing group power scales that have
been constructred from these data reveal a wide range of reactivity covering four orders of magnitude. Intramolecular
competition experiments have demonstrated that the obtained reactivity scale provides accurate predictions of
regioselectivity within molecules with multiple competing directing groups. This work contributes to our understanding and
control of regioselectivity in metal-catalysed C-H activation reactions. | Daria Timofeeva; David Lindsay; William Kerr; David Nelson | Physical Organic Chemistry; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74d21bdbb898cbea39928/original/quantitative-prediction-of-selectivity-in-iridium-catalysed-hydrogen-isotope-exchange-reactions.pdf |
60c73e99337d6c6acfe2639a | 10.26434/chemrxiv.7058033.v1 | Flux Melting of Metal-Organic Frameworks | <div>Recent demonstrations of melting in the metal-organic framework (MOF) family have created</div><div>interest in the interfacial domain between inorganic glasses and amorphous organic polymers. The</div><div>chemical and physical behaviour of porous hybrid liquids and glasses is of particular interest,</div><div>though opportunities are limited by the inaccessible melting temperatures of many MOFs. Here,</div><div>we show that the synthetic processing technique of flux melting, ‘borrowed’ from the inorganic</div><div>domain, may be applied to MOFs in order to melt materials which do not possess an accessible</div><div>liquid state in their pure form. We employ the high-temperature liquid state of one MOF as a solvent</div><div>for a secondary, non-melting MOF component. Differential scanning calorimetry, small- and wideangle</div><div>X-ray scattering, electron microscopy and X-ray total scattering techniques are used to show</div><div>the flux melting of the crystalline component within the liquid. Gas adsorption and positron</div><div>annihilation lifetime spectroscopy measurements show that this results in enhanced, accessible</div><div>porosity to a range of guest molecules, in the resultant flux melted MOF glass.</div> | Louis Longley; Sean M. Collins; Glen J. Smales; Ilknur Erucar; Ang Qiao; Jingwei Hou; Cara M. Doherty; Aaron Thornton; Anita
J. Hill; Xiao Yu; Nicholas J. Terrill; Andrew J Smith; Seth M. Cohen; Paul A. Midgley; David
A. Keen; Shane G. Telfer; Thomas Bennett | Polymer blends; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2018-09-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e99337d6c6acfe2639a/original/flux-melting-of-metal-organic-frameworks.pdf |
63a07e7916e9a836d12dd3bb | 10.26434/chemrxiv-2022-8f5zr | A DFT Evaluation of Molecular Reactivity of Volatile Organic Compounds in Support of Chemical Ionization Mass Spectrometry | Gas-phase molecular properties of volatile organic compounds (VOCs) play an important role in the selection of gas-phase reagent ions for chemical ionization mass spectrometry (CI-MS). We apply hybrid density functional theory (DFT) to compute proton affinity (PA), ionization energy (IE), and global reactivity parameters for VOCs, which are widely regarded as the primary
sources of taints and off-flavors in wine. Atomic polar tensor (APT) charges and total energies at the stationary point for neutral and protonated molecules are also computed. PA and IE values determine the CI-MS mode of reactions, either proton transfer or electron transfer from the reagent gas ions to VOCs.
Global reactivity parameters, such as chemical potential (µ), chemical hardness (η), softness (σ), and electrophilic nature (ω) as obtained from frontier molecular orbitals, are considered useful in rationalizing the chemical reactivity patterns of the molecules. A benchmark calculation of indole molecule with MP2, B3LYP, and M06-2X DFT methods at thermodynamically and kinetically stable protonation sites further supports the applied DFT method. Since
limited data are available on computed parameters, the reported values would support CI-MS quantification of trace-level VOCs not only in wine but also in various food products. | MANJEET BHATIA | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational; Quantum Computing | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63a07e7916e9a836d12dd3bb/original/a-dft-evaluation-of-molecular-reactivity-of-volatile-organic-compounds-in-support-of-chemical-ionization-mass-spectrometry.pdf |
67c29d9881d2151a028eb5ed | 10.26434/chemrxiv-2025-hfw7h | Near-Infrared Organic Structures with Extended Lifetimes to Unlock the Potential of In Vivo Fluorescence Lifetime Imaging | In vivo fluorescence lifetime (FLT) imaging is an emerging and promising modality with the potential to provide additional biological information compared to fluorescence intensity (FI) imaging. Until now, nearly all studies evaluating the benefits of FLT imaging in vivo have been conducted using cyanine dyes. While these fluorophores are highly successful for conventional in vivo fluorescence imaging due to their unmatched brightness in the NIR-I region (700-900 nm), they might be suboptimal for FLT imaging. Indeed, NIR-I cyanines are characterized by short singlet excited-state lifetime (generally below 1 ns) making it challenging to differentiate them from tissue autofluorescence. Therefore, there is a pressing need for biocompatible fluorophores with longer FLTs. Herein, we report a novel bioconjugatable water-soluble NIR-emissive aza-BODIPY dye with extended FLT values in physiological conditions, compared to cyanine dyes (increase of 100% compared to IRDye® 800CW). The suitability of aza-BODIPY for FLT imaging when conjugated to an antibody was assessed to enhance this technology. Beyond rational design and synthesis of a long-wavelength fluorophore with attractive features for in vivo FLT imaging, this study also highlights for the first time the impact of the conjugation method on the FLT characteristics of the resulting fluorescent antibody conjugates. | Elisa CHAZEAU; Hassan AL-SABEA; Simone JANSSEN; Lukasz MATEUSIAK; Thomas VAN DEN DRIES; Thomas LAPAUW; Sevada SAHAKIAN; Marcus C. M. STROET; Hans INGELBERTS; Sophie HERNOT; Anthony ROMIEU; Christine GOZE; Franck DENAT | Biological and Medicinal Chemistry; Organic Chemistry; Analytical Chemistry; Biochemical Analysis; Imaging; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c29d9881d2151a028eb5ed/original/near-infrared-organic-structures-with-extended-lifetimes-to-unlock-the-potential-of-in-vivo-fluorescence-lifetime-imaging.pdf |
671d306b1fb27ce124b0e6c9 | 10.26434/chemrxiv-2024-nqwpb | RULE-IT: AN ONLINE PLATFORM FOR REACTION NETWORK EXPLORATIONS FOR CHEMICAL
EVOLUTION | Exploring the chemical space of prebiotic reactions is crucial for understanding the emergence of
life. However, the combinatorial explosion of compounds and the lack of user-friendly computational
tools pose significant challenges. To address these issues, we developed Rule-it, a web platform that
enables prebiotic chemists to build, expand, prune, and visualize chemical reaction networks. The
platform integrates experimental data and provides a comprehensive framework for studying chemical
evolution. By simplifying the generation and analysis of reaction networks, Rule-it aims to advance
research in prebiotic chemistry. | Bruno Cuevas-Zuviria; Tymofii Sokolskyi | Theoretical and Computational Chemistry; Organic Chemistry; Earth, Space, and Environmental Chemistry; Combinatorial Chemistry; Space Chemistry; Chemoinformatics - Computational Chemistry | CC BY NC 4.0 | CHEMRXIV | 2024-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671d306b1fb27ce124b0e6c9/original/rule-it-an-online-platform-for-reaction-network-explorations-for-chemical-evolution.pdf |
60c74778f96a00b6f8286f1d | 10.26434/chemrxiv.11591835.v1 | Cationic Biphotonic Lanthanide Luminescent Bioprobes Based on Functionalized Cross-Bridged Cyclam Macrocycles | <p>Cationic
lanthanide complexes are generally able to spontaneously internalize into living
cells. Following our previous works based on diMe-cyclen framework, a second
generation of cationic water-soluble lanthanide complexes based on a
constrained cross-bridged cyclam macrocycle functionalized with donor-p-conjugated picolinate antennas has
been prepared with europium(III) and ytterbium(III). Their spectroscopic
properties were thoroughly investigated in various solvents and rationalized
with the help of DFT calculations. A significant improvement is observed in the
case of the Eu<sup>3+</sup> complex, while the Yb<sup>3+</sup> analogous conserve
an excellent brightness in aqueous solvent. Two-photon (2P) microscopy imaging
experiments on living T24 human cancer cells confirmed the spontaneous
internalization of the probes and images with good signal-to-noise have been
obtained in the classical NIR-to-visible configuration with Eu<sup>3+</sup> luminescent
bioprobe and in the NIR-to-NIR with the Yb<sup>3+</sup> one.</p> | Jonathan Mendy; Amandine Roux; Jean-Christophe Mulatier; Alain Duperray; Alexei Grichine; Yannick Guyot; Sophie Brasselet; François Riobé; Chantal Andraud; Boris Le Guennic; Véronique Patinec; Raphael Tripier; Maryline Beyler; Olivier MAURY; Anh Thy Bui; Damien Curton | Biophysical Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-01-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74778f96a00b6f8286f1d/original/cationic-biphotonic-lanthanide-luminescent-bioprobes-based-on-functionalized-cross-bridged-cyclam-macrocycles.pdf |
64256a3a62fecd2a83ad504f | 10.26434/chemrxiv-2023-079b9 | Towards the controlled enzymatic synthesis of LNA containing oligonucleotides | Enzymatic, de novo XNA synthesis represents an alternative method for the production of long oligonucleotides containing chemical modifications at distinct locations. While such an approach is currently developed for DNA, controlled enzymatic synthesis of XNA remains at a relative state of infancy. In order to protect the masking groups of 3’-O-modified LNA and DNA nucleotides against removal caused by phosphatase and esterase activities of polymerases, we report the synthesis and biochemical characterization of nucleotides equipped with ether and robust ester moieties. While the resulting ester-modified nucleotides appear to be poor substrates for polymerases, ether-blocked LNA and DNA nucleotides are readily incorporated into DNA. However, removal of the protecting groups and modest incorporation yields represent obstacles for LNA synthesis via this route. On the other hand, we have also shown that the template-independent RNA polymerase PUP represents a valid alternative to the TdT and we have also explored the possibility of using engineered DNA polymerases to increase substrate tolerance for such heavily modified nucleotide analogs. | Nazarii Sabat; Dace Katkevica; Karlis Pajuste; Marie Flamme; Andreas Stämpfli; Martins Katkevics; Steven Hanlon; Serena Bisagni; Kurt Püntener; Filippo Sladojevich; Marcel Hollenstein | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64256a3a62fecd2a83ad504f/original/towards-the-controlled-enzymatic-synthesis-of-lna-containing-oligonucleotides.pdf |
66b369565101a2ffa8610518 | 10.26434/chemrxiv-2024-xm0td | A dynamic loop in halohydrin dehalogenase HheG regulates activity and enantioselectivity in epoxide ring opening | Halohydrin dehalogenase HheG and its homologs are remarkable enzymes for the efficient ring opening of sterically demanding internal epoxides using a variety of nucleophiles. The enantioselectivity of respective wild-type enzymes, however, is usually insufficient for application and frequently requires improvement by protein engineering. We herein demonstrate that the highly flexible N-terminal loop of HheG, comprising residues 39 to 47, has a tremendous impact on the activity as well as enantioselectivity of this enzyme in the ring opening of structurally diverse epoxide substrates. Thus, highly active and enantioselective HheG variants could be accessed through targeted engineering of this loop. In this regard, variant M45F displayed almost 10-fold higher specific activity than wild type in the azidolysis of cyclohexene oxide, yielding the corresponding product (1S,2S)-2-azidocyclohexan-1-ol in 96%eeP (in comparison to 49%eeP for HheG wild type). Moreover, this variant was also improved regarding activity and enantioselectivity in the ring opening of cyclohexene oxide with other nucleophiles, demonstrating even inverted enantioselectivity with cyanide and cyanate. In contrast, a complete loop deletion yielded inactive enzyme. Concomitant computational analyses of HheG M45F in comparison to wild type enzyme revealed that mutation M45F promotes the productive binding of cyclohexene oxide and azide in the active site by establishing non-covalent C-H ··π interactions between epoxide and F45. These interactions further position one of the two carbon atoms of the epoxide ring closer to the azide resulting in higher enantioselectivity. Additionally, stable and enantioselective cross-linked enzyme cystals of HheG M45F were successfully generated after combination with mutation D114C. | Marcel Staar; Lina Ahlborn; Miquel Estévez-Gay; Katharina Pallasch; Sílvia Osuna; Anett Schallmey | Catalysis; Biocatalysis | CC BY 4.0 | CHEMRXIV | 2024-08-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b369565101a2ffa8610518/original/a-dynamic-loop-in-halohydrin-dehalogenase-hhe-g-regulates-activity-and-enantioselectivity-in-epoxide-ring-opening.pdf |
60c73d88469df4f132f42703 | 10.26434/chemrxiv.5840883.v1 | Benchmarking Several van der Waals Dispersion Approaches for the Description of Intermolecular Interactions | Seven methods, including three van der Waals
density functionals (vdW-DFs) and four different variants of the
Tkatchenko-Scheffler (TS) methods, are tested on the A24, L7, and Taylor
<i>et al.</i>'s "blind" test sets. It is found that for these systems,
the vdW-DFs perform better that the TS methods. In particular, the
vdW-DF-cx functional gives binding energies that are the closest to the
reference values, while the many body correction of TS does not always
lead to an improvement in the description of molecular systems. In light
of these results, several directions for further improvements to
describe van der Waals interactions are discussed.<br /> | Julien Claudot; Won June Kim; Anant Dixit; Hyungjun Kim; Tim Gould; Dario Rocca; Sébastien Lebègue | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2018-02-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d88469df4f132f42703/original/benchmarking-several-van-der-waals-dispersion-approaches-for-the-description-of-intermolecular-interactions.pdf |
66740cda5101a2ffa80b1c66 | 10.26434/chemrxiv-2024-s4hlm | Surface modified ZnONFs with Oleic acid to fabricate nanobiosensors for uric acid detection | In the present study, we employed an ex-situ process to modify the surface of zinc oxide
nanoflowers (ZnONFs). Initially, we synthesized ZnONFs using the hydrothermal method.
Subsequently, we capped the synthesized ZnONFs using the ultra-sonication method. The
capped ZnONFs were then extensively characterized using various techniques, including UVvisible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning
and transmission electron microscopy. We then electrophoretically coated the synthesized
capped ZnONFs onto bare ITO electrodes to create uric acid biosensors. The bioelectrode,
UOx/Oleic acid-ZnONFs/ITO, was formed by applying EDC-NHS to the Oleic acid
ZnONFs/ITO electrode and then chemically immobilizing the Uricase enzyme. We evaluated
the performance of the UOx/Oleic acid-ZnONFs/ITO bioelectrode by measuring its ability to
detect uric acid concentrations in a linear range from 0.005 to 1.0 mM. The bioelectrode
demonstrated a low limit of detection (LOD) of 0.0044 µA/mM and an outstanding sensitivity
of 685.4 µA/mM/cm². The fabricated uric acid biosensors exhibited a shelf life of over 30 days
with a single interval.
| Priyanka Dutta; Md Ramiz Raza | Analytical Chemistry; Nanoscience; Biochemical Analysis; Electrochemical Analysis; Nanofabrication; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66740cda5101a2ffa80b1c66/original/surface-modified-zn-on-fs-with-oleic-acid-to-fabricate-nano-biosensors-for-uric-acid-detection.pdf |
67b4986381d2151a02fccff9 | 10.26434/chemrxiv-2025-7mfcm-v2 | H-Tunneling Rotamerization in Glycine Imine | Quantum mechanical tunneling governs chemical reactivity at cryogenic temperatures. Here we present the near-infrared (NIR) light-induced generation of a higher energy conformer of glycine imine and its H-tunneling CO bond rotamerization in solid argon (Ar), para-hydrogen (p-H2), and dinitrogen (N2) at cryogenic temperatures. The tunneling half-life for the CO bond rotamerization highly depends on the host matrix and is approximately 5 h in Ar, 18 h in p-H2 and N2. Surprisingly, experiments in p-H2 revealed a much longer half-life than in Ar, indicating the formation of a dinitrogen complex after photolysis of the azide precursor. Deuteration of the carboxylic acid group completely inhibits the CO bond D-tunneling rotamerization. We conducted Wentzel−Kramers−Brillouin (WKB) and canonical variational transition state theory in combination with multidimensional small curvature tunneling corrections (CVT/SCT) tunneling calculations at the B3LYP/cc-pVTZ level of theory. The gas-phase tunneling half-life is 11 h according to the one-dimensional WKB model and 1 h according to the multidimensional CVT/SCT model, both aligning well with our experimental results. | Vladimir D. Drabkin; André K. Eckhardt | Physical Chemistry; Organic Chemistry; Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67b4986381d2151a02fccff9/original/h-tunneling-rotamerization-in-glycine-imine.pdf |
655a24fa6e0ec7777f4449a2 | 10.26434/chemrxiv-2023-tgtd7 | Probing the surface charge of condensates using microelectrophoresis | Biomolecular condensates play an important role in cellular organization. Coacervates are commonly used as model systems that mimic the physiochemical properties of biomolecular condensates, and are simultaneously studied as protocell models. The surface of condensates plays a key role in governing the exchange of molecules between condensates and their surroundings, the accumulation of species at the interface, and the stability of condensates against coalescence. However, most important surface properties, including the surface charge, remain poorly characterized and understood. The surface potential of coacervates is often measured using laser doppler electrophoresis, which assumes a size-independent electrophoretic mobility. Here, we show that this assumption is incorrect for condensates and present an alternative method to study the electrophoretic mobility of coacervates by microelectrophoresis and single-particle tracking, using electric fields of 1-15 V/cm. Coacervates have a size-dependent electrophoretic mobility, originating from their fluid nature, from which a well-defined zeta potential is calculated. We demonstrate the performance of our methodology on several complex coacervates and condensate models, which all exhibit size-dependent mobility. Interestingly, microelectrophoresis measurements revealed that polylysine chains are enriched at the surface of polylysine/polyaspartic acid complex coacervates, which causes the negatively charged protein ɑ-synuclein to adsorb and accumulate at the interface. Addition of ATP was able to invert the surface charge and displace the adsorbed ɑ-synuclein from the surface, which could suppress its interface-catalyzed aggregation. Together, these findings show how condensate surface charge can be measured and affected, making this microelectrophoresis platform combined with automated single-particle tracking a promising characterization technique for both biomolecular condensates and coacervate protocells. | Merlijn van Haren; Brent Visser; Evan Spruijt | Physical Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Biophysical Chemistry; Interfaces; Self-Assembly | CC BY NC 4.0 | CHEMRXIV | 2023-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655a24fa6e0ec7777f4449a2/original/probing-the-surface-charge-of-condensates-using-microelectrophoresis.pdf |
65d5d5a29138d23161a0e6d2 | 10.26434/chemrxiv-2024-gwdwk | Enantioselective synthesis of sealutomicin C | The sealutomicins are a family of anthraquinone antibiotics featuring an enediyne (sealutomicin A) or Bergman-cyclized aromatic ring (sealutomicins B – D). Herein we report the development of an enantioselective organocatalytic method for the synthesis of dihydroquinolines and the use of the developed method in the total synthesis of sealutomicin C which features a transannular cyclization of an aryl lithium onto a gamma-lactone as a second key step. | Stuart Astle; Sean Guggiari; James Frost; Hamish Hepburn; David Klauber; Kirsten Christensen; Jonathan Burton | Organic Chemistry; Natural Products; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d5d5a29138d23161a0e6d2/original/enantioselective-synthesis-of-sealutomicin-c.pdf |
67bee1d2fa469535b9005f51 | 10.26434/chemrxiv-2025-chsf0-v2 | A set of Quantum–Mechanically Derived Force Fields for Natural and Synthetic Retinal Photoswitches | The diverse biological functions of rhodopsins are all triggered by photoexcitation of retinal protonated Schiff base chromophores. This diversity can be traced back not only to variations in the protein scaffolds in which the chromophore is embedded, but also to the different isomeric forms of the chromophore itself, whose role is crucial in several processes. Although most computational approaches for these systems often require classical molecular dynamics, efforts in providing a set of parameters able to accurately and consistently model through molecular mechanics several isomeric chromophores are lacking in literature. The most recent efforts entail either refinements of general purpose force fields, which lack in accuracy, or parameterisation strategies that include environmental effects, making the resulting parameters not transferable to a different embedding. In this work, we provide accurate intramolecular force fields based on data purposely computed using Møller–Plesset second order perturbation theory, specifically tailored for varied natural retinal Protonated Schiff Bases and synthetic analogues often employed in retinal-based photoswitches. We demonstrate the quality of our quantum–mechanically derived force fields (QMD–FFs) through a wide set of validation tests. These consistently indicate an excellent description of each chromophore in terms of equilibrium geometries, conformational landscapes, and optical properties in comparison to literature data, experimental measurements, and reference QM calculations. Our intramolecular QMD–FFs, distributed in electronic format, can be adopted to describe these chromophores in complex environments, exploiting in- termolecular parameters compatible with the ones available in literature for biological macromolecules. | Razan Daoud; Simone Veglianti; Anna Piras; Abderrahmane Semmeq; Samuele Giannini; Giacomo Prampolini; Daniele Padula | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bee1d2fa469535b9005f51/original/a-set-of-quantum-mechanically-derived-force-fields-for-natural-and-synthetic-retinal-photoswitches.pdf |
66eedc9a51558a15efaa3ac0 | 10.26434/chemrxiv-2024-6b14l-v3 | Gallium: A Universal Promoter Switching CO2 Methanation Catalysts to Produce Methanol | Hydrogenation of CO2 to methanol is foreseen as a key step to close the carbon cycle and enable sustainable development. In this study, we show that introducing Ga into silica-supported nanoparticles based on group 8-9 transition noble metals (M = Ru, Os, Rh, and Ir – MGa@SiO2) switches their reactivity from producing methane (sel. >97%) to producing methanol (50% CH3OH/DME sel.) alongside CO as the only byproduct. These silica-supported catalysts, prepared via a surface organometallic chemistry approach, consist of small, alloyed and narrowly distributed MGa nanoparticles, as evidenced by X-Ray absorption spectroscopy (XAS) and CO adsorption studies. Notably, detailed in-situ XAS and diffuse reflectance FT-IR spectroscopy (DRIFTS) studies complemented with density functional theory (DFT) calculations indicate that Ga generates stable MGa alloys, which persist during CO2 hydrogenation and favor the formation of methoxyl species, thus driving the overall reaction to methanol formation while suppressing methanation. | Wei Zhou; Colin Hansen; Weicheng Chao; Enzo Brack; Scott Docherty; Christian Ehinger; Yuhao Wang; Chunliang Wang; Christophe Copéret | Catalysis; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2024-09-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66eedc9a51558a15efaa3ac0/original/gallium-a-universal-promoter-switching-co2-methanation-catalysts-to-produce-methanol.pdf |
610aee20424ea341a58349f9 | 10.26434/chemrxiv-2021-8s8mr | Porphyrin as a Versatile Visible-Light-Activatable Organic/Metal Hybrid Photoremovable Protecting Group | Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical applications. For the past half century, organic and metal-complex PPGs were considered mutually exclusive classes, each of which providing unique sets of physical and chemical properties thanks to their distinctive structures. Here, we introduce the meso-methylporphyrin group as a prototype hybrid-class PPG that unites traditionally exclusive elements of organic and metal-complex PPGs within a single structure. We show that the porphyrin scaffold allows extensive modularity by functional separation of the metal-binding chromophore and up to four sites of leaving group release. The insertion of metal ions can be used to tune their spectroscopic, photochemical, and biological properties. We provide a detailed description of the photoreaction mechanism studied by steady-state and transient absorption spectroscopies and quantum-chemical calculations. Our approach applied herein could facilitate access to a hitherto untapped chemical space of potential PPG scaffolds. | Adiki Raja Sekhar; Youhei Chitose; Jiří Janoš; Sahar Israeli Dangoor; Andrea Ramundo; Ronit Satchi Fainaro; Petr Slavíček; Petr Klán; Roy Weinstain | Physical Chemistry; Organic Chemistry; Organometallic Chemistry; Photochemistry (Org.); Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/610aee20424ea341a58349f9/original/porphyrin-as-a-versatile-visible-light-activatable-organic-metal-hybrid-photoremovable-protecting-group.pdf |
63dcdf115c37ece322a875f1 | 10.26434/chemrxiv-2023-lb827 | Soft Matter under Pressure: Pushing Particle-Field Molecular Dynamics to the Isobaric Ensemble | Hamiltonian hybrid particle-field molecular dynamics is a computationally efficient method to study large soft matter systems. In this work, we extend this approach to constant pressure (NPT) simulations. We reformulate the calculation of internal pressure from the density field by taking into account the intrinsic spread of the particles in space, which naturally lead to a direct anisotropy in the pressure tensor. The anisotropic contribution is crucial for reliably describing the physics of systems under pressure, demonstrated by a series of tests on analytical and monoatomic model systems as well as realistic water/lipid biphasic systems. Using Bayesian optimization, we parameterise the field interactions of phospholipids to reproduce the structural properties of their lamellar phases, including area per lipid, and local density profiles. The resulting model excels in providing pressure profiles in qualitative agreement with all-atom modeling, surface tension, and area compressibility in quantitative agreement with experimental values, indicating the correct description of long wavelength undulations in large membranes. Finally, we demonstrate that the model is capable of reproducing the formation of lipid droplets inside a lipid bilayer. | Samiran Sen; Morten Ledum; Sigbjørn Løland Bore; Michele Cascella | Theoretical and Computational Chemistry; Physical Chemistry; Biological and Medicinal Chemistry; Biophysics; Computational Chemistry and Modeling; Interfaces | CC BY NC 4.0 | CHEMRXIV | 2023-02-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63dcdf115c37ece322a875f1/original/soft-matter-under-pressure-pushing-particle-field-molecular-dynamics-to-the-isobaric-ensemble.pdf |
643adbb873c6563f14f074db | 10.26434/chemrxiv-2023-h3wdj | Exploring CO2 Hydrogenation to Methanol at a CuZn--ZrO2 Interface via DFT Calculation | Multi-component heterogeneous catalysts are among the top candidates for converting greenhouse gases into valuable compounds. Combinations of Cu, Zn, and ZrO2 (CZZ) have emerged as promisingly efficient catalysts for CO2 hydrogenation to methanol. To explore the catalytic mechanism, density functional theory (DFT) calculations and the energetic span model (ESM) were used to study CO2 conversion routes to methanol on CuZn-ZrO2 interfaces with a varying Zn content. Our results demonstrate that the presence of Zn sites at the interface improves CO2 binding. However, the adsorption and activation energies are insensitive to Zn concentration. The calculations also show that the hydrogenation of adsorbate oxygen atoms at the interface is kinetically more favourable and requires hydrogen spillover from the metal to the zirconia. This leads to barriers that are lower than those reported on interface or metal-only sites in previous literature. While DFT calculations alone are unable to identify which one of the competing pathways is more favourable, the ESM model predicts that the carboxyl pathway has a higher turnover frequency than the formate route. Our findings also show the importance of considering effects such as hydrogen spillover which take place at a metal-oxide interface when modelling complex catalytic environments. | Aku Lempelto; Lars Gell; Toni Kiljunen; Karoliina Honkala | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2023-04-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643adbb873c6563f14f074db/original/exploring-co2-hydrogenation-to-methanol-at-a-cu-zn-zr-o2-interface-via-dft-calculation.pdf |
60c74062842e655ee1db1ca5 | 10.26434/chemrxiv.7723226.v1 | Structure, anion, and solvent effects on cation response in ESI-MS | <p>The
abundance of an ion in an electrospray ionization mass spectrum is dependent on
many factors beyond just solution concentration. Even in cases where the ions
are permanently charged and do not rely on protonation or other chemical
processes to acquire the necessary charge, factors such as cation structure,
molecular weight, solvent, and the identity of the anion can perturb results. Screening
of a variety of combinations of cation, anion and solvent provided insight into
some of the more important factors. Rigid cations and high conductivity anions
tended to provide the highest responses, while acetonitrile was the most
accurate solvent for reflecting solution composition. Functional groups that
had affinity for the solvent tended to depress response. These observations
will provide predictive power when accounting for ions that for reasons of high
reactivity can not be isolated.</p><br /> | Isaac Omari; Parmissa Randhawa; Jaiya Randhawa; Jenny Yu; J Scott McIndoe | Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2019-02-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74062842e655ee1db1ca5/original/structure-anion-and-solvent-effects-on-cation-response-in-esi-ms.pdf |
634624d7692d8d83bbe32734 | 10.26434/chemrxiv-2022-7qm8l | Synthesis of Aromatic Carbonyl Thiourea PI-28 Derivatives for the Development of Radicle Elongation Inhibitor of Parasitic Weeds | Aromatic carbonyl thiourea PI-28 has been focused on as a lead compound for the developing radicle elongation inhibitors in germinating Orobanche minor dry seeds. In this study, we have synthesized PI-28 and its derivatives using commercially available phenols, 2-chloroacetamide, and aryl isothiocyanates. In this method, 2-aryloxyacetanilides, which are also attractive as bioactive compounds, were obtained as byproducts. These compounds were formed due to the loss of isothiocyanate moiety from the formed aromatic carbonyl thioureas. | Motohiro Sonoda; Yusuke Mimura; Shizuki Noda; Atsushi Okazawa | Organic Chemistry; Agriculture and Food Chemistry; Bioorganic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/634624d7692d8d83bbe32734/original/synthesis-of-aromatic-carbonyl-thiourea-pi-28-derivatives-for-the-development-of-radicle-elongation-inhibitor-of-parasitic-weeds.pdf |
63ae991fa53ea645b35c5dac | 10.26434/chemrxiv-2022-qqvd6 | Exploring the effects of mutagenesis on
FusionRed using excited state QM/MM
dynamics and classical force field simulations | Fluorescent proteins (FPs) are a powerful tool for examin-
ing tissues, cells, and subcellular components in vivo and in
vitro. FusionRed is a particular FP variant mutated from
mKate2 that, in addition to lower cytotoxicity and aggregation rates, has shown potential for acting as a tunable photoswitch. This was posited to stem partially from the presence of a bulky side chain at position 158 and a further stabilizing residue at position 157. In this work, we apply computational techniques including classical molecular dynamics (MD) and combined quantum mechanics/molecular mechanics simulations (QM/MM) to explore the effect of mutagenesis at these locations in FusionRed on the chromophore structure, the excited state surface, and relative positional stability of the chromophore in the protein pocket. We find specific connections between the statistical sampling of the underlying protein structure and the nonradiative decay mechanisms from excited state dynamics. A single mutation (C158I) which restricts the motion of the chromophore via a favorable hydrophobic interaction corresponds to an increase in FQY, while a second rescue mutation (C158I-A157N) partially restores the flexibility of the chromophore and photoswitchability with favorable water interactions on the surface of the protein that counteracts the original interaction. We suggest that applying this understanding of structural features that inhibit or favor rotation on the excited state can be applied for rational design of new, tunable and red photoswitches. | Ashlyn Murphy; Mark Hix; Alice Walker | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2022-12-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63ae991fa53ea645b35c5dac/original/exploring-the-effects-of-mutagenesis-on-fusion-red-using-excited-state-qm-mm-dynamics-and-classical-force-field-simulations.pdf |
670ae17b12ff75c3a13cd7d9 | 10.26434/chemrxiv-2024-w1m55 | Localized Boron Sites in Large Pore Borosilicate Zeolite EMM-59 Determined by Electron Crystallography | The structure of a novel large pore borosilicate zeolite EMM-59 (|C19H42N2|8[B5.2Si218.8O448]) with localized framework boron sites was determined using three-dimensional electron diffraction (3D ED) and scanning transmission electron microscopy (STEM) imaging. EMM-59 was synthesized using 2,2-(cyclopentane-1,1-diyl)bis(N,N-diethyl-N-methylethan-1-aminium) as an organic structure-directing agent (OSDA). The framework has a three-dimensional intersecting channel system delimited by 12 × 10 × 10-ring openings and contains 28 T and 60 oxygen atoms in the asymmetric unit, making it the most complex monoclinic zeolite. The 3D ED data collected from as-made EMM-59 under cryogenic conditions revealed three symmetry-independent locations of the OSDAs and STEM imaging showed that the OSDAs are flexible and adopt different molecular conformations in channels with identical structural environments. The framework boron atoms were exclusively found in T-sites of 4-rings, especially those shared by multiple 4-rings. The tetrahedral BO4 with the highest boron content (38.6%) was transformed into a trigonal BO3 after the OSDAs were removed upon calcination. Its location and the boron content could also be identified by STEM imaging. | Jung Cho; Elina Kapaca; Bin Wang; Ross Mabon; Hilda B Vroman; Xiaodong Zou; Allen W Burton; Tom Willhammar | Inorganic Chemistry; Crystallography – Inorganic | CC BY NC 4.0 | CHEMRXIV | 2024-10-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670ae17b12ff75c3a13cd7d9/original/localized-boron-sites-in-large-pore-borosilicate-zeolite-emm-59-determined-by-electron-crystallography.pdf |
60c74329ee301c6654c78f4e | 10.26434/chemrxiv.8947397.v1 | A Glycal-Based Photoaffinity Probe That Enriches Sialic Acid Binding Proteins | <p>To identify sialic acid binding proteins from complex proteomes, three photocrosslinking affinity-based probes were constructed using Neu5Ac (<b>5 </b>and <b>6</b>) and Neu5Ac2en (<b>7</b>) scaffolds. Kinetic inhibition assays and Western blotting revealed the Neu5Ac2en-based <b>7 </b>to be an effective probe for the labeling of a purified gut microbial sialidase (BDI_2946) and a purified human sialic acid binding protein (hCD33). Additionally, LC-MS/MS affinity-based protein profiling verified the ability of <b>7</b>to enrich a low-abundance sialic acid binding protein (complement factor H) from human serum thus validating the utility of this probe in a complex context.</p> | Peter Thuy-Boun; Dennis Wolan | Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2019-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74329ee301c6654c78f4e/original/a-glycal-based-photoaffinity-probe-that-enriches-sialic-acid-binding-proteins.pdf |
60c743f6bb8c1a01693da415 | 10.26434/chemrxiv.9724889.v1 | Ambient Complexation Reaction of Zinc Acetate and Ascorbic acid Leads to a New Form of Nanoscale Particles with Emergent Optical Properties | We report room temperature complexation reaction mediated formation of luminescent nanoscale particles from an aqueous mixture of ascorbic acid and zinc acetate.<br /> | Srestha Basu; Archismita Hajra; Arun Chattopadhyay | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743f6bb8c1a01693da415/original/ambient-complexation-reaction-of-zinc-acetate-and-ascorbic-acid-leads-to-a-new-form-of-nanoscale-particles-with-emergent-optical-properties.pdf |
663b3c1e21291e5d1db9d7ba | 10.26434/chemrxiv-2023-nfmkc-v2 | Pressure-controlled formation of discontinuous clogs in tapered microchannels | In suspension flows through microchannels with parallel walls, rigid particles form clogs that grow continuously in the upstream direction. However, introducing a slight taper to channel walls leads to a qualitatively different clogging mechanism. Clogs of rigid particles do not grow continuously in these tapered pores. Instead, new clogs form upstream of pre-existing clogs, truncating their growth, and thereby creating multiple distinct clogs within a channel. We refer to this novel phenomenon as discontinuous clogging. Here, we investigate its features by analyzing the dimensions and locations of discontinuous clogs in parallel tapered pores. Measurements reveal the discontinuity of clog growth depends strongly on flow driving pressure and particle volume fraction. Increasing volume fraction increases clogging frequency and positions the clogs upstream, in wider regions of the channels. Two regimes of driving pressure appear to exist as the discontinuous clogs are observed to become dramatically longer above a critical pressure. Interestingly, these long clogs are located downstream, towards the channel outlet, at the lowest volume fraction. However, they are increasingly located upstream as volume fraction increases. The dependence of clog location on pressure and volume fraction lends insight into bridging mechanism. Particles arriving simultaneously to a given location can span the channel width to form a bridge, which happens easily at higher volume fractions. Permanent clogs form when driving pressure is lower than the force the bridges can sustain. As driving pressure increases, however, it can overcome the force chains, preventing formation of new permanent clogs, and pushing particles further downstream. | Olukayode Majekodunmi; Sara Hashmi | Materials Science; Chemical Engineering and Industrial Chemistry; Fluid Mechanics | CC BY 4.0 | CHEMRXIV | 2024-05-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/663b3c1e21291e5d1db9d7ba/original/pressure-controlled-formation-of-discontinuous-clogs-in-tapered-microchannels.pdf |
60eeeca5338e9285990b0583 | 10.26434/chemrxiv-2021-tnrs7 | Inactivation of novel coronavirus and alpha variant by photo-renewable CuxO/TiO2 nanocomposites | In order to reduce infection risk of novel coronavirus (SARS-CoV-2), we developed photocatalysts with nanoscale rutile TiO2 (4–8 nm) and CuxO (1–2 nm or less). Their extraordinarily small size leads to high dispersity and good optical transparency, besides large active surface area. Those photocatalysts can be applied to white and translucent latex paints and a transparent varnish. Although Cu2O clusters involved in the paint coating undergo gradual aerobic oxidation in the dark, the oxidized clusters are re-reduced under >380 nm light. The paint coating inactivated novel coronavirus and its alpha (B.1.1.7) variant under irradiation with fluorescent light for 3 h. The coating also exhibited antivirus effects on influenza A virus, feline calicivirus and bacteriophage Qβ. The photocatalysts would be applied to practical coatings and lower the risk of coronavirus infection via solid surfaces. | Tetsu Tatsuma; Makoto Nakakido; Takeshi Ichinohe; Yoshinori Kuroiwa; Kengo Tomioka; Chang Liu; Nobuhiro Miyamae; Tatsuya Onuki; Kouhei Tsumoto; Kazuhito Hashimoto; Toru Wakihara | Biological and Medicinal Chemistry; Materials Science; Nanoscience; Catalysts; Nanostructured Materials - Materials; Thin Films | CC BY NC ND 4.0 | CHEMRXIV | 2021-07-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60eeeca5338e9285990b0583/original/inactivation-of-novel-coronavirus-and-alpha-variant-by-photo-renewable-cux-o-ti-o2-nanocomposites.pdf |
60c74ccaf96a00b05e287840 | 10.26434/chemrxiv.12546389.v1 | Minimizing Polymorphic Risk Through Cooperative Computational and Experimental Exploration | <div>
<p>We combine state-of-the-art computational
crystal structure prediction (CSP) techniques with a wide range of experimental
crystallization methods to understand and explore crystal structure in
pharmaceuticals and minimize the risk of unanticipated late-appearing
polymorphs. Initially, we demonstrate
the power of CSP to rationalize the difficulty in obtaining polymorphs of the
well-known pharmaceutical isoniazid and show that CSP provides the structure of
the recently discovered, but unsolved, Form III of this drug despite there
being only a single known form for almost 70 years. More dramatically, our blind CSP study
predicts a significant risk of polymorphism for the related iproniazid.
Employing a wide variety of experimental techniques, including high-pressure
experiments, we experimentally obtained the first three known non-solvated
crystal forms of iproniazid, all of which were successfully predicted in the
CSP procedure. We demonstrate the power
of CSP methods and free energy calculations to rationalize the observed
elusiveness of the third form of iproniazid, the success of high-pressure
experiments in obtaining it, and the ability of our synergistic
computational-experimental approach to “de-risk” solid form landscapes.</p>
</div> | Christopher R. Taylor; Matthew T. Mulvee; Domonkos S. Perenyi; Michael R. Probert; Graeme Day; Jonathan Steed | Computational Chemistry and Modeling; Self-Assembly; Structure; Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ccaf96a00b05e287840/original/minimizing-polymorphic-risk-through-cooperative-computational-and-experimental-exploration.pdf |
65574388dbd7c8b54b729214 | 10.26434/chemrxiv-2023-gxmxr | GPT-4-powered analysis and prediction of experiments through an effective chain-of-thought prompting strategy: a case study of selective catalytic reduction of NOx with NH3 by metal-oxide composites | The chemistry laboratories of the future are poised to undergo a significant transformation, largely driven by the advent and integration of large language models (LLMs) into everyday tasks and workflows. As we stand at the threshold of this exciting fusion of chemistry research with artificial intelligence (AI), a pressing question arises: "In what ways can LLMs enhance and contribute to the field of chemistry?" This study investigates a potential application of LLMs in interpreting and predicting experimental outcomes based on various experimental variables, by leveraging the human-like reasoning and inference capabilities of LLMs to process and analyse the presented information. This study centres on the selective catalytic reduction of NOx with NH3 using metal-oxide composites, presenting a chemistry challenge for evaluating GPT-4's ability to discern correlations. We specifically assess how GPT-4 relates experimental variables—including the catalyst's composition, synthesis conditions, and operational parameters—to the corresponding outcome, namely the catalytic performance. We implement the Chain of Thought (CoT) concept to create reasoning paths that establish relationships, which are then reinput into GPT-4 to generate inferences. This involves formulating a series of logical steps, akin to human problem-solving, to uncover connections within the data. The results of these reasoning paths serve as a feedback loop, thereby enriching the depth and accuracy of GPT-4's subsequent inferences. Here, we introduce a specialized CoT prompting strategy, termed "Ordered-and-Structured" CoT (OSCoT), wherein each individual feature or aspect of the problem is systematically and sequentially examined. This contrasts with the baseline "one-pot" CoT (OPCoT) approach, where all information is processed in a simultaneous manner. The OSCoT strategy's sequential analysis of each problem aspect significantly enhances the quality and precision of the inferences generated by GPT-4. Our findings show that GPT-4, powered by OSCoT, can accurately predict catalytic performances for both binary and ternary metal-oxide composites. | Muyu Lu; Fengyu Gao; Xiaolong Tang; Linjiang Chen | Catalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65574388dbd7c8b54b729214/original/gpt-4-powered-analysis-and-prediction-of-experiments-through-an-effective-chain-of-thought-prompting-strategy-a-case-study-of-selective-catalytic-reduction-of-n-ox-with-nh3-by-metal-oxide-composites.pdf |
65dd06b1e9ebbb4db9555326 | 10.26434/chemrxiv-2023-xghmd-v4 | The Free Energy Density of a Fluid and its Role in Solvation and Binding | The concept that a fluid has a position-dependent free energy density appears in the literature but has not been fully developed or accepted. We set this concept on an unambiguous theoretical footing via the following strategy. First, we set forth four desiderata that should be satisfied by any definition of the position-dependent free energy density, f(R), in a system comprising only a fluid and a rigid solute: its volume integral, plus the fixed internal energy of the solute, should be the system free energy; it deviates from its bulk value, f_bulk, near a solute but should asymptotically approach f_bulk with increasing distance from the solute; it should go to zero where the solvent density goes to zero; and it should be well-defined in the most general case of a fluid made up of flexible molecules with an arbitrary interaction potential. Second, we use statistical thermodynamics to formulate a definition of the free energy density that satisfies these desiderata. Third, we show how any free energy density satisfying the desiderata may be used to analyze molecular processes in solution. In particular, because the spatial integral of f(R) equals the free energy of the system, it can be used to compute free energy changes that result from the rearrangement of solutes, as well as the forces exerted on the solutes by the solvent. In particular, we discuss the thermodynamic analysis of water in protein binding sites to inform ligand design. Finally, we discuss related literature and address published concerns regarding the thermodynamic plausibility of a position-dependent free energy density. The theory presented here has applications in theoretical and computational chemistry and may be further generalizable beyond fluids, such as to solids and macromolecules. | Michael K. Gilson; Tom Kurtzman | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC 4.0 | CHEMRXIV | 2024-02-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65dd06b1e9ebbb4db9555326/original/the-free-energy-density-of-a-fluid-and-its-role-in-solvation-and-binding.pdf |
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