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65119094b927619fe7ca1d96 | 10.26434/chemrxiv-2023-sbbhc-v2 | Data-Driven Insights into the Fluorescence of Asphaltene Aggregates Using Extended Frenkel Exciton Model | The origin of the fluorescence redshift during asphaltene aggregation remains debated due to the great diversity of asphaltene molecules, while the extended Frenkel exciton model provided a theoretical framework for studying multi-chromophore systems such as asphaltene aggregates. We investigated the fluorescence energy of hundreds of asphaltene dimers based on 132 experimentally determined asphaltene monomer structures. Our result shows that the dimer’s fluorescence energy is always lower than both of its monomers regardless of its intermolecular conformation, with its redshift dominated by superexchange. The dimer oscillator strength predominantly depends on the monomer with the lower fluorescence energy, and the involvement of charge-transfer states and the cancellation between monomer transition dipole moments suppressed the fluorescence especially when two monomers have similar fluorescence energy. The above findings hold for all asphaltene dimers despite their diversity, which offers a theoretical interpretation for comprehending the relationship between asphaltene aggregation and its fluorescence variation. Furthermore, this work provides theoretical insights into other research areas related to organic planar conjugated systems with multiple chromophores. | Fangning Ren; Fang Liu | Theoretical and Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65119094b927619fe7ca1d96/original/data-driven-insights-into-the-fluorescence-of-asphaltene-aggregates-using-extended-frenkel-exciton-model.pdf |
65eee1c2e9ebbb4db9711daf | 10.26434/chemrxiv-2024-0vttl | Hyperhardness and hypersoftness of atoms and their ions | The theory of reactivity based on cDFT has been supplemented with the new method of calculation of the atomic and local indices. With the use of previously derived relationship of the electron density gradient to the softness kernel and to the linear response function we deliver analytical scheme to obtain significant reactivity indices - the electron density derivatives: local softness s(r), local hypersoftness [∂s(r)/∂N] for atoms. The global hyperhardness and the global derivative [∂S/∂N] have also been obtained. The local derivatives have been applied in the analysis of responses of atoms to perturbation by an external potential ∆v(r) by the alchemical approach. The vital role of the local softness has been confirmed; the potential role of the hypersoftness has been indicated for reactions in a confinement. | Jarosław Zaklika; Piotr Ordon; Ludwik Komorowski | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2024-03-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65eee1c2e9ebbb4db9711daf/original/hyperhardness-and-hypersoftness-of-atoms-and-their-ions.pdf |
60c74d67337d6c672ee27dbb | 10.26434/chemrxiv.12617012.v1 | Thioether-Linked Azobenzene-Based Liquid Crystal Dimers Exhibiting the Twist-Bend Nematic Phase over a Wide Temperature Range | <a>Two homologous series of sulfur-containing thioether-linked 4-cyanoazobenzene-based
liquid crystal (LC) dimers</a> were developed: <a>a symmetric series based on 4-cyanoazobenzene arms [(</a>CN)AzoS<i>n</i>SAzo(CN)] and a non-symmetric series based on
4-cyanoazobenzene and 4-cyanobiphenyl arms [(CN)AzoS<i>n</i>SCB]. They contained different flexible oligomethylene
spacers (C<i><sub>n</sub></i>H<sub>2<i>n</i></sub>) consisting of odd numbers of carbon atoms (<i>n</i> = 3, 5, 7, 9, and 11). The symmetric (CN)AzoS<i>n</i>SAzo(CN) dimers with <i>n</i>
= 5, 7, 9, and 11 showed an elusive monotropic twist–bend nematic (N<sub>TB</sub>)
phase, while all the non-symmetric (CN)AzoS<i>n</i>SCB dimers exhibited the N<sub>TB</sub> phase. Notably,
the N<sub>TB</sub> phase observed for non-symmetric (CN)AzoS7SCB could be supercooled to room temperature, leading to a glassy N<sub>TB</sub>
phase. (CN)AzoS9SCB showed a similar tendency accompanied by partial
crystallization. <a>These are the first reported examples of
azobenzene-based LC </a>dimers exhibiting a broad temperature range of N<sub>TB</sub> phases supercooled
to room temperature. Such prominent stability of the N<sub>TB</sub> phase is due
to the supercooling effect assisted by the synergy of molecular bend arising from
thioether linkages and non-symmetric mesogenic arms. The phase-transition temperatures were overall higher for symmetric (CN)AzoS<i>n</i>SAzo(CN) than for non-symmetric (CN)AzoS<i>n</i>SCB. It is assumed that the difference in the mesogenic arm structures hardly
influenced their molecular geometry or anisotropy in terms of entropy changes. | Yuki Arakawa; Kenta Komatsu; Yuko Ishida; Hideto Tsuji | Supramolecular Chemistry (Org.); Liquid Crystals | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74d67337d6c672ee27dbb/original/thioether-linked-azobenzene-based-liquid-crystal-dimers-exhibiting-the-twist-bend-nematic-phase-over-a-wide-temperature-range.pdf |
66b34a5e01103d79c5042912 | 10.26434/chemrxiv-2024-rllrl | Communicating Chemistry Innovation to the Public | Very few scholarly studies have been published on communicating chemistry to the public, and even less on publicly communicating chemistry research. Ccommunicating achievements in chemistry research, on the other hand, is an important component of research (and technology) management. New chemical products and new synthetic and analytical chemical processes often have a broad and lasting societal, economic and environmental impact. This trait, differentiating chemistry from other basic sciences, is reinforced by the sustainability challenge to make economic growth compatible with long-term well-being for all people and the environment. This study fills a gap in the literature and suggests avenues on how to conduct said communication based on the methodological autonomy of chemistry as scientific discipline. | Rosaria Ciriminna; Rafael Luque; Cristina Della Pina; Mario Pagliaro | Chemical Education; Chemical Education - General | CC BY NC 4.0 | CHEMRXIV | 2024-08-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b34a5e01103d79c5042912/original/communicating-chemistry-innovation-to-the-public.pdf |
675df012085116a1336bf882 | 10.26434/chemrxiv-2024-fz16p-v2 | Archerfish: A Retrofitted 3D Printer for High-throughput Combinatorial Experimentation via Continuous Printing | The maturation of 3D printing technology has enabled low-cost, rapid prototyping capabilities for mainstreaming accelerated product design. The materials research community has recognized this need, but no universally accepted rapid prototyping technique currently exists for material design. Toward this end, we develop Archerfish, a 3D printer retrofitted to dispense liquid with in-situ mixing capabilities for performing high-throughput combinatorial printing (HTCP) of material compositions. Using this HTCP design, we demonstrate continuous printing throughputs of up to 250 unique compositions per minute, 100x faster than similar tools such as OpenTrons that utilize stepwise printing with ex-situ mixing. We validate the formation of these combinatorial "prototype" material gradients using hyperspectral image analysis and energy-dispersive X-ray spectroscopy. Furthermore, we describe hardware challenges to realizing reproducible, accurate, and precise composition gradients with continuous printing, including those related to precursor dispensing, mixing, and deposition. Despite these limitations, the continuous printing and low-cost design of Archerfish demonstrate promising accelerated materials screening results across a range of materials systems from nanoparticles to perovskites. | Alexander E. Siemenn; Basita Das; Eunice Aissi; Fang Sheng; Lleyton Elliott; Blake Hudspeth; Marilyn Meyers; James Serdy; Tonio Buonassisi | Materials Science; Hybrid Organic-Inorganic Materials; Materials Processing; Thin Films | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675df012085116a1336bf882/original/archerfish-a-retrofitted-3d-printer-for-high-throughput-combinatorial-experimentation-via-continuous-printing.pdf |
61e97a4a6afbef12526b44cb | 10.26434/chemrxiv-2022-mmdn6-v2 | Revealing the Influence of Diverse Secondary Metal Cations on Redox-Active Palladium Complexes | Incorporation of redox-inactive metals into redox-active complexes and catalysts attracts attention for engendering new reactivity modes, but this strategy has not been extensively investigated beyond the first-row of the transition metals. Here, the isolation and characterization of the first series of heterobimetallic complexes of palladium with mono-, di-, and tri-valent redox-inactive metal ions are reported. A Reinhoudt-type heteroditopic ligand with a salen-derived [N2,O2] binding site for Pd and a crown-ether-derived [O6] site has been used to prepare isolable adducts of the Lewis acidic redox-inactive metal ions (Mn+). Comprehensive data from single-crystal X-ray diffraction analysis reveal distinctive trends in the structural properties of the heterobimetallic species, including an uncommon dependence of the Pd•••M distance on Lewis acidity. The reorganization energy associated with reduction of the heterobimetallic species is strongly modulated by Lewis acidity, with the slowest heterogeneous electron transfer kinetics associated with the strongest incorporated Lewis acids. This hitherto unexplored reorganization energy penalty for electron transfer contrasts with prior thermodynamic studies, revealing that kinetic parameters should be considered in studies of reactivity involving heterobimetallic species. | Riddhi Golwankar; Amit Kumar; Victor Day; James Blakemore | Inorganic Chemistry; Coordination Chemistry (Inorg.); Electrochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-01-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61e97a4a6afbef12526b44cb/original/revealing-the-influence-of-diverse-secondary-metal-cations-on-redox-active-palladium-complexes.pdf |
6779d5e681d2151a02e71e63 | 10.26434/chemrxiv-2025-0l0b0 | Fighting Cancer and Alzheimer’s Disease: QuantumFuture’s Docking (QFD) Identifies Dozens of Potent, Safe IDO1 Inhibitors from Natural Products | Indoleamine 2,3-dioxygenase 1 (IDO1) is implicated in Alzheimer’s disease, Parkinson’s disease, and various cancers, underscoring the need for potent and nontoxic inhibitors. In our previous work, we introduced QFVina and QFVinardo, highlighting the integration of high-level quantum mechanical (QM) conformational data with AutoDock Vina’s vina and Vinardo scoring functions. Building on these methods, we now introduce the generalized QuantumFuture’s Docking (QFD) framework and demonstrate its first broad application, featuring a newly curated library of approximately 30,000 natural products, each rigorously screened for very low predicted toxicity. Using ab initio DFT-D4 calculations (rev-SCAN functional, def2-TZVP basis set) to obtain accurate conformational strain energies, QFD was applied to 16 protein targets (eight with and eight without a heme cofactor), revealing several dozen top-scoring ligands that combine strong binding with minimal toxicity. Interestingly, the Vinardo and dkoes scoring functions emphasized different subsets of promising hits, highlighting the advantage of using multiple scoring perspectives. These potential IDO1 inhibitors are prime candidates for further refinement via QM/MM and/or molecular dynamics (MD) simulations to account for ligand and protein flexibility. We encourage experimental validation to accelerate the development of these low-toxicity compounds for therapeutic applications in neurodegenerative diseases and cancer. | Laszlo Fusti-Molnar | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems | CC BY 4.0 | CHEMRXIV | 2025-01-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6779d5e681d2151a02e71e63/original/fighting-cancer-and-alzheimer-s-disease-quantum-future-s-docking-qfd-identifies-dozens-of-potent-safe-ido1-inhibitors-from-natural-products.pdf |
658bbd7d9138d231619af676 | 10.26434/chemrxiv-2023-j7m58 | Three-dimensional van der Waals Open Frameworks | Open framework materials are constructed by connecting molecular components via strong bonds. Here, we show van der Waals interaction, which has been believed to be too weak for the framework construction, joints molecular building blocks into a series of robust three-dimensional frameworks, so-called van der Waals frameworks (WaaFs). The success relies on the use of metal-organic polyhedra (MOPs) with a size over 2 nm as building blocks. The well-defined faces composed of large aromatic molecules increase the intermolecular contact area to gain interaction energy over 400 kJ/mol. The octahedral shape of MOPs directs their packing into a diamond network with large extrinsic porosity. We confirm that one of the WaaFs shows over 2,000 m2 g-1 specific surface area. | Shun Tokuda; Shuhei Furukawa | Inorganic Chemistry; Bonding; Coordination Chemistry (Inorg.); Supramolecular Chemistry (Inorg.); Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-12-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/658bbd7d9138d231619af676/original/three-dimensional-van-der-waals-open-frameworks.pdf |
60c747454c891973b4ad2c96 | 10.26434/chemrxiv.11592018.v1 | The Quest for the Ideal Base: Rational Design of a Nickel Precatalyst Enables Mild, Homogeneous C–N Cross-Coupling | Palladium-catalyzed amination reactions using soluble organic bases have provided a solution to the many issues associated with heterogeneous reaction conditions. Still, homogeneous C–N cross-coupling approaches cannot yet employ bases as weak and economical as trialkylamines. Furthermore, organic base-mediated methods have not been developed for Ni(0/II) catalysis, despite some advantages of such systems over analogous Pd-based catalysts. We designed a new air-stable and easily prepared Ni(II) precatalyst bearing an electron-deficient bidentate phosphine ligand that enables the cross-coupling of aryl triflates with aryl amines using triethylamine (TEA) as base. The method is tolerant of sterically-congested coupling partners, as well as those bearing base- and nucleophile-sensitive functional groups. With the aid of density functional theory (DFT) calculations, we determined that the electron-deficient auxiliary ligands decrease both the pKa of the Ni-bound amine and the barrier to reductive elimination from the resultant Ni(II)–amido complex. Moreover, we determined that precluding Lewis acid-base complexation between the Ni catalyst and the base, due to steric factors, is important for avoiding catalyst inhibition. | Richard Liu; Joseph Dennis; Stephen L. Buchwald | Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c747454c891973b4ad2c96/original/the-quest-for-the-ideal-base-rational-design-of-a-nickel-precatalyst-enables-mild-homogeneous-c-n-cross-coupling.pdf |
6654565f21291e5d1d60f764 | 10.26434/chemrxiv-2024-5fqsq | Establishment and characterization of noro-VLP measurement by digital ELISA | Highly sensitive viral analytical techniques are essential tools for preventing the spread of infections. In this study, we established a digital enzyme-linked immunosorbent assay (ELISA) system to quantify norovirus proteins with high sensitivity. We used norovirus-like particles (noro-VLPs) as a surrogate for norovirus and constructed two digital ELISA systems using two different antibody pairs. The quantitative performance of the noro-VLP measurement using each digital ELISA system was evaluated. Both assay systems exhibited high sensitivity, good linearity, and high stability. The first system exhibited a limit of detection (LOD) of 87 pg/mL, correlation coefficient (R2) of 0.9984, inter-assay variation of 5.5 %, and intra-assay variation of 5.2 %. The second system exhibited an LOD of 19 pg/mL, R2 of 0.9984, inter-assay variation of 4.5 %, and intra-assay variation of 2.5 %. Comparison of the two systems using the same calibrant for unpurified and fractionated noro-VLPs revealed that the quantitative values for unpurified noro-VLPs were the same, whereas those for fractionated noro-VLPs were dramatically different. Our findings indicate that the reactivity to various components in the noro-VLP solution was altered depending on the different antibodies. Furthermore, our study highlights the importance of using appropriate calibrants, which contain the same ratio of components as the noro-VLP analyte, to afford accurate measurements. | Takema Hasegawa; Yuriko Adachi; Kazumi Saikusa; Megumi Kato | Analytical Chemistry; Biochemical Analysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6654565f21291e5d1d60f764/original/establishment-and-characterization-of-noro-vlp-measurement-by-digital-elisa.pdf |
60c75675337d6c1135e28e2a | 10.26434/chemrxiv.14251787.v1 | Electrochemical Nozaki–Hiyama–Kishi Coupling: Scope, Applications, and Mechanism | One of the most oft-employed methods for C–C bond formation involving the coupling of vinyl-halides with aldehydes catalyzed by Ni and Cr (Nozaki–Hiyama–Kishi, NHK) has been rendered more practical using an electroreductive manifold. Although early studies pointed to the feasibility of such a process those precedents were never applied by others due to cumbersome setups and limited scope. Here we show that a carefully optimized electroreductive procedure can enable a more sustainable approach to NHK, even in an asymmetric fashion on highly complex medicinally relevant systems. The e-NHK can even enable non-canonical substrate classes, such as redox-active esters, to participate with low loadings of Cr when conventional chemical techniques fail. A combination of detailed kinetics, cyclic voltammetry, and in situ UV-vis spectroelectrochemistry of these processes illuminates the subtle features of this mechanistically intricate process. | Yang Gao; david hill; wei hao; Brendon
J. McNicholas; julien Vantourout; Ryan Hadt; Sarah Reisman; Donna Blackmond; Phil Baran | Organic Synthesis and Reactions; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75675337d6c1135e28e2a/original/electrochemical-nozaki-hiyama-kishi-coupling-scope-applications-and-mechanism.pdf |
6435f8c5a41dec1a56e64577 | 10.26434/chemrxiv-2023-r7b01 | Autonomous, multi-property-driven molecular discovery: from predictions to measurements and back | A closed-loop, autonomous molecular discovery platform driven by integrated machine learning tools was developed to accelerate the design of molecules with desired properties. Two case studies are demonstrated on dye-like molecules, targeting absorption wavelength, lipophilicity, and photo-oxidative stability. In the first, the platform experimentally realized 312 unreported molecules across three automatic iterations of molecular design-make-test-analyze cycles while exploring the structure–function space of four rarely reported scaffolds. In each iteration, the property-prediction models which guided the exploration learned the structure–property space of diverse inexpensive scaffold derivatives realized through using multi-step syntheses. Conversely, the second study exploited property models trained on a chemical space with pre-existing examples to discover 6 top-performing molecules within the structure-property space. By closing the molecular discovery cycle of prediction, synthesis, measurement, and model retraining, the platform demonstrates the potential for integrated platforms to automatically understand a local chemical space and discover functional molecules. | Brent Koscher ; Richard B. Canty; Matthew A. McDonald; Kevin P. Greenman; Charles J. McGill; Camille L. Bilodeau; Wengong Jin; Haoyang Wu; Florence H. Vermeire; Brooke Jin; Travis Hart; Timothy Kulesza; Shih-Cheng Li; Tommi S. Jaakkola; Regina Barzilay; Rafael Gómez-Bombarelli; William H. Green; Klavs F Jensen | Theoretical and Computational Chemistry; Organic Chemistry; Chemical Engineering and Industrial Chemistry; Organic Synthesis and Reactions; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-04-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6435f8c5a41dec1a56e64577/original/autonomous-multi-property-driven-molecular-discovery-from-predictions-to-measurements-and-back.pdf |
60c73d4f337d6c997be2610d | 10.26434/chemrxiv.5616115.v1 | The Matter Simulation (R)evolution | To date, the program for the development of methods and models for atomistic and continuum simulation directed toward chemicals and materials has reached an incredible degree of sophistication and maturity. Currently, one can witness an increasingly rapid emergence of advances in computing, artificial intelligence, and robotics. This drives us to consider the future of computer simulation of matter from the molecular to the human length and time scales in a radical way that deliberately dares to go beyond the foreseeable next steps in any given discipline. This perspective article presents a view on this future development that we believe is likely to become a reality during our lifetime. | Alan Aspuru-Guzik; Roland Lindh; Markus Reiher | Computational Chemistry and Modeling; Theory - Computational | CC BY 4.0 | CHEMRXIV | 2017-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d4f337d6c997be2610d/original/the-matter-simulation-r-evolution.pdf |
60c74b8b469df4db58f43f20 | 10.26434/chemrxiv.12349694.v1 | Dual Catalytic Enantioselective Desymmetrization of Allene-Tethered Cyclohexanones | <p>The
construction of enantioenriched azabicyclo[3.3.1]nonan-6-one heterocycles via
an enantioselective desymmetrization of allene-linked cyclohexanones, enabled
through a dual catalytic system, that provides synchronous activation of the
cyclohexanone with a chiral prolinamide and the allene with a copper(I) co-catalyst
to deliver the stereodefined bicyclic core, is described. Successful application
to oxygen analogues was also achieved, thereby providing a new enantioselective
synthetic entry to architecturally complex bicyclic ethereal frameworks. The
mechanistic pathway and the origin of enantio- and diastereoselectivities has
been uncovered using density functional theory (DFT) calculations.</p> | Lin Zhang; Ken Yamazaki; Jamie Leitch; Ruben Manzano; Victoria Atkinson; Trevor Hamlin; Darren J. Dixon | Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74b8b469df4db58f43f20/original/dual-catalytic-enantioselective-desymmetrization-of-allene-tethered-cyclohexanones.pdf |
65731dc329a13c4d47f9f28d | 10.26434/chemrxiv-2023-18qkh | Single-particle photoluminescence measures a heterogenous distribution of differential circular absorbance of gold nanoparticle aggregates near constricted thioflavin T molecules | The chirality of biomacromolecules is critical for their function, but the optical signal of this chirality is small in the visible range. Plasmonic nanoparticles are antennas that can couple to this chiral signal. Here, we examine the molecular-scale mechanism behind the induced circular dichroism of gold nanorods (AuNRs) in a solution with insulin fibrils and the fibril-intercalating dye thioflavin T (ThT) with polarization-resolved single-molecule fluorescence and single-particle photoluminescence (PL) imaging. We compared the PL upon excitation by left- and right-handed circularly polarized light to calculate the differential absorbance of AuNRs near insulin fibrils with and without ThT. Overall, our results indicate that AuNRs do not act as chiral absorbers near constricted ThT molecules. Instead, we hypothesize that fibrils promote AuNR aggregation, and this templating is mediated by subtle changes in the solution conditions; under the right conditions, a few significantly chiral aggregates contribute to a large net circular dichroism. | Saaj Chattopadhyay; Maciej Lipok; Zechariah Pfaffenberger; Joanna Olesiak-Bańska; Julie Biteen | Physical Chemistry; Analytical Chemistry; Nanoscience; Microscopy; Plasmonic and Photonic Structures and Devices; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-12-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65731dc329a13c4d47f9f28d/original/single-particle-photoluminescence-measures-a-heterogenous-distribution-of-differential-circular-absorbance-of-gold-nanoparticle-aggregates-near-constricted-thioflavin-t-molecules.pdf |
64b7ef3cae3d1a7b0dfdff7c | 10.26434/chemrxiv-2023-1644z-v2 | Leveraging Bismuth Immiscibility to Create Highly Concave Noble Metal Nanoparticles | The nanoscale integration of metals with differences in structure and electronics, while important for manipulating surface adsorption, does not typically yield structures with well-defined morphologies in colloidal synthesis. To create structures with unusually undercoordinated surfaces, we leverage the immiscibility of face-centered cubic noble metals with rhombohedral Bi to synthesize well-defined nanostructures with controllable concavity. With Au, three distinct morphologies can be achieved: concave tetrahedra, stella octangula (dual tetrahedron), and concave stella octangula. With Pd, we synthesize concave tetrahedra. Structural and compositional analysis shows that only ~ 6 x10 -6 moles of surface Bi are needed to realize these morphologies. Electrocatalytic experiments and simulations reveal that the concave Au architectures are highly active toward alcohol oxidation compared to non-Bi-directed concave nanoparticles and that surface Bi is critical for adsorption. This integration of immiscible elements provides a powerful strategy for creating highly active nanoparticles with precision. | Melissa King; Yuting Xu; Noah Mason; Porvajja Nagarajan; Fanglin Che; Michael Ross | Inorganic Chemistry; Nanoscience; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Plasmonic and Photonic Structures and Devices; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b7ef3cae3d1a7b0dfdff7c/original/leveraging-bismuth-immiscibility-to-create-highly-concave-noble-metal-nanoparticles.pdf |
672bbc04f9980725cf56ad4c | 10.26434/chemrxiv-2024-p6qn3 | Chalcogen Vacancies as Key Drivers of Distinct Physicochemistry in MoS2, MoSe2, and MoTe2 Transition-Metal Dichalcogenide Monolayers | The physicochemical properties of Mo-bearing transition-metal dichalcogenide (TMD) monolayers are critical to their catalytic potential. However, these properties are generally viewed as similar across monolayers, which limits their versatility and potential for synergy in processes such as the reduction reactions of carbon dioxide (CRR), nitrogen (NRR), and oxygen (ORR). This work investigates the role of chalcogen vacancies in modulating the physicochemistry of MoS2, MoSe2, and MoTe2 through density-functional-theory (DFT) computations, focusing on the adsorption of CO, NO, and NO2. Our findings reveal that chalcogen vacancies not only enhance surface reactivity but also impart unique physicochemical characteristics to each material. These effects stem from intrinsic bonding differences within each TMD, resulting in distinct charge availability around exposed Mo atoms and variations in vacancy size, which shape specific surface interactions. Chalcogen vacancies play a more significant role in defining the unique properties of MoS2, MoSe2, and MoTe2 than the chalcogen atoms themselves. While interaction energy differences between pristine monolayers are minimal (under 0.1 eV), vacancies amplify them to over 1 eV, representing an order-of-magnitude increase. Additionally, varying vacancy sizes among the monolayers influence how species incorporate into vacancies and interact with Mo atoms, further enhancing the differences. This variability unlocks substantial potential of TMD sheets for distinct surface chemistries, transforming them from relatively similar to markedly different as defect density rises. Consequently, our findings underscore the potential of Mo-bearing TMDs to achieve unique catalytic performance through defect engineering, providing valuable insights for tailoring these materials toward specialized applications in photocatalysis and electrocatalysis. | Emilia Piosik; Maciej J. Szary | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Theory - Computational; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2024-11-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672bbc04f9980725cf56ad4c/original/chalcogen-vacancies-as-key-drivers-of-distinct-physicochemistry-in-mo-s2-mo-se2-and-mo-te2-transition-metal-dichalcogenide-monolayers.pdf |
648f7867e64f843f41fafe6e | 10.26434/chemrxiv-2023-pc33q | In situ Hyperpolarization Enables Benchtop NMR of Heteronuclei at Natural Isotopic Abundance | Without employing isotopic labeling, we demonstrate generation of 15N and 13C NMR signals for molecules containing -NH2 motifs using benchtop NMR spectrometers (1-1.4 T). Specifically, high-SNR detection of ammonia, 4-aminopyridine, benzylamine, and phenethylamine dissolved in methanol or dichloromethane, is demonstrated after only 10 seconds of parahydrogen bubbling using signal amplification by reversible exchange (SABRE) and applying a pulse sequence based on spin-lock induced crossing (SLIC). Optimization of the sequence parameters allowed achieving up to 12 % 15N and 0.4 % 13C polarization in situ without need for the sample transfer typically employed in other hyperpolarization methods. The provided methodology can find applications for detecting mM concentrated solution-state chemicals in various samples relevant to industry and research. | Raphael Kircher; Jingyan Xu; Danila Barskiy | Physical Chemistry; Analytical Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-06-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/648f7867e64f843f41fafe6e/original/in-situ-hyperpolarization-enables-benchtop-nmr-of-heteronuclei-at-natural-isotopic-abundance.pdf |
60c74844842e65ed3adb2b5f | 10.26434/chemrxiv.11872245.v1 | Illuminating the Impact of Nanoparticle Size and Surface Chemistry on Interfacial Position | In
this manuscript we begin by preparing bulk Pickering emulsions of water:octanol
at varying aqueous pH values, using ionizable carboxyl polystyrene
nanoparticles of 320 nm and 810 nm diameter. Remarkably we observe two emulsion
phase inversions, one resulting from an increase in pH and a second due to an
increase in particle size. To illuminate the mechanism of the macroscopic phase
inversion, we turn to the super resolution microscopy technique <i>interface Point Accumulation for Imaging and
Nanoscale Topography</i> (iPAINT) to measure in-situ the contact angles of
single carboxyl polystyrene particles at the water:octanol interface. Importantly,
we identify a significant decrease in contact angle over the increase of pH and
particle diameter, respectively. Additionally, the non-negligible dependence of
contact angle on particle size was shown to hold regardless of particle surface
chemistry. | Emma Giakoumatos; Antonio Aloi; Ilja Voets | Nanostructured Materials - Materials; Microscopy; Interfaces | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74844842e65ed3adb2b5f/original/illuminating-the-impact-of-nanoparticle-size-and-surface-chemistry-on-interfacial-position.pdf |
60c73d8d0f50db61393954b5 | 10.26434/chemrxiv.5845635.v1 | CO2 and Water Activation on Ceria Nanocluster Modified TiO2 Rutile (110) | Surface modification of TiO<sub>2</sub> with metal oxide nanoclusters is
a strategy for the development of new photocatalyst materials. We have studied modification
of the (110) surface of rutile TiO<sub>2</sub> with ceria nanoclusters using
density functional theory corrected for on-site Coulomb interactions (DFT+U).
We focus on the impact of surface modification on key properties governing the
performance of photocatalysts, including light absorption, photoexcited charge
carrier separation, reducibility and surface reactivity. Our results show that
adsorption of the CeO<sub>2</sub> nanoclusters, with compositions Ce<sub>5</sub>O<sub>10</sub>
and Ce<sub>6</sub>O<sub>12</sub>, is favourable at the rutile (110) surface and
that the nanocluster-surface composites favour non-stoichiometry in the
adsorbed ceria so that reduced Ce ions will be present in the ground state. The
presence of reduced Ce ions and low coordinated O sites in the nanocluster lead
to the emergence of energy states in the energy gap of the TiO<sub>2</sub>
host, which potentially enhance the visible light response. We show, through an
examination of oxygen vacancy formation, that the composite systems are
reducible with moderate energy costs. Photoexcited electrons and holes localize
on Ce and O sites of the supported nanoclusters. The interaction of CO<sub>2</sub>
and H<sub>2</sub>O is favourable at multiple sites of the reduced CeO<sub>x</sub>-TiO<sub>2</sub>
composite surfaces. CO<sub>2</sub> adsorbs and activates, while H<sub>2</sub>O
spontaneously dissociates at oxygen vacancy sites. | Michael Nolan; Stephen Rhatigan | Nanocatalysis - Catalysts & Materials; Computational Chemistry and Modeling; Clusters; Photochemistry (Physical Chem.); Surface | CC BY NC ND 4.0 | CHEMRXIV | 2018-02-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d8d0f50db61393954b5/original/co2-and-water-activation-on-ceria-nanocluster-modified-ti-o2-rutile-110.pdf |
63359d230e3c6a9d412d0869 | 10.26434/chemrxiv-2022-r3v13 | The conformational behavior and structure of monosubstituted 1,3,5-trisilacyclohexanes. Part III: 1-Methyl-1,3,5-trisilacyclohexane | 1-Methyl-1,3,5-trisilacyclohexane was synthesized and its structure and conformational properties have been determined by gas electron diffraction (GED) and quantum chemical (QC) calculations. The molecule may exist in two forms differing from each other by the substituents' position. QC results shows that the equatorial conformer is predicted to be slightly more stable than the axial conformer, note that one method (M06-2X) with basis set 6-311G** shows an equal amount of Ax and Eq conformers: ratio (Ax/Eq) = (30-50) : (70-50)% (depending on method and basis set). From the GED data, the molar fractions of the conformers were found to be Ax:Eq=54(10):46(10) at 280(5) K. A temperature-dependent Raman experiment resulted in an Ax:Eq ratio of 58(4):42(4). Conformational properties are compared in series of analogous 1-X-1- (hetero)cyclohexanes. | Liubov Kuzmina; Ingvar Arnason; Nanna Jonsdottir; Sergey Shlykov | Physical Chemistry; Organic Chemistry; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63359d230e3c6a9d412d0869/original/the-conformational-behavior-and-structure-of-monosubstituted-1-3-5-trisilacyclohexanes-part-iii-1-methyl-1-3-5-trisilacyclohexane.pdf |
60c74224bdbb8951cea3843b | 10.26434/chemrxiv.8216714.v1 | Optical Control of Small Molecule-Induced Protein Degradation | <p>As an emerging approach to protein perturbation, small molecule-induced protein degradation has gained significant attention as both a chemical tool and a potential therapeutic. To enable discreet spatiotemporal control over its activity, we have developed a broadly applicable approach for the optical control of small molecule-induced protein degradation. Installation of photolabile caging groups onto ligands recruiting Von Hippel-Lindau (VHL) and cereblon (CRBN) E3 ubiquitin ligases enabled optical control over protein degradation. </p> | Yuta Naro; Kristie Darrah; Alexander Deiters | Biochemistry; Chemical Biology; Ligand Design | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74224bdbb8951cea3843b/original/optical-control-of-small-molecule-induced-protein-degradation.pdf |
60c74bf8567dfe3818ec5078 | 10.26434/chemrxiv.12407831.v1 | Multi-fidelity Statistical Machine Learning for Molecular Crystal Structure Prediction | The prediction of crystal structures from first principles requires highly accurate energies for large numbers of putative crystal structures. The accuracy of solid state density functional theory (DFT) calculations is often required, but hundreds or more structures can be present in the low energy region of interest, so that the associated computational costs are prohibitive. Here, we apply statistical machine learning to predict expensive hybrid functional DFT (PBE0) calculations using a multi-fidelity approach to re-evalute the energies of crystal structures predicted with an inexpensive force field. The method uses an autoregressive Gaussian process, making use of less expensive GGA DFT (PBE) calculations to bridge the gap between the force field and PBE0 energies. The method is benchmarked on the crystal structure landscapes of three small, hydrogen bonding organic molecules and shown to produce accurate predictions of energies and crystal structure ranking using small numbers of the most expensive calculations; the PBE0 energies can be predicted with errors of less than 1 kJ/mol with between 4.2-6.8% of the cost of the full calculations. As the model that we have developed is probabilistic, we discuss how the uncertainties in predicted energies impact on assessment of the energetic ranking of crystal structures. | Olga Egorova; Roohollah Hafizi; David C. Woods; Graeme Day | Computational Chemistry and Modeling; Machine Learning; Quantum Mechanics; Self-Assembly; Structure; Crystallography | CC BY 4.0 | CHEMRXIV | 2020-06-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74bf8567dfe3818ec5078/original/multi-fidelity-statistical-machine-learning-for-molecular-crystal-structure-prediction.pdf |
626a8922ef2ade5212406d11 | 10.26434/chemrxiv-2021-r2q6z-v2 | SARS-Cov-2 Delta Variant Decreases Nanobody Binding and ACE2 Blocking Effectivity | The Delta variant spreads more rapidly than previous variants of SARS-CoV-2. This variant comprises several mutations on the receptor-binding domain (RBD_Delta) of its spike (S) glycoprotein, which binds to the peptidase domain (PD) of angiotensin-converting enzyme 2 (ACE2) receptors in host cells. The RBD-PD interaction has been targeted by antibodies and nanobodies to prevent viral infection, but their effectiveness against the Delta variant remains unclear. Here, we investigated RBD_Delta-PD interactions in the presence and absence of nanobodies H11-H4, H11-D4, and Ty1 by performing 21.8 µs of all-atom molecular dynamics (MD) simulations. Unbiased simulations revealed that Delta variant mutations strengthen RBD binding to ACE2 by increasing the hydrophobic interactions and salt bridge formation, but weaken interactions with H11-H4, H11-D4, and Ty1. Among these nanobodies H11-H4 and H11-D4 bind RBD without overlapping ACE2. They were unable to dislocate ACE2 from RBD_Delta when bound side by side with ACE2 on RBD. Steered MD simulations at comparable loading rates to atomic force microscopy (AFM) experiments estimated lower rupture forces of the nanobodies from RBD_Delta compared to ACE2. Our results suggest that existing nanobodies are less effective to inhibit RBD_Delta-PD interactions and a new generation of nanobodies will be needed to neutralize the Delta variant. | Mert Golcuk; Aysima Hacisuleyman; Sema Zeynep Yilmaz; Elhan Taka; Ahmet Yildiz; Mert Gur | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626a8922ef2ade5212406d11/original/sars-cov-2-delta-variant-decreases-nanobody-binding-and-ace2-blocking-effectivity.pdf |
60c74807ee301c177bc797ed | 10.26434/chemrxiv.11840025.v1 | Task-Specific Ionic Liquid Enables Highly Efficient Low Temperature Desalination by Directional Solvent Extraction | Seawater desalination plays a
critical role in addressing the global water shortage challenge, and
directional solvent extraction (DSE) is an emerging desalination technology to
address this challenge. Herein, we demonstrate that through a combination of
target-directed synthesis and computational simulations, task-specific ionic
liquids (ILs) may significantly advance current DSE technology by improving the
energy efficiency toward impacting the global water-energy nexus. | Jiaji Guo; Zachary D. Tucker; Yu Wang; Brandon L. Ashfeld; Tengfei Luo | Environmental Science; Water Purification | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74807ee301c177bc797ed/original/task-specific-ionic-liquid-enables-highly-efficient-low-temperature-desalination-by-directional-solvent-extraction.pdf |
62a0e74f70f8a76efdfbd265 | 10.26434/chemrxiv-2022-vc84b | A high-throughput assay for identifying diverse antagonists of the binding interaction between the ACE2 receptor and the dynamic spike proteins of SARS-CoV-2 | SARS-CoV-2, a coronavirus strain that started a worldwide pandemic in early 2020, attaches to human cells by binding its spike (S) glycoprotein to a host receptor protein angiotensin-converting enzyme 2 (ACE2). Blocking the interaction between the S protein and ACE2 has emerged as an important strategy for preventing viral infection. We systematically developed and optimized an AlphaLISA assay to investigate binding events between ACE2 and the ectodomain of the SARS-CoV-2 S protein (S-614G: residues 1–1208 with a D614G mutation). Using S-614G permits discovering potential allosteric inhibitors that stabilize the S protein in a conformation that impedes its access to ACE2. Over 30,000 small molecules were screened in a high-throughput format for activity against S-614G and ACE2 binding using the AlphaLISA assay. A viral entry assay was used to validate hits using lentiviral particles pseudotyped with the full-length S protein of the Wuhan-1 strain. Two compounds identified in the screen, oleic acid and suramin, blocked the attachment of S-614G to ACE2 and S protein-driven cell entry into Calu-3 and ACE2-overexpressing HEK293T cells. Oleic acid inhibits S-614G binding to ACE2 far more potently than to the receptor-binding domain (RBD, residues 319–541 of SARS-CoV-2 S), potentially indicating a non-competitive mechanism. The results indicate that using the full-length ectodomain of the S protein can be important for identifying allosteric inhibitors of ACE2 binding. The approach reported here represents a rapidly adaptable format for discovering receptor binding inhibitors to S-proteins of future coronavirus strains. | Rachel Sammons; Amanda Bohanon; Anvinth Kowtha; Audrey Dejong; Eun Cho; Tamer Kaoud; Kevin Dalby | Biological and Medicinal Chemistry; Biochemistry; Cell and Molecular Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62a0e74f70f8a76efdfbd265/original/a-high-throughput-assay-for-identifying-diverse-antagonists-of-the-binding-interaction-between-the-ace2-receptor-and-the-dynamic-spike-proteins-of-sars-co-v-2.pdf |
60c740ad0f50db33ab3959be | 10.26434/chemrxiv.7824089.v1 | Hybrid Charge-Transfer Semiconductors: (C7H7)SbI4, (C7H7)BiI4, and Their Halide Congeners | <p>The
family of hybrid metal-halide semiconductors (C<sub>7</sub>H<sub>7</sub>)MX<sub>4</sub>
(M = Bi<sup>3+</sup>, Sb<sup>3+</sup>; X = Cl<sup>–</sup>, Br<sup>–</sup>, I<sup>–</sup>)
was synthesized. The optical and electronic properties of the new compounds
were elucidated, revealing electronic band gaps that span the visible region. The
tropylium cations stack into columns separated by chains of edge-sharing M-X
octahedra to yield a low dimensional crystal structure with electron and hole
charge carriers confined to the organic and inorganic components, respectively.</p> | Iain Oswald; Eve M. Mozur; Ian P. Moseley; Hyochul Ahn; James R. Neilson | Hybrid Organic-Inorganic Materials; Solid State Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740ad0f50db33ab3959be/original/hybrid-charge-transfer-semiconductors-c7h7-sb-i4-c7h7-bi-i4-and-their-halide-congeners.pdf |
60c751399abda24d44f8db9f | 10.26434/chemrxiv.13135811.v1 | A Chemical Map of NaSiCON Electrode Materials for Sodium-ion Batteries | <div><div><div><p>Na-ion batteries are promising devices for smart grids and electric vehicles due to cost effectiveness arising from the overall abundance of sodium (Na) and its even geographical distribution. Among other factors, the energy density of Na-ion batteries is limited by the positive electrode chemistry. NaSICON-based positive electrode materials are known for their wide range of electrochemical potentials,[1],[2],[3] high ionic conductivity, and most importantly their structural and thermal stabilities. Using first- principles calculations, we chart the chemical space of 3<i>d</i> transition metal-based NaSICON phosphates of formula Na<sub>x</sub>MM’(PO<sub>4</sub>)<sub>3</sub> (with M and M’= Ti, V, Cr, Mn, Fe, Co and Ni), to analyze their thermodynamic stabilities and the intercalation voltages for Na+ ions. Specifically, we computed the Na insertion voltages and related properties of 28 distinct NaSICON compositions. We investigated the thermodynamic stability of Na-intercalation in previously unreported NaxMn<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> and Na<sub>x</sub>VCo(PO<sub>4</sub>)<sub>3</sub>. The calculated quaternary phase diagrams of the Na-P-O-Co and Na-P-O-Ni chemical systems explain the origin of the suspected instability of Ni and Co-based NaSICON compositions. From our analysis, we are also able to rationalize anomalies in previously reported experimental data in this diverse and important chemical space.</p></div></div></div> | Baltej Singh Gill; Ziliang Wang; Sunkyu Park; Gopalakrishnan Sai Gautam; Jean-Nöel Chotard; Laurence Croguennec; Dany Carlier; Anthony K. Cheetham; Christian Masquelier; Pieremanuele Canepa | Computational Chemistry and Modeling; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c751399abda24d44f8db9f/original/a-chemical-map-of-na-si-con-electrode-materials-for-sodium-ion-batteries.pdf |
6690299701103d79c5bcbde0 | 10.26434/chemrxiv-2024-7lggj | Uncertainty Quantification in Machine Learning for Glass Transition Temperature Prediction of Polymers | Machine learning (ML) has become an important technique in materials science, markedly accelerating the discovery and design of novel materials, and concurrently lowering the burden of experimental costs. Uncertainty quantification (UQ) plays a pivotal role in the accurate prediction and innovative design of novel materials through ML techniques. In this study, we perform a comprehensive evaluation of six UQ methods in ML, including ensemble, Gaussian process regression (GPR), Monte Carlo dropout (MCD), Mean-variance estimation (MVE), Bayesian neural network (BNN) and Evidential deep learning (EDL), for predictions on the glass transition temperature (T_g) of polymers. We assess the accuracy and performance of these UQ methods using three metrics, including Spearman’s rank correlation coefficient, calibration and sparsification, offering a substantial reference for data-driven polymer design. Our analysis encompasses test data, out-of-distribution data from experiments and molecular dynamics simulations, and high-T_g polymer data for UQ analysis of ML predictions. The results indicate that ML models are robust and effective in predicting polymer’s T_g values for testing and experimental data. However, correlating actual errors with uncertainties (standard deviations) poses a significant challenge, with ML models frequently exhibiting overconfidence with low uncertainties. Moreover, the accuracy of ML predictions improves when the data with large uncertainties are excluded, suggesting a potential strategy for refining ML model’s performance. | Hao Tang; Tianle Yue; Ying Li | Polymer Science | CC BY 4.0 | CHEMRXIV | 2024-07-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6690299701103d79c5bcbde0/original/uncertainty-quantification-in-machine-learning-for-glass-transition-temperature-prediction-of-polymers.pdf |
6624e94921291e5d1d4de618 | 10.26434/chemrxiv-2024-6f898 | Directionality Reversal and Shift of Rotational Axis in a Hemithioindigo Macrocyclic Molecular Motor | Molecular motors are central driving units for nanomachinery and control of their directional motions is of fundamental importance for their functions. Light-driven variants use an easy to provide, easy to dose, and waste free fuel with high energy content, which makes them particularly interesting for many applications. Typically, light-driven molecular motors work via rotations around dedicated chemical bonds (e.g. double bonds) where directionality of the rotation is dictated by the steric effects of asymmetry in close vicinity to the rotation axis. In this work we show how unidirectional rotation around a virtual axis can be realized by reprogramming a molecular motor. To this end, a classical light-driven motor is restricted by macrocyclization and its intrinsic directional rotation is transformed into a directional rotation of the macrocyclic chain in the opposite direction. Further, solvent polarity changes allow to toggle the function of this molecular machine between a directional motor and a non-directional photoswitch. In this way a new concept for the design of molecular motors is delivered together with an elaborate control over their motions and functions by simple solvent changes. The possibility of sensing the environmental polarity and correspondingly adjusting directionality of motions opens up a next level of control and responsiveness to light-driven nanoscopic motors. | Lilli Reißenweber; Edgar Uhl; Frank Hampel; Peter Mayer; Henry Dube | Physical Chemistry; Organic Chemistry; Nanoscience; Stereochemistry; Nanodevices; Photochemistry (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2024-04-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6624e94921291e5d1d4de618/original/directionality-reversal-and-shift-of-rotational-axis-in-a-hemithioindigo-macrocyclic-molecular-motor.pdf |
622b1fc453225f52c13da9f3 | 10.26434/chemrxiv-2022-9jqdm | Organosuperbase Catalyzed 1,1-Diboration of Alkynes | 1,1-diboryl alkenes are versatile building blocks in organic synthesis and medicinal chemistry. There have been only a small number of established methods to prepare this class of compounds and most of them used transition metal catalysts, which are undesirable in the preparation of bioactive compounds. Herein, we report an unprecedented application of P1-tBu as an organocatalyst to promote 1,1-diboration reactions of unactivated aromatic as well as electron-deficient terminal alkynes. The strong basicity of this phosphazene enables the activation of reaction substrates while its steric bulk allows for high regio- and stereo-selectivity to be obtained. A combination of experimental and computational studies suggests interesting mechanistic insights for these phosphazene-catalyzed diboration reaction, which are also discussed in detail. | Son Hoai Doan; Nhan Nu Hong Ton; Binh Khanh Mai; Thanh Vinh Nguyen | Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/622b1fc453225f52c13da9f3/original/organosuperbase-catalyzed-1-1-diboration-of-alkynes.pdf |
60c7546f469df46a7cf44f49 | 10.26434/chemrxiv.13662185.v1 | Microwave-Assisted Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones Using Acid-Functionalized Mesoporous Polymer | Synthesis and application of acid-functionalized mesoporous polymer catalyst for the synthesis of
3,4-Dihydropyrimidin-2(1H)-ones via Biginelli condensation reaction under microwave
irradiation is investigated. Several analytical techniques such as FT-IR, BET, TEM, SEM and EDX
were employed to characterize the synthesized polymeric catalyst. High acidity (1.15 mmol g-1
),
high surface area (90.44 m2
g
-1
) and mesoporous nature of the catalyst effectively promoted the
synthesis of 3,4-Dihydropyrimidin-2(1H)-ones. Microwave irradiation shows higher yield (89-98
%) as compared to conventional heating (15-25 % yield) under our optimized reaction conditions
such as 1:1:1.2 molar ratio of aldehyde/ethylacetoacetate/urea, catalyst loading of 6 wt.% (with
respect to aldehyde), the temperature of 80 °C and microwave power of 50 W. The synthesized
Biginelli products were fully characterized by 1H and 13C NMR. The reusability of the catalyst
was investigated up to 5 successive cycles and it showed great stability towards the synthesis of
3,4-Dihydropyrimidin-2(1H)-ones without any significant depreciation in yields. | Bishwajit Changmai; Kalyani Rajkumari; diparjun das; Samuel Lalthazuala Rokhum | Acid Catalysis; Heterogeneous Catalysis; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7546f469df46a7cf44f49/original/microwave-assisted-synthesis-of-3-4-dihydropyrimidin-2-1h-ones-using-acid-functionalized-mesoporous-polymer.pdf |
66f6f3dbcec5d6c1426eb8f1 | 10.26434/chemrxiv-2024-3g6b9 | Correlating Negative Thermal Expansion and Thermal Conductivity in Two-dimensional Carbon-based Materials | Negative thermal expansion (NTE) is a fascinating phenomenon where certain materials contract upon heating. The phonon transport properties of two-dimensional carbon-based allotropes are poorly understood in terms of their NTE properties. This work with a specific focus on carbon-based allotropes, explores the underlying mechanisms of the thermal conductivity (TC) and NTE of graphene, haeckelite, pentahexoctite, s-graphene, 6.6.12 and delta Graphynes (Gys). High TC is imperative for efficiently dissipating heat in electronic devices, whereas thermoelectric devices need to be thermally resistive with low TC. Delta-Gy shows highest NTE as well as lowest TC and vice versa is true for graphene. Graphene displays a lower degree of anisotropic TC, while s-graphene exhibits the highest level of anisotropic TC. The behaviour of their TC are understood on the basis of soft-phonon modes, phonon group velocity (vg), phonon lifetime (τ) and mean free path (MFP). The acoustic and optical phonon branches play a key role in determining both TC and NTE of the materials. Out-of-plane buckling of a two-dimensional materials can suppress heat conductivity by increasing the phonon scattering. Buckling is also shown to increase the NTE. A precise control on the pore sizes 5-7 (Haeckelite), 5-6-8 (Pentahexoctite), and 4-8 (s-graphene), 6-12-14 (6.6.12-Gy) and 6-14 (delta-Gy) can make a big impact on their soft unit modes. This investigation not only deepens our understanding of NTE and TC but also highlights the potential of future applications of carbon-based materials with controlled thermal expansion properties in nanotechnology, composites, and beyond. | Soumya Mondal; Ayan Datta | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f6f3dbcec5d6c1426eb8f1/original/correlating-negative-thermal-expansion-and-thermal-conductivity-in-two-dimensional-carbon-based-materials.pdf |
677d4ae16dde43c9089f4179 | 10.26434/chemrxiv-2025-47rf0 | Modulating Surface Redox Reactions and Solvated Electron Emission on Boron-Doped Diamond by (Photo)Electrochemistry | The interplay between photo- and electrochemical reactions fundamentally influences charge transfer processes at solid-liquid interfaces. Nevertheless, chemical processes at semiconductor surfaces triggered by light excitation under applied potential remain poorly explored. This work deciphers the synergistic role of potential and light excitation on boron-doped diamond electrodes in producing either surface redox reactions or emission of solvated electrons in water. The role of diamond surface termination on electron affinity, band bending, and charge extraction is identified in a photoelectrochemical cell. While photocurrent is observed for excitation as low as 3.5 eV, we show that it is mostly induced by surface redox reactions, whereas solvated electrons are detected only for excitation above the bandgap (5.47 eV). Solvated electrons are generated irrespective of band bending, which only affects the emission yield. Depending on the surface band bending, photoreduction of the hydroxylated surface groups and photooxidation of the -H surface groups can be induced by direct photoexcitation in the range of 4.2-4.8 eV. The surface of the diamond can be electrochemically reduced when the Fermi level of the oxidized surface decreases below the H⁺/H₂ redox potential. On the other hand, the hydrogenated surface oxidizes spontaneously for potentials at which the Fermi level drops below the occupied CH surface states, depending on both the pH and electron affinity of the surface. This work provides fundamentally new insights into (photo)redox processes on diamond materials, which may find applications in photoelectrochemical solar fuel generation or energy storage. | Arsène Chemin; Louis Godeffroy; Marin Rusu; Michael Drisch; Maik Finze; Peter Knittel; Anke Krueger; Tristan Petit | Materials Science; Catalysis; Energy; Carbon-based Materials; Electrocatalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677d4ae16dde43c9089f4179/original/modulating-surface-redox-reactions-and-solvated-electron-emission-on-boron-doped-diamond-by-photo-electrochemistry.pdf |
626bd792d048edf14c558264 | 10.26434/chemrxiv-2022-2pmzq | C-H functionalization of heterocycles with triplet carbenes via an unexpected 1,2-alkyl radical migration | The C-H functionalization of indole heterocycles constitutes a key strategy to leverage the synthesis of endogenous signaling molecules such as tryptamine or tryptophol. Herein, we report on the photocatalytic reaction of ethyl diazoacetate with indole, which shows an unusual solvent dependency. While C2-functionalization occurs under protic conditions, the use of aprotic solvents leads to a complete reversal of selectivity and exclusive C3-functionalization occurs. To rationalize for this unexpected reactivity switch, we have conducted detailed theoretical and experimental studies, which suggest the participation of a triplet carbene intermediate that undergoes initial C2-functionalization. A distinct cationic [1,2]-alkyl radical migration then leads to formation of C3-functionalized indole. We conclude with the application of this photocatalytic reaction to access oxidized tryptophol derivatives including gram-scale synthesis and derivatization reactions. (46 examples, up to 93% yield). | Claire Empel; Sripati Jana; Łukasz Ciszewski; Katarzyna Zawada; Chao Pei; Dorota Gryko; Rene M. Koenigs | Theoretical and Computational Chemistry; Organic Chemistry; Catalysis; Physical Organic Chemistry; Homogeneous Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626bd792d048edf14c558264/original/c-h-functionalization-of-heterocycles-with-triplet-carbenes-via-an-unexpected-1-2-alkyl-radical-migration.pdf |
60c7570d702a9b701f18c9f0 | 10.26434/chemrxiv.14365583.v1 | Water as Hydrogen Source for Highly Efficient Conversion of Biomass-Derived Levulinic Acid into γ-Valerolactone over Raney Ni Catalyst | <p>Gamma
(γ)-valerolactone (GVL) is a promising liquid for energy and carbon-based
chemicals. Although many researches regarding the GVL synthesis from
carbohydrate biomass, most of them involve the use of noble metals accompanying
with the high-purity and high-pressure gaseous hydrogen, existing high cost in
large-scale application and safety risk during the transportation and operation
process. In this paper, the cheap metal Fe was employed as a reductant for
splitting water to produce hydrogen under mild hydrothermal conditions, and commercial
Raney Ni was used as a catalyst for in
situ hydrogenation of biomass-derived levulinic acid (LA). More than 95% yield of GVL can
be attained at 150 <sup>o</sup>C for 2 h and ~ 90% yield of GVL was also
achieved at 100 <sup>o</sup>C by increasing the reaction time to 5 h.
Furthermore, Raney Ni remains the stable catalytic activity after being
recycled for 4 times at 150 <sup>o</sup>C. This work provides a safe and facile
process for highly efficient hydrogenation of biomass-derived LA to GVL without
precious metals.</p> | Zhuang Ma; Binbin Jin; Yalin Guo; Xuejun Li; Guodong Yao; Yangyuan Zhou | Environmental Science; Wastes | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7570d702a9b701f18c9f0/original/water-as-hydrogen-source-for-highly-efficient-conversion-of-biomass-derived-levulinic-acid-into-valerolactone-over-raney-ni-catalyst.pdf |
62e3abbcadb01e6a66b12afe | 10.26434/chemrxiv-2022-fdkv1 | Degradable Glycopolyester-Like Nanoparticles by Radical Ring-Opening Polymerization | A small library of degradable polyester-like glycopolymers was successfully prepared by the combination of radical ring-opening copolymerization (rROP) of 2-methylene-1,3-dioxepane (MDO) with vinyl ether (VE) derivatives, and a Pd-catalyzed thioglycoconjugation. The resulting thioglycopolymers were formulated into self-stabilized thioglyconanoparticles which were stable up to 4 months and were enzymatically degraded. Nanoparticles and their degradation products exhibited a good cytocompatibility on two healthy cell lines. Interactions between thioglyconanoparticles and lectins were investigated and highlighted the presence of both specific carbohydrate/lectin interactions and non-specific hydrophobic interactions. Fluorescent thioglyconanoparticles were also prepared either by encapsulation of Nile Red, or by the functionalization of the polymer backbone with Rhodamine B. Such nanoparticles were used to prove the cell internalization of the thioglyconanoparticles by lung adenocarcinoma (A549) cells which underlined the great potential of P(CKA-co-VE) copolymers for biomedical applications | Théo Pesenti; Daniel Domingo-Lopez; Emilie Gillon; Nada Ibrahim; Samir Messaoudi; Anne Imberty; Julien Nicolas | Polymer Science; Drug delivery systems | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62e3abbcadb01e6a66b12afe/original/degradable-glycopolyester-like-nanoparticles-by-radical-ring-opening-polymerization.pdf |
6179a55a45f1ee6b4e4001fb | 10.26434/chemrxiv-2021-kszpg | Competitive Gold/Nickel Transmetalation | Transmetalation is a key method for the construction of element-element bonds. Here, we disclose the reactivity of [NiII(Ar)(I)(diphosphine)] compounds with arylgold(I) transmetalating agents, which is directly relevant to cross-coupling catalysis. Both aryl-for-iodide and unexpected aryl-for-aryl transmetalation are witnessed. Despite the strong driving force expected for Au-I bond formation, aryl scrambling can occur during transmetalation and may complicate the outcomes of attempted catalytic cross-coupling reactions. | Mitchell Demchuk; Joseph Zurakowski; Brady Austen; David Nelson; Marcus Drover | Inorganic Chemistry; Organometallic Chemistry; Bond Activation; Ligands (Organomet.); Theory - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6179a55a45f1ee6b4e4001fb/original/competitive-gold-nickel-transmetalation.pdf |
60c75338bb8c1a03653dbfe2 | 10.26434/chemrxiv.13385186.v1 | Interfacial Electron Transfer and Ion Solvation in the Solid Electrolyte Interphase | <div><div><div><p>As a chemically and structurally well-defined model for redox processes in the solid electrolyte interphase of battery electrodes, we investigate electron transfer to lithium ions at the interface between a platinum metal anode and a solid polymer electrolyte. Studied electrolytes include LiTFSI (lithium bis(trifluoromethane)sulfonimide) salts in polyethylene oxide and poly(diethylene oxide-alt-oxymethylene), as well as in the as- sociated liquid electrolytes 1,2-dimethoxyethane and tetraglyme.</p></div></div></div> | Jeongmin Kim; Brett Savoie; Thomas Miller | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75338bb8c1a03653dbfe2/original/interfacial-electron-transfer-and-ion-solvation-in-the-solid-electrolyte-interphase.pdf |
66c34fdfa4e53c4876db99a9 | 10.26434/chemrxiv-2024-trn26 | Cu-S Planes in a Metal-Organic Framework for Selective Electrochemical Conversion of CO2 to Formate | The electrochemical reduction of CO2 into value-added chemicals is pivotal for advancing toward carbon neutrality and sustainable energy sources. However, achieving high selectivity for specific products remains challenging due to numerous potential reaction pathways. In this work, we present an innovative copper-sulfur planar structure, Cu-S-BDC, within a metal-organic framework (MOF) catalyst, which demonstrates remarkable selectivity towards formate as the sole carbon product. Notably, it achieves a 59% Faradaic efficiency (FE) for formate at -0.4 V vs. the reversible hydrogen electrode (RHE) in a 1 M KOH electrolyte. The reaction mechanism uncovers that the Cu-S catalytic sites within the MOF stabilize the HCOO* intermediate, thereby facilitating selective formate production. Additionally, we elucidate the electronic properties of the MOF, revealing a narrow band gap of 1.203 eV, which enhances the charge transfer within the quasi-2D inorganic building unit structure of the MOF and consequently increases the electrochemical reaction current density. This study highlights the potential of engineering the metal coordination environment within MOFs to enhance both product selectivity and conductivity in electrochemical CO2 reduction. | Khatereh Roohi; Mohammad Soleimani ; Nabil Khossossi; Stefano Canossa ; Ali Kosari; Seyedamirhossein Mohseni Armaki; Majid Ahmadi; Ewout van der Veer; Mahinder Ramdin; Praasanth Ravi Anusuyadevi; Prasad Gonugunta; Arjan Mol; Poulumi Dey; Peyman Taheri | Materials Science; Catalysis; Chemical Engineering and Industrial Chemistry; Electrocatalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c34fdfa4e53c4876db99a9/original/cu-s-planes-in-a-metal-organic-framework-for-selective-electrochemical-conversion-of-co2-to-formate.pdf |
67d3f83b81d2151a02582d64 | 10.26434/chemrxiv-2025-zns4w | Exploiting Supercooled Medium-Chain Lipids and Surfactant Combinations for Solid-Phase Dominant Nanostructured Lipid Carrier Production | Nanostructured lipid carriers (NLCs) are a promising delivery system for poorly water-soluble drugs, including lipophilic peptides. However, NLCs often display unpredictable drug partitioning between solid and liquid lipid phases, potentially compromising controlled release profiles. Here, we demonstrate a novel hybrid NLC approach that directs drug loading primarily to the solid phase while maintaining the structural advantages of established NLCs. Using cyclosporine A (CsA) as a model peptide, we exploited the significant solubility differential between medium-chain solid lipids (glyceryl caprylate: 338.95 ± 77.68 mg/mL; glyceryl caprate: 88.63 ± 8.80 mg/mL) and liquid lipid component (soy liquid lecithin: 1.39 ± 0.09 mg/mL) to create a natural concentration gradient favouring a solid phase loading. By strategically combining these medium-chain lipids with selective surfactants, particularly PEG-100 stearate, we enabled the controlled transformation of initially supercooled melts into organised Type I imperfect crystal structures that effectively encapsulate CsA within the solid lipid matrix. This approach allowed single-step hybrid NLC production at temperatures up to 20 °C lower than conventional methods while reducing homogenization power requirements by 38%. Our optimised formulations maintained particle size (<200nm), polydispersity (<0.3), and spherical morphology during four-week storage at 4 °C, room temperature, and 40 °C. Most notably, the controlled CsA release profiles in simulated intestinal fluid confirmed successful drug entrapment within the solid lipid matrix rather than the liquid phase. This work presents a robust strategy for producing stable, solid-phase dominant NLCs at reduced processing temperatures, with significant implications for controlled drug delivery and continuous manufacturing processes. | Daniel Sedough-Abbasian; Jiaming Mu; Jerin George Joseph; Gavin Andrews; Sheiliza Carmali | Materials Science; Nanoscience; Core-Shell Materials; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience | CC BY NC 4.0 | CHEMRXIV | 2025-03-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d3f83b81d2151a02582d64/original/exploiting-supercooled-medium-chain-lipids-and-surfactant-combinations-for-solid-phase-dominant-nanostructured-lipid-carrier-production.pdf |
67b59690fa469535b9fdb03f | 10.26434/chemrxiv-2025-f9955 | Determining Site Requirements for Reactive Species in Multi-Site Catalysis on Metal Surfaces Using Excluded Areas | Many metal-catalyzed reactions (e.g., hydrogenolysis, (de)hydrogenation, and hydro-deoxygenation) involve reactive species with molecular volumes that extend beyond the cross-sectional areas of exposed metal atoms. The kinetic behaviors of such reactions are well described by lattice-based models that account for adsorbates occupying multiple adjacent sites (i.e., exposed metal atoms). Site requirements are often inferred from the number of metal atoms an adsorbate coordinates to, which can underpredict the number of contiguous sites that are inaccessible to co-adsorbates by lateral repulsion. Here, we instead determine adsorbate site requirements from the surface areas they exclude from co-adsorbates. These areas are determined from adsorbate structures, optimized previously using density functional theory (DFT), by projecting their molecular volumes onto the surface plane (AS) or by tracing their areas with a circular probe that represents co-adsorbates (Aenc). These excluded areas agree with those inferred from the experimentally measured saturation coverages of eight polyatomic adsorbates on Pt(111) and Ni(111). They predict a number of sites needed for ethane hydrogenolysis on Ir nanoparticles (two to three exposed Ir atoms) that is consistent with previous kinetic measurements and DFT calculations. The areas further estimate site requirements for benzene hydrogenation on Pt nanoparticles (six exposed Pt atoms) that accurately describe rate dependences on benzene pressure, under physically realistic benzene and H-adatom coverages and with adsorption enthalpies consistent with experimental benchmarks. Excluded areas therefore offer a practical and accurate way to determine site requirements in multi-site kinetic models, facilitating mechanistic studies and guiding ab initio catalyst design for reactions of bulky molecules that inevitably cover multiple contiguous surface atoms. | Ari F. Fischer | Theoretical and Computational Chemistry; Physical Chemistry; Catalysis; Theory - Computational; Heterogeneous Catalysis; Chemical Kinetics | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67b59690fa469535b9fdb03f/original/determining-site-requirements-for-reactive-species-in-multi-site-catalysis-on-metal-surfaces-using-excluded-areas.pdf |
636079501db0bd0aee4173fe | 10.26434/chemrxiv-2022-mtlwb | The Formal Cross-Coupling of Amines and Carboxylic Acids to Form sp3–sp2 Carbon–Carbon Bonds | Amines and carboxylic acids are abundant building blocks for synthesis that classically are united to form an amide bond. To access new pockets of chemical space we are interested in the development of complementary amine–acid coupling reactions. In particular, the formation of carbon–carbon bonds by formal deamination and decarboxylation would be an impactful addition to the synthesis toolbox. Here we report a formal cross coupling of alkyl amines and aryl carboxylic acids to form C(sp3)–C(sp2) bonds following pre-activation of the amine–acid building blocks as a pyridinium salt and N-acyl-glutarimide respectively. Under nickel-catalyzed reductive cross-coupling conditions, a diversity of simple and complex substrates are united in good to excellent yield. High-throughput experimentation was essential to the development of the reaction, and to the discovery of performance-enhancing additives such as cyclic imides, RuCl3 and GaCl3. Preliminary mechanistic investigations suggest that RuCl3 supports the decarbonylation event, increasing reaction selectivity. Numerous amine or acid containing pharmaceuticals are successfully diversified under the optimized conditions. | James L. Douthwaite; Ruheng Zhao; Eunjae Shim; Babak Mahjour; Paul Zimmerman; TIMOTHY CERNAK | Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/636079501db0bd0aee4173fe/original/the-formal-cross-coupling-of-amines-and-carboxylic-acids-to-form-sp3-sp2-carbon-carbon-bonds.pdf |
66707cfc5101a2ffa8cb0228 | 10.26434/chemrxiv-2024-rr07j | Enabling Electrochemical C-O and C-N Arylation Libraries using Alternating Polarity in Flow | Etherification and amination of aryl halide scaffolds are commonly used reactions in parallel medicinal chemistry to rapidly scan structure-activity relationships with abundant building blocks. Electrochemical methods for aryl etherification and amination demonstrate broad functional group tolerance and extended nucleophile scope compared to traditional methods. Nevertheless, there is a need for robust and scale-transferable workflows for electrochemical library synthesis. Herein we describe a platform for automated electrochemical synthesis of C-X arylation (X = NH, OH) libraries in flow. A comprehensive DOE identifies an optimal protocol which generates high yields across > 30 aryl halide scaffolds, diverse amines (including electron-deficient sulfonamides, sulfoximines, amides, and anilines) and alcohols (including serine residues within peptides). Reaction sequences are automated on commercially available equipment to generate libraries of anilines and aryl ethers. The unprecedented application of potentiostatic alternating polarity in flow is essential to avoid accumulating electrode passivation. Moreover, it enables reactions to be performed in air, without supporting electrolytes and with high reproducibility over consecutive runs. Our method represents a powerful means to rapidly generate nucleophile independent C-X arylation libraries using flow electrochemistry. | Jennifer Morvan; Koen P L Kuijpers; Dayne Fanfair; Bingqing Tang; Karolina Bartkowiak; Lars Van eynde; Evelien Renders; Scott Wolkenberg; Jesus Alcazar; Peter JJA Buijnsters; Mary-Ambre Carvalho; Alexander X Jones | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Electrocatalysis; Homogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2024-06-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66707cfc5101a2ffa8cb0228/original/enabling-electrochemical-c-o-and-c-n-arylation-libraries-using-alternating-polarity-in-flow.pdf |
629df71e97e76a377cc7f06e | 10.26434/chemrxiv-2022-rjqbn | Quantitative Sustainable Design (QSD) for the Prioritization of Research, Development, and Deployment of Technologies: A Tutorial and Review | The pursuit of sustainability has catalyzed broad investment in the research, development, and deployment (RD&D) of innovative water, sanitation, and resource recovery technologies, yet the lack of transparent and agile methodologies to navigate the expansive landscape of technology development pathways remains a critical challenge. This challenge is further complicated by the higher levels of uncertainty that are intrinsic to early-stage technologies. In this work, we review and synthesize published literature on the sustainability analyses of water and related technologies to present Quantitative Sustainable Design (QSD) – a methodology to expedite and support technology RD&D. With a shared lexicon and a structured approach, QSD facilitates interdisciplinary communication and research consistency. In introducing QSD, we review existing studies to highlight best practices and discuss them in the context of the specific steps of QSD, which include defining the problem space, establishing simulation algorithms, and characterizing system sustainability across economic, environmental, human health, and social dimensions. Next, we summarize tools for QSD execution and provide recommendations to account for uncertainty in this process. We further discuss applications of QSD in the fields of water/wastewater and beyond (e.g., renewable fuels, circular economy) in combination with uncertainty, sensitivity, and scenario analyses to generate the desired types of insight. Finally, we identify future research needs for sustainability analyses to advance technology RD&D. Ultimately, QSD can be used to elucidate the complex and intertwined connections among design decisions, technology characteristics, contextual factors, and sustainability indicators, thereby supporting transparent, consistent, and agile RD&D. | Yalin Li; John Trimmer; Steven Hand; Xinyi Zhang; Katherine Chambers; Hannah Lohman; Rui Shi; Diana Byrne; Sherri Cook; Jeremy Guest | Earth, Space, and Environmental Chemistry; Chemical Engineering and Industrial Chemistry; Environmental Science; Wastes; Water Purification | CC BY 4.0 | CHEMRXIV | 2022-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629df71e97e76a377cc7f06e/original/quantitative-sustainable-design-qsd-for-the-prioritization-of-research-development-and-deployment-of-technologies-a-tutorial-and-review.pdf |
66d90071cec5d6c142297715 | 10.26434/chemrxiv-2024-8jxvh | Optically Transparent Porous Salt Thin Films Enable In Situ Characterization of Structure- and Depth-Dependent Post-Synthetic Metalation | Post-synthetic metalation and metathesis chemistry are central to rational synthesis of metal-organic frameworks (MOFs) that are unavailable by direct self-assembly. The rate, extent, and distribution of post-synthetically modified sites is challenging to characterize due to the microcrystallinity and heterogeneity of many materials. Here we describe the deposition of optically transparent, permanently porous thin films comprised of a peripherally carboxylated free-base porphyrin and a cationic porous molecular cage. The films are assembled via layer-by-layer growth controlled by Coulombic charge pairing, which allows for systematic control over the thickness of the obtained films. The obtained thin films are optically transparent monoliths that retain the permanent porosity of the corresponding porous salts. Postsynthetic metalation of these films with Mn(HMDS)2 affords the corresponding Mn(II) porphyrin-based materials (HMDS = hexamethyldisilazide). In situ spectroscopic monitoring, made possible by the optical transparency and synthetically controlled optical density of the films, enables metalation kinetics and extent to be directly monitored. We demonstrate both structure- and thickness-dependence on metalation kinetics. These results provide a unique window into the molecular scale mechanisms that underpin materials synthesis. | Joe Simmons; Subham Sarkar; Andrew Ezazi; Aishanee Sur; Ethan Iverson; Merissa Morey; Austin Chivington; Jaime Grunlan; David Powers; Eric Bloch | Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d90071cec5d6c142297715/original/optically-transparent-porous-salt-thin-films-enable-in-situ-characterization-of-structure-and-depth-dependent-post-synthetic-metalation.pdf |
666293f1418a5379b0448863 | 10.26434/chemrxiv-2024-7w8mr-v2 | Ligand-controlled alteration of nuclear trajectories during photoinduced intersystem crossing in bis-meridional Fe(II) complexes | The intersystem crossing dynamics of two bis-meridional iron(II) complexes are studied by femtosecond transient M-edge X-ray near edge absorption spectroscopy (XANES) with a tabletop high-harmonic extreme ultraviolet (XUV) spectrometer. Visible-light photoexcitation of Fe(tpy)2(BF4)2 (where tpy = terpyridine) creates a metal-to-ligand charge transfer (MCLT) state that decays in 170 fs to a metal-centered triplet state (3MC), followed by 38 fs decay by intersystem crossing to a metal-centered quintet (5MC). Coherent oscillations on the 5MC surface are observed as a modulation in the XANES spectrum with a frequency of 103 cm-1 and a spectral shape that is characteristic of the symmetric Fe-N stretch. These dynamics and spectra are similar to those previously observed for Fe(phen)32+ (phen = phenanthroline). In contrast, transient spectroscopy of Fe[(4-CF3)2bpca]2 (bpca= bis(2-pyridylcarbonyl)amide) reveals a lower-frequency 42 cm-1 coherent oscillation. Ligand field multiplet calculations combined with ab initio ligand field theory identify this oscillation as a ligand bending mode, highlighting the ligand field sensitivity of M-edge XANES. The activation of different vibrational modes in Fe(tpy)2(BF4)2 and Fe[(4-CF3)2bpca]2 is explained by mapping their excited-state potential energy surfaces using density functional theory. In the latter complex, the nuclear trajectory follows initial expansion along the Fe-Naxial coordinate until reaching the 3MC/5MC seam. After intersystem crossing, the quintet state is significantly displaced along the coordinate corresponding to the ligand rocking mode, which therefore dominates the subsequent trajectory. | Ryan Ash; Kaili Zhang; Conor Rankine; Justin Malme; Thomas Penfold; Gregory Girolami; Josh Vura-Weis | Physical Chemistry; Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666293f1418a5379b0448863/original/ligand-controlled-alteration-of-nuclear-trajectories-during-photoinduced-intersystem-crossing-in-bis-meridional-fe-ii-complexes.pdf |
63d82b175391e5d2ea6c1cf7 | 10.26434/chemrxiv-2023-03m0b | Model-based evaluation and data requirements for parallel kinetic experimentation and data-driven reaction identification and optimization | Recently there has been growing interest in implementing the high-throughput approach to access the dynamics of chemical processes across different fields. With an ever-increasing amount of data catalyzed by high-throughput experimentation, the development of fully-integrated workflows becomes crucial. These workflows should combine novel experimental tools and interpretation methods to convert the data into valuable information. To design feasible data-driven workflows it is necessary to estimate the value of information and balance it with the number of experiments and resources required. Basing this kind of workflow on actual physical models appears to be a more feasible strategy as compared to data-extensive empirical statistical methods. Here we show an algorithm that constructs and evaluates kinetic models of different complexity. The algorithm facilitates the evaluation of the experimental data quality and quantity requirements needed for reliable discovery of the rates driving the corresponding chemical models. The influence of the quality and quantity of data on the obtained results was indicated by the accuracy of the estimates of the kinetic parameters. We also show that this method can be used to find correct reaction scenarios directly from simulated kinetic data with little to no overfitting. Well-fitting models for theoretical data can then be used as a proxy for optimizing the underlying chemical systems. Taking real physical effects into account, this approach goes beyond: we show that with the kinetic models one can make a direct, unbiased, quantitative connection between kinetic data and the reaction scenario. | Nathan Jiscoot; Evgeny Uslamin; Evgeny Pidko | Physical Chemistry; Catalysis; Organometallic Chemistry; Heterogeneous Catalysis; Kinetics and Mechanism - Organometallic Reactions; Chemical Kinetics | CC BY NC 4.0 | CHEMRXIV | 2023-01-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63d82b175391e5d2ea6c1cf7/original/model-based-evaluation-and-data-requirements-for-parallel-kinetic-experimentation-and-data-driven-reaction-identification-and-optimization.pdf |
640661f26642bf8c8f14b77c | 10.26434/chemrxiv-2023-k633r | Design principle of heparanase inhibitors: a combined in vitro and in silico study | Heparanase (HPSE) is an enzyme responsible for the cleavage of heparan sulfate (HS) side chains from heparan sulfate proteoglycans (HSPGs). The enzymatic activity of HPSE contributes to ECM remodeling, regulates growth factors, and its overexpression has been implicated in various types of cancer and inflammation, making it a highly promising therapeutic target. In the last two decades, a number of HPSE inhibitors have been reported by labs worldwide, with most of them belonging to the saccharide-based category. So far, few of the small molecule HPSE inhibitors have progressed into clinical trials and none has gained approval by regulatory agencies, leaving a blank in HPSE drug discovery. Here we present the discovery of a novel HPSE small molecule inhibitor by high-throughput screening using an ultrasensitive HPSE enzymatic activity detecting probe developed in our lab and provide the mechanisms of action behind the HPSE inhibition of the small molecule. By doing a series of molecular dynamics (MD) simulations, we discovered the binding profiles on the derivatives of the lead compound. We summarized the essential structural features of the lead compound to provide insights into the design of future HPSE small molecule inhibitors. | Yuzhao Zhang; Meijun Xiong; Zixin Chen; Gustavo Seabra; Jun Liu; Chenglong Li; Lina Cui | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2023-03-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/640661f26642bf8c8f14b77c/original/design-principle-of-heparanase-inhibitors-a-combined-in-vitro-and-in-silico-study.pdf |
64074cae0e6a36fabae380f9 | 10.26434/chemrxiv-2023-dkvdg-v2 | Does φ-Aromaticity exist in prismatic {Bi6}-based clusters? | In a recent paper (Peerless et al. Nat. Chem. 15, 347-356, (2023)), the authors isolated the heterometallic cluster containing at its heart the prismatic {Bi6}-based cluster. To explain its exceptionally high abundance and selective formation tendency (as compared to other Zintl clusters) as well as the unusual magnetic-response properties, the authors introduced the so-called phi-aromaticity. Here, we show that introducing a new type of aromaticity in this case is unjustified and misleading. | Dariusz Szczepanik; Miquel Solà | Theoretical and Computational Chemistry; Inorganic Chemistry; Bonding; Coordination Chemistry (Inorg.); Theory - Computational | CC BY 4.0 | CHEMRXIV | 2023-03-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64074cae0e6a36fabae380f9/original/does-aromaticity-exist-in-prismatic-bi6-based-clusters.pdf |
643fc9f183fa35f8f6e5cc55 | 10.26434/chemrxiv-2022-9h79w-v2 | Fragments quantum descriptors in classification of bio-accumulative compounds | The aim of the following research is to assess the applicability of calculated quantum properties of molecular fragments as molecular descriptors in machine learning classification task. The research is based on bio-concentration and QM9-extended databases. A number of compounds with results from quantum-chemical calculations conducted with Psi4 quantum chemistry package was also added to the quantum properties database. Classification results are compared with a baseline of random guesses and predictions obtained with the traditional RDKit generated molecular descriptors. Chosen classification metrics show that results obtained with fragments quantum descriptors fall between results from baseline and those provided by molecular descriptors widely applied in cheminformatics. However a combination of both classes of features proved to yield the best results in the classification of test set. | Bartłomiej Fliszkiewicz; Marcin Sajdak | Theoretical and Computational Chemistry; Earth, Space, and Environmental Chemistry; Environmental Science; Quantum Computing; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-04-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643fc9f183fa35f8f6e5cc55/original/fragments-quantum-descriptors-in-classification-of-bio-accumulative-compounds.pdf |
60c745840f50db18053962b5 | 10.26434/chemrxiv.10031882.v1 | Rh(III)-Catalyzed Direct Access to 2,3-Substituted β-N-Glycosyl Indoles Through C-H Activation/annulation Coupling of β-N-Aryl Glycosides with Substituted Internal Alkynes | An efficient and selective C-H activation/annulation of readily available β-N-aryl glycosides with various
alkynes has been established. Using [Cp*RhCl2]2 as a catalyst and AgSbF6 in DCE, this protocol proved to be general to
prepare a variety of 2,3-substituted N-glycosyl indoles in good yields with exclusive β-selectivity. | Samir Messaoudi; Olivier Provot; Mouad Alami; Guangkuan Zhao; Mingxiang Zhu | Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745840f50db18053962b5/original/rh-iii-catalyzed-direct-access-to-2-3-substituted-n-glycosyl-indoles-through-c-h-activation-annulation-coupling-of-n-aryl-glycosides-with-substituted-internal-alkynes.pdf |
60c74de1702a9b4d4618b926 | 10.26434/chemrxiv.12668810.v1 | Determination of the δ 2H Values of High Molecular Weight Lipids by High Temperature GC Coupled to Isotope Ratio Mass Spectrometry | <div>Rationale: The hydrogen isotopic composition of lipids (δ 2Hlipid) is widely used in food</div><div>science and as a proxy for past hydrological conditions. Determining the δ 2H values of large,</div><div>well-preserved triacylglycerides and other uniquely microbial lipids, such as glycerol dialkyl</div><div>glycerol tetraether (GDGT) lipids, is thus of widespread interest but has so far not been </div><div>possible due to their size which prohibits analysis by traditional gas chromatography</div><div>pyrolysis isotope ratio mass spectrometry (GC-P-IRMS).</div><div>Methods: We determined the δ 2H values of large, polar molecules and applied high</div><div>temperature gas chromatography (GC) methods on a modified GC-P-IRMS system. The</div><div>methods were validated using authentic standards of large, functionalised molecules</div><div>(triacylglycerides, TAG), purified reference standards of GDGTs, and compared to δ 2H</div><div>values determined by elemental analyser pyrolysis isotope ratio mass spectrometry (EA-PIRMS); and subsequently applied to the analysis of GDGTs in a sample from a methane</div><div>seep and a Welsh peat.</div><div>Results: δ 2H values of TAGs agreed within error between different between GC-P-IRMS and</div><div>EA-P-IRMS, with GC-P-IRMS showing 3-5 ‰ precision for 10 ng H injected. Archaeal lipid</div><div>GDGTs with up to three cyclisations could be analysed: δ 2H values were not significantly</div><div>different between methods with standard deviations of 5 to 6 ‰. When environmental</div><div>samples were analysed, δ 38 2H values of isoGDGTs were 50 ‰ more negative than those of</div><div>terrestrial brGDGTs.</div><div>Conclusions: Our results indicate that the high temperature GC-P-IRMS (HTGC-P-IRMS)</div><div>method developed here is appropriate to determine the δ 2H values of TAGs, GDGT lipids</div><div>with up to two cyclisations, and potentially other high molecular weight compounds. The</div><div>methodology will widen the current analytical window for biomarker and alimentary light</div><div>stable isotope analyses. Moreover, our initial measurements suggest that bacterial and</div><div>archaeal GDGT δ 2H values can record environmental and ecological conditions</div> | Sabine Lengger; Yuki Weber; Kyle W. Taylor; Sebastian
H. Kopf; Robert Berstan; Ian D. Bull; Jan-Peter Mayser; William D. Leavitt; Jerome Blewett; Ann Pearson; Richard D. Pancost | Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74de1702a9b4d4618b926/original/determination-of-the-2h-values-of-high-molecular-weight-lipids-by-high-temperature-gc-coupled-to-isotope-ratio-mass-spectrometry.pdf |
60c75675567dfe1349ec64aa | 10.26434/chemrxiv.14252681.v1 | Seed Mediated Synthesis of Colloidal Halide Perovskite Nanoplatelets | <p><b>Two-dimensional lead
halide perovskite nanoplatelets (2D LHP NPLs) have been emerging as one of the most
promising semiconductor nanomaterials due to their narrow absorption and
emission line widths, tunable bandgaps, high exciton binding energies, high
defect tolerance as well as highly localized energy states. Colloidal synthesis
of 2D LHP NPLs is generally performed using hot-injection or ligand assisted
precipitation techniques (LARP). In the LARP method, perovskites are
synthesized in polar solvents, which decrease the stability of the 2D LHP NPLs
due to their weakly bonded nature. In fact, the presence of residual polar
solvent in the LHP NPL colloid can cause deterioration of thickness uniformity,
degradation of NPLs to parent precursors, and undesired phase transformations. Herein,
for the first time, we report facile seed-mediated synthesis route of
monolayer, 2-monolayers, and thicker lead halide perovskite nanoplatelets
without using A site cation halide salt (AX</b><b>;</b><b>
A = Cesium, methylammonium, formamidinium and, X = Cl, Br, I) and long chain
alkylammonium halide salts (LX; L = oleylammonium, octylammonium, butylammonium
and, X = Cl, Br, I). The seed solution has been synthesized by reacting lead
(II) halide salt and coordinating ligands (oleylamine or octylamine and oleic
acid) in nonpolar high boiling solvent (1-octadecene). The seed mediated
synthesis has been carried out in hexane by reacting seed solution with A-site
cation precursors (Cs-oleate, FA-oleate, or diluted MA solution in hexane) under
ambient conditions. More importantly, the seed mediated growth of NPLs has been
tracked for the first time by performing in-situ optical measurements.
Furthermore, the optical properties and morphologies of the seeds have been extensively
studied. We find that our facile synthesis route provides highly stable,
monodisperse NPLs with narrow absorption, and photoluminescence line widths (68-201
meV), and high PLQY (37.6-1.66% for 2ML NPLs). Furthermore, anion exchange
reactions have been performed by mixing pre-synthesized LHP NPLs with counter
halide seeds. The optical properties of NPLs have been affectively tuned by
postsynthetic chemical reactions without changing the thickness of the NPLs. We
anticipate that our new synthetic route provides
further understanding of growth dynamics of LHP NPLs.</b></p> | C. Meric Guvenc; sinan balci | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75675567dfe1349ec64aa/original/seed-mediated-synthesis-of-colloidal-halide-perovskite-nanoplatelets.pdf |
60c74dea0f50dba430397103 | 10.26434/chemrxiv.12673742.v1 | Two-Step Machine Learning Enables Optimized Nanoparticle Synthesis | <p>In materials science, the discovery of recipes that yield nanomaterials with defined optical properties is costly and time-consuming. In this study, we present a two-step framework for a machine learning driven high-throughput microfluidic platform to rapidly produce silver nanoparticles with a desired absorbance spectrum. Combining a Gaussian Process based Bayesian Optimization (BO) with a Deep Neural Network (DNN), the algorithmic framework is able to converge towards the target spectrum after sampling 120 conditions. Once the dataset is large enough to train the DNN with sufficient accuracy in the region of the target spectrum, the DNN is used to predict the colour palette accessible with the reaction synthesis. While remaining interpretable<i> </i>by humans, the proposed framework efficiently optimizes the nanomaterial synthesis, and can extract fundamental knowledge of the relationship between chemical composition and optical properties, such as the role of each reactant on the shape and amplitude of the absorbance spectrum.</p> | Flore Mekki-Berrada; Zekun Ren; Tan Huang; Wai Kuan Wong; Fang Zheng; Jiaxun Xie; Isaac Parker Siyu Tian; Senthilnath Jayavelu; Zackaria Mahfoud; Daniil Bash; Kedar Hippalgaonkar; Saif Khan; Tonio Buonassisi; Qianxiao Li; Xiaonan Wang | Machine Learning; Artificial Intelligence | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dea0f50dba430397103/original/two-step-machine-learning-enables-optimized-nanoparticle-synthesis.pdf |
65158e45a69febde9ed8b213 | 10.26434/chemrxiv-2023-f7djm-v2 | Optochemical control of the growth of antibiotic-resistant bacteria using arylazopyrazole-modified norfloxacin | In addition to discovering new antibiotics to combat antibiotic resistance, there is a critical need to develop novel strategies that could limit off-target effects and unnecessary exposure of antibiotics to bacteria in our body and environment, respectively. We report a set of novel, photoswitchable arylazopyrazole-modified norfloxacin antibiotics that presents a high degree of bidirectional photoisomerization, impressive fatigue resistance, and reasonably high cis half-lives, and exhibits antibacterial activity selectively against Gram-positive bacteria; the cis isomers of most compounds were found to have near equal or greater potency than the norfloxacin, rendering them bactericidal. Remarkably, a visible-light-responsive p-SMe-substituted derivative against the norfloxacin-resistant S. aureus bacteria showed extremely high antimicrobial activity with a MIC of 0.25 ug/mL in the irradiated state and a 24-fold potency difference between irradiated and non-irradiated states. The antimicrobial activity of the irradiated state can be retained for more than 7 hours. The cell-killing ability of this compound was further visualized by Live/Dead cell staining assay and FACS studies. Theoretical calculation and molecular docking studies were performed to identify the underlying reason behind the high-affinity binding of the irradiated form to the topoisomerase IV. | Subhas Samanta; Supriya Bhunia; Santosh Kumar Jana; Soumik Sarkar; Arpan Das; Sukhendu Mandal | Biological and Medicinal Chemistry; Organic Chemistry; Photochemistry (Org.); Biochemistry; Chemical Biology | CC BY NC 4.0 | CHEMRXIV | 2023-09-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65158e45a69febde9ed8b213/original/optochemical-control-of-the-growth-of-antibiotic-resistant-bacteria-using-arylazopyrazole-modified-norfloxacin.pdf |
61b85563dcbea2b28ca3d769 | 10.26434/chemrxiv-2021-6q4b9 | Metal-Hydrogen-Pi-Bonded Organic Frameworks | We report the synthesis and characterization of a new series of permanently porous, three-dimensional metal-organic frameworks (MOFs), M-HAF-2 (M= Fe, Ga or In), constructed from tetratopic, hydroxamate-based, chelating linkers. The structure of M-HAF-2 was determined by three-dimensional electron diffraction (3DED), revealing a unique interpenetrated hcb-a net topology. This unusual topology is enabled by the presence of free hydroxamate groups, which lead to the formation of a diverse network of cooperative interactions comprising single metal-hydroxamate nodes, staggered π–π interactions between linkers and H-bonding interactions between metal-coordinated and free hydroxamate groups. Such extensive, multimodal interconnectivity is reminiscent of the complex noncovalent interaction networks of proteins and endows M-HAF-2 frameworks with good thermal and exceptionally high chemical stability and allows them to readily undergo post-synthetic metal exchange (PSE). We demonstrate that M-HAF-2 can serve as versatile porous materials for ionic separations, likely aided by one-dimensional channels lined by continuously π-stacked aromatic groups and H-bonding hydroxamate functionalities. As a new addition to the small group of hydroxamate-based MOFs, M-HAF-2 represents a structural merger between MOFs and hydrogen-bonded organic frameworks (HOFs). | laura samperisi; xiaodong zou; zhehao huang; akif tezcan; jie zhu; seth cohen; Mark Kalaj; Jerika Chiong; Jake Bailey; Zhiyin Zhang; Chung-Jui Yu; eric sikma | Inorganic Chemistry; Coordination Chemistry (Inorg.); Organometallic Compounds | CC BY NC ND 4.0 | CHEMRXIV | 2021-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61b85563dcbea2b28ca3d769/original/metal-hydrogen-pi-bonded-organic-frameworks.pdf |
6213cfecc86ae26f2c29716e | 10.26434/chemrxiv-2022-wkdpt | Strong anti-kinetoplastid activity of silver nanoparticle-coated biochar | Neglected tropical diseases including Chagas disease, also known as American trypanosomiasis and leishmaniasis remains a serious health problem in several endemic. To address this medical problem, much has been done in the past 15 years to design nanomaterials with effective anti-kinetoplastids activity, particularly those nanomaterials based on gold and silver nanoparticles. Herein, we describe a simple method to prepare silver-loaded biochar by pyrolysis of silver nitrate-impregnated agrowaste powder (from olive stones). The resulting Biochar@Ag was prepared at 400 °C for 15 minutes only and the yield was found to be 36.5 %. The supported metallic Ag nanoparticles have triangular shape in the nanoscale regime (< 100 nm) and a loading of 7.85 mmol per gram of Biochar@Ag. The Biochar@Ag showed promising antiparasitic activity against promastigotes stage of L. donovani, L. amazonensis and epimastigotes of T. cruzi with and IC50 of 9.942 ± 0.900 ppm; 14.555 ± 1.035 ppm and 12.154 ± 0.206 ppm, respectively. From the above, this work conclusively demonstrates that slow pyrolysis is a unique thermochemical approach to valorize agrowastes into highly effective anti-kinetoplastid silver-loaded biochar with remarkably low cytotoxicity towards murine macrophages. | Youssef Snoussi; Inés Sifaoui; Ahmed Khalil; Arvind Bhakta; Laurent Michely ; Rémy Pires; Stéphane Bastide; Oleg Semyonov; Pavel Postnikov; José Enrique-Piñero Barroso; Jacob Lorenzo Morales; Mohamed Chehimi | Biological and Medicinal Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Bioengineering and Biotechnology; Microbiology; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-02-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6213cfecc86ae26f2c29716e/original/strong-anti-kinetoplastid-activity-of-silver-nanoparticle-coated-biochar.pdf |
632108251856847faf14fb4d | 10.26434/chemrxiv-2022-k7gdl | Bridging the Gap between the X-ray Absorption Spectroscopy and the Computational Catalysis Communities in Heterogeneous Catalysis: A Perspective on the Current and Future Research Directions | X-ray absorption spectroscopy (XAS), (Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near-Edge Structure (XANES)), is a key technique within the heterogeneous catalysis community to probe the structure and properties of active site(s) for a diverse range of catalytic materials. However, the interpretation of the raw experimental data to derive an atomistic picture of the catalyst requires modeling and analysis; the EXAFS data are compared to a model and a goodness of fit parameter is used to judge the best fit. This EXAFS modeling can often be non-trivial and time-consuming; overcoming or improving these limitations remains a central challenge for the community. Considering these limitations, this Perspective highlights how recent developments in analysis software, increased availability of reliable computational models and application of data science tools can be used to improve the speed, accuracy, and reliability of EXAFS interpretation. In particular, we emphasize the advantages of combining theory and EXAFS as a unified technique that should be treated as a standard (when applicable) to identify catalytic sites and not two separate complementary methods. Building on the recent trends in the computational catalysis community, we also present a community-driven approach to adopt FAIR Guiding Principles for the collection, analysis, dissemination, and storage of XAS data. Written with both the experimental and theory audience in mind, we provide unified roadmap to foster collaborations between the two communities. | Rachita Rana; FERNANDO D. VILA; Ambarish Kulkarni; Simon R. Bare | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632108251856847faf14fb4d/original/bridging-the-gap-between-the-x-ray-absorption-spectroscopy-and-the-computational-catalysis-communities-in-heterogeneous-catalysis-a-perspective-on-the-current-and-future-research-directions.pdf |
64932303853d501c0045b6b0 | 10.26434/chemrxiv-2023-jd51z | A spectIR-fluidic reactor for monitoring fast chemical reaction kinetics with on-chip attenuated total reflection Fourier transform infrared spectroscopy | Microfluidics has emerged as a powerful technology with diverse applications in microbiology, medicine, chemistry, and physics. While its potential for controlling and studying chemical reactions is well recognized, the extraction and utilization of the vast amounts of high-quality information generated within microfluidic devices remain challenging. This is mainly due to the limited tools available for in situ measurements of chemical reactions. In this study, we present a proof-of-concept spectIR-fluidic reactor design that combines microfluidics with Fourier transform infrared (FTIR) spectroscopy for in situ kinetic studies of fast reactions. By integrating a multi-ridge silicon attenuated total reflection (ATR) wafer into the microfluidic device, we enable multi-point measurements for precise reaction time monitoring. This work establishes a validated foundation for studying a wide range of chemical reactions using ATR-FTIR spectroscopy, which will enable simultaneous quantification of reagents, intermediates, and products. The spectIR-fluidic platform offers customizable designs, allowing for the investigation of reactions with various time scales, and has the potential to significantly advance reaction optimization and pathway exploration. | Nan Jia; Leon de Oliveira; André Bégin-Drolet; Jesse Greener | Analytical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64932303853d501c0045b6b0/original/a-spect-ir-fluidic-reactor-for-monitoring-fast-chemical-reaction-kinetics-with-on-chip-attenuated-total-reflection-fourier-transform-infrared-spectroscopy.pdf |
65105b6fb927619fe7bc4081 | 10.26434/chemrxiv-2022-ph262-v3 | Switchable organocatalysis from N-heterocyclic carbene-carbodiimide adducts with tunable release temperature | N-Heterocyclic carbenes (NHCs) are powerful organocatalysts, but practical applications often require in situ generation from stable precursors that “mask” the NHC reactivity via reversible binding. Previously established “masks” are often simple small molecules, such that the NHC structure is used to control both catalytic activity and activation temperature, leading to undesirable tradeoffs. Herein, we show that NHC-carbodiimide (CDI) adducts can be masked precursors for switchable organocatalysis and that the CDI substituents can control the reaction profile without changing the NHC structure. Large electronic variations on the CDI (e.g., alkyl versus aryl) drastically change the catalytically active temperature, whereas smaller perturbations (e.g., different para-substituted phenyls) tune the catalyst release within a narrower window. This control was demonstrated for three classic NHC-catalyzed reactions, each influencing the NHC-CDI equilibrium in different ways. Our results introduce a new paradigm for controlling NHC organocatalysis as well as present practical considerations for designing appropriate masks for various reactions. | Le Dung Pham; Red Smith-Sweetser; Briana Krupinsky; Carolyn Dewey; Jessica Lamb | Organic Chemistry; Catalysis; Polymer Science; Organic Compounds and Functional Groups; Physical Organic Chemistry; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65105b6fb927619fe7bc4081/original/switchable-organocatalysis-from-n-heterocyclic-carbene-carbodiimide-adducts-with-tunable-release-temperature.pdf |
6259c44aed4d88e9170c0062 | 10.26434/chemrxiv-2022-kcxf7 | Generative Adversarial Neural Networks for Denoising Coherent Multidimensional Spectra | Ultrafast spectroscopy often involves measuring weak signals and long data acquisition times. Spectra are typically collected as a “pump-probe” spectrum by measuring differences in intensity across laser shots. Shot-to-shot intensity fluctuations are most often the primary source of noise in ultrafast spectroscopy. Here we present a novel approach for denoising ultrafast two-dimensional infrared (2D IR) spectra using conditional generative adversarial neural networks (cGANNs). The cGANN approach is able to eliminate shot-to-shot noise and reconstruct the lineshapes present in the noisy input spectrum. We present a general approach for training the cGANN using matched pairs of noisy and clean synthetic 2D IR spectra based on the Kubo-lineshape model for a three-level system. Experimental shot-to-shot laser noise is added to synthetic spectra to recreate the noise profile present in measured experimental spectra. The cGANNs can recover lineshapes from synthetic 2D IR spectra with signal-to-noise ratios as low as 2:1, while largely preserving the key features such as center frequencies, linewidths, and diagonal elongation. In addition, we benchmark the performance of the cGANN using experimental 2D IR spectra of an ester carbonyl vibrational probe and demonstrate that by applying the cGANN denoising approach, we can extract the frequency-frequency correlation function (FFCF) from reconstructed spectra using a nodal-line slope analysis. Finally, we provide a set of practical guidelines for extending the denoising method to other coherent multidimensional spectroscopies. | Ziareena Al-Mualem; Carlos Baiz | Physical Chemistry; Spectroscopy (Physical Chem.) | CC BY NC 4.0 | CHEMRXIV | 2022-04-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6259c44aed4d88e9170c0062/original/generative-adversarial-neural-networks-for-denoising-coherent-multidimensional-spectra.pdf |
670b64c651558a15efe99366 | 10.26434/chemrxiv-2024-6578h | Melamine-driven solvation effect promotes oxygen reduction on platinum catalyst: machine learning-aided free energy calculations | The modification of Pt surfaces by organic compounds such as melamine is known to enhance the activity of the oxygen reduction reaction (ORR) and improve catalyst durability against potential cycling. Here, we present the mechanism of activity enhancement elucidated by first-principles (FP) free energy calculations using thermodynamic integration within finite-temperature molecular dynamics simulations. These calculations accelerate phase space sampling, including nanosecond-scale fluctuations of interfacial water, by employing machine-learned force fields. The errors introduced by the force fields are corrected via thermodynamic integration from the machine-learned potential to the FP potential, allowing us to obtain accurate FP free energies. The results reveal that melamine destabilizes the OH adsorbate, an intermediate in the ORR, thereby accelerating the OH removal step and pushing the catalytic activity to the top of the volcano plot. This behavior is similar to what is observed on Pt(1-x)Cux alloy surfaces evaluated using the same method. However, the mechanism of OH destabilization by melamine differs entirely from that on alloy surfaces. Unlike alloys, melamine does not shift the d-band center or shorten the metal-metal distance. Instead, melamine disrupts the hydrogen bonds between the OH adsorbate and the surrounding interfacial water. Structural and vibrational analyses have revealed that the solvation structure changes induced by melamine are manifested as alterations in the radial distribution function of water near the OH adsorbate and as a blue shift in the O-H stretching vibrations of interfacial water. These findings indicate that manipulating interfacial solvation with organic compounds could be a promising approach to enhance catalytic activity without compromising durability. | Ryosuke Jinnouchi; Saori Minami | Theoretical and Computational Chemistry; Physical Chemistry; Catalysis; Theory - Computational; Machine Learning; Electrocatalysis | CC BY 4.0 | CHEMRXIV | 2024-10-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670b64c651558a15efe99366/original/melamine-driven-solvation-effect-promotes-oxygen-reduction-on-platinum-catalyst-machine-learning-aided-free-energy-calculations.pdf |
673accfe5a82cea2fa7d0ae9 | 10.26434/chemrxiv-2024-22gt7-v2 | Dissociation Dynamics of CO2 on Cu(110) Studied Over a Wide Range of Incident Energies | In this work, we have studied the dissociation dynamics of CO2 on a Cu(110) surface using molecular beams with incidence energies ranging from 0.28 eV to 4.6 eV. The incident energy dependence of the initial dissociative reaction probabilities (S0) of CO2 showed two distinct characteristics. At first, S0 exhibits a rapid increase from 1.8 × 10−4 at 0.28 eV to more than 150-fold at 2 eV. Beyond this, only a small increase by less than a factor of 1.5 was observed in the 2 eV to 4.6 eV range, with the S0 being 4.1 × 10−2 at 4.6 eV. Incident angle-dependent measurements reveal total energy scaling to be followed. Measurements using a heated nozzle showed no observable enhancement in S0 due to the vibrational energy of the incident molecules, with an upper limit of vibrational efficacy estimated to be 0.25. Furthermore, an increase in O-atom saturation coverage (resulting from CO2 dissociation) from 0.5 ML to 0.66 ML was observed at high impact energies (> 3 eV), suggesting that newer dissociation sites become accessible at higher energies. | Saurabh Kumar Singh; Pranav Ravindra Shirhatti | Physical Chemistry; Catalysis; Heterogeneous Catalysis; Surface | CC BY 4.0 | CHEMRXIV | 2024-11-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673accfe5a82cea2fa7d0ae9/original/dissociation-dynamics-of-co2-on-cu-110-studied-over-a-wide-range-of-incident-energies.pdf |
6446ba7a83fa35f8f6305239 | 10.26434/chemrxiv-2023-j51kq | Screen printed carbon nanotube chemiresistive pH sensor on paper-based microfluidics | In this study, the authors presented a simple and cost-effective method for fabricating a carbon nanotubes (CNTs)-based paper-based sensing device via screen printing to determine solution pH. CNTs were chosen due to their high surface area and excellent mechanical and electrical properties, making them useful for various applications, including biological and chemical sensing. The paper-based device was fabricated using paper, a low-cost and accessible substrate, which also has a porous structure for capillary action. The hydrophobic and hydrophilic regions were established using wax printing and paper surface plasmon treatment to control the dimensions of the sensing channels. The CNTs ink was screen printed onto the paper, and the length and width of the sensing channels were controlled by the hydrophobic pattern design and mask design. The amount of CNTs printed was also easily controlled by varying the concentrations of the carbon ink. The resulting CNT-based films on paper were repeatedly produced with a homogeneous thickness. The fabricated sensors showed a linear response range from pH 3 to pH 10, with an optimal L/W ratio of 4, and an electrical signal was generated by measuring the channel resistance using conductive silver leads. This screen printing method provides a facile and low-cost approach for fabricating paper-based sensors that can be used for various sensing applications, including point-of-care diagnosis and environmental monitoring. | Rahul Sharma; Amit Patel | Analytical Chemistry; Agriculture and Food Chemistry; Analytical Chemistry - General; Analytical Apparatus; Environmental Analysis | CC BY 4.0 | CHEMRXIV | 2023-04-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6446ba7a83fa35f8f6305239/original/screen-printed-carbon-nanotube-chemiresistive-p-h-sensor-on-paper-based-microfluidics.pdf |
65a6f327e9ebbb4db9508102 | 10.26434/chemrxiv-2024-k0z70 | Heteroepitaxial MOF-on-MOF photocatalyst for solar-driven water splitting | Assembly of different Metal-Organic Frameworks (MOFs) into hybrid MOF-on-MOF heterostructures has been established as a promising approach to develop unique synergistic performances for a variety of applications. Here we report the synthesis of MOF-on-MOF heterostructures by the epitaxial growth of MIL-88B(Fe) onto UiO-66(Zr)-NH2 nanoparticles. The face-selective design and appropriate energy band structure alignment of the selected MOF constituents have permitted its application as active heterogeneous photocatalyst for solar-driven water splitting. The composite achieves apparent quantum yields for photocatalytic overall water splitting at 400 and 450 of about 0.9 %, values that compare much favourably with previous analogous reports. Understanding of this high activity has been gained by spectroscopic and electrochemical characterization together with STEM-EDX and HRTEM-EDX measurements. This study exemplifies the possibility of developing MOF-on-MOF heterostructures with outstanding activity towards photocatalytic water splitting under solar light. | Thibaut Le Huec; Antón López-Francés; Isabel Abánades Lázaro; Sergio Navalón; Herme G. Baldoví; Mónica Giménez-Marqués | Inorganic Chemistry; Nanoscience; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Coordination Chemistry (Inorg.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a6f327e9ebbb4db9508102/original/heteroepitaxial-mof-on-mof-photocatalyst-for-solar-driven-water-splitting.pdf |
61f6e97071868d0bd0c419c6 | 10.26434/chemrxiv-2022-ml80t | Reference Raman Spectrum and Mapping of Cryptosporidium parvum Oocysts | Cryptosporidium parvum is a protozoan parasite and among the most infectious diarrhea-causing pathogens, leading to severe health problems for malnourished children and immunocompromised individuals. Outbreaks are common even in developed countries, originating from water or food contamination and resulting in suffering and large costs for society. Therefore, robust, fast and highly specific detection strategies of Cryptosporidium are needed. Label-free detection techniques such as Raman spectroscopy have been suggested, however high-resolution reported spectra in the literature are limited. In this work, we report reference Raman spectra at 3 cm^{-1} resolution for viable and inactivated Cryptosporidium oocysts of the species C. parvum, gathered at a single oocyst level using a laser tweezers Raman spectroscopy system. We furthermore provide tentative Raman peak assignments for the Cryptosporidium oocysts, along with Raman mapping of the oocysts' heterogeneous internal structure. Finally, we compare the C. parvum Raman spectrum with other common enterotoxigenic pathogens: Escherichia coli, Vibrio cholerae, Bacillus cereus and Clostridium difficile. Our results show a significant difference between C. parvum Raman spectra and the other pathogens. | Dmitry Malyshev; Tobias Dahlberg; Rasmus Öberg; Lars Landström; Magnus Andersson | Biological and Medicinal Chemistry; Analytical Chemistry; Microscopy; Spectroscopy (Anal. Chem.); Microbiology | CC BY 4.0 | CHEMRXIV | 2022-02-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61f6e97071868d0bd0c419c6/original/reference-raman-spectrum-and-mapping-of-cryptosporidium-parvum-oocysts.pdf |
6621d94b91aefa6ce1dce2e6 | 10.26434/chemrxiv-2024-pqzct | Fabrication of High-Density Microarchitected Tungsten via DLP 3D Printing | Current additive manufacturing (AM) techniques for tungsten, such as powder bed fusion and directed energy deposition, often generate parts with rough surfaces. Vat photopolymerization presents a promising alternative for fabricating intricate tungsten structures with high shape fidelity and low surface roughness. However, existing vat photopolymerization approaches suffer from surface defects and low final density, leading to compromised mechanical properties. Therefore, achieving high-density tungsten structures using vat photopolymerization remains a crucial challenge. This work presents a straightforward and reliable method for fabricating complex, micro-architected tungsten structures with superior density and hardness. The approach utilizes a water-based photoresin with exceptional tungsten ion loading capacity. The photoresin is then patterned using digital light processing (DLP) to create intricate tungsten-laden precursors. A meticulously designed three-step debinding and sintering process subsequently achieves three-dimensional tungsten structures with dense surface morphology and minimal internal defects. The microstructures achieve a minimum feature size of 35 μm, a low surface roughness of 2.86 μm, and demonstrate exceptional mechanical properties. This new method for structuring tungsten opens doors to a broad range of applications, including micromachining, collimators, detectors, and metamaterials. | Junyu Cai; Songhua Ma; Wenbin Yi; Jieping Wang | Materials Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-04-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6621d94b91aefa6ce1dce2e6/original/fabrication-of-high-density-microarchitected-tungsten-via-dlp-3d-printing.pdf |
672c72e7f9980725cf6ba714 | 10.26434/chemrxiv-2024-hp2dx-v2 | Highly Loaded ROS-Responsive Theranostic Lenvatinib-Prodrug Nanoparticles Produced by Dispersion Polymerization | Nanoparticles represent a powerful class of materials for drug delivery, leveraging their small size for passive targeting through the enhanced permeation and retention (EPR) effect in tumors. This universal approach in tumor targeting offers several advantages over free therapeutics, particularly when combined with imaging capabilities. While a plethora of nanoparticles exists for various imaging techniques, the number of nanoparticles with therapeutic functions is much smaller, due to the synthetic challenges present for incorporation and release of an active drug. Here, we present a strategy to transform the tyrosine kinase inhibitor (TKI) Lenvatinib into a polymerizable prodrug monomer, enabling its incorporation into biodegradable polyimidazole-based particles. This drug monomer is then polymerized and thus incorporated into the nanoparticles via direct arylation in a dispersion polymerization approach. The polyimidazole backbone allows for high drug loading of up to 89 wt%. Additionally, the photoacoustic properties of the polyimidazole nanoparticles are preserved after drug incorporation. Moreover, the backbone remains degradable upon exposure to hydrogen peroxide, facilitating drug release. This approach enables covalent packaging of a chemically inert drug, for which no alternative prodrug approaches exist. The result is a new theranostic nanoagent. | Sarah Spiewok; Felicitas Jansen; Jiaying Han; Markus Lamla; Max von Delius; Christian Trautwein; Laura De Laporte; Alexander JC Kuehne | Biological and Medicinal Chemistry; Nanoscience; Drug Discovery and Drug Delivery Systems; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-11-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672c72e7f9980725cf6ba714/original/highly-loaded-ros-responsive-theranostic-lenvatinib-prodrug-nanoparticles-produced-by-dispersion-polymerization.pdf |
673af1a55a82cea2fa7f7cf6 | 10.26434/chemrxiv-2024-l4l99 | Understanding the Epidemiology of Asthma in Africa: Current Trends, Challenges, and Future Directions | Asthma, a chronic respiratory disorder, poses a significant and growing public health burden in Africa, driven by diverse environmental exposures, limited healthcare access, and demographic shifts such as urbanization. This seminar examines the epidemiological profile of asthma across the continent, detailing its prevalence, geographic disparities, and contributing factors, including environmental allergens, air pollutants, infectious diseases, and lifestyle transitions. Additionally, it explores variations in clinical presentations and risk factors specific to African populations. Discussions highlight the disparities in asthma care, such as restricted access to healthcare services, challenges in adapting international treatment guidelines to African contexts, and the potential of community-driven health initiatives to enhance patient outcomes. Notable gaps in research, particularly the scarcity of longitudinal studies and data on underrepresented populations, are identified as barriers to effective intervention development. To address these challenges, the seminar advocates for prioritizing asthma research focused on African-specific contexts and implementing tailored public health strategies. It concludes with a call to stakeholders in the health sector to integrate asthma management into broader policy frameworks, emphasizing sustainable, evidence-based solutions to mitigate its escalating impact on the continent. | Marvellous Eyube | Biological and Medicinal Chemistry; Biochemistry; Chemical Biology | CC BY 4.0 | CHEMRXIV | 2024-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673af1a55a82cea2fa7f7cf6/original/understanding-the-epidemiology-of-asthma-in-africa-current-trends-challenges-and-future-directions.pdf |
60c74eecee301c3c64c7a5cd | 10.26434/chemrxiv.12812000.v1 | What’s in an Atom? a Comparison of Carbon and Silicon-Centered Amidinium···carboxylate Frameworks | <div><div><div><p>Despite their apparent similarity, framework materials based on tetraphenylmethane and tetraphenylsilane building blocks often have quite different structures and topologies. Herein, we describe a new silicon tetraamidinium compound and use it to prepare crystalline hydrogen bonded frameworks with carboxylate anions in water. The silicon-containing frameworks are compared with those prepared from the analogous carbon tetraamidinium: when biphenyldicarboxylate or tetrakis(4-carboxyphenyl)methane anions were used similar channel-containing networks are observed for both the silicon and carbon tetraamidinium. When terephthalate or bicarbonate anions were used, different products form. Insights into possible reasons for the different products are provided by a survey of the Cambridge Structural Database and quantum chemical calculations, both of which indicate that, contrary to expectations, tetraphenylsilane derivatives have less geometrical flexibility than tetraphenylmethane derivatives, i.e. they are less able to distort away from ideal tetrahedral bond angles.</p></div></div></div> | Stephanie Boer; Li-Juan Yu; Tobias Genet; Kaycee Low; Duncan Cullen; Michael Gardiner; Michelle Coote; Nicholas White | Physical Organic Chemistry; Supramolecular Chemistry (Org.); Supramolecular Chemistry (Inorg.); Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74eecee301c3c64c7a5cd/original/what-s-in-an-atom-a-comparison-of-carbon-and-silicon-centered-amidinium-carboxylate-frameworks.pdf |
660e40a021291e5d1d05c09d | 10.26434/chemrxiv-2023-qsrxp-v2 | Development of Novel Methods for QSAR Modeling by Machine Learning Repeatedly: A Case Study on Drug Distribution to Each Tissue | AI is expected to help identify excellent candidates in drug discovery. However, we face a lack of data as it is time consuming and expensive to acquire raw data perfectly for many compounds. Hence, we tried to develop a novel QSAR method to predict a parameter more precisely from an incomplete dataset via optimizing data handling by making use of predicted explanatory variables. As a case study we focused on the tissue-to-plasma partition coefficient (Kp), which is an important parameter for understanding drug distribution in tissues and building the physiologically based pharmacokinetic (PBPK) model, is a representative of small and sparse datasets. In this study, we predicted the Kp values of 119 compounds in nine tissues (adipose, brain, gut, heart, kidney, liver, lung, muscle, and skin), while some of these were not available. To fill the missing values in Kp for each tissue, firstly we predicted those Kp values by the non-missing dataset using a random forest (RF) model with in vitro parameters (log P, fu, Drug Class, and fi) like a classical prediction by a QSAR model. Next, to predict the tissue-specific Kp values in a test dataset, we constructed a second RF model with not only in vitro parameters but also the Kp values of other tissues (i.e. other than target tissues) predicted by the first RF model as explanatory variables. Furthermore, we tested all possible combinations of explanatory variables and selected the model with the highest predictability from the test dataset as the final model. The evaluation of Kp prediction accuracy based on the root-mean-square error and R2-value revealed that the proposed models outperformed other machine learning methods, such as the conventional RF and message-passing neural networks. Significant improvements were observed in the Kp values of adipose tissue, brain, kidney, liver, and skin. These improvements indicated that the Kp information of other tissues can be used to predict the same for a specific tissue. Additionally, we found a novel relationship between each tissue by evaluating all combinations of explanatory variables. In conclusion, we developed a novel RF model to predict Kp values. We hope that this method will be applied to various problems in the field of experimental biology which often contains missing values in the near future. | Koichi Handa; Saki Yoshimura; Michiharu Kageyama; Takeshi Iijima | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Drug Discovery and Drug Delivery Systems; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2024-04-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/660e40a021291e5d1d05c09d/original/development-of-novel-methods-for-qsar-modeling-by-machine-learning-repeatedly-a-case-study-on-drug-distribution-to-each-tissue.pdf |
60c758f7469df409e6f4578a | 10.26434/chemrxiv.14552553.v2 | Trapping an Unusual Pentacoordinate Carbon Atom in a Neutral Trialuminum Complex | <div>A neutral trialuminum complex incorporates a pentacoordinate carbon through a methylidene bridge linking the three metal atoms. The rigid electron-deficient Al<sub>3</sub> core stabilizes the</div><div>hypercoordinate carbon atom resulting in the shortest equatorial Al–C distance reported for such systems.</div> | Nery Villegas-Escobar; Javier Martínez; Ricardo A. Matute; Sebastian Saltarini; constantin G. daniluc; Lutz. H. Gade; Rene S. Rojas | Bonding; Coordination Chemistry (Inorg.); Main Group Chemistry (Inorg.); Theory - Inorganic; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758f7469df409e6f4578a/original/trapping-an-unusual-pentacoordinate-carbon-atom-in-a-neutral-trialuminum-complex.pdf |
60c741e4469df43622f42ecb | 10.26434/chemrxiv.8146103.v1 | On-Demand Guest Release from MOF-5 Sealed with Nitrophenylacetic Acid Photocapping Groups | Recently, we demonstrated that triphenylacetic acid could be used to seal dye molecules within MOF-5, but guest release required digestion of the framework by treatment with acid. We prepared the sterically bulky photocapping group [bis-(3-nitro-benzyl)-amino]-(3-nitro-phenyl)-acetic acid (PC1) can prevent Crystal violet dye diffusion from inside MOF-5 until removed by photolysis. | Jingjing Yan; Rick Homan; Corrianna Boucher; Prem N. Basa; Katherine Fossum; Ron Grimm; John MacDonald; Shawn Burdette | Photochemistry (Org.); Hybrid Organic-Inorganic Materials | CC BY NC ND 4.0 | CHEMRXIV | 2019-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741e4469df43622f42ecb/original/on-demand-guest-release-from-mof-5-sealed-with-nitrophenylacetic-acid-photocapping-groups.pdf |
60c758020f50db44a4398390 | 10.26434/chemrxiv.14485407.v1 | Catalytic Intramolecular Aminoarylation of Unactivated Alkenes with Aryl Sulfonamides | Arylethylamines are abundant motifs in myriad natural products and pharmaceuticals, so efficient methods to synthesize them are valuable in drug discovery. In this work, we disclose an intramolecular alkene aminoarylation cascade that exploits the electrophilicity of a nitrogen-centered radical to form a C–N bond, then repurposes the nitrogen atom’s sulfonyl activating group as a traceless linker to form a subsequent C–C bond. This photoredox catalysis protocol enables the preparation of densely substituted arylethylamines from commercially abundant aryl sulfonamides under mild conditions. Reaction optimization, scope, mechanism, and synthetic applications are discussed. | Efrey Noten; Rory McAtee; Corey Stephenson | Photocatalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758020f50db44a4398390/original/catalytic-intramolecular-aminoarylation-of-unactivated-alkenes-with-aryl-sulfonamides.pdf |
629467c0e2ef7a49b1f10bd2 | 10.26434/chemrxiv-2021-v9djt-v3 | Addressing Missing Data in GC×GC Metabolomics: Identifying Missingness Type and Evaluating the Impact of Imputation Methods on Experimental Replication | Missing data is a significant issue in metabolomics that is often neglected when conducting data pre-processing, particularly when it comes to imputation. This can have serious implications for downstream statistical analyses and lead to misleading or uninterpretable inferences. In this study, we aim to identify the primary types of missingness that affect untargeted metabolomics data and compare strategies for imputation using two real-world comprehensive two-dimensional gas chromatog-raphy (GC×GC) data sets. We also present these goals in the context of experimental replication whereby imputation is conducted in a within-replicate-based fashion—the first description and evaluation of this strategy—and introduce an R package MetabImpute to carry out these analyses. Our results conclude that, in these two data sets, missingness was most likely of the missing at-random (MAR) and missing not-at-random (MNAR) types as opposed to missing completely at-random (MCAR). Gibbs sampler imputation and Random Forest gave the best results when imputing MAR and MNAR compared against single-value imputation (zero, minimum, mean, median, and half-minimum) and other more sophisticated approach-es (Bayesian principal components analysis and quantile regression imputation for left-censored data). When samples are replicated, within-replicate imputation approaches led to an increase in the reproducibility of peak quantification compared to imputation that ignores replication, suggesting that imputing with respect to replication may preserve potentially important features in downstream analyses for biomarker discovery. | Trenton J. Davis; Tarek R. Firzli; Emily A. Higgins Keppler; Matt Richardson; Heather D. Bean | Biological and Medicinal Chemistry; Analytical Chemistry; Chemoinformatics; Bioinformatics and Computational Biology | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629467c0e2ef7a49b1f10bd2/original/addressing-missing-data-in-gc-gc-metabolomics-identifying-missingness-type-and-evaluating-the-impact-of-imputation-methods-on-experimental-replication.pdf |
673ca6475a82cea2faab16ad | 10.26434/chemrxiv-2024-q0m2n | Quality Control of Graphene Field-Effect Transistor Arrays Using Slit-Scanning Raman Microscopy | Large-scale graphene films enable the integration of graphene field-effect transistor (GFET) arrays onto chips. However, the transfer characteristics display variability across the array. This significant statistical variation in graphene quality, combined with the lack of standardized protocols, poses a major challenge to commercialization. In this study, we present a rapid, extensive, and high-resolution inspection technique using slit-scanning Raman microscopy. Raman imaging of all GFETs in the arrays were performed before conducting electrical measurements. The G-band and 2D-band peak positions were used to determine the hole carrier density (nH) in the GFETs. Variations in nH values across the arrays correlated with the VDP values, a critical parameter of FET performance, validating this approach as an inspection method. Moreover, Raman peaks were tracked across 100 GFETs at different processing stages, revealing that spatial variations originated during the wet-transfer process. This method is vital for the scalable manufacturing of graphene devices. | Shota Ushiba; Tomomi Nakano; Yuka Tokuda; Shinsuke Tani; Masahiko Kimura; Kazuhiko Matsumoto | Nanoscience; Nanodevices; Nanofabrication; Nanostructured Materials - Nanoscience | CC BY 4.0 | CHEMRXIV | 2024-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673ca6475a82cea2faab16ad/original/quality-control-of-graphene-field-effect-transistor-arrays-using-slit-scanning-raman-microscopy.pdf |
60c740adf96a00f555286322 | 10.26434/chemrxiv.7823828.v1 | Cross-Peaks in Simple 2D NMR Experiments from Chemical Exchange of Transverse Magnetization | Two-dimensional correlation measurements such as COSY, NOESY, HMQC and HSQC experiments are central to small molecule and biomolecular NMR spectroscopy, and commonly form the basis of more complex experiments designed to study chemical exchange occurring during additional mixing periods. However, exchange occurring during chemical shift evolution periods can also influence the appearance of such spectra. While this is often exploited through one-dimensional lineshape analysis ('dynamic NMR'), the analysis of exchange across multiple chemical shift evolution periods has received less attention. Here we report that chemical exchange-induced cross-peaks can arise in even the simplest two-dimensional NMR experiments. These cross-peaks can have highly distorted phases that contain rich information about the underlying exchange process. The quantitative analysis of such peaks, from a single 2D spectrum, can provide a highly accurate characterization of underlying exchange processes. | Chris Waudby; Tom Frenkiel; John Christodoulou | Biophysics; Theory - Computational; Chemical Kinetics; Physical and Chemical Processes; Quantum Mechanics; Spectroscopy (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2019-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740adf96a00f555286322/original/cross-peaks-in-simple-2d-nmr-experiments-from-chemical-exchange-of-transverse-magnetization.pdf |
60c74f58702a9ba8dc18bb6b | 10.26434/chemrxiv.12885494.v1 | NPClassifier: A Deep Neural Network-Based Structural Classification Tool for Natural Products | <div>
<div>
<div>
<p>Computational approaches such as genome and metabolome mining are becoming essential to
natural products (NP) research. Consequently, demands for automated NP classification system
for massive data are increasing. The semantic ontology of NPs classifies molecules based on
the taxonomy of the producing organism, the nature of the biosynthetic pathway, their
biological properties, as well as the presence of chemical substructures. Thus, a holistic and
automatic NP classification framework could have considerable value to comprehensively
navigate the relatedness of NPs. Here, we introduce NPClassifier, the first deep-learning tool
for the automated structural classification of NPs. We expect that NPClassifier will accelerate
NP discovery by facilitating and enabling large-scale genome and metabolome mining efforts
and linking of NP structures to their underlying bioactivity.
</p>
</div>
</div>
</div> | Hyunwoo kim; Mingxun Wang; Christopher Leber; Louis-Felix Nothias; Raphael Reher; Kyo Bin Kang; Justin J. J. van der Hooft; Pieter Dorrestein; William Gerwick; Garrison Cottrell | Natural Products; Bioinformatics and Computational Biology | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f58702a9ba8dc18bb6b/original/np-classifier-a-deep-neural-network-based-structural-classification-tool-for-natural-products.pdf |
6531da85c3693ca993ae1f35 | 10.26434/chemrxiv-2023-csptk | Access to multifunctionalized tetrasubstituted carbon centers bearing up to three different heteroatoms via tandem geminal chlorofluorination of 1,2-dicarbonyl compounds | The incorporation of non-carbon heteroatoms into organic molecules typically instills characteristic and often valuable functionalities. The co-presence of different heteroatoms can further broaden their utility through the synergistic cooperative effects, which may even lead to the discovery of formerly unavailable properties that are not just a simple accumulation of each function. However, despite the increasing interest in the controllable installation of heteroatoms, it has been extremely challenging to construct carbon centers having three different heteroatoms in a synthetically useful manner. In this work, our group’s tandem geminal chlorofluorination (Cl, F) strategy was applied to rationally designed heteroatom-bearing 1,2-dicarbonyl substrates including α-keto thioesters (S), α-keto N-acylindole (N), and α-keto acylsilane (Si), resulting in the practical production of doubly or triply hetero-functionalized tetrasubstituted carbon centers with excellent site-selectivity. | Ha Eun Kim; Mugeon Song; Sunjoo Hwang; Won-jin Chung | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6531da85c3693ca993ae1f35/original/access-to-multifunctionalized-tetrasubstituted-carbon-centers-bearing-up-to-three-different-heteroatoms-via-tandem-geminal-chlorofluorination-of-1-2-dicarbonyl-compounds.pdf |
67316fabf9980725cfc7e199 | 10.26434/chemrxiv-2024-16j0s-v2 | Nanodroplets of Metal Carbonate Conform to Critical Nuclei of Classical Nucleation Theory | Mineral nucleation is a fundamental process of paramount importance to various fields, including geology, biomineralization, and industrial manufacturing. Recently, studies on the biominerals of calcium carbonate and phosphate have revealed the presence of a dense liquid phase prior to the formation of an amorphous solid phase. However, there is vigorous debate on whether the nucleation of calcium carbonate clusters can be adequately described by the classical nucleation theory (CNT) or if one must turn to the non-classical nucleation theory. Here, we show that liquid-liquid phase separation (LLPS) occurs in a non-aqueous solution where magnesium and calcium carbonates are dissolved in ethanol with excess triethylamine. The nanodroplets can be kinetically trapped by triethylamine. The size and number of the nanodroplets, in the vicinity of critical nuclei, can be adequately described within the framework of CNT. We found that bicarbonate-like species formed by triethylamine, CO2, and ethanol molecules are in constant exchange with sizable carbonate clusters. Our results demonstrate that the concepts of critical nuclei and the energy barrier of nucleation are indeed physically relevant. We argue that nanodroplets comprising highly solvated carbonate clusters are the key entities in the nucleation process, which falls within the realm of CNT. | Shu Li Li; Lin Yi-Tan; Hsi-Ching Tseng; Yuan-Jia Fan; Shing-Jong Huang; Eric Chung-Yueh Yuan; Chun-Yi David Lu; Jerry Chun Chung Chan | Materials Science; Biological Materials | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67316fabf9980725cfc7e199/original/nanodroplets-of-metal-carbonate-conform-to-critical-nuclei-of-classical-nucleation-theory.pdf |
60c740e89abda26e65f8bdaf | 10.26434/chemrxiv.7885760.v1 | A General Fitting Function to Estimate Apparent Reaction Orders of Kinetic Profiles | The rapid development of analytical methods in recent decades has resulted in a wide range of readily available and accurate reaction-monitoring techniques, which allow for easy determination of high-quality concentration-time data of chemical reactions. However, while the acquisition of kinetic data has become routine in the development of new chemical reactions and the study of their mechanisms, not all the information contained therein is utilized because of a lack of suitable analysis tools which unnecessarily complicates mechanistic studies. Herein, we report on a general method to analyze a single concentration-time profile of chemical reactions and extract information regarding the reaction order with respect to substrates, the presence of multiple kinetic regimes, and the presence of kinetic complexities, such as catalyst deactivation, product inhibition, and substrate decomposition.<br /> | Robert Pollice | Heterogeneous Catalysis; Homogeneous Catalysis; Reaction (Organomet.); Chemical Kinetics | CC BY NC ND 4.0 | CHEMRXIV | 2019-03-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740e89abda26e65f8bdaf/original/a-general-fitting-function-to-estimate-apparent-reaction-orders-of-kinetic-profiles.pdf |
60dc7f047d46cd2012fab870 | 10.26434/chemrxiv-2021-28tq5 | The min-max test: an objective method for discriminating mass spectra | Deciding whether the mass spectra of seized drug evidence and a reference standard are measurements of two different compounds is a central challenge in forensic chemistry. Normally, an analyst will compute a mass spectral similarity score between spectra from the sample and reference and make a judgment using both the score and their visual interpretation of the spectra. This approach is inherently subjective and not ideal when rapid assessment of several samples is necessary. Making decisions using only the score and a threshold value greatly improves analysis throughput and removes analyst-to-analyst subjectivity, but selecting an appropriate threshold is itself a non-trivial task. In this manuscript, we describe and evaluate the min max test – a simple and objective method for classifying mass spectra that leverages replicate measurements from each sample to remove analyst subjectivity. We demonstrate that the min max test has an intuitive interpretation for decision-making, and its performance exceeds thresholding with similarity scores even when the best performing threshold for a fixed dataset is prescribed. Determining whether the underlying framework of the min-max test can incorporate retention indices for objectively deciding whether spectra are measurements of the same compound is on-going work. | Arun Moorthy; Edward Sisco | Analytical Chemistry; Chemoinformatics; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2021-07-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60dc7f047d46cd2012fab870/original/the-min-max-test-an-objective-method-for-discriminating-mass-spectra.pdf |
64871a854f8b1884b73004d4 | 10.26434/chemrxiv-2023-zx95t | Charting the CO2 capture performance of a phase-change metal-organic framework in a pressure-vacuum swing adsorption process | Metal-organic frameworks (MOFs) that display step-shaped adsorption isotherms, i.e., phase-change MOFs, represent a relatively small subset of all known MOFs. Yet, they are rapidly emerging as promising sorbents to achieve excellent gas separation performances with little energy demand. In this work, we assessed F4_MIL-140A(Ce), a recently discovered phase-change MOF adsorbent for CO2 capture in two scenarios using a pressure-vacuum swing adsorption process, namely a coal-fired power plant flue gas (12.5 %mol CO2), and a steel plant flue gas (25.5 %mol CO2). Four CO2 and three N2 adsorption isotherms were collected on F4_MIL-140A(Ce) over a range of temperatures and modelled using a bespoke equation for step-shaped isotherms. We accurately measured the heat capacity of F4_MIL-140A(Ce), a key thermodynamic property for a sorbent, using a method based on differential scanning calorimetry that overcomes the issues associated with the poor thermal conductivity of MOF powders. We then used these experimental data as input in a process optimisation framework and we compared the CO2 capture performance of F4_MIL-140A(Ce) to that of other “canonical” sorbents, including, zeolite 13X, activated carbon and three MOFs (i.e., HKUST-1, UTSA-16 and CALF-20). We found that F4_MIL-140A(Ce) outranks other sorbents, in terms of recovery and purity, in most of the simulated process conditions. We attribute such promising performance to the non-hysteretic step-shaped isotherm, the low uptake capacity for N2 and the mild heat of CO2 adsorption displayed by F4_MIL-140A(Ce). | David Danaci; Elena Pulidori; Luca Bernazzani; Camille Petit; Marco Taddei | Physical Chemistry; Chemical Engineering and Industrial Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64871a854f8b1884b73004d4/original/charting-the-co2-capture-performance-of-a-phase-change-metal-organic-framework-in-a-pressure-vacuum-swing-adsorption-process.pdf |
64f7849bdd1a73847f421656 | 10.26434/chemrxiv-2023-hrpvd | Bacterial natural product discovery by heterologous expression | Natural products have found important applications in the pharmaceutical and agricultural sectors. In bacteria, the genes that encode the biosynthesis of natural products are often colocalized in the genome, forming biosynthetic gene clusters. It has been predicted that only 3% of natural products encoded in bacterial genomes have been discovered thus far, in part because gene clusters may be poorly expressed under laboratory conditions. Heterologous expression can help realize bioinformatics predictions into products. However, challenges remain such as gene cluster prioritization, cloning of the complete gene cluster, appropriate expression, product identification, and isolation of products in practical yields. Here we reviewed the literature from the past five years (January 2018 to June 2023) to identify studies that discovered natural products by heterologous expression. From the 50 studies identified, we present analyses of the rationale for gene cluster prioritization, cloning methods, biosynthetic class, source taxa, and host choice. Combined, the 50 studies led to the discovery of 63 new families of natural products, supporting heterologous expression as a promising way to access novel chemistry. However, the success rate of natural product detection varied from 11% to 32% based on four large-scale studies that were identified. The low success rate makes it apparent that much remains to be improved. The potential reasons for failure and points to be considered to improve the chances of success are discussed. | Adjo Kadjo; Alessandra Eustaquio | Biological and Medicinal Chemistry; Bioengineering and Biotechnology | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64f7849bdd1a73847f421656/original/bacterial-natural-product-discovery-by-heterologous-expression.pdf |
611c281f58eb569338926cc9 | 10.26434/chemrxiv-2021-mmvwx-v2 | Short and Long-Range Electron Transfer Compete to Determine Free-Charge Yield in Organic Semiconductors | Understanding how Frenkel excitons efficiently split to form free-charges in low-dielectric constant organic semiconductors has proven challenging, with many different models proposed in recent years to explain this phenomenon. Here, we present evidence that a simple model invoking a modest amount of charge delocalization, a sum over the available microstates, and the Marcus rate constant for electron transfer can explain many seemingly contradictory phenomena reported in the literature. We use an electron-accepting fullerene host matrix dilutely sensitized with a series of electron donor molecules to test this hypothesis. The donor series enables us to tune the driving force for photoinduced electron transfer over a range of 0.7 eV, mapping out normal, optimal, and inverted regimes for free-charge generation efficiency, as measured by time-resolved microwave conductivity. However, the photoluminescence of the donor is rapidly quenched as the driving force increases, with no evidence for inverted behavior, nor the linear relationship between photoluminescence quenching and charge-generation efficiency one would expect in the absence of additional competing loss pathways. This behavior is self-consistently explained by competitive formation of bound charge-transfer states and long-range or delocalized free-charge states, where both rate constants are described by the Marcus rate equation. Moreover, the model predicts a suppression of the inverted regime for high-concentration blends and efficient ultrafast free-charge generation, providing a mechanistic explanation for why Marcus-inverted-behavior is rarely observed in device studies. | Joshua M. Carr; Taylor G. Allen; Bryon W. Larson; Iryna G. Davydenko; Raghunath R. Dasari; Stephen Barlow; Seth R. Marder; Obadiah G. Reid; Garry Rumbles | Physical Chemistry; Materials Science; Energy; Photovoltaics; Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/611c281f58eb569338926cc9/original/short-and-long-range-electron-transfer-compete-to-determine-free-charge-yield-in-organic-semiconductors.pdf |
60d9fcdf2616116c338cb080 | 10.26434/chemrxiv-2021-bcml2 | Structured Liquid Batteries | Here we describe structured liquid batteries, whose membranes self-form via coacervation of polyelectrolytes. The membrane serves as an ion conductor, a physical barrier, and a structural support. Complexation of redox-active small molecules with their complementary polyelectrolyte also mitigates the crossover. The reconfigurability of liquids allows the cell to conform to prescribed patterns and the cells are rechargeable for hundreds of hours. | Jiajun Yan; Thomas Russell; Brett Helms | Materials Science; Polymer Science; Polyelectrolytes - Polymers; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-06-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60d9fcdf2616116c338cb080/original/structured-liquid-batteries.pdf |
65ba5075e9ebbb4db95aa4e9 | 10.26434/chemrxiv-2024-wqjcw | Easy access to high-melting sulfurated copolymers and their self-assembling block polymers
from phenylisothiocyanate and oxetane | Although sulfurated polymers promise unique properties, their controlled synthesis, particularly when it
comes to complex and functional architectures, remains challenging. Here, we show that the copolymerization of
oxetane and phenyl isothiocyanates quantitatively forms polythioimidocarbonates with narrow molecular weight
distributions (Mn = 5–80 kg/mol with Đ ≤ 1.2; Mn,max = 124 kg/mol). Studying their thermal properties through a
specially developed self-nucleation procedure, high melting points up to 181 ºC are revealed for which π-stacking
phenyl substituents and kinetically controlled linkage selectivity are key factors. Tolerance to macro-chain transfer
agents and controlled propagation allows the synthesis of double crystalline and amphiphilic block copolymers that
enables application in crystallization-driven self-assembly, an unventured territory for sulfurated copolymers. | Jenny Stephan; Jorge Olmedo-Martínez; Mathias Dimde; Daniel Braatz; Robert Langer; Alejandro Müller; Holger Schmalz; Alex Plajer | Polymer Science | CC BY 4.0 | CHEMRXIV | 2024-02-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65ba5075e9ebbb4db95aa4e9/original/easy-access-to-high-melting-sulfurated-copolymers-and-their-self-assembling-block-polymers-from-phenylisothiocyanate-and-oxetane.pdf |
61d47f995b23d4982b141453 | 10.26434/chemrxiv-2022-lg7h8 | Visualizing the Avogadro Number | Background
On the occasion of the redefinition of the Avogadro constant in May 2019, a brief history and some didactic reflections on its magnitude are presented.
Purpose
Some analogies are reviewed and others are suggested to help visualize the extent of its magnitude, and their usefulness is assessed.
Design/Method
These analogies are set in the teaching context of the first and second courses of the degrees in several scientific and technic disciplines. Their effectiveness is discussed for the first time on the basis of a questionnaire filled by the corresponding students.
Results
The suggestions for educating and learning are that the most helpful models, following the opinion of the students, are those related to more substantial items, for example, neurons, individuals, planets, above analogies on geometric constructions.
Conclusions
Challenging current thought, pictorial descriptions are not all the times so advantageous.
| Jesus Vicente de Julián-Ortiz; Lionello Pogliani; Emili Besalú | Chemical Education; Chemical Education - General | CC BY NC 4.0 | CHEMRXIV | 2022-02-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d47f995b23d4982b141453/original/visualizing-the-avogadro-number.pdf |
60c745bc469df4d081f43543 | 10.26434/chemrxiv.10208717.v1 | The Isolation of Pyrroloformamide Congeners and Characterization of Its Biosynthetic Gene Cluster from Streptomyces sp. CB02980 Revealed a Unified Mechanism for Dithiolopyrrolone Biosynthesis | Dithiolopyrrolones are microbial natural products containing a disulfide or thiosulfonate bridge embedded in a unique bicyclic structure. In the current study, two new dithiolopyrrolones, pyrroloformamide C (<b>3</b>) and pyrroloformamide D (<b>4</b>), were isolated from <i>Streptomyces </i>sp. CB02980, together with the known pyrroloformamides <b>1 </b>and <b>2</b>. The biosynthetic gene cluster for pyrroloformamides was identified from <i>S</i>. sp. CB02980, which shared high sequence similarity with those of dithiolopyrrolones, including holomycin and thiolutin. Gene replacement of pyfE, which encodes a non-ribosomal peptide synthetase, abolished the production of <b>1</b>－<b>4</b>. Overexpression of <i>pyfN</i>, a type II thioesterase gene, increased the production of <b>1</b> and <b>2</b>. The structure elucidation and biosynthetic characterization of pyrroloformamides <b>1</b> - <b>4</b> may inspire future efforts to discover new dithiolopyrrolones, which are promising drug leads for the treatment of infectious diseases or cancer. | Wenqing Zhou; Haoyu Liang; Xiangjing Qin; Danfeng Cao; Xiangcheng Zhu; Jianhua Ju; Ben Shen; Yanwen Duan; Yong Huang | Natural Products | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745bc469df4d081f43543/original/the-isolation-of-pyrroloformamide-congeners-and-characterization-of-its-biosynthetic-gene-cluster-from-streptomyces-sp-cb02980-revealed-a-unified-mechanism-for-dithiolopyrrolone-biosynthesis.pdf |
60c74646567dfe2a53ec45cf | 10.26434/chemrxiv.11288675.v1 | Nickel(II)-Methyl Complexes Adopting Idealized Seesaw Geometries | We report four-coordinate
nickel(II)-methyl complexes of tris-carbene borate ligands which adopt rare seesaw
geometries. Experimental and computational results suggest the structural
distortion from threefold symmetry results from a combination of electronic
stabilization of the singlet state, strong field donors, and constrained angles
from the chelating ligand. | Ethan A. Hill; Norman Zhao; Alexander S. Filatov; John Anderson | Coordination Chemistry (Inorg.); Organometallic Compounds; Transition Metal Complexes (Inorg.); Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74646567dfe2a53ec45cf/original/nickel-ii-methyl-complexes-adopting-idealized-seesaw-geometries.pdf |
60c74f7f469df4b057f446d0 | 10.26434/chemrxiv.12909887.v1 | Why Is THCA Decarboxylation Faster than CBDA? an in Silico Perspective | Tetrahydrocannabinol
acid (THCA) and cannabidiol acid (CBDA), the two crucial organic components in
cannabis and hemp, decarboxylate at different rates to their more active
neutral forms. Theoretical calculations are used herein to analyze how the
remote annulated ring or pendant substituent influences the rate determining steps
of the decarboxylation processes. The uncatalyzed keto-enol tautomerization
that precedes decarboxylation is found to be extremely slow in both cases
albeit with a ten-fold preference for CBDA. A single molecule of methanol
dramatically enhances the reaction rates by allowing for tautomerization
through a more favorable six-membered ring transition state. Methanol-catalyzed
tautomerization is found to be faster in THCA than in CBDA. This difference
results from both the larger dipole moment of the THCA scaffold as well as its
greater rigidity relative to CBDA. The greater dipole moment leads to a
somewhat better binding of methanol. The lower entropic penalty in THCA towards
tautomerization leads to faster decarboxylation. | Weiying He; Paul J. Foth; Markus Roggen; Glenn M. Sammis; Pierre Kennepohl | Physical Organic Chemistry; Process Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f7f469df4b057f446d0/original/why-is-thca-decarboxylation-faster-than-cbda-an-in-silico-perspective.pdf |
64b01425ae3d1a7b0d9d9afa | 10.26434/chemrxiv-2023-6gdwh | Finite difference representation of information-theoretic approach in density functional theory | Using density-based quantities to establish a qualitative or even quantitative framework to predict molecular reactivity in density functional theory is of considerable interest in the current literature. Recent developments in information-theoretic approach (ITA) represent such a trend. Traditionally, we represent ITA quantities in terms of the electron density, shape function, and atoms in molecules. In this contribution, we expand the theoretical framework of ITA by introducing a new representation. To that end, we make use of the first-order partial derivative of ITA quantities with respect to the number of total electrons and then approximate them in the finite difference approximation. The new representation has both local (three-dimensional) and global (condensed to atoms) versions. Its close relationship with Fukui function from conceptual density functional theory was derived analytically and confirmed numerically. Extensions of our present approach to include other types of derivatives are discussed. This work not only enriches the theoretical framework of ITA with a new representation, but also provides opportunities to expand its territory as well as the scope of its applicability in dealing with molecular processes and chemical reactivity from a new perspective. | Chunna Guo; Meng Li; Chunying Rong; Shubin Liu | Theoretical and Computational Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-07-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b01425ae3d1a7b0d9d9afa/original/finite-difference-representation-of-information-theoretic-approach-in-density-functional-theory.pdf |
6645e318418a5379b06e7b15 | 10.26434/chemrxiv-2024-g3s0h | A comprehensive review on biomethane production from biogas separation and its techno-economic assessments | Biogas offers significant benefits as a renewable energy source, contributing to decarbonization, waste management, and economic development. This comprehensive review examines the historical, technological, economic, and global aspects of biomethane production, focusing on the key players such as China, the European Union, and North America, and associated opportunities and challenges as well as future prospects from an Australia perspective. The review begins with an introduction to biogas, detailing its composition, feedstock sources, historical development, and anaerobic digestion (AD) process. Subsequently, it delves into major biomethane production technologies, including physicochemical absorption, high-pressure water scrubbing (HPWS), amine scrubbing (AS), pressure swing adsorption (PSA), membrane permeation/separation (MP), and other technologies including organic solvent scrubbing and cryogenic separation. The study also discusses general guidelines of techno-economic assessments (TEAs) regarding biomethane production, outlining the methodologies, inventory analysis, environmental life cycle assessment (LCA), and estimated production costs. Challenges and opportunities of biogas utilization in Australia are explored, highlighting and referencing global projections, polarization in production approaches, circularity in waste management, and specific considerations for Australia. The review concludes discussing future perspectives for biomethane, emphasizing the importance of technological advancements, policy support, and investment in realizing its full potential for sustainable energy and waste management solutions. | Ross SWINBOURN; Chaoen Li; Feng Wang | Materials Science; Energy; Chemical Engineering and Industrial Chemistry | CC BY NC 4.0 | CHEMRXIV | 2024-05-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6645e318418a5379b06e7b15/original/a-comprehensive-review-on-biomethane-production-from-biogas-separation-and-its-techno-economic-assessments.pdf |
629eb7f3d18cdfde8951ffff | 10.26434/chemrxiv-2022-fjlf3-v2 | Direct Hydroxylarylation of Benzylic Carbons (sp3/sp2/sp) via Radical-Radical Cross-Coupling Powered by Paired Electrolysis | Diaryl alcohol moieties are widespread in pharmaceuticals. Existing methods for the synthesis of diaryl alcohols require the use of pre-functionalized benzylic alcohols, aromatic aldehydes or ketones as starting materials. Herein, the first convergent paired electrochemical approach to the direct hydroxylarylation of unactivated benzylic carbons (sp3/sp2/sp) is declared. This protocol features direct functionalization of unactivated benzylic C(sp3)–H bonds and benzylic sp2/sp-carbons, mild conditions (open air, room temperature), environmentally friendly procedure (without any external catalyst/mediator/additive), and direct access to sterically hindered alcohols from inexpensive and readily available alkyl/alkenyl/alkynylbenzenes. Mechanistic studies, including divided-cell experiments, isotope labeling, radical trapping, electron paramagnetic resonance (EPR), reaction kinetics, and cyclic voltammetry, strongly support the proposed radical-radical cross-coupling between transient ketyl radicals and persistent radical anions. Gram-scale synthesis and diversification of drug derivative have visualized the tremendous potential of this protocol for practical applications. | Xiao-Wen Wang; Rui-Xue Li; Yang Deng; Zhi Guan; Chu-Sheng Huang; Yan-Hong He | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629eb7f3d18cdfde8951ffff/original/direct-hydroxylarylation-of-benzylic-carbons-sp3-sp2-sp-via-radical-radical-cross-coupling-powered-by-paired-electrolysis.pdf |
6401d4429789de3dd9d886b7 | 10.26434/chemrxiv-2023-1kqm3 | Inverse design of viral infectivity-enhancing peptide fibrils from continuous protein-vector embeddings | Amyloid-like nanofibers from self-assembling peptides can promote viral gene transfer for therapeutic applications. Traditionally, new sequences are discovered either from screening large libraries or by creating derivatives of known active peptides. However, the discovery of de novo peptides, which are sequence-wise not related to any known active peptides, is limited by the difficulty to rationally predict structureactivity relationships because their activities typically have multi-scale and multi-parameter dependencies. Here, we used a small library of 163 peptides to predict de novo sequences for viral infectivity enhancement using a machine learning (ML) approach based on natural language processing. Specifically, we trained an ML model using continuous vector representations of the peptides, which were previously shown to retain relevant information embedded in the sequences. We used the trained ML model to sample the sequence space of peptides with 6 amino acids to identify promising candidates. These 6-mers were then further screened for charge and aggregation propensity. The resulting 16 new 6-mers were tested and found to be active with a 25% hit rate. Strikingly, these de novo sequences are the shortest active peptides for infectivity enhancement reported so far and show no sequence relation to the training set. Moreover, by screening the chemical space, we discovered the first hydrophobic peptide fibrils with a moderately negative surface charge that can enhance infectivity. Hence, this ML strategy is a time- and cost-efficient way for expanding the chemical space of short functional self-assembling peptides exemplified for therapeutic viral gene delivery. | Kübra Kaygisiz; Arghya Dutta; Lena Rauch-Wirth; Christopher V. Synatschke; Jan Münch; Tristan Bereau ; Tanja Weil | Theoretical and Computational Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Machine Learning; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6401d4429789de3dd9d886b7/original/inverse-design-of-viral-infectivity-enhancing-peptide-fibrils-from-continuous-protein-vector-embeddings.pdf |
672105f55a82cea2fa36a053 | 10.26434/chemrxiv-2024-0npph-v2 | A Highly Efficient Ferulic Acid Decarboxylase from Capronia coronata: Characterization and Biocatalytic Applications | Ferulic acid decarboxylases (FDCs) are versatile biocatalysts that catalyze reversible (de)carboxylation of unsaturated aromatic and aliphatic compounds, holding significant potential for applications in biocatalytic decarboxylation reactions and in CO2 conversion into chemicals. In this study, we characterized the FDC from Capronia coronata (CcFDC) with a focus on its activity, kinetic properties, substrate specificity, and carboxylation potential. The enzyme exhibited a high turnover frequency (TOF) of 1857 min⁻¹ and a total turnover number (TTN) of 110,013 for trans-cinnamic acid, suggesting strong productivity for decarboxylation to yield biostyrene. Substrate profiling revealed a broad substrate scope, with CcFDC demonstrating activity toward several cinnamic acid derivatives and lignin-derived compounds. Molecular docking studies supported these findings by identifying key structural features that influence substrate binding and activity. Importantly, CcFDC was shown to facilitate the carboxylation of styrene and furoic acids under mild conditions using bicarbonate as a carbon source, leading to detectable amounts of carboxylation products, suggesting a potential biocatalyst to mediate conversion of CO2 into commodity chemicals. | Frederik Vig Benfeldt; Fang Wang; Nicoline Bredahl; Renjun Gao; Zheng Guo; Bekir Engin Eser | Biological and Medicinal Chemistry; Catalysis; Biochemistry; Bioengineering and Biotechnology; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672105f55a82cea2fa36a053/original/a-highly-efficient-ferulic-acid-decarboxylase-from-capronia-coronata-characterization-and-biocatalytic-applications.pdf |
623840f7a4ed95cf5427b23e | 10.26434/chemrxiv-2022-8r3bv | Solution [2 + 2] photopolymerization of biomass-derived nonrigid monomers enabled by energy transfer catalysis | The [2 + 2] photopolymerization has been known for more than fifty years and widely applied in many fields. However, this process was typically conducted in solid state, while the corresponding [2 + 2] photopolymerization of simple non-rigid diolefinic monomers were rarely achieved in solution under visible light, owing to the lack of monomer preassembly and low/no absorption of visible light. In fact, the [2 + 2] photopolymerization of simple biscinnamate monomers remains an unsolved problem. Here, we demonstrate that energy transfer catalysis could overcome the low efficiency in the intersystem crossing to triplet states of monomers, and enable the [2 + 2] photopolymerization of biomass-derived biscinnamate monomers in solution for the first time. As no preassembly is required, this solution polymerization protocol is applicable to biscinnamate monomers with different linker structures, and allows copolymerization between different biscinnamate monomers to regulate polymer mechanical properties. A series of cyclobutane-imbedded polyesters (Mw ranged from 25.3 kDa to 61.3 kDa) become accessible, which shown excellent solubility in organic solvents and good processability, in sharp contrast to the properties of the biscinnamate polymers obtained before via the solid state photopolymerization methods. | Yu Jiang; Qiang Ma; Xun Zhang; Junfang Li; Saihu Liao | Catalysis; Polymer Science; Polymerization (Polymers); Homogeneous Catalysis; Photocatalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/623840f7a4ed95cf5427b23e/original/solution-2-2-photopolymerization-of-biomass-derived-nonrigid-monomers-enabled-by-energy-transfer-catalysis.pdf |
60c75218469df44fe7f44afa | 10.26434/chemrxiv.13251356.v1 | H2S Stability of Metal-Organic Frameworks: A Computational Assessment | <p>The
H<sub>2</sub>S stability of a range of MOFs was systematically assessed by first-principle
calculations. The most likely degradation mechanism was first determined and we
identified the rate constant of the degradation reaction as a reliable
descriptor for characterizing the H<sub>2</sub>S stability of MOFs. A
qualitative H<sub>2</sub>S stability ranking was thus established for the list
of investigated materials. Elemental structure-stability relationships were
further envisaged considering several variables including the nature of the linkers
and their grafted functional groups, the pore size, the nature of metal sites and
the presence/nature of coordinatively unsaturated sites. This knowledge enabled
the anticipation of the H<sub>2</sub>S stability of one prototypical MOF, e.g. MIL-91(Ti),
which has been previously proposed as a good candidate for CO<sub>2</sub>
capture. This computational strategy enables an accurate and easy handling
assessment of the H<sub>2</sub>S stability of MOFs and offers a solid
alternative to experimental characterizations that require the manipulation of
a highly toxic and corrosive molecule. </p> | Pengbo Lyu; Guillaume Maurin | Organometallic Compounds; Kinetics and Mechanism - Organometallic Reactions; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75218469df44fe7f44afa/original/h2s-stability-of-metal-organic-frameworks-a-computational-assessment.pdf |
60c758740f50db4bad398447 | 10.26434/chemrxiv.14546901.v1 | Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling | <b>Whereas considerable advances have recently been achieved in radical-involved
catalytic asymmetric C-N bond formation, there has been little progress in the corresponding
C-O bond-forming processes. Here we describe a photoinduced copper-catalyzed
cross-coupling of readily oxime esters and 1,3-dienes to generate diversely
substituted allylic esters with high regio- and enantioselectivity (>75
examples; up to 95% ee). The reaction proceeds at room temperature under
excitation by purple light-emitting diodes and features the use of a single, earth-abundant
copper-based chiral catalyst as both the photoredox catalyst for radical
generation and the source of asymmetric induction in C-O coupling. Combined experimental
and DFT computational studies suggest the formation of π-allylcopper complex from redox-active oxime esters as bifunctional
reagents and 1,3-dienes through a radical-polar crossover process.</b> | Jun Chen; Yu-Jie Liang; Peng-Zi Wang; Guo-Qing Li; Bin Zhang; Hao Qian; Xiao-Die Huan; Wei Guan; Wen-Jing Xiao; Jia-Rong Chen | Photochemistry (Org.); Stereochemistry; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758740f50db4bad398447/original/photoinduced-copper-catalyzed-asymmetric-c-o-cross-coupling.pdf |
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