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61a7687b6d4e8f850aa5f602 | 10.26434/chemrxiv-2021-mr3p9 | Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios | The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees antibody-to-drug (DAR) ratios, in particular on native antibodies. Here we report a glycoengineering methodology to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel-Michael addition chemistry. This three step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions. | Antonio Angelastro; Alexey Barkhanskiy; Ashley P. Mattey; Edward G. Pallister; Reynard Spiess; William Goundry; Perdita Barran; Sabine L. Flitsch | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61a7687b6d4e8f850aa5f602/original/galactose-oxidase-enables-modular-assembly-of-conjugates-from-native-antibodies-with-high-drug-to-antibody-ratios.pdf |
60c752c2702a9b761a18c218 | 10.26434/chemrxiv.13340942.v1 | Multiscale Simulations of SARS-CoV-2 3CL Protease Inhibition with Aldehyde Derivatives. Role of Protein and Inhibitor Conformational Dynamics in the Reaction Mechanism | <p>We here investigate the mechanism of SARS-CoV-2 3CL protease inhibition by one of the most promising families of inhibitors, those containing an aldehyde group as warhead. These compounds are covalent inhibitors that inactivate the protease forming a stable hemithioacetal complex. Inhibitor 11a is a potent inhibitor that has been already tested in vitro and in animals. Using a combination of classical and QM/MM simulations we determined the binding mode of the inhibitor into the active site and the preferred rotameric state of the catalytic histidine. In the noncovalent complex the aldehyde group is accommodated into the oxyanion hole formed by the NH main chain groups of residues 143 to 145. In this pose, P1-P3 groups of the inhibitor mimic the interactions established by the natural peptide substrate. The reaction is initiated with the formation of the catalytic dyad ion pair after a proton transfer from Cys145 to His41. From this activated state, covalent inhibition proceeds with the nucleophilic attack of the deprotonated Sg atom of Cys145 to the aldehyde carbon atom and a water mediated proton transfer from the Ne atom of His41 to the aldehyde oxygen atom. Our proposed reaction transition state structure is validated by comparison with x-ray data of recently reported inhibitors, while the activation free energy obtained from our simulations agrees with the experimentally derived value, supporting the validity of our findings. Our study stresses the interplay between the conformational dynamics of the inhibitor and the protein with the inhibition mechanism and the importance of including conformational diversity for accurate predictions about the inhibition of the main protease of SARS-CoV-2. The conclusions derived from our work can also be used to rationalize the behavior of other recently proposed inhibitor compounds, including aldehydes and ketones with high inhibitory potency.</p> | Carlos A. Ramos-Guzmán; J. Javier Ruiz-Pernía; Iñaki Tuñón | Biochemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752c2702a9b761a18c218/original/multiscale-simulations-of-sars-co-v-2-3cl-protease-inhibition-with-aldehyde-derivatives-role-of-protein-and-inhibitor-conformational-dynamics-in-the-reaction-mechanism.pdf |
623ba6435c8dae6c93f4a0c8 | 10.26434/chemrxiv-2021-dgb6l-v4 | Highly Active Platinum Single-Atom Catalyst grafted onto 3D Carbon Cloth Support for the Electrocatalytic Hydrogen Evolution Reaction | Platinum single-atom catalysts (PtSACs) on 3D support are emerging as the new frontier in catalysis due to their atom-economy, outstanding performance, and the advantage to bridge the gap between homogeneous and heterogeneous catalysis. Here we report on a simple, single-step electrochemical grafting attachment of a metal-selective ligand, 2,6:2’,2”-terpyridine, and the synthesis of platinum single-atom electrocatalyst via metal uptake from aqueous salt solution. At an ultra-low loading of 0.26 ±0.02 μgcm-2 of platinum, the single-atom catalysts supported on porous 3D carbon cloth electrode via chemical bonding revealed higher mass activity ratios, up to 83.0 at η = 50 mV/RHE, compared to the commercial catalyst 20 % Pt/C. Using hydrogen binding energy as the descriptor for efficiency, density functional theory calculations show that promoting hydrogen evolution using terpyridine-Pt proceeds when the catalyst is in a 2+ charge state and with a single hydroxy co-ligand attached to Pt catalytic center. Calculations predict an HER overpotential of about 0.28 V. The electro-grafted terpyridine ligand proved to act as effective scavenger for leached platinum from the counter electrode during extended operational hours. The method to make the PtSAC is facile, non-hazardous and versatile without involving any elaborate pre- and/or post-treatment steps and, the cost of the added platinum to the ligand is only 0.1 US$m-2. | Po-Wei Yu; Sait Elmas; Tanglaw Roman; Xun Pan; Yanting Yin; Christopher T. Gibson; Gunther G. Andersson; Mats R. Andersson | Materials Science; Catalysis; Energy; Electrocatalysis; Heterogeneous Catalysis; Fuel Cells | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/623ba6435c8dae6c93f4a0c8/original/highly-active-platinum-single-atom-catalyst-grafted-onto-3d-carbon-cloth-support-for-the-electrocatalytic-hydrogen-evolution-reaction.pdf |
663a27f721291e5d1da84172 | 10.26434/chemrxiv-2024-mshjh | Truncations and in silico Docking to Enhance the Analytical Response of Aptamer-Based Biosensors | Aptamers are short oligonucleotides capable of binding specifically to various targets (i.e., small molecules, proteins, and whole cells) which have been introduced in biosensors such as in the electrochemical aptamer-based (E-AB) sensing platform. E-AB sensors are comprised of a redox-reporter-modified aptamer attached to an electrode that undergoes, upon target addition, a binding-induced change in electron transfer rates. To date, E-AB sensors have faced a limitation in the translatability of aptamers into the sensing platform presumably because sequences obtained from Systematic Evolution of Ligands by Exponential Enrichment (SELEX) are typically long (> 80 nucleotides) and that obtaining structural information remains time and resource consuming. In response, we explore the utility of aptamer base truncations and in silico docking to improve their translatability into E-AB sensors. Here, we first apply this to the glucose aptamer, which we characterize in solution using NMR methods to guide design and translate truncated variants in E-AB biosensors. We further investigated applicability of the truncation and computational approaches to five other aptamer systems (vancomycin, cocaine, methotrexate, theophylline, and ochratoxin A) from which we derived functional E-AB sensors. We foresee that our strategy will increase the success rate of translating aptamers into sensing platforms to afford low-cost measurements of molecules directly in undiluted complex matrices. | Minh-Dat Nguyen; Meghan Osborne; Guy Terence Prevot; Zachary Churcher; Philip Johnson; Lena Simine; Philippe Dauphin Ducharme | Biological and Medicinal Chemistry; Analytical Chemistry; Electrochemical Analysis; Bioengineering and Biotechnology; Biophysics | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/663a27f721291e5d1da84172/original/truncations-and-in-silico-docking-to-enhance-the-analytical-response-of-aptamer-based-biosensors.pdf |
64463457e4bbbe4bbf2b45a6 | 10.26434/chemrxiv-2023-q4bfm-v2 | Selective oxidation of methane to methanol over Au/H-MOR | Selective oxidation of methane to methanol by molecular oxygen is a fascinating route for upgrading abundant methane resource and represents one of the most challenging reactions in chemistry due to the overwhelmingly higher reactivity of the product versus the reactant. Here, we report that monometallic gold nanoparticles loaded on mordenite zeolite efficiently catalyze the selective oxidation of methane to methanol by molecular oxygen in the presence of carbon monoxide in aqueous medium. The methanol productivity reaches 1300 μmol gcat−1 h−1 or 280 mmol gAu-1 h-1 with 75% selectivity at 150 °C, outperforming most of those reported under comparable conditions. Both hydroxyl radicals and hydroperoxide species participate in the activation and conversion of methane; the lower affinity of methanol on gold mainly accounts for higher methanol selectivity. | Wangyang Wang; Wei Zhou; Yuchen Tang; Weicheng Cao; Scott R. Docherty; Fangwei Wu; Kang Cheng; Qinghong Zhang; Christophe Copéret; Ye Wang | Catalysis; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2023-04-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64463457e4bbbe4bbf2b45a6/original/selective-oxidation-of-methane-to-methanol-over-au-h-mor.pdf |
66eaeece12ff75c3a1b55332 | 10.26434/chemrxiv-2024-q6ssd | Toward Ab initio Simulation of Operando Raman Spectroscopy: Application to Sulfur/Carbon Copolymer Cathodes in Li-S Batteries | Sulfur/carbon copolymers have emerged as a promising alternative for conventional crystalline sulfur cathodes for lithium-sulfur batteries. Among these, sulfur–n–1,3– diisopropenylbenzene (S/DIB) copolymers, which present a network of DIB molecules interconnected via sulfur chains, have particularly shown a good performance and, there- fore, have been under intensive experimental and theoretical investigations. However, their structural complexity and flexibility have hindered a clear understanding of their structural evolution during redox reactions at an atomistic level. Here, by performing state-of-the-art finite-temperature ab initio Raman spectroscopy simulations, we inves- tigate the spectral fingerprints of S/DIB copolymers during consecutive reactions with lithium. We discuss in detail Raman spectral changes in particular frequency ranges which are common in S/DIB copolymers having short sulfur chains and those consisting of longer ones. We also highlight those distinctive spectroscopic fingerprints specific to local S/DIB structures containing only short or long sulfur chains. This distinction could serve to help distinguish between them experimentally. Our theoretically predicted results are in a good agreement with experimental Raman measurements on coin cells at different discharge stages. This work represents, for the first time, an attempt to compute operando Raman spectra using quantum-chemical calculations and provides a guideline for Raman spectral changes of arbitrary electrodes during the discharge. | Rana Kiani; Huiying Sheng; Timo Held; Oliver Löhmann; Sebastian Risse; Daniel Sebastiani; Pouya Partovi-Azar | Theoretical and Computational Chemistry; Physical Chemistry; Energy | CC BY 4.0 | CHEMRXIV | 2024-09-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66eaeece12ff75c3a1b55332/original/toward-ab-initio-simulation-of-operando-raman-spectroscopy-application-to-sulfur-carbon-copolymer-cathodes-in-li-s-batteries.pdf |
60c7563f0f50db38c439805b | 10.26434/chemrxiv.14219879.v1 | Modular Zwitterion-Functionalized Poly(Isopropyl Methacrylate) Polymers for Hosting Luminescent Lead-Halide Perovskite Nanocrystals | Inorganic lead-halide perovskite nanocrystals (NCs) are an exciting class
of luminescent materials with high defect tolerance and broad spectral
tunability, but such NCs are vulnerable to degradation under ambient conditions.
Here, we report a class of modular zwitterion-functionalized isopropyl methacrylate polymers designed to
stabilize a wide variety of perovskite NCs of different compositions, while also
enabling processing in green solvents. Specifically, we report polymers in
which the zwitterion spacing is tuned to accommodate the different lattice
parameters of CsPb(Cl<sub>1-<i>x</i></sub>Br<i><sub>x</sub></i>)<sub>3</sub> and
CsPbI<sub>3</sub> NCs, and we report partially fluorinated polymers prepared to
accommodate the needs of infrared-emitting NCs. We show that as-synthesized
CsPbBr<sub>3</sub>, CsPbI<sub>3</sub>, and Yb<sup>3+</sup>:CsPbCl<sub>3</sub>
NCs are easily transferred into these zwitterionic polymers <i>via</i> a simple
ligand-exchange procedure. These NC/polymer composites were then cast into thin
films that showed substantially improved photoluminescence (PL) and stability compared
with more conventional NC/polymer films. Specifically, CsPbBr<sub>3</sub> and
CsPbI<sub>3</sub> NCs in films of their appropriately designed polymers had PL
quantum yields of ~90% and ~80%, respectively. PL quantum yields decreased
under continuous illumination, but self-healed completely after dark storage.
We also found that all the NC compositions studied here maintain their PL
quantum yields in NC/polymer composite films even after 1 year of ambient
storage. These encouraging results demonstrate the utility of such modular zwitterion-functionalized
polymers for hosting specific perovskite NCs, potentially opening avenues for
robust new photonic applications of this important class of NCs. | Theodore A. Cohen; Yunping Huang; Nico A. Bricker; Connor S. Juhl; Tyler J. Milstein; J. Devin MacKenzie; Christine K. Luscombe; Daniel R. Gamelin | Nanostructured Materials - Materials; Fluoropolymers; Coordination polymers; Nanostructured Materials - Nanoscience; Polymers | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7563f0f50db38c439805b/original/modular-zwitterion-functionalized-poly-isopropyl-methacrylate-polymers-for-hosting-luminescent-lead-halide-perovskite-nanocrystals.pdf |
618ee8b4642380d618d11d07 | 10.26434/chemrxiv-2021-kwf6m | Catalytic, contra-Thermodynamic Alkene Isomerization | The positional isomerization of C–C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here we report the discovery of a dual catalyst system that promotes contra-thermodynamic positional alkene isomerization under photochemical irradiation, providing access to terminal alkene isomers directly from conjugated, internal alkene starting materials. The utility of the method is demonstrated in the deconjugation of diverse electron rich/poor alkenes and through strategic application to natural product synthesis. Mechanistic studies are consistent with a regiospecific bimolecular homolytic substitution (SH2') mechanism proceeding through an allyl-cobaloxime intermediate. | Gino Occhialini; Vignesh Palani; Alison Wendlandt | Organic Chemistry; Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/618ee8b4642380d618d11d07/original/catalytic-contra-thermodynamic-alkene-isomerization.pdf |
60c74585702a9b7d1c18aa21 | 10.26434/chemrxiv.10028597.v1 | A Practical Iron-Based Newman-Kwart Rearrangement Under Oxidative Conditions | Herein, we report that iron(II)/ammonium persulfate in aqueous acetonitrile mediates the Newman-Kwart rearrangement of <i>O</i>-aryl carbamothioates. Electron-rich substrates react rapidly under moderate heating to afford the rearranged products in excellent yields. The mild conditions, rapid reaction rates, and suitability for scale up offer immediate practical benefits to access functionalised thiophenols. | Thibault Gendron; Raul Pereira; Hafsa Yusuf Abdi; Timothy Witney; Erik Arstad | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74585702a9b7d1c18aa21/original/a-practical-iron-based-newman-kwart-rearrangement-under-oxidative-conditions.pdf |
6329ebdf975e9425ff8229fe | 10.26434/chemrxiv-2022-1lq2j | Reliable and Accurate Prediction of Single Residue pKa Values Through Free Energy Perturbation Calculations | Accurate prediction of the pKa’s of protein residues is crucial to many applications in biological simulation and drug discov-ery. Here we present the use of free energy perturbation (FEP) calculations for the prediction of single protein residue pKa values. We begin with an initial set of 191 residues with experimentally determined pKa values. To isolate sampling limita-tions from force field inaccuracies, we develop an algorithm to classify residues whose environments are significantly affect-ed by crystal packing effects. We then report an approach to identify buried histidines that require significant sampling be-yond what is achieved in typical FEP calculations. We therefore define a clean dataset not requiring algorithms capable of predicting major conformational changes on which other pKa prediction methods can be tested. On this data set, we report an RMSE of 0.76 pKa units for 35 ASP residues, 0.51 pKa units for 44 GLU residues, and 0.67 pKa units for 76 HIS resi-dues. | Dilek Coskun; Wei Chen; Anthony Clark; Chao Lu; Edward Harder; Lingle Wang; Richard Friesner; Edward Miller | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Physical and Chemical Properties; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6329ebdf975e9425ff8229fe/original/reliable-and-accurate-prediction-of-single-residue-p-ka-values-through-free-energy-perturbation-calculations.pdf |
641b63d9dab08ad68f8a4131 | 10.26434/chemrxiv-2023-mb5wz | Silica particles convert thiol-containing molecules to disulfides | Synthetic amorphous silica is a common food additive and a popular cosmetic ingredient. Mesoporous silica nanoparticles are also widely studied for their potential use in drug delivery and imaging applications because of their unique properties, such as tunable pore sizes, large surfaces areas, and assumed biocompatibility. Such a nanomaterial, when consisting of pure silicon dioxide, is generally considered to be inert, but in this study, we showed that oxidation yields for different compounds were facilitated by simply incubating aqueous solutions with pure silica particles in the dark. Three thiol-containing molecules, L-cysteine, glutathione, and D-penicillamine, were studied separately, and it was found that more than 95% of oxidation happened after incubating any of these compounds with mesoporous silica nanoparticles in the dark for a day at room temperature. Oxidation increased over incubation time and more oxidation was found for particles having larger surface areas. For nonporous silica nanoparticles, yields of oxidation were different based on structures of molecules, correlating with steric hindrance while accessing surfaces. We propose that the silyloxy radical on silica surfaces is what facilitates oxidation. Density functional theory calculations were conducted for total energy changes for reactions between different aqueous species and silicon dioxide surfaces. These calculations identified two most plausible pathways of lowest energy to generate SiO• radicals from water radical cations and •OH radicals, previously known to exist at water interfaces. | Yangjie Li; Kurt W. Kolasinski; Richard N. Zare | Theoretical and Computational Chemistry; Physical Chemistry; Analytical Chemistry; Mass Spectrometry; Interfaces | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/641b63d9dab08ad68f8a4131/original/silica-particles-convert-thiol-containing-molecules-to-disulfides.pdf |
6304ed39eadd9a9d387ebede | 10.26434/chemrxiv-2022-rgqfx | Biased quartz crystal microbalance method for studies of CVD surface chemistry induced by plasma electrons | In a recently presented chemical vapor deposition (CVD) method, plasma electrons are used as reducing agents for deposition of metals. The plasma electrons are attracted to the substrate surface by a positive substrate bias. Here, we present how a standard quartz crystal microbalance (QCM) system can be modified to allow applying a DC bias to the QCM sensor to attract plasma electrons to it and thereby also enable in situ growth monitoring during the electron-assisted CVD method. We show initial results from mass gain evolution over time during deposition of iron films using the biased QCM and how the biased QCM can be used for process development and provide insight to the surface chemistry by time-resolving the CVD method. Post deposition analyzes of the QCM crystals by cross-section electron microscopy and high-resolution X-ray photoelectron spectroscopy, show that the QCM crystals are coated by an iron-containing film and thus function as substrates in the CVD process. A comparison of the areal mass density given by the QCM crystal and the areal mass density from elastic recoil detection analysis and Rutherford backscattering spectrometry was done to verify the function of the QCM setup. Time-resolved CVD experiments show that this biased QCM method holds great promise as one of the tools for understanding the surface chemistry of the newly developed CVD method. | Pentti Niiranen; Hama Nadhom; Michal Zanaska; Robert Boyd; Mauricio Sortica; Daniel Primetzhofer; Daniel Lundin; Henrik Pedersen | Physical Chemistry; Materials Science; Analytical Chemistry; Thin Films; Analytical Apparatus; Surface | CC BY 4.0 | CHEMRXIV | 2022-08-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6304ed39eadd9a9d387ebede/original/biased-quartz-crystal-microbalance-method-for-studies-of-cvd-surface-chemistry-induced-by-plasma-electrons.pdf |
6787ff6381d2151a024d0188 | 10.26434/chemrxiv-2025-32vjk | Directed Evolution and Unusual Protonation Mechanism of Pyridoxal Radical C–C Coupling Enzymes for the Enantiodivergent Photobiocatalytic Synthesis of Non-Canonical Amino Acids | Visible light-driven pyridoxal radical biocatalysis has emerged as a new strategy for the stereoselective synthesis of valuable noncanonical amino acids in a protecting-group-free fashion. In our previously developed dehydroxylative C−C coupling using engineered PLPdependent tryptophan synthases, an enzyme-controlled unusual a-stereochemistry reversal and pH-controlled enantiopreference were observed. Herein, through high-throughput photobiocatalysis, we evolved a set of stereochemically complementary PLP radical enzymes, allowing the synthesis of both L- and D-amino acids with enhanced enantiocontrol across a broad pH window. These newly engineered L- and D-amino acid synthases permitted the use of a broad range of organoboron substrates, including boronates, trifluoroborates and boronic acids, with excellent efficiency. Mechanistic studies unveiled unexpected PLP racemase activity with our earlier PLP enzyme variants. This promiscuous racemase activity was abolished in our evolved amino acid synthases, shedding light on the origin of enhanced enantiocontrol. Further mechanistic investigations suggest a switch of proton donor to account for the stereoinvertive formation of D-amino acids, highlighting an unusual stereoinversion mechanism which is rare in conventional two-electron PLP enzymology. | Lei Cheng; Zhiyu Bo; Benjamin Krohn-Hansen; Yang Yang | Organic Chemistry; Catalysis | CC BY NC 4.0 | CHEMRXIV | 2025-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6787ff6381d2151a024d0188/original/directed-evolution-and-unusual-protonation-mechanism-of-pyridoxal-radical-c-c-coupling-enzymes-for-the-enantiodivergent-photobiocatalytic-synthesis-of-non-canonical-amino-acids.pdf |
666c025001103d79c5327197 | 10.26434/chemrxiv-2024-v8chs | Magneto-electrochemical ammonia synthesis: Boosting nitrite reduction activity by the optimized magnetic field induced in spin polarized system | Using low and optimized magnetic field along with electric field is a novel strategy to facilitate electrochemical nitrite reduction. Here, we report for the first time on the synthesis of ammonia via magneto-electrocatalytic methods that use spin-thrusted β-MnPc in a magnetic field of 95 mT. The calculated rate of ammonia generation was 16603.4 µg h-1 mgcat-1, which is almost twice that of the non-polarized MnPc catalyst. Additionally, the faradaic efficiency at –0.9V vs. RHE was found to be 92.9%, significantly higher compared to the non-polarized MnPc catalyst. In presence of external magnetic field, MnPc catalysts provide a better electron transfer channel which results in a lower charge transfer resistance and hence better electrochemical performances. DFT result further verifies that magnetic field induced β-MnPc has a lower potential barrier (0.51 eV) for the protonation of NO* (PDS) than non-polarized β-MnPc (1.08 eV), which confirms the enhanced electrochemical nitrite reduction to ammonia aided by external magnetic field.
| Ashadul Adalder; Koushik Mitra; Narad Barman; Ranjit Thapa; Sourav Bhowmick; Uttam Kumar Ghorai | Inorganic Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry; Electrochemistry; Electrocatalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666c025001103d79c5327197/original/magneto-electrochemical-ammonia-synthesis-boosting-nitrite-reduction-activity-by-the-optimized-magnetic-field-induced-in-spin-polarized-system.pdf |
63863ca81234cb2b0e278dc0 | 10.26434/chemrxiv-2022-s63x6 | Bis(aluminyl)magnesium: a source of nucleophilic or radical aluminium-centred reactivity | The homoleptic magnesium bis(aluminyl) compound Mg[Al(NON)]2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl -9,9-dimethylxanthene) can be accessed from K2[Al(NON)]2 and MgI2 and shown to possess a non-linear geometry (Al–Mg–Al = 164.8(1)) primarily due to the influence of dispersion interactions. This compound acts a four-electron reservoir in the reductive defluorination of SF6, and reacts thermally with polar substrates such as MeI via nucleophilic attack through aluminium, consistent with the QT-AIM charges calculated for the metal centres, and a formal description as a Al(I)–Mg(II)–Al(I) trimetallic. On the other hand, under photolytic activation, the reaction with 1,5-cyclooctadiene leads to the stereoselective generation of transannular cycloaddition products consistent with radical based chemistry, emphasizing the covalent nature of the Mg–Al bonds and a description as a Al(II)–Mg(0)–Al(II) synthon. | Liam Griffin; Mathias Ellwanger; Jonathon Clark; Aisling Roper; Andreas Heilmann; Simon Aldridge | Inorganic Chemistry; Organometallic Chemistry; Main Group Chemistry (Inorg.); Main Group Chemistry (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63863ca81234cb2b0e278dc0/original/bis-aluminyl-magnesium-a-source-of-nucleophilic-or-radical-aluminium-centred-reactivity.pdf |
60c745f6ee301c7622c79403 | 10.26434/chemrxiv.10291976.v1 | Tailorable Phase and Structural MnO2 as Electrode for Highly Efficient Hybrid Capacitive Desalination (HCDI) | Hybrid
capacitive deionization (HCDI) is
an emerging and promising technology for water desalination and has been
extensively explored in recent years. Designing
a structure tailorable electrode material has been proved to be a valid
strategy for achieving a higher salt adsorption capacity (SAC). In this study, <a></a><a>MnO<sub>2</sub> materials with tailorable
phase compositions and regulatory microstructures were prepared hydrothermally
and then evaluated as electrodes for removal of ions from NaCl solution in a
membrane-free HCDI cell.</a> MnO<sub>2</sub> electrode
materials tested in HCDI system include poorly crystalline δ-MnO<sub>2</sub> with
a lot of amorphous phases (MnO<sub>2</sub>-1h), crystalline δ-MnO<sub>2</sub>
with amorphous MnO<sub>2</sub> (MnO<sub>2</sub>-2h), MnO<sub>2</sub> mixtures of
α-, δ-, and amorphous MnO<sub>2</sub> (MnO<sub>2</sub>-5h), and <a></a><a>α-MnO<sub>2</sub>
nanowire</a> with minor amorphous MnO<sub>2</sub> (MnO<sub>2</sub>-12h).
It is notable that the phase composition along with the microstructures of MnO<sub>2</sub>
materials rather than their surface areas determines the SAC values. When the cell voltage is 1.2 V, the <a></a><a>lamellar</a> structured MnO<sub>2</sub>-1h electrode
demonstrates the highest SACs of
13.84 mg g<sup>-1</sup> in 100 mg L<sup>-1</sup> NaCl, and 21.32 mg g<sup>-1</sup> in 500 mg L<sup>-1</sup> NaCl solution, respectively. The
desalination efficiencies are remarkable and far greater than other MnO<sub>2</sub>-based
electrodes under similar conditions (e.g., NaCl concentrations, cell voltage,
etc.). This study sheds light on the
significance of understanding the fundamental of both phase composition and
microstructure in governing the desalination performance of MnO<sub>2</sub>
electrodes. | Jie Jin; Man Li; Mengting Tang; Yang Li; Yangyang Liu; Hui Cao; Feihu Li | Electrochemistry; Water Purification | CC BY NC ND 4.0 | CHEMRXIV | 2019-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745f6ee301c7622c79403/original/tailorable-phase-and-structural-mn-o2-as-electrode-for-highly-efficient-hybrid-capacitive-desalination-hcdi.pdf |
674782687be152b1d01f8bb0 | 10.26434/chemrxiv-2024-lg04j | Alumina Supported Iron Catalysts for the Selective Acetylene Hydrogenation under Industrial Front-End Conditions | The removal of acetylene traces from ethylene streams coming from the steam cracker is carried out in the industry on an annual scale of several million tonnes using Pd-Ag/Al2O3 catalysts. The substitution of palladium containing catalysts with more abundant, cheap and non-toxic materials is a first crucial step towards a more sustainable chemical industry. Since iron is one of the most abundant metals and can be mined in almost all regions world wide, it is an ideal catalyst material. In this work, we present the development of alpha alumina supported iron catalysts with 1 wt%, 5 wt% and 10 wt% iron loading and their application in the selective acetylene hydrogenation under industrially applied front-end conditions. The catalysts were prepared via simple incipient wetness impregnation and were analyzed via XRD, XRF, TPR, TEM and N2-Physisorption. The catalysts were subsequently calcined, reduced and tested in the selective acetylene hydrogenation. After an activation phase, the catalysts show excellent activity and selectivity in the acetylene hydrogenation at 90 °C without significant ethylene hydrogenation. The excellent catalytic activity underline the great potential of iron based catalysts as an alternative to conventional Pd-containing materials. | Hannah Lamers; Malte Schummer; Martin Lucas; Marcus Rose | Catalysis; Chemical Engineering and Industrial Chemistry; Reaction Engineering; Heterogeneous Catalysis | CC BY 4.0 | CHEMRXIV | 2024-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674782687be152b1d01f8bb0/original/alumina-supported-iron-catalysts-for-the-selective-acetylene-hydrogenation-under-industrial-front-end-conditions.pdf |
60c74cef4c89199747ad3716 | 10.26434/chemrxiv.11836731.v2 | Coupling Droplet Microfluidics with Mass Spectrometry for Ultrahigh-Throughput Analysis up to and Above 30Hz. | High and ultra-high-throughput label-free sample analysis is required by many applications, extending from environ-mental monitoring to drug discovery and industrial biotechnology. HTS methods predominantly are based on a targeted workflow, which can limit their scope. Mass spectrometry readily provides chemical identity and abundance for complex mixtures and here, we use microdroplet generation microfluidics to supply picolitre aliquots for analysis at rates up to and including 33 Hz. This is demon-strated for small molecules, peptides and proteins up to 66 kDa on three commercially available mass spectrometers from salty solutions to mimic cellular environments. Designs for chip-based interfaces that permit this coupling are presented and the merits and challenges of these interfaces are discussed. On an Orbitrap platform droplet infusion rates of 6 Hz are used for the analysis of cytochrome c, on a DTIMS Q-TOF similar rates were obtained and on a TWIMS Q-TOF utilizing IM-MS software rates up to 33 Hz are demonstrated. The potential of this approach is demonstrated with proof of concept experiments on crude mixtures including egg white, unpurified recombinant protein and a biotransformation supernatant. | Emily Kempa; Clive Smith; Xin Li; bruno bellina; Keith Richardson; Steven Pringle; James L. Galman; Nicholas J. Turner; Perdita Barran | Analytical Chemistry - General; Mass Spectrometry; High-throughput Screening | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74cef4c89199747ad3716/original/coupling-droplet-microfluidics-with-mass-spectrometry-for-ultrahigh-throughput-analysis-up-to-and-above-30hz.pdf |
65bef2c2e9ebbb4db99eb43b | 10.26434/chemrxiv-2024-5ssd9 | Power-Law Fluid Flow in Diverse Converging-Diverging Geometries of Corrugated Channels | Gaining insights into the behavior of non-Newtonian fluids, including power-law fluids, within corrugated channels is essential for numerous industrial processes. In this paper, we introduce an analytical approach to establish the connection between pressure drop and flow rate in laminar flow conditions, specifically focusing on the flow of power-law fluids within 2D Planar converging-diverging corrugated channels. We explore five distinct converging-diverging geometries such as linear wedge, parabolic wedge, hyperbolic profile, hyperbolic cosine profile, and the sinusoidal converging-diverging channels. We derive analytically the pressure-flow rate relations using the lubrication approximation in these channels. For the validations, the derived expressions converges to the Newtonian flow physics when the viscosity is assumed constant. The versatility of this method allows its application to various fluid types and channel shapes within defined constraints, serving as a valuable framework for numerical integration when obtaining analytical expressions becomes challenging due to mathematical intricacies or practical considerations. | Ashish Garg | Polymer Science; Chemical Engineering and Industrial Chemistry; Fluid Mechanics; Transport Phenomena (Chem. Eng.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65bef2c2e9ebbb4db99eb43b/original/power-law-fluid-flow-in-diverse-converging-diverging-geometries-of-corrugated-channels.pdf |
64782415be16ad5c5742e070 | 10.26434/chemrxiv-2023-b677r | Phase-diagram observation of liquid–liquid phase separation in the poly-L-lysine/ATP system and diagram-based application strategy | Liquid–liquid phase separation (LLPS) is essential to understand biomacromolecule compartmentalization in living cells and to form soft-matter structures for chemical reactions and drug delivery systems. However, the importance of detail experimental phase diagrams of modern LLPS systems tend to be overlooked nowadays. Even for poly-L-lysine (PLL)/ATP system, one of the most widely used LLPS models, detailed phase diagram of LLPS have not been obtained. Herein, we report the first phase diagram of the (PLL)/ATP system and demonstrate the feasibility of phase-diagram based research design not only for understanding the physical properties of LLPS systems but also for realizing biophysical and medical applications. We established an experimental handy model of the droplet formation/disappearance process by forming a concentration gradient in a chamber as extracting a suitable condition on the phase-diagram including the two-phase droplet region. As a proof of concept of pharmaceutical application, we added a human immunoglobulin G (IgG) solution to PLL/ATP system. Using the knowledge of the phase diagram, we enabled to form IgG/PLL droplets clearly in the pharmaceutically required IgG concentration of ca. 10 mg/mL. This study provides a guidance for using the phase diagram to analyze and utilize LLPS | Tomohiro Nobeyama; Tomohiro Furuki; Kentaro Shiraki | Biological and Medicinal Chemistry; Biophysics | CC BY 4.0 | CHEMRXIV | 2023-06-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64782415be16ad5c5742e070/original/phase-diagram-observation-of-liquid-liquid-phase-separation-in-the-poly-l-lysine-atp-system-and-diagram-based-application-strategy.pdf |
60c73f5c4c891926efad1f74 | 10.26434/chemrxiv.7325210.v1 | Enantioselective Allylation from Allene, a Petroleum Cracking Byproduct | <p>Allene (C3H4) gas is produced and separated on million-metric-ton scale per year during petroleum refining but is only rarely employed in chemical manufacturing. Meanwhile, the addition of an allyl group (C3H5) to ketone-containing molecules is among the most common</p>
<p>and prototypical reactions in organic synthesis. Herein, we report that the combination of allene with environmentally benign hydrosilanes can replace harsher, more wasteful, and more</p>
<p>expensive allylmetal reagents in enantioselective ketone allylation reactions. This process is catalyzed by an earth-abundant metal and commercially available ligands, operates without specialized equipment or pressurization, and tolerates a broad range of functional groups. Furthermore, the exceptional chemoselectivity of our catalyst system enables industrially relevant C3 hydrocarbon mixtures of allene with methylacetylene and propylene to be applied</p>
<p>directly. Based on our strategy, we anticipate the rapid development of methods that leverage this unexploited feedstock as a surrogate for existing nucleophilic allylation reagents.</p> | Richard Y. Liu; Yujing Zhou; Yang Yang; Stephen L. Buchwald | Organic Synthesis and Reactions; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2018-11-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5c4c891926efad1f74/original/enantioselective-allylation-from-allene-a-petroleum-cracking-byproduct.pdf |
658e4b29e9ebbb4db9f4dc8c | 10.26434/chemrxiv-2023-wd5cr-v3 | NLP meets Materials Science: Quantifying the presentation of materials data in scientific literature | The recent and sudden emergence of Large Language Models have profoundly changed the landscape around how we approach and interact with information. Materials Science, given its highly complex and multifaceted nature, is a space we intend for Natural Language Processing to absolutely flip the script related to progress, learning, and especially new materials discovery, as a result of enhanced data accessibility. We explore the underlying patterns and structures of data expression across a number of randomly selected materials science papers, annotating relevant data by type (category) and source (channel) as a starting point to future Materials Science specific information extraction and LLM development. | Hasan M. Sayeed; Wade Smallwood; Sterling G. Baird; Taylor D. Sparks | Materials Science | CC BY NC 4.0 | CHEMRXIV | 2023-12-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/658e4b29e9ebbb4db9f4dc8c/original/nlp-meets-materials-science-quantifying-the-presentation-of-materials-data-in-scientific-literature.pdf |
62746e12a42e9cec2e35a767 | 10.26434/chemrxiv-2022-fnqnj | Development of a novel PKC ligand using machine learning model: synthesis and PKC surrogate binding of the simplified analogues of alotaketals | We have designed and synthesized a new PKC ligand with a novel skeleton based on alotaketals through in silico screening, docking analysis, and molecular dynamics simulation. We found that the new ligand has a higher affinity for PKCα-C1A than for PKCδ-C1B. This compound is expected to serve as the basis for developing PKC ligands with isozyme selectivity. | Jumpei Maki; Asami Oshimura; Chihiro Tsukano; Ryo Yanagita; Yutaka Saito; Yasubumi Sakakibara; Kazuhiro Irie | Organic Chemistry; Natural Products | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62746e12a42e9cec2e35a767/original/development-of-a-novel-pkc-ligand-using-machine-learning-model-synthesis-and-pkc-surrogate-binding-of-the-simplified-analogues-of-alotaketals.pdf |
639c306ea2da4b33a405e05a | 10.26434/chemrxiv-2022-8n0f0 | Simulation of two-dimensional infrared Raman spectroscopy with application to proteins | Two-dimensional infrared Raman spectroscopy is a powerful technique for studying the structure and interaction in molecular and biological systems. Here, we present a new implementation of the simulation of the two-dimensional infrared Raman signals. The implementation builds on the Numerical Integration of the Schr ̈odinger Equa- tion approach. It combines the prediction of dynamics from molecular dynamics with a map-based approach for obtaining Hamiltonian trajectories and response function calculations. The new implementation is tested on the amide-I region for two pro- teins, where one is dominated by α-helices and the other by β-sheets. We find that the predicted spectra agree well with experimental observations. The present imple- mentation and findings pave the way for future applications for the interpretation of two-dimensional infrared Raman spectra.
| Carleen D. N. van Hengel; Kim E. van Adrichem; Thomas L. C. Jansen | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/639c306ea2da4b33a405e05a/original/simulation-of-two-dimensional-infrared-raman-spectroscopy-with-application-to-proteins.pdf |
60c74cc5469df40b57f44142 | 10.26434/chemrxiv.12529565.v1 | Studying the Cellular Distribution of Highly Phototoxic Platinated Metalloporphyrins Using Isotope Labelling | We report the synthesis of novel tetraplatinated metalloporphyrin-based photosensitizers (PSs) for photodynamic therapy (PDT), their characterization, cellular uptake and localization, as well as the determination of their <i>in vitro</i> light-induced anticancer properties. The PSs show excellent phototoxic indexes up to 5800 against HeLa cells, which is, to the best of our knowledge, the highest value reported for any porphyrin so far. Furthermore, isotopic labelling of the porphyrin with a highly enriched <sup>67</sup>Zn isotope was performed in order to determine the distribution ratio of zinc to platinum by ICP-MS, allowing to differentiate between naturally occurring zinc and <sup>67</sup>Zn that was introduced into the cells by the PS. We conclude that the platinum units within the platinum-PS conjugates help to solubilize the PS and, at the same time, act as cell-penetrating vectors, enhancing the efficiency of the PS without causing a significant dark toxicity.<br /> | Riccardo Rubbiani; Wenyu Wu; Anu Naik; Michele Larocca; Lukas Schneider; Roxane Padrutt; Vipin Babu; Christiane König; Doris Hinger; Caroline Maake; Stefano Ferrari; Gilles Gasser; Bernhard Spingler | Organic Synthesis and Reactions; Photochemistry (Org.); Bioinorganic Chemistry; Coordination Chemistry (Inorg.); Drug Discovery and Drug Delivery Systems; Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74cc5469df40b57f44142/original/studying-the-cellular-distribution-of-highly-phototoxic-platinated-metalloporphyrins-using-isotope-labelling.pdf |
60c748d0842e65da91db2c4f | 10.26434/chemrxiv.11926938.v2 | Size-Dependent Interaction of Nanoparticles with Non-ionic Bilayers | Understanding the mechanism of transit of a nanoparticle (NP) through a biomimetic bilayer has been at the forfront of research for the design of efficient drug-delivery mechanisms, nanotechnology and biomedicine. Establishing a consistent picture of how the transit mechanism depends on the physiochemical property of a NP is critical to understanding what approach may be the most effective for nanomedicine design. In this study, using molecular simulation techniques, we have analyzed the key properties of a NP that may affect the mechanism of transit - the effect of size and hydrophobicity. By using a continuum model of a NP based on the Hamaker potential, we have created NP of tunable hydrophobic properties. The effect of hydrophilic, hydrophobic, and mixed properties of the NP is analyzed against a biomimetic bilayer - we show that this model can illustrate three distinct properties - where the hydrophilic type shows rupture of the bilayer, the hydrophobic type showing a entrapment of the NP around the hydrophobic tailgroups of the bilayer, and the mixed type showing a distinct, direct translocation type mechanism. Increasing the NP size shows different effects for each type of NP, and hence, may provide insight into the design of NPs with these types of mechanisms involved. | Sang Noh; Rebecca Notman | Nanostructured Materials - Nanoscience; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c748d0842e65da91db2c4f/original/size-dependent-interaction-of-nanoparticles-with-non-ionic-bilayers.pdf |
6496bef14821a835f3536bff | 10.26434/chemrxiv-2023-n5fv2 | Coupling the Coupling: Dissecting the Role of Tau’s Microtubule-Binding Repeats in Modulating Amyloid-beta Aggregation and Toxicity Profiles in Alzheimer’s Disease | The accumulation of neurofibrillary tangles and senile plaques composed of tau and amyloid-beta (Abeta) aggregates, respectively, is observed in the brain of Alzheimer’s disease (AD). Efforts have been made to elucidate the link between the aggregation of tau and Abeta and the development of AD; however, the pathological implication of their co-aggregation remains unclear. Here we report that the microtubule-binding domain of tau, critical for its aggregation, has direct contacts onto Abeta
and alters the aggregation behavior of Abeta in a distinct manner, which in turn affects the Ab-associated toxicity under both extracellular and intracellular conditions. Our mechanistic investigations illuminate that the fragments with the balanced hydrophobicity and hydrophilicity properties in the microtubule-binding domain of tau can form adducts with monomeric and dimeric Abeta to varying degrees, which may determine their impact on the aggregation and toxicity of Ab. These findings offer new avenues for understanding and treating AD by highlighting the interplay between tau and Abeta in the pathogenesis. | Mingeun Kim; Yuxi Lin; Eunju Nam; Sungsu Lim; Yun Kyung Kim; Young-Ho Lee; Mi Hee Lim | Biological and Medicinal Chemistry; Analytical Chemistry; Spectroscopy (Anal. Chem.); Biochemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6496bef14821a835f3536bff/original/coupling-the-coupling-dissecting-the-role-of-tau-s-microtubule-binding-repeats-in-modulating-amyloid-beta-aggregation-and-toxicity-profiles-in-alzheimer-s-disease.pdf |
66c6fa7aa4e53c4876397fe5 | 10.26434/chemrxiv-2024-57klw | Machine learning-assisted c-RASAR modeling of a curated set of orally active nephrotoxic drugs: Similarity-based predictions from close source neighbors | Cheminformatics and Machine Learning (ML) have seen exponential progress in the last decade, in the field of chemical risk assessment, due to their efficiency, accuracy, and reliability. The constant evolution of New Approach Methodologies (NAM) has inspired researchers around the globe to deviate from conventional approaches and adopt or develop new, “unconventional” methods. The classification Read-Across Structure-Activity Relationship (c-RASAR) is an unconventional approach that utilizes similarity and error-based information from the nearest neighboring compounds into a Machine Learning modeling framework, resulting in enhanced predictivity. Although this technique has so far been applied to molecular descriptors, we have applied this approach in the present study on molecular fingerprints along with conventional molecular descriptors for ML-based model development from a recently reported highly curated set of orally active nephrotoxic drugs. We initially developed ML models using nine different linear and non-linear algorithms separately on molecular descriptors and MACCS fingerprints, thus generating 18 different ML QSAR models. Using the chemical spaces defined by the modeling descriptors and fingerprints, the similarity and error-based RASAR descriptors were computed, and the most discriminating RASAR descriptors were used to develop another set of 18 different ML c-RASAR models. All 36 models were cross-validated 20 times with a 5-fold cross-validation strategy, and their predictivity was checked on the test set data. A multi-criteria decision-making strategy – the Sum of Ranking Differences (SRD) approach - was adopted to identify the best-performing model based on robustness and external validation parameters. This statistical analysis suggested that the c-RASAR models had an overall good performance, while the best-performing model was also a c-RASAR model. This model was used to screen a true external set data prepared from the known nephrotoxic compounds of DrugBankDB. These results also showed that our model efficiently identifies nephrotoxic compounds. The t-SNE analyses on the descriptors, fingerprints, and the RASAR descriptor spaces inferred that the RASAR descriptors efficiently encode the chemical information, as evident from the tight and distinct clustering of the data points. Additionally, the molecular descriptors and the corresponding RASAR descriptors were used to identify potential activity cliffs using the ARKA framework. | Arkaprava Banerjee; Kunal Roy | Theoretical and Computational Chemistry; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c6fa7aa4e53c4876397fe5/original/machine-learning-assisted-c-rasar-modeling-of-a-curated-set-of-orally-active-nephrotoxic-drugs-similarity-based-predictions-from-close-source-neighbors.pdf |
6116833e711750e6fae8863d | 10.26434/chemrxiv-2021-d1f05 | Pb-oxo Interactions in Uranyl Hybrid Materials: a Combined Experimental and Computational Analysis of Bonding and Spectroscopic Properties | Reported are the syntheses and characterization of six new heterometallic UO22+/Pb2+ compounds. These materials feature rare instances of M-oxo interactions, which influence bonding properties of the uranyl cation. The spectroscopic effects of these interactions were measured using diffuse reflectance, luminescence and Raman spectroscopy. Computational density functional theory (DFT) based natural bonding orbital (NBO) and quantum theory of atoms in molecules (QTAIM) methods indicate interactions arise predominantly through charge transfer between cationic units via the electron donating uranyl O spx lone pair orbitals and electron accepting Pb2+ p orbitals. The interaction strength varies as a function of Pb-oxo interaction distance and angle with energy values ranging from ranging from 0.47 kcal/mol in the longer contacts to 21.94 kcal/mol in the shorter contacts. Uranyl units with stronger interactions display an asymmetric bond weakening and a loss of covalent character in the U=O bonds interacting closely with the Pb2+ ion. Luminescence quenching is observed in cases where strong Pb-oxo interactions are present, and is accompanied by significant red-shifting of the uranyl symmetric Raman stretch. Changes to inner sphere uranyl bonding manifest as a weakening of the U=O bond as a result of interaction with the Pb2+ ion. | Dominique M. Brager; Aaron D. Nicholas; Mark H. Schofield; Christopher L. Cahill | Inorganic Chemistry; Lanthanides and Actinides; Nuclear Chemistry; Crystallography – Inorganic | CC BY NC 4.0 | CHEMRXIV | 2021-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6116833e711750e6fae8863d/original/pb-oxo-interactions-in-uranyl-hybrid-materials-a-combined-experimental-and-computational-analysis-of-bonding-and-spectroscopic-properties.pdf |
60d59e66261611243d8c30fc | 10.26434/chemrxiv-2021-3blgm | A Reproducible and Scalable Method for Producing Fluorescent Polystyrene Nanoparticles | In this work polystyrene nanoparticles (PS NPs) were fabricated from an emulsion of PS/toluene in water using various surfactants, and purified via dialysis in a simple procedure. The synthesis process was carried out at room temperature, without hazardous chemicals, and with a workload of 5 hours. The investigation was performed to evaluate the limits for production of PS NPs with comparable properties. A robust PS NP synthesis procedure was developed, repeated, and tested by three independent researches. The procedure was up-scaled to prove the applicability of the method and the NPs were prepared with four different hydrophobic dyes. All products were found to be comparable, and it was concluded that the method reported here can provide PS NPs with or without dye dopants, and that it provides access to PS NPs with an average diameter of 25 nm in a reproducible size distribution. | Dávid Bartoš; Lu Wang; Andy S. Anker; Morten Rewers; Olivia Aalling-Frederiksen; Kirsten Marie Ørnsbjerg Jensen; Thomas Just Sørensen | Materials Science; Nanoscience; Dyes and Chromophores; Optical Materials; Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2021-06-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60d59e66261611243d8c30fc/original/a-reproducible-and-scalable-method-for-producing-fluorescent-polystyrene-nanoparticles.pdf |
6256d0baed4d88408d08e0cc | 10.26434/chemrxiv-2022-vr6fm | An Amorphous Teflate Doped Aluminium Chlorofluoride: A Solid Lewis Superacid for the Dehydrofluorination of Fluoroalkanes | An anion doped aluminium chlorofluoride AlCl0.1F2.8(OTeF5)0.1 (ACF-teflate) was synthesized. The material contains pentafluoroorthotellurate (teflate) groups, which mimic fluoride ions electronically, but are sterically more demanding. They are embedded into the amorphous structure. The latter was studied by PDF analysis, EXAFS data and MAS NMR spectroscopy. The mesoporous powder is a Lewis superacid, and ATR-IR spectra of adsorbed CD3CN reveal a blue-shift of the adsorption band by 73 cm1, which is larger than the shift for SbF5. Remarkably, ACF-teflate catalyzes dehydrofluorination reactions of monofluoroalkanes to yield olefins in C6D6. In these cases, no Friedel-Crafts products were formed. | Thomas Braun; Minh Bui; Kurt Hoffmann; Sebastian Riedel; Christian Heinekamp; Kerstin Scheurell; Gudrun Scholz; Tomasz Stawski; Franziska Emmerling | Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6256d0baed4d88408d08e0cc/original/an-amorphous-teflate-doped-aluminium-chlorofluoride-a-solid-lewis-superacid-for-the-dehydrofluorination-of-fluoroalkanes.pdf |
60c74295469df4b3bdf42ff2 | 10.26434/chemrxiv.6823352.v3 | Fatty Acid Fueled Transmembrane Chloride Transport | We report an example of the use of fatty acids to drive chloride transport by creating a pH gradient across a vesicular lipid bilayer membrane. Addition of an unselective squaramide-based chloride transporter (which transports both H<sup>+</sup>and Cl<sup>-</sup>) facilitates the transport of HCl from the vesicle (driven by the pH gradient) so creating a chloride gradient. Addition of further aliquots of fatty acid ‘fuel’ can initiate further transport of chloride out of the vesicle by re-establishing the pH gradient. This is an example of a prototypical chloride pumping system. | Ethan N.W. Howe; Philip Gale | Supramolecular Chemistry (Org.); Biochemistry; Cell and Molecular Biology | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74295469df4b3bdf42ff2/original/fatty-acid-fueled-transmembrane-chloride-transport.pdf |
62bc2c61d66f68f88fb61eb7 | 10.26434/chemrxiv-2022-22s75-v2 | A Density Functional Theory for the Average Electron Energy | A formally exact density functional theory (DFT) determination of the average electron energy is presented. Our theory, which is based on a different accounting of energy functional terms, partially solves one well known downside of conventional Kohn-Sham (KS) DFT: that electronic energies have but tenuous connections to physical quantities. Calculated average electron energies are close to experimental ionization potentials in one-electron systems, demonstrating a surprisingly small effect of self-interaction and other exchange-correlation errors in established DFT methods. Remarkable agreement with ab initio quantum mechanical calculations of multi-electron systems is demonstrated using several flavors of DFT, and we argue for the use of the average electron energy as a design criterion for density functional approximations. | Stefano Racioppi ; Phalgun Lolur; Per Hyldgaard; Martin Rahm | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62bc2c61d66f68f88fb61eb7/original/a-density-functional-theory-for-the-average-electron-energy.pdf |
67c6d46481d2151a0202990a | 10.26434/chemrxiv-2025-rr2nh | Polaronic competition triggers the H2O2 evolution on perovskite oxides during water oxidation | Perovskite oxides, particularly calcium-based perovskites (CaMO3), are promising catalysts for the oxygen evolution reaction (OER) due to their high efficiency and economic feasibility. However, a comprehensive mechanistic understanding that elucidates the relationship between catalytic selectivity and mechanistic pathways has yet to be achieved. In this study, we employ density functional theory (DFT) to investigate the OER mechanism in a series of Ca-based perovskites. Our findings indicate that early transition metals in CaMO3 favor a conventional OER pathway, characterized by a four-step concerted proton-electron transfer process leading to O2 formation from H2O. In contrast, perovskites containing Mn, Fe, and Co exhibit two proton-electron transfer steps, favoring the selective formation of hydrogen peroxide (H2O2) over O2. This shift in selectivity is attributed to polaronic effects, which strengthen the metal-oxo bonding, enabling a transition from conventional OER to H2O2 evolution. Furthermore, we reveal that the thermodynamic stability of these perovskites in aqueous environments is significantly influenced by pH, where acidic conditions destabilize the perovskite structure. These insights suggest that modulating polaronic effects and maintaining high pH environments are key to optimizing both the stability and catalytic activity of perovskite oxides in OER applications. | Mohsen Sotoudeh; Axel Groß | Theoretical and Computational Chemistry; Materials Science; Catalysis | CC BY 4.0 | CHEMRXIV | 2025-03-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c6d46481d2151a0202990a/original/polaronic-competition-triggers-the-h2o2-evolution-on-perovskite-oxides-during-water-oxidation.pdf |
60c74bfb9abda239b3f8d1b5 | 10.26434/chemrxiv.12380726.v1 | Industry-applicable, efficient hydrogen evolution reaction through an interface-activated bimetallic electrode with seawater photolysis in alkaline media | <p><a><b>Hydrogen
evolution reaction (HER) electrocatalysts over platinum (Pt) in an alkaline
medium is crucial for hydrogen economy. Herein, we demonstrate new concept “interface-active
electrode” to transform naturally inert alkaline HER materials towards
industry-applicable HER electrocatalyst, comprised of interface-rich NiP<sub>2</sub>-FeP<sub>2</sub>
on Cu nanowires that required overpotential as low as 23.6 and 357 mV at -10 and
-1000 mA/cm<sup>2</sup>, respectively, with exceptional stability at the industrial
current density of -1 A cm<sup>-2</sup>, superior to commercial Pt under
alkaline solution. Structural characterization and theoretical calculations
revealed the abundant interface between facets of NiP<sub>2</sub>-FeP<sub>2 </sub>on
Cu exhibits optimum H adsorption-free energy than Pt and lower kinetic barrier
for water dissociation (Δ<i>G</i><sub>B</sub> = 0.16 eV), boosting alkaline HER.
Additionally, when integrated in a water splitting device, generated 10 mA/cm<sup>2
</sup>at only </b></a><b>1.42, 1.4, and 1.31 V </b><b>under 1 M KOH, artificial seawater at
25 ̊C and 100 ̊C, respectively, along with high solar-to-hydrogen (STH)
conversion efficiency of 19.85</b><b> %. </b></p> | Ashwani Kumar; Viet Quoc Bui; Jinsun Lee; Amol R. Jadhav; Yoseph Whang; Min Gyu Kim; Yoshiyuki Kawazoe; Hyoyoung Lee | Nanostructured Materials - Materials; Fuels - Energy Science | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74bfb9abda239b3f8d1b5/original/industry-applicable-efficient-hydrogen-evolution-reaction-through-an-interface-activated-bimetallic-electrode-with-seawater-photolysis-in-alkaline-media.pdf |
60c73d4f469df40babf4269f | 10.26434/chemrxiv.5602750.v1 | Evidence of charge transfer to atomic and molecular adsorbates on graphitic-like ZnO/X(111) (X = Cu, Ag, Au) ultrathin films | ZnO bilayers grown on Cu(111), Ag(111), and Au(111) surfaces form graphitic-like flat structures. They belong to the class of two-dimensional materials. We show, by means of density functional theory (DFT) calculations including dispersion, that Au, NO2, and O2 species adsorbed on ZnO/Cu(111) induce a spontaneous net charge transfer (CT) via electron tunneling from the Cu support through the insulating ZnO film, resulting in the formation of negatively charged atomic, Au<sup>-</sup>, or molecular, NO<sub>2</sub><sup>-</sup> and O<sub>2</sub><sup>-</sup>, adsorbates. We show for the case of gold that the CT is found also for ZnO/Ag(111) and ZnO/Au(111) interfaces. The stabilization of the anionic species is accompanied by a polaronic distortion of the ZnO lattice. Other molecules with low electron affinity such as NO and CO<sub>2</sub>, on the contrary, do not induce the CT. However, charge transfer and activation of two CO<sub>2</sub> molecules to form an oxalate species, [C<sub>2</sub>O<sub>4</sub>]<sup>2-</sup>, is promoted by a single Au anion, and similar catalytic activity is expected for the negatively charged Au clusters. By comparing the properties of the metal supported ZnO films with those of the free-standing ZnO bilayer, we demonstrate the key role of the metal/oxide interface. These results are relevant in the field of methanol synthesis based on ZnO/Cu catalysts where ultrathin layers of ZnO supported on Cu are formed under reaction conditions. | Ho Viet Thang; Sergio Tosoni; Gianfranco Pacchioni | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2017-11-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d4f469df40babf4269f/original/evidence-of-charge-transfer-to-atomic-and-molecular-adsorbates-on-graphitic-like-zn-o-x-111-x-cu-ag-au-ultrathin-films.pdf |
60c74c2b469df4830df44020 | 10.26434/chemrxiv.12058575.v3 | Catalyst Control of Selectivity in the C–O Bond Alumination of Biomass Derived Furans | Non-catalysed and catalysed reactions of aluminium reagents with furans, dihydrofurans and dihydropyrans were investigated and lead to the ring-expanded products due to the formal insertion of the aluminium reagent into a C–O bond of the heterocycle. Specifically, the reaction of [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl, 1) with furan, 2-methylfuran, 2,3-dimethylfuran and 2-methoxyfuran proceeded between 25 and 80 ºC leading to ring-expanded and dearomatised products due to the net transformation of a sp2 C–O bond into a sp2 C–Al bond. The kinetics of the reaction of 1 with furan were found to be 1st order with respect to 1 with activation parameters ΔH‡ = +19.7 (± 2.7) kcal mol-1, ΔS‡ = –18.8 (± 7.8) cal K-1 mol-1 and ΔG‡298 K = +25.3 (± 0.5) kcal mol-1 and a KIE of 1.0 ± 0.1. DFT calculations support a stepwise mechanism involving an initial (4+1) cycloaddition of 1 with furan to form a bicyclic intermediate that rearranges by an a-migration. The selectivity of ring-expansion is influenced by factors that weaken the sp2 C–O bond through population of the s*-orbital. Inclusion of [Pd(PCy3)2] as a catalyst in these reactions results in expansion of the substrate scope to include 2,3-dihydrofurans and 3,4-dihydropyrans but also improves the selectivity. Under catalysed conditions, the C–O bond that breaks is that adjacent to C–H bond. The aluminium(III) dihydride reagent [{(MesNCMe)2CH}AlH2] (Mes = 2,4,6-trimethylphenyl, 2) can also be used under catalytic conditions to effect a dehydrogenative ring-expansion of furans. Further mechanistic analysis of the Pd-catalysed reaction of 1 with furan shows that C–O bond functionalisation occurs via an initial C–H bond alumination. Kinetic products can be isolated that are derived from installation of the aluminium reagent at the 2-position of the heterocycle. C–H alumination proceeds with a strong primary KIE of 4.8 ± 0.3 consistent with a turnover limiting step involving oxidative addition of the C–H bond to a palladium catalyst. Isomerisation of the kinetic C–H aluminated product to the thermodynamic C–O ring expansion product is an intramolecular process that is again catalysed by [Pd(PCy3)2]. DFT calculations suggest that the key C–O bond breaking step involves attack of an aluminium based metalloligand on the 2-palladated heterocycle. The new methodology has been applied to the upgrading of molecules derived from furfuraldehyde, an important platform chemical from biomass. | Thomas N hooper; Ryan Brown; Feriel Rekhroukh; Martí Garçon; Andrew J. P. White; Paulo J. Costa; Mark Crimmin | Coordination Chemistry (Inorg.); Kinetics and Mechanism - Inorganic Reactions; Main Group Chemistry (Inorg.); Organometallic Compounds; Transition Metal Complexes (Inorg.); Homogeneous Catalysis; Bond Activation; Catalysis; Coordination Chemistry (Organomet.); Kinetics and Mechanism - Organometallic Reactions; Main Group Chemistry (Organomet.); Small Molecule Activation (Organomet.); Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74c2b469df4830df44020/original/catalyst-control-of-selectivity-in-the-c-o-bond-alumination-of-biomass-derived-furans.pdf |
60c744a7ee301ce17cc791a8 | 10.26434/chemrxiv.9876473.v1 | Phosphonium-Based Binary and Ternary Super-Concentrated Liquid Electrolytes for Magnesium Batteries | Here we describe the use of organo ionic phosphonium salts to access a broad range of useful binary and ternary (super)-concentrated liquid electrolytes for rechargeable magnesium batteries. | miles arthur white; Emily V. Carino; Julian Self; Kristin Persson; Brett Helms | Theory - Computational; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.); Structure | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744a7ee301ce17cc791a8/original/phosphonium-based-binary-and-ternary-super-concentrated-liquid-electrolytes-for-magnesium-batteries.pdf |
60c757b7337d6cb764e29086 | 10.26434/chemrxiv.14453106.v1 | A Geometric Deep Learning Approach to Predict Binding Conformations of Bioactive Molecules | Understanding the interactions formed between a ligand and its molecular target is key to guide the optimization of molecules. Different experimental and computational methods have been key to understand better these intermolecular interactions. Herein, we report a method based on geometric deep learning that is capable of predicting the binding conformations of ligands to protein targets. Concretely, the model learns a statistical potential based on distance likelihood which is tailor-made for each ligand-target pair. This potential can be coupled with global optimization algorithms to reproduce experimental binding conformations of ligands. We show that the potential based on distance likelihood described in this paper performs similar or better than well-established scoring functions for docking and screening tasks. Overall, this method represents an example of how artificial intelligence can be used to improve structure-based drug design. | Oscar Méndez-Lucio; Mazen Ahmad; Ehecatl Antonio del Rio-Chanona; Jörg Kurt Wegner | Bioinformatics and Computational Biology; Computational Chemistry and Modeling; Machine Learning; Artificial Intelligence | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757b7337d6cb764e29086/original/a-geometric-deep-learning-approach-to-predict-binding-conformations-of-bioactive-molecules.pdf |
60c73f5af96a000ca128608b | 10.26434/chemrxiv.7303460.v1 | Graph Theory Approach to High-Throughput Surface Adsorption Structure Generation | We present a methodology for graph based enumeration of surfaces and unique chemical adsorption structures bonded to those surfaces. Utilizing the graph produced from a bulk structure, we create a unique graph representation for any general slab cleave and further extend that representation to include a large variety of catalytically relevant adsorbed molecules. We also demonstrate simple geometric procedures to generate 3D initial guesses of these enumerated structures. While generally useful for generating a wide variety of structures used in computational surface science and heterogeneous catalysis, these techniques are also key to facilitating an informatics approach to the high-throughput search for more effective catalysts.<br /> | Jacob Boes; Osman Mamun; Kirstin Winther; Thomas Bligaard | Computational Chemistry and Modeling; Chemoinformatics - Computational Chemistry; Surface | CC BY 4.0 | CHEMRXIV | 2018-11-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5af96a000ca128608b/original/graph-theory-approach-to-high-throughput-surface-adsorption-structure-generation.pdf |
60c75919337d6cd2c5e29332 | 10.26434/chemrxiv.14642253.v1 | Breaking Isolation to Form New Networks: pH-Triggered Changes in Connectivity Inside Lipid Nanoparticles | <p>There is a growing demand to develop smart
nanomaterials that are structure-responsive as they have the potential to offer
enhanced dose, temporal and spatial control of compounds and chemical processes.
The naturally occurring pH gradients found throughout the body make pH an
attractive stimulus for guiding the response of a nanocarrier to specific
locations or (sub)cellular compartments in the body. Here we have engineered
highly sensitive lyotropic liquid crystalline nanoparticles that reversibly
respond to changes in pH by altering the connectivity within their structure at physiological
temperatures. At pH 7.4, the nanoparticles have an
internal structure consisting of discontinuous inverse micellar ‘aqueous pockets’
based on space group Fd3m. When the pH is ≤6, the
nanoparticles change from a compartmentalized to an accessible porous internal
structure based on a 2D inverse hexagonal phase (plane group p6mm). <a></a><a>We validate the internal symmetry of the nanoparticles using Small Angle X-ray
Scattering and cryogenic Transmission Electron Microscopy. The high resolution
electron microscopy images obtained have allowed us for the first time to
directly visualize the internal structure of the Fd3m nanoparticles and resolve
the two different-sized inverse micelles that make up the structural motif
within the Fd3m unit cell, which upon structural analysis reveal excellent
agreement with theoretical geometrical models. </a></p> | Zexi Xu; John M. Seddon; Paul Beales; Michael Rappolt; Arwen Tyler | Biocompatible Materials; Controlled-Release Systems; Liquid Crystals; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience; Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75919337d6cd2c5e29332/original/breaking-isolation-to-form-new-networks-p-h-triggered-changes-in-connectivity-inside-lipid-nanoparticles.pdf |
60c752c39abda22699f8de82 | 10.26434/chemrxiv.13345250.v1 | Predicting Hydrogen Storage in MOFs via Machine Learning | <div><p>The H<sub>2</sub> storage capacities of a diverse set of 918,734 metal-organic frameworks (MOFs) sourced from 19 databases is predicted via machine learning (ML). Using only 7 structural features as input, ML identifies 8,282 MOFs with the potential to exceed the capacities of state-of-the-art materials under physisorptive conditions. The identified MOFs are predominantly hypothetical compounds having low densities (<0.31 g cm<sup>-3</sup>) in combination with high surface areas (> 5,300 m<sup>2</sup> g<sup>-1</sup>), void fractions (~0.90), and pore volumes (>3.3 cm<sup>3</sup> g<sup>-1</sup>). In addition, the relative importance of the input features are characterized, and dependencies on the ML algorithm and training set size are quantified. The single most important features for predicting H<sub>2</sub> uptake are pore volume (for gravimetric capacity) and void fraction (for volumetric capacity). The ML models are available for use via the web, allowing for rapid and accurate predictions of usable hydrogen capacities for MOFs with only minimal structural data as input; for the simplest models only a single input feature is required.</p></div> | Alauddin Ahmed; Donald Siegel | Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752c39abda22699f8de82/original/predicting-hydrogen-storage-in-mo-fs-via-machine-learning.pdf |
610424190321141618b8db2d | 10.26434/chemrxiv-2021-kk47l-v3 | Polyhydroxylated cyclopentane β-amino acids derived from D-mannose and D-galactose: synthesis and protocol for incorporation into peptides | A stereoselective synthesis of polyhydroxylated cyclopentane β-amino acids from hexoses is reported.
The reaction sequence comprises as key steps a Ring Closing Metathesis of a polysubstituted diene
intermediate, followed by the stereoselective aza-Michael functionalization of the resulting cyclopent-1-
ene-1-carboxylic acid ester. Examples of synthesis of polysubstituted 2-aminocyclopentanecarboxylic acid
derivatives starting from protected D-mannose and D-glucose are presented. A general protocol for the
incorporation of these highly functionalized alicyclic β-amino acids into peptides is also reported. | Fernando Fernández; Alberto G. Fernández; Rosalino Balo; Víctor M. Sánchez-Pedregal; Miriam Royo; Raquel G. Soengas; Ramón J. Estévez; Juan C. Estévez | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/610424190321141618b8db2d/original/polyhydroxylated-cyclopentane-amino-acids-derived-from-d-mannose-and-d-galactose-synthesis-and-protocol-for-incorporation-into-peptides.pdf |
62df80747f3aa66967f76666 | 10.26434/chemrxiv-2022-l5qms | Control of stereogenic oxygen in a helically chiral oxonium ion | The pyramidal inversion of trisubstituted nitrogen, phosphorus and sulfur compounds and its impact on configurational stability is a fundamental and well-recognized stereochemical phenomenon that is widely exploited. In contrast, the chemistry of oxonium ions – compounds bearing three substituents on a positively charged oxygen atom – is poorly developed and there are few applications in synthesis beyond their existence as reactive intermediates. There are no examples of configurationally stable oxonium ions in which the oxygen atom is the sole stereogenic centre, likely due to the low barrier to oxygen pyramidal inversion, and the perception that all oxonium ions are highly reactive. Here we describe the design, synthesis and characterization of a helically chiral triaryloxonium ion in which inversion of the oxygen lone pair is prevented through geometric restriction to enable it to function as a determinant of configuration. A combined synthesis and quantum calculation approach delineate design principles that enable configurationally stable and room-temperature isolable salts to be generated. We show that the barrier to inversion is >110 kJ mol-1 and outline a process for resolution. This constitutes the only example of a chiral non-racemic and configurationally stable molecule in which the oxygen atom is the sole stereogenic centre. | Owen Smith; Mihai Popescu; Madeleine Hindson; Robert Paton; Jonathan Burton; Martin Smith | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Stereochemistry | CC BY NC 4.0 | CHEMRXIV | 2022-07-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62df80747f3aa66967f76666/original/control-of-stereogenic-oxygen-in-a-helically-chiral-oxonium-ion.pdf |
627d78073f1e7c4157bc3998 | 10.26434/chemrxiv-2022-r4bfq-v4 | Bring Chemical Intuition to Chips: Transferable Chemical-intuitive Model to Predict Photophysics of Organic Aggregates | While machine-learning methods indicated good adaptability for machine-learning algorithms in the pan-chemistry field by its breakthroughs in pharmacy. Materials research still benefits from such new techniques fewer due to the inconsistency in the paradigm of study in the diversely different subareas which demand special treatment individually. In this contribution, we proposed an innovative design of the embedding method, which is inspired by chemical intuition, to bring neural networks into the field for modelling photophysics of the organic light-emitting materials in condensed states. We outline this framework and demonstrate its successful implementation in the predictive classification of fluorophores by its mechanisms, direction of spectra shift from solution to solid-state, and regression of spectral features, including emission peaks wavelengths in pristine solid-state and nano-aggregates. Our work may serve as an example for a specific area of materials research to transfer the empirical chemical intuition into machine-learning models and build comprehensive performance-oriented pre-screening systems to develop new compounds with demanded characters. | Junyi Gong; Ziwei Deng; Huilin Xie; Zheng Zhao; Ben Zhong Tang | Theoretical and Computational Chemistry; Physical Chemistry; Machine Learning; Chemoinformatics - Computational Chemistry; Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/627d78073f1e7c4157bc3998/original/bring-chemical-intuition-to-chips-transferable-chemical-intuitive-model-to-predict-photophysics-of-organic-aggregates.pdf |
632adf31fee74e1bf644aded | 10.26434/chemrxiv-2022-xbfbc | Fourfold Double-Bond Substituted Hemiindigo: Highly Functionalized Red-Light Responsive Photoswitches | Molecular photoswitches are indispensable tools for responsive chemical nanosystems and are nowadays used in virtually all branches of the natural sciences. Hemiindigo (HI) derivatives were recently introduced as potent photoswitches but full applicability was hampered by the limited possibilities for their functionalization and structural alteration. Here we report on a short and easy to diversify synthesis yielding fourfold double-bond substituted HIs. The resulting chromophores are shown to offer an advantageous property profile combining red-light responsiveness, high thermal bistability, strong isomer accumulations in both switching directions, and strong photochromism. With this progress a new structural realm has been opened up for HI photoswitches, that can now be synthetically tailored to highly advanced applications in e.g. molecular machines and multi-switching research, photoisomerization mechanism studies, or smart and addressable materials generation. | Maximilian Sacherer; Frank Hampel; Henry Dube | Physical Chemistry; Organic Chemistry; Nanoscience; Organic Synthesis and Reactions; Photochemistry (Org.); Physical Organic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632adf31fee74e1bf644aded/original/fourfold-double-bond-substituted-hemiindigo-highly-functionalized-red-light-responsive-photoswitches.pdf |
6790bb416dde43c908bcbe88 | 10.26434/chemrxiv-2024-4nfk8-v3 | Highly Z-selective Julia–Kocienski Olefination Using N-sulfonylimines and Its Mechanistic Insights from DFT Calculations | The Julia–Kocienski (JK) olefination is a powerful and widely used method for alkene synthesis, particularly favoring E-selective olefination. However, highly Z-selective variants remain underexplored. In this study, we report a highly Z-selective JK olefination (Z ratio >99:1) using N-sulfonylimines as electrophilic partners instead of traditional aldehydes. This approach exhibits broad substrate compatibility, accommodating a variety of sulfones and N-sulfonylimines with functional groups such as electron-donating and electron-withdrawing substituents, amides, halogens, carboxylic acids, and hydroxyls. The reaction enables efficient synthesis of valuable Z-alkenes, including (Z)-α,β-unsaturated amides, Z-alkenyl halides, and Z-trisubstituted alkenes, under mild and general conditions. Mechanistic investigations using DFT calculations revealed that Z-selectivity is established during the 1,2-addition step, contrasting with conventional Z-selective JK olefination, where the Smiles rearrangement step governs selectivity. This study not only expands the synthetic arsenal for stereoselective olefin synthesis but also provides a versatile and general method for constructing Z-olefins with high precision and efficiency. | Takuma Chizaki; Koichi Fujiwara; Junko Fujimoto; Tetsuo Narumi; Satoshi Shuto; Mizuki Watanabe | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6790bb416dde43c908bcbe88/original/highly-z-selective-julia-kocienski-olefination-using-n-sulfonylimines-and-its-mechanistic-insights-from-dft-calculations.pdf |
61093882032114fa07b99dff | 10.26434/chemrxiv-2021-qk2ns | Discovering a hidden binding site of spermidine synthase
inhibitors for Chagas disease by combining molecular
simulations and X-ray crystallography | Background
Chagas disease is caused by the parasite Trypanosoma cruzi and is one of the neglected tropical diseases. Although two types of drugs are currently available, new drugs are still required because they have serious side effects. To develop a therapeutic agent for trypanosomiasis, we focused on spermidine synthase (SpdSyn) as the target protein and determined the hidden binding site which was not identified in the X-ray structure for obtaining seed compounds using a computational simulation.
Methodology/Principal Findings
Molecular dynamics (MD) simulation was performed for TcSpdSyn to predict new binding sites. These results indicated that the highly druggable binding site was discovered around Glu22. We also conducted docking simulation for the new binding site and in vitro assay to determine half-maximal inhibitory concentration (IC50) value. Furthermore, to confirm ligand of binding site and pose, we conducted X-ray crystallographic studies. As a result, two compounds were discovered as inhibitors of TcSpdSyn with IC50 values of 82.27 and 43.41 μM, respectively. X-ray crystallographic analysis shows that two inhibitors are bound to the hidden binding site which is detected by computational simulation.
Conclusions/Significance
MD simulation revealed that there are new sites in the TcSpdSyn that are not an active site. This site exists near Glu22 and Asp77, and crystal structures revealed that compounds 1 and 2 are bound to the hidden binding site, as predicted by MD simulations, and interacts with Glu22 and Asp77 through hydrogen bonds. 4MCHA which has been reported as known inhibitor binds to the TcSpdSyn active site while interacting with Asp171. Therefore, these inhibitors we discovered differs in binding mode from a known inhibitor and this new binding site is useful for antitrypanosomiasis target.
| Ryunosuke Yoshino; Nobuaki Yasuo; Yohsuke Hagiwara; Takashi Ishida; Daniel Ken Inaoka; Yasushi Amano; Yukihiro Tateishi; Kazuki Ohno; Ichiji Namatame; Tatsuya Niimi; Masaya Orita; Kiyoshi Kita; Yutaka Akiyama; Masakazu Sekijima | Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61093882032114fa07b99dff/original/discovering-a-hidden-binding-site-of-spermidine-synthase-inhibitors-for-chagas-disease-by-combining-molecular-simulations-and-x-ray-crystallography.pdf |
614c685fa7b2492df135fe8e | 10.26434/chemrxiv-2021-dfnxk | Profiling single-molecule reaction kinetics under nanopore confinement | The development of single-molecule reaction inside nanoconfinement is benefit to study the intrinsic molecular mechanism of a complex chemical reaction. However, the reaction kinetics model of single-molecule reaction inside confinement remains elusive. Herein we engineered the Aerolysin nanopore reactor to elaborate the single-molecule reaction kinetics inside nanoconfinement. By identifying bond forming and non-forming events directly, a four-state kinetics model is proposed for the first time. Our results demonstrated that the single-molecule reaction kinetics inside a nanopore depends on the voltage-dependent frequency of captured individual reactant and the fraction of effective collision inside nanopore confined space. This new insight will guide the design of nanoconfinement for resolving the single-molecule chemistry, and shed light on the mechanistic understanding of dynamic covalent chemistry in-side a nanopore | Wei Liu; Zhonglin Yang; Chaonan Yang; Yi-Lun Ying; Yi-Tao Long | Physical Chemistry; Organic Chemistry; Analytical Chemistry; Electrochemical Analysis; Biophysical Chemistry; Chemical Kinetics | CC BY NC 4.0 | CHEMRXIV | 2021-09-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/614c685fa7b2492df135fe8e/original/profiling-single-molecule-reaction-kinetics-under-nanopore-confinement.pdf |
619c951164a7078ea27c5109 | 10.26434/chemrxiv-2021-kldh7 | Stereochemical engineering of a peptide macrocycle allosteric inhibitor of phospho-Akt2 controls cell penetration by fine-tuning macrocycle-cell membrane interactions | We report the development of a cell-penetrant cyclic loop biligand that selectively binds, in vitro, to the phosphorylated Ser474 site of Protein Kinase B (p-Akt2) with high affinity (KD = 10 nM). The cyclic loop biligand consists of a linear peptide joined to a macrocycle peptide through triazole linkage, and it was isolated through two iterative in situ screens. This biligand allosterically inhibited kinase activity of Akt2 but it was cell-impermeable, as isolated from the screening process. Since Akt2 is an oncoprotein hyperactivated via phosphorylation at Ser474 in cancers, we sought to visualize p-Akt2 in live cancer cells using the developed biligand. To this end, we matured this biligand into a cell-penetrant reagent through systematic iterations of its chemical structure to promote cell-penetrating properties, while retaining its binding and inhibition for p-Akt2. Two retro-inverso, N-methylated versions of the macrocyclic ligand were developed which were uptaken by live cancer cells, while retaining their high affinities for pAkt2. Interestingly, the stereochemistry of two amino acid residues in the cell-penetrant ligands exhibited strong influence on their extent of cell penetration. This phenomenon of difference in cell penetration was explored through metadynamics simulations of each ligand in the cell membrane. It was found that the ligand uptaken to a greater extent by cells had more intramolecular interactions with itself and had fewer cholesterol molecules associated with it, which aided in its cell-penetration. | Arundhati Nag; Amirhossein Mafi; Samir Das; Mary Beth Yu; Belen Alvarez-Villalonga; William Goddard; James Heath | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/619c951164a7078ea27c5109/original/stereochemical-engineering-of-a-peptide-macrocycle-allosteric-inhibitor-of-phospho-akt2-controls-cell-penetration-by-fine-tuning-macrocycle-cell-membrane-interactions.pdf |
67351bdd7be152b1d0fd9f60 | 10.26434/chemrxiv-2024-swzp7 | Total Synthesis of (–)-Cordycicadin D and 3,4-trans-Cordycicadins A and B: Entry to the 3,4-trans-Fused Cordycicadin Framework | Cordycicadins A–D are four C20 polyketides, all containing a gamma-lactone fused to a 10-membered lactone. The proposed biosynthetic pathway for the cordycicadins anticipates the formation of two more natural products which are unknown. We report the total synthesis of (–)-cordycicadin D and the two anticipated natural products 3,4-trans-cordycicadins A and B. The targets were convergently assembled, in a biomimetic fashion, via an efficient ketene trapping-intramolecular Michael addition sequence that delivered the requisite 3,4-trans-fused framework with high diastereoselectivity, enabled by the synthesis of complex dioxenones that serve as in situ ketene precursors. Recognition of the embedded polyketide symmetry enabled the use of a divergent-convergent synthetic stratergy, based on the use of two products from an early-stage enzymatic resolution. The synthetic routes afforded (–)-cordycicadin D in 14 steps and 3,4-trans-cordycicadins A and B in 13 steps (longest linear sequence). This work confirms the structure of (–)-cordycicadin D, and notes that observed instability of the anticipated natural product 3,4-trans-cordycicadin B during purification may explain why it is yet to be isolated. | Liam Hunt; Phillip Grant; Grace Shimokura; Daniel Furkert; Margaret Brimble | Organic Chemistry; Natural Products; Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67351bdd7be152b1d0fd9f60/original/total-synthesis-of-cordycicadin-d-and-3-4-trans-cordycicadins-a-and-b-entry-to-the-3-4-trans-fused-cordycicadin-framework.pdf |
6263fbd7368ab6bc108a589e | 10.26434/chemrxiv-2022-mn3h3 | Unexpected isomerization of oxetane-carboxylic acids | We unexpectedly discovered that popular oxetane-carboxylic acids are intrinsically unstable. They easily isomerize into lactones under storage at rt, or under slight heating. Chemists should keep in mind the high instability of these common molecules, as this could dramatically affect the reaction yields and lead to negative results (especially in those reactions that require heating). | Bohdan Chalyk; Anastasiia Grynyova; Kateryna Filimonova; Tymofii Rudenko; Dmitry Dibchak; Pavel Mykhailiuk | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC 4.0 | CHEMRXIV | 2022-04-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6263fbd7368ab6bc108a589e/original/unexpected-isomerization-of-oxetane-carboxylic-acids.pdf |
6272601943d1f082821f2e02 | 10.26434/chemrxiv-2022-j66dm | Controlled microfluidic droplet acoustoinjection on one chip | We present an all-in-one acoustofluidics device for controlled acoustic field-mediated injection of surfactant stabilized water-in-oil droplets. The microfluidic channels and interdigitated transducer (IDT) channels are produced on the same master wafer and cast within one PDMS slab, making our acoustofluidics device simple to construct while retaining the same height for all channels. The IDTs with a curved, serpentine, paired and focusing geometry are easily embedded into the PDMS slab by filling the IDT channels with low melting point metal alloy. In this article, we propose the working mechanism of our embedded IDTs, which we call acoustoinjection, and carry out a precise characterization by laser doppler vibrometry (LDV) and infrared imaging to describe the injection of droplets within microfluidic channels. Although we observe that the device has acoustic resonance in the MHz frequency domain, we show that it operates most efficiently for acoustoinjection in the kHz frequency domain. In this frequency domain, our acoustofluidics device generates a pressure wave that causes destabilization of the surfactant-supported droplet interface enabling the injection of aqueous solution into the water-phase of the droplet with minimum heat generation. We show droplet injection for different surfactant concentrations, droplet passing speeds, and injection rates with high accuracy. This integrated device has the potential to serve as an alternative to electric field mediated picoinjection technologies by acoustic field-mediated and non-harmful manipulation of droplets with bio-content. | Christoph Frey; Jacqueline A. De Lora; Timotheus Jahnke; Yuanzhen Wang; Sebastian Weber; Ilia Platzman; Joachim P. Spatz | Physical Chemistry; Biophysical Chemistry | CC BY 4.0 | CHEMRXIV | 2022-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6272601943d1f082821f2e02/original/controlled-microfluidic-droplet-acoustoinjection-on-one-chip.pdf |
60c73edbf96a0064bd285fdd | 10.26434/chemrxiv.7160789.v1 | Tilting a Ground State Reactivity Landscape by Vibrational Strong Coupling | Site-selectivity is fundamental for steering chemical reactivity towards a given product and various efficient chemical methods have been developed for this purpose. Here we explore a very different approach by using vibrational strong coupling (VSC) between a reactant and the vacuum field of a microfluidic optical cavity. For this purpose, the reactivity of a compound bearing two possible silyl bond cleavage sites, at Si-C and Si-O, was studied as a function of VSC of its various vibrational modes in the dark. The results show that VSC can indeed tilt the reactivity landscape to favor one product over the other. Thermodynamic parameters reveal the presence of a large activation barrier and significant changes to the activation entropy, confirming the modified chemical landscape under strong coupling. This study shows for the first time that VSC can impart site-selectivity for chemical reactions without the need for chemical intervention. | Anoop Thomas; Lucas Lethuillier-Karl; Kalaivanan Nagarajan; Robrecht M. A. Vergauwe; Jino George; Thibault Chervy; Atef Shalabney; Eloïse Devaux; Cyriaque Genet; Joseph Moran; Thomas W. Ebbesen | Physical Organic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2018-10-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73edbf96a0064bd285fdd/original/tilting-a-ground-state-reactivity-landscape-by-vibrational-strong-coupling.pdf |
60c7422c842e658677db2015 | 10.26434/chemrxiv.8239157.v1 | Activation Energy and NBO Interaction Approaches to the Determination of the Relative Resonance Acceptor Strengths of CN, NO, COMe, CHO and NO2 Groups from the Ring-Opening of 1,2-Benzo-3-Carbomethoxycyclobutenes | <p>The relative resonance-acceptor ability based on the activation energies for the outward ring-openings of 1,2-benzo-3-carbomethoxycyclobutenes bearing CN, NO, COMe, CHO and NO<sub>2</sub> as C6 and C7 substituents is different from that based on the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interactions in the inward opening transition structures. The differential activation energy (∆G<sup>‡</sup>) predicts outward ring-opening and, in contrast, the differential s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energy predicts inward opening, throughout. The relative resonance-acceptor ability estimated from the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energies is more realistic than that from the activation energies.</p> | Veejendra Yadav; Arpita Yadav | Physical Organic Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7422c842e658677db2015/original/activation-energy-and-nbo-interaction-approaches-to-the-determination-of-the-relative-resonance-acceptor-strengths-of-cn-no-co-me-cho-and-no2-groups-from-the-ring-opening-of-1-2-benzo-3-carbomethoxycyclobutenes.pdf |
64b7c5ecb605c6803bff910d | 10.26434/chemrxiv-2023-qzx85 | Visible light promoted [3+2]-cycloaddition in the synthesis of cyclopenta[b]chromenocarbonitrile derivatives | In the manuscript, a novel method for the preparation of cyclopenta[b]chromenocarbonitrile derivatives via [3+2] cycloaddition reaction of substituted 3-cyanochromones and N-cyclopropyloamines initiated by visible light catalysis in the presence of Eosin Y as a photocatalyst has been described. The key parameters responsible for the success of the described strategy are: visible light, small amount of photoredox catalyst, anhydrous solvent and inert atmosphere. | Ewelina Kowalska; Mateusz Dyguda; Angelika Artelska; Anna Albrecht | Organic Chemistry; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b7c5ecb605c6803bff910d/original/visible-light-promoted-3-2-cycloaddition-in-the-synthesis-of-cyclopenta-b-chromenocarbonitrile-derivatives.pdf |
60c75392f96a0012f62884aa | 10.26434/chemrxiv.13514440.v1 | Estimating the Geothermal Electricity Generation Potential of Sedimentary Basins Using genGEO (The Generalizable GEOthermal Techno-Economic Simulator) | <p><b>Abstract</b></p><p>Sedimentary basins are ubiquitous, naturally
porous and permeable, and the geothermal heat in these basins can be extracted
with geologic water or CO<sub>2</sub> and used to generate electricity. Despite
this, the broad potential that these formations may have for electricity
generation is unknown. Here we investigate this potential, which required the
creation of the <u>gen</u>eralizable <u>GEO</u>thermal techno-economic
simulator (genGEO). genGEO is built with only publicly available data and uses
five standalone, but integrated, models that directly simulate all components
of geothermal power plants to estimate electricity generation and cost. As a
result of this structure, genGEO, or a portion of it, can be applied or
extended to study any geothermal power technology. In contrast, the current
techno-economic tools for geothermal power plants rely on characterizations of
unpublished ASPEN results and are thus not generalizable enough to be applied
to sedimentary basin geothermal power plants which use subsurface CO<sub>2</sub>.</p>
<p>In this study, we present genGEO as
open-source software, validate it with industry data, and compare its estimates
to other geothermal techno-economic tools. We then apply genGEO to sedimentary
basin geothermal resources and find that using CO<sub>2</sub> as a subsurface
heat extraction fluid compared to water decreases the cost of geothermal
electricity across most geologic conditions that are representative of
sedimentary basins. Using genGEO results and p50 geologic data, we produce
supply curves for sedimentary basin geothermal power plants in the U.S., which
suggests that there is present-day potential to profitably increase the
capacity of geothermal power by ~10% using water as the subsurface heat
extraction fluid. More capacity is available at lower cost when CO<sub>2</sub>
is used as the subsurface fluid, but realizing this capacity requires
geologically storing between ~2 and ~7 MtCO<sub>2</sub>/MW<sub>e</sub>. But
developing sedimentary basin resources in the short-term using subsurface water
may not eliminate options for CO₂-based power plants in the long-term because the least-cost order of
sedimentary basins is not the same for both CO<sub>2</sub> and water. With
sufficient geologic CO<sub>2</sub> storage, developing sedimentary basins using
CO<sub>2</sub>- and water-based power plants may be able to proceed in
parallel.</p> | Benjamin Adams; Jonathan Ogland-Hand; Jeffrey M. Bielicki; Philipp Schädle; Martin Saar | Fluid Mechanics; Thermodynamics (Chem. Eng.); Power | CC BY 4.0 | CHEMRXIV | 2021-01-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75392f96a0012f62884aa/original/estimating-the-geothermal-electricity-generation-potential-of-sedimentary-basins-using-gen-geo-the-generalizable-ge-othermal-techno-economic-simulator.pdf |
64c971b2ce23211b20f4626f | 10.26434/chemrxiv-2023-21f9b | Unraveling the Bürgi-Dunitz Angle with Precision: The Power of a Two-Dimensional Energy Decomposition Analysis | Understanding the geometrical preferences in chemical reactions is crucial for advancing the field of organic chemistry and improving synthetic strategies. One such preference, the Bürgi-Dunitz angle, is central to nucleophilic addition reactions involving carbonyl groups. This study successfully employs a novel two-dimensional Distortion-Interaction/Activation-Strain Model in combination with a two-dimensional Energy Decomposition Analysis to investigate the origins of the Bürgi-Dunitz angle in the addition reaction of CN– to (CH3)2C=O. We constructed a 2D potential energy surface defined by the distance between the nucleophile and carbonylic carbon atom and by the attack angle, followed by an in-depth exploration of energy components including strain and interaction energy. Our analysis reveals that the Bürgi-Dunitz angle emerges from a delicate balance between two key factors: strain energy and interaction energy. High strain energy, as a result of the carbonyl compound distorting to avoid Pauli repulsion, is encountered at high angles, thus setting the upper bound. On the other hand, interaction energy is shaped by a dominant Pauli repulsion when the angles are lower. This work emphasizes the value of the 2D Energy Decomposition Analysis as a refined tool, offering both quantitative and qualitative insights into chemical reactivity and selectivity. | Israel Fernández; F. Matthias Bickelhaupt; Dennis Svatunek | Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64c971b2ce23211b20f4626f/original/unraveling-the-burgi-dunitz-angle-with-precision-the-power-of-a-two-dimensional-energy-decomposition-analysis.pdf |
60c744c0469df43b39f433d6 | 10.26434/chemrxiv.9913976.v1 | Self-Sorting of Two Imine-Based Metal Complexes: Balancing Kinetics and Thermodynamics in Constitutional Dynamic Networks | A major hurdle in the development of complex constitutional dynamic
networks (CDNs) is the lack of strategies to simultaneously control the
output of two (or more) interconnected dynamic processes over several
species, namely reversible covalent imine bonds formation and dynamic
metal-ligand coordination. We have studied in detail the factors
influencing the fidelity of the self-sorting process (concentration,
electronic and steric parameters of the organic components, nature of
the metal cations) of 11 constitutional dynamic libraries containing two
different amines, aldehydes and metals salts into two imine-based metal
complexes, having no overlap in term of their compositions. In all the
cases, the outcome of the process was primarily determined by the
ability of the octahedral metal ions to select its pair of components
from the initial pool of components, the composition of the weaker
tetrahedral complex being imposed by the components rejected by the
octahedral metal ions. Different octahedral metal ions required
different level of precision in the “assembling instructions” provided
by the organic components of the CDN to guide it towards a sorted
output. The concentration of the reaction mixture, the electronic and
steric properties of the initial components of the library were all
found to influence the lifetime of unwanted metastable intermediates
formed during the assembling of the two complexes. | Jean-François Ayme; Jean-Marie Lehn | Supramolecular Chemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744c0469df43b39f433d6/original/self-sorting-of-two-imine-based-metal-complexes-balancing-kinetics-and-thermodynamics-in-constitutional-dynamic-networks.pdf |
60c7474af96a00b1b8286eef | 10.26434/chemrxiv.7711418.v2 | Site-selective enzymatic C‒H amidation for synthesis of diverse lactams | <p>Please note that this work has been retracted by the authors.</p><p><br /></p><p>After publication of the Report “Site-selective enzymatic C‒H amidation for synthesis of diverse lactams” in <i>Science </i>(<i>1, also linked in metadata</i>), efforts to reproduce the work showed that the enzymes do not catalyze the reactions with the activities and selectivities claimed. Careful examination of the first author’s lab notebook then revealed missing contemporaneous entries and raw data for key experiments. The authors therefore have retracted the article from <i>Science</i> and are now retracting the preprint from ChemRxiv. The original paper can be accessed by selecting “Version 1” of the preprint below, or by accessing <a href="https://doi.org/10.26434/chemrxiv.7711418.v1">https://doi.org/10.26434/chemrxiv.7711418.v1</a>. </p><p><br /></p><p><b><i> Inha Cho, Zhi-Jun Jia, Frances H. Arnold*</i></b></p><p><br /></p><p>Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.</p><p><br /></p><p>*Corresponding author. Email: [email protected]</p><p><br /></p><p><b>References</b></p><p>1. I. Cho, Z.-J. Jia, F. H. Arnold, <i>Science</i> <b>364</b>, 575 (2019). DOI: 10.1126/science.aaw9068<br /></p><p><br /></p><p><br /></p><p>*******************************************************************************************</p><p><br /></p><p>Directed evolution of cytochrome P450 enzymes fine-tunes site selectivity of new-to-nature C‒H amidation for modular, sustainable and scalable preparation of enantio-enriched β-, γ- and δ-lactams.<br /></p> | Inha Cho; Zhijun Jia; Frances H. Arnold | Organic Synthesis and Reactions; Stereochemistry; Biochemistry; Cell and Molecular Biology; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7474af96a00b1b8286eef/original/site-selective-enzymatic-c-h-amidation-for-synthesis-of-diverse-lactams.pdf |
63bc092aee6f18fce09953aa | 10.26434/chemrxiv-2023-wzj3r | Performance of common density functionals for excited states of tetraphenyldibenzoperiflanthene | Time-dependent density functional theory is the method of choice to efficiently calculate excitation spectra with the functional and basis set choice allowing to compromise between accuracy and computational cost. In this work the performance of different functionals as well as the second-order approximate coupled cluster singles and doubles model CC2 is evaluated by comparing the results to experimental results of the example molecule tetraphenyldibenzoperiflanthene (DBP). Functional choice has a significant impact on the spectrum of DBP. The performance of a number of different functionals was evaluated, quantified, and, where possible, discussed. The best functional, tuned-CAM-B3LYP, is used to investigate DBP on a surface of hexagonal boron nitride (h-BN). The resulting spectrum shows excellent agreement with experimental results for a monolayer of DBP on h-BN. | Tim Schrader; Eva Perlt; Torsten Fritz; Marek Sierka | Theoretical and Computational Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63bc092aee6f18fce09953aa/original/performance-of-common-density-functionals-for-excited-states-of-tetraphenyldibenzoperiflanthene.pdf |
60c741c7702a9bc2e818a2fe | 10.26434/chemrxiv.8126690.v1 | Renormalization Group Theory Applied to the CPA Equation of State: Impacts on Phase Equilibrium and Derivative Properties | Calculation of thermodynamic properties such as vapor-liquid phase behavior with equations of state is largely and successfully employed in chemical engineering applications.<br />However, in the proximities of the critical point, the different density-fluctuation scales inherent to critical phenomena introduce significant changes in these thermodynamic properties, with which the classical equations of state are not prepared to deal.<br />Aiming at correcting this failure, we apply a renormalization-group methodology to the CPA equation of state in order to improve the thermodynamic description in the vicinity of critical points.<br />We use this approach to compute vapor-liquid equilibrium of pure components and binary mixtures, as well as derivative properties such as speed of sound and heat capacity.<br />Our results show that this methodology is able to provide an equation of state with the correct non-classical behavior, thus bringing it in consonance with experimental observation of vapor-liquid equilibrium and derivative properties in near-critical conditions. | Gabriel Silva; Charlles Abreu; Frederico W. Tavares | Computational Chemistry and Modeling; Thermodynamics (Chem. Eng.); Physical and Chemical Properties; Statistical Mechanics; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-05-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741c7702a9bc2e818a2fe/original/renormalization-group-theory-applied-to-the-cpa-equation-of-state-impacts-on-phase-equilibrium-and-derivative-properties.pdf |
66db0414cec5d6c14251a6a9 | 10.26434/chemrxiv-2024-7vvr8-v2 | Synthesis and Characterization of New Formylpyrazolones and Schiff bases | The reaction of 1-benzyl- and 1-(2-phenylethyl)- 3-methyl-5-pyrazolone with POCl3 and DMF affords N,N- dimethylaminothylidene derivatives that in acid or basic medium can be transformed into the corresponding aldehydes at the carbon 4 of the heterocycle. The dimethylenamine can also be more easily obtained by reacting pyrazolones with the dimethyl acetal of N,N-dimethylformamide. Starting from the aldehydes or the N,N-dimethylenamines is possible to obtain new enamines. The advantages of using dimethylenamines are the absence of the enol as an undesired byproduct and that there is no need to prepare the aldehyde to obtain Schiff bases. Overall, the yields can be classified as acceptable. The aldehydes can be described as 5-hydroxypyrazole-4-carbaldehydes in chloroform solutions, but in solid phase they are dicarbonyl compounds. The Schiff bases exhibit an enamine structure in chloroform solution and in solid phase. | Julio Belmar M.; Kristofer Bonilla W.; Claudio Jiménez A.; David Villaman | Organic Chemistry; Organometallic Chemistry; Organic Synthesis and Reactions; Ligand Design; Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66db0414cec5d6c14251a6a9/original/synthesis-and-characterization-of-new-formylpyrazolones-and-schiff-bases.pdf |
60c7506f469df46594f44871 | 10.26434/chemrxiv.13041830.v1 | Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines | The rational design of conformationally
controlled foldable modules can lead to a deeper insight into the
conformational space of complex biological molecules where non-covalent
interactions such as hydrogen bonding and π-stacking are known to play a
pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities
and hence, are ideal molecules for designing foldable modules that can mimic
the secondary structures of bio-molecules. The π-stacking induced folding of
bis-squaraines tethered using aliphatic primary and secondary-diamine linkers
of varying length is explored with a simple strategy of invoking small
perturbations involving the length linkers and degree of substitution. Solution
phase NMR investigations in combination with molecular dynamics simulations
suggest that bis-squaraines predominantly exist as extended conformations. Structures
elucidated by X-ray crystallography confirmed a variety of folded and extended
secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of
π-stacking relative to N–H···O hydrogen bonds. | Abhishek Singh; Reman K. Singh; G Naresh Patwari | Computational Chemistry and Modeling; Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7506f469df46594f44871/original/hierarchy-of-stacking-determines-the-conformational-preference-of-bis-squaraines.pdf |
60c7526bbdbb897281a3a287 | 10.26434/chemrxiv.13256831.v2 | Nitrogen Heterocyclic Carbene (NHC) as a Versatile Oxygen Atom Acceptor that Abstracts Oxygen Atom from Aldehydes and CO2 A Computational Research | The formal oxygen atom transfer (OAT) reaction
with nitrogen heterocyclic carbenes (NHCs) as oxygen atom acceptor was designed
and studied by density functional theory (DFT) calculations. Several properly
designed NHCs were predicted to exhibit high reactivity towards the formal OAT
reaction with aldehydes, in the presence of an intramolecular phosphine motif,
which provides a new method to generate phosphorus ylide from aldehydes.
Furthermore, the OAT reaction of NHCs with carbon dioxide (CO<sub>2</sub>) was
predicted to occur at room temperature to release carbon monoxide, aided by an
intramolecular nucleophile. These results may give insights about new
methodologies for ylide preparation and CO<sub>2</sub> reduction. | Yumiao Ma | Organic Synthesis and Reactions; Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7526bbdbb897281a3a287/original/nitrogen-heterocyclic-carbene-nhc-as-a-versatile-oxygen-atom-acceptor-that-abstracts-oxygen-atom-from-aldehydes-and-co2-a-computational-research.pdf |
60c74f23bb8c1a3caa3db892 | 10.26434/chemrxiv.12854813.v1 | Visible-Light-Promoted Metal-Free Ammoxidation of C(sp3)-H bonds | The metal-free activation of C(<i>sp</i><sup>3</sup>)-H bonds to value-added
products is of paramount importance in organic synthesis. Herein, we report the
use of the commercially available organic dye 2,4,6-triphenylpyrylium tetrafluoroborate (TPP) for the conversion of methylarenes
to the corresponding aryl nitriles via a photo process. Applying this
methodology, a variety of cyanobenzenes have been synthesized in good to
excellent yield under metal- and cyanide-free conditions. We demonstrate the
scope of the method with over 50 examples including late-stage functionalization
of drug molecules (celecoxib) and complex structures such as L-menthol, amino
acids and cholesterol derivatives. Further, the presented synthetic protocol is
applicable for gram-scale reactions. In addition to methylarenes, selected examples
for the cyanation of aldehydes, alcohols and oximes are demonstrated as well. Detailed
mechanistic investigations have been carried out using time-resolved luminescence
quenching studies, control experiments and NMR‑ spectroscopic as well as
kinetic studies, all supporting the proposed catalytic cycle. | Kathiravan Murugesan; Karsten Donabauer; Burkhard Koenig | Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f23bb8c1a3caa3db892/original/visible-light-promoted-metal-free-ammoxidation-of-c-sp3-h-bonds.pdf |
60c73d924c89196e82ad1c35 | 10.26434/chemrxiv.5930314.v1 | Raman Signal Enhancement by Quasi-Fractal Geometries of Gold Nanoparticles | <div><p>The
synthesis of star-like gold nanoparticles (SGNs) in a temperature-controlled
environment allows for temperature modulation and facilitates the growth of highly
branched nanoparticles. By increasing the synthesis temperature, the level of
branching increases as well. These highly branched features represent a
distinctly novel, quasi-fractal nanoparticle morphology, referred to herein as gold
nano caltrops (GNC). The increased surface roughness, local curvature and
degree of inhomogeneity of GNC lend themselves to generating improved
enhancement of the scattering signals in surface-enhanced Raman spectroscopy
(SERS) via a mechanism in which the localized surface plasmon sites, or “hot
spots,” provide the engine for the signal amplification, rather than the more
conventional surface plasmon. Here, the synthesis procedure and the
surface-enhancing capabilities of GNC are described and discussed in comparison
with SGN.</p></div><div><br /></div> | Richard Darienzo; Tatsiana Mironava; Rina Tannenbaum | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2018-02-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d924c89196e82ad1c35/original/raman-signal-enhancement-by-quasi-fractal-geometries-of-gold-nanoparticles.pdf |
656fd3d629a13c4d47bcde14 | 10.26434/chemrxiv-2023-gwnl8 | Machine learning force field ranking of candidate solid electrolyte interphase structures in Li-ion batteries | The Solid-Electrolyte Interphase (SEI) formed in lithium-ion batteries is a vital but poorly-understood class of materials, combining organic and inorganic components. An SEI allows a battery to function by protecting electrode materials from unwanted side reactions. We use a combination of classical sampling and a novel machine learning model to produce the first set of SEI candidate structures ranked by predicted energy, to be used in future machine learning applications and compared to experimental results. We hope that this work will be the start of a more quantitative understanding of lithium-ion battery interphases and an impetus to development of machine learning models for battery materials. | James Stevenson; Garvit Agarwal; Leif Jacobson | Theoretical and Computational Chemistry; Materials Science; Organometallic Chemistry; Machine Learning; Electrochemistry - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2023-12-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/656fd3d629a13c4d47bcde14/original/machine-learning-force-field-ranking-of-candidate-solid-electrolyte-interphase-structures-in-li-ion-batteries.pdf |
62911ea76209e054c3540cb8 | 10.26434/chemrxiv-2022-ns4v4 | Investigation of Ion-Electrode Interactions of Linear Polyimides and Alkali Metal Ions for Next Generation Alternative-Ion Batteries | Organic electrode materials offer unique opportunities to utilize ion-electrode interactions to develop diverse, versatile, and high-performing secondary batteries, particularly for applications requiring high power densities. However, a lack of well-defined structure-property relationships for redox-active organic materials restricts the advancement of the field. Herein, we investigate a family of diimide-based polymer materials with several charge-compensating ions (Li+, Na+, K+) in order to systematically probe how redox-active moeity, ion, and polymer flexibility dictate their thermodynamic and kinetic properties. When favorable ion-electrode interactions are employed (e.g., soft K+ anions with soft perylenediimide dianions), the resulting batteries demonstrate increased working potentials and improved cycling stabilities. Further, for all polymers examined herein, we demonstrate that K+ accesses the highest percentage of redox-active groups due to its small solvation shell/energy. Through crown ether experiments, cyclic voltammetry, and activation energy measurements, we provide insights into the charge compensation mechanisms of three different polymer structures and rationalize these findings in terms of the differing degrees of improvements observed when cycling with K+. Critically, we find that the most flexible polymer enables access to the highest fraction of active sites due to the small activation energy barrier during charge/discharge. These results suggest that improved capacities may be accessible by employing more flexible structures. Overall, our in-depth structure-activity investigation demonstrates how variables such as polymer structure and cation can be used to optimize battery performance and enable the realization of novel battery chemistries. | Cara Gannett; Jaehwan Kim; Dave Tirtariyadi; Phillip Milner; Hector Abruna | Organic Chemistry; Polymer Science; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62911ea76209e054c3540cb8/original/investigation-of-ion-electrode-interactions-of-linear-polyimides-and-alkali-metal-ions-for-next-generation-alternative-ion-batteries.pdf |
60c756eaee301c5d5ac7b461 | 10.26434/chemrxiv.14346953.v1 | High-Entropy 2D Carbide MXenes | <p>Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are a fast-growing family of 2D materials. MXenes 2D flakes have <i>n </i>+ 1 (<i>n</i> = 1 – 4) atomic layers of transition metals interleaved by carbon/nitrogen layers, but to-date remain limited in composition to one or two transition metals. In this study, through the use of four transition metals, we report the synthesis of multi-principal element high-entropy M<sub>4</sub>C<sub>3</sub>T<i><sub>x</sub></i> MXenes. Specifically, we introduce two high-entropy MXenes, TiVNbMoC<sub>3</sub>T<i><sub>x</sub></i> and TiVCrMoC<sub>3</sub>T<i><sub>x</sub></i>, as well as their precursor TiVNbMoAlC<sub>3</sub> and TiVCrMoAlC<sub>3 </sub>high-entropy MAX phases. We used a combination of real and reciprocal space characterization (x-ray diffraction, x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, and scanning transmission electron microscopy) to establish the structure, phase purity, and equimolar distribution of the four transition metals in high-entropy MAX and MXene phases. We use first-principles calculations to compute the formation energies and explore synthesizability of these high-entropy MAX phases. We also show that when three transition metals are used instead of four, under similar synthesis conditions to those of the four-element MAX phase, two different MAX phases can be formed (<i>i.e.</i> no pure single-phase forms). This finding indicates the importance of configurational entropy in stabilizing the desired single-phase high-entropy MAX over multiphases of MAX, which is essential for the synthesis of phase-pure high-entropy MXenes. The synthesis of high-entropy MXenes significantly expand the compositional variety of the MXene family to further tune their properties, including electronic, magnetic, electrochemical, catalytic, high temperature stability, and mechanical properties. </p> | Srinivasa Kartik Nemani; BOWEN ZHANG; Brian C. Wyatt; Zachary D. Hood; Sukriti Manna; Rasoul Khaledialidusti; Weichen Hong; Michael G. Sternberg; Subramanian Sankaranarayanan; Babak Anasori | Alloys; Carbon-based Materials; Ceramics; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience; Theory - Inorganic; Transition Metal Complexes (Inorg.); Materials Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c756eaee301c5d5ac7b461/original/high-entropy-2d-carbide-m-xenes.pdf |
60c7459d337d6c5071e26fec | 10.26434/chemrxiv.10062014.v1 | A Chemistry Based Service-Learning Course in New Orleans: Increasing Student Interest and Self-Efficacy in STEM | <p>An important problem in STEM education is the low student retention rate. Non-traditional science courses that utilize more active-participation and learning are attractive as tools to increase student persistence and interest in STEM. Herein is described the content and implementation of a chemistry-based service-learning course that was offered in Spring 2019. The course features a well-rounded curriculum and diverse activities. The enrolled undergraduate students were not only taught chemistry concepts (general chemistry and supramolecular chemistry) but were also asked to present the chemical concepts using attention-grabbing demonstrations to public-school students in the New Orleans area. In addition, the course covered multiple non-science topics, including the pedagogy of service learning, background on the New Orleans public-school system, and how to work with the community. The course also involved targeted student reflection activities/surveys and interfaced with the Tulane Center for Public Service. Results from a paired set of anonymous “before and after” student surveys lead us to suggest that the undergraduate students exhibited an increased desire towards STEM careers. The students also expressed, in general, higher confidence in the retention of chemical concepts that this course taught when compared to concepts retained from a standard general chemistry lab course. As importantly, this course provided the opportunity for students to engage with members of the New Orleans community.</p> | Ryan Vik; Emily Schmidt; Cooper Battle; Janarthanan Jayawickramarajah | Chemical Education - General | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7459d337d6c5071e26fec/original/a-chemistry-based-service-learning-course-in-new-orleans-increasing-student-interest-and-self-efficacy-in-stem.pdf |
620a5e114e899e03d54d5d8f | 10.26434/chemrxiv-2022-3j2ls | Cyanine Masking: A Strategy to Test Functional Group Effects on Antibody Conjugate Targeting | Conjugates of small molecule and antibodies are broadly employed diagnostic and therapeutic agents. Appending a small molecule to an antibody often significantly impacts the properties of the resulting conjugate. Here we detail a systematic study investigating the effect of various functional groups on the properties of antibody-fluorophore conjugates. This was done through the preparation and analysis of a series of masked heptamethine cyanines (CyMasks) bearing amides with varied functional groups. These were designed to exhibit a broad range of physical properties, and include hydrophobic (-NMe2), pegylated (NH-PEG-8 or NH-PEG-24), cationic (NH-(CH2)2NMe3+) anionic (NH-(CH2)2SO3-), and zwitterionic (N-(CH2)2NMe3+)-(CH2)3SO3-) variants. The CyMask series was appended to tumor targeting monoclonal antibodies (mAbs) and analyzed for effects on tumor targeting, clearance and non-specific organ uptake. Among the series, zwitterionic and cationic dye conjugates showed the highest tumor-to-background ratio (TBR), although the latter also exhibited an elevated liver-to-background ratio (LBR). Overall, these studies provide a strategy to test the functional group effects and suggest that zwitterionic substituents are an attractive strategy to mask hydrophobic payloads, with the potential to improve the properties of bioconjugates in vivo. | Ek Raj Thapaliya; Syed Usama; Nimit Patel; Yang Feng; Joseph Kalen; Brad St Croix; Martin Schnermann | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2022-02-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/620a5e114e899e03d54d5d8f/original/cyanine-masking-a-strategy-to-test-functional-group-effects-on-antibody-conjugate-targeting.pdf |
63650521aa2784d2d359bb01 | 10.26434/chemrxiv-2022-jfddl | Identification of Novel MR1 Ligands Derived from Herbal Medicines by MR1-Presentation Reporter Screening and Their Structure-Activity Relationship | Mucosal-associated invariant T (MAIT) cells are innate-like T cells that are modulated by ligands presented on MHC class I-related proteins (MR1). These cells have attracted attention as potential drug targets because of their involvement in the initial response to infection and various disorders. Herein, we have established the MR1-presentation reporter assay system employing split-luciferase, which enables the efficient exploration of MR1 ligands. Using our screening system, we identified herbal medicine-derived MR1 ligands, including coniferyl aldehyde, which have an ability to inhibit the MR1–MAIT cell axis. Coniferyl aldehyde comprises phenylpropanoids and is a novel motif for MR1 ligands. Further structure-activity relationship study revealed the key structural features of ligands required for MR1 recognition. These results will contribute to uncovering the mode of action of herbal medicines and their analogs, and to developing novel MAIT cell modulators. | Takuro Matsuoka; Akira Hattori; Shinya Oishi; Norihito Arichi; Hideaki Kakeya; Sho Yamasaki; Hiroaki Ohno; Shinsuke Inuki | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63650521aa2784d2d359bb01/original/identification-of-novel-mr1-ligands-derived-from-herbal-medicines-by-mr1-presentation-reporter-screening-and-their-structure-activity-relationship.pdf |
60c748050f50db576c3966d7 | 10.26434/chemrxiv.11832993.v1 | Synthesis of Azetidines via Visible Light-Mediated Intermolecular [2+2] Photocycloaddition | <p>Intermolecular [2+2] photocycloadditions represent a powerful method for the synthesis of highly strained, four-membered rings. While this approach is commonly employed for the synthesis of oxetanes and cyclobutanes, the synthesis of azetidines via intermolecular aza Paternò-Büchi reactions remains highly underdeveloped. Herein we report a visible light-mediated intermolecular aza Paternò-Büchi reaction that utilizes glyoxylate oximes as reactive intermediates activated via triplet energy transfer. This approach is characterized by its operational simplicity, mild conditions and broad scope, and allows for the synthesis of highly functionalized azetidines from readily available precursors.<b></b></p> | Marc R. Becker; Emily R. Wearing; Corinna Schindler | Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c748050f50db576c3966d7/original/synthesis-of-azetidines-via-visible-light-mediated-intermolecular-2-2-photocycloaddition.pdf |
65332c982431cc1dac3130f1 | 10.26434/chemrxiv-2023-5h5l5 | A Density Functional Theory Investigation of Ammonia Oxidation on the M-doped β-Ni(OH)2 (M = Cr, Co, Cu, Fe) Surfaces | The ammonia oxidation reaction (AOR) has applications as a sustainable energy source and in wastewater remediation. Nickle based catalysts for the AOR reaction are ideal as they are cost efficient, have longer lifetimes than more expensive alterna- tives, and can produce value-added products. Dopants can be applied to these nickle catalysts to further increase their value. This work explores the effects on reaction potentials when β-Ni(OH)2 is doped with chromium, cobalt, copper, or iron using den- sity functional theory to model the AOR. Limiting potentials for dinitrogen production improved when β-Ni(OH)2 was doped with chromium and cobalt. Limiting potentials for nitrite production remained consistent when the β-Ni(OH)2 was doped with cobalt or iron. Compared to the pristine β-Ni(OH)2 surface, there was no improvement in the limiting potential of nitrate formation for any of the doped surfaces. This research be- gins to unfold the importance of exploring dopant addition to β-Ni(OH)2 as a method of improving the catalysts activity for the AOR. | Shayne Johnston; Rachelle Choueiri; Xinrun Liu; Brendan Laframboise; Stephen Tatarchuk; Leanne Chen | Theoretical and Computational Chemistry; Catalysis; Energy; Computational Chemistry and Modeling; Electrocatalysis; Energy Storage | CC BY NC 4.0 | CHEMRXIV | 2023-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65332c982431cc1dac3130f1/original/a-density-functional-theory-investigation-of-ammonia-oxidation-on-the-m-doped-ni-oh-2-m-cr-co-cu-fe-surfaces.pdf |
60c75856bb8c1a39de3dc9e9 | 10.26434/chemrxiv.14541801.v1 | Ca4Sb2O and Ca4Bi2O: Two Promising Mixed-Anion Thermoelectrics | <pre>The environmental burden of fossil fuels and the rising impact of global warming have created an urgent need for sustainable clean energy sources. This has led to widespread interest in thermoelectric (TE) materials to recover part of the 60 % of global energy currently wasted as heat as usable electricity. Oxides are particularly attractive as they are thermally stable, chemically inert, and formed of earth-abundant elements, but despite intensive efforts there have been no reports of oxide TEs matching the performance of flagship chalcogenide materials such as PbTe, Bi<sub>2</sub>Te<sub>3</sub> and SnSe. A number of ternary X<sub>4</sub>Y<sub>2</sub>Z mixed-anion systems, including oxides, have predicted band gaps in the useful range for several renewable-energy applications, including as TEs, and some also show the complex crystal structures indicative of low lattice thermal conductivity. In this study, we use <i>ab initio</i> calculations to investigate the TE performance of two structurally-similar mixed-anion oxypnictides, Ca<sub>4</sub>Sb<sub>2</sub>O and Ca<sub>4</sub>Bi<sub>2</sub>O. Electronic-structure and band-alignment calculations using hybrid density-functional theory (DFT), including spin-orbit coupling, suggest that both materials are likely to be <i>p</i>-type dopable with large charge-carrier mobilities. Lattice-dynamics calculations using third-order perturbation theory predict ultra-low lattice thermal conductivities of about 0.8 and 0.5 W m<sup>-1 </sup>K<sup>-1 </sup>above 750 K. Nanostructuring to a crystal grain size of 20 nm is predicted to further reduce the room temperature thermal conductivity by around 40 %. Finally, we use the electronic- and thermal-transport calculations to estimate the thermoelectric figure of merit <i>ZT</i>, and show that with <i>p</i>-type doping both oxides could potentially serve as promising earth-abundant oxide TEs for high-temperature applications.</pre> | Warda Rahim; Jonathan Skelton; David Scanlon | Theory - Inorganic; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2021-05-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75856bb8c1a39de3dc9e9/original/ca4sb2o-and-ca4bi2o-two-promising-mixed-anion-thermoelectrics.pdf |
60c759514c89195df3ad4d46 | 10.26434/chemrxiv.14332901.v2 | Elucidating Pt-Based Nanocomposite Catalysts for the Oxygen Reduction Reaction in Rotating Disk Electrode and Gas Diffusion Electrode Measurements | In
the present study we compare different nanoparticle (NP) composites (nanocomposites)
as potential electrocatalysts for the oxygen reduction reaction (ORR). The
nanocomposites consist of a mixture of Pt and Ir NPs and Pt and Au NPs,
respectively, that are immobilized onto a high surface area carbon support. Pt NPs
supported on the same carbon support serve as benchmark. The performance
testing was performed in a conventional rotating disk electrode (RDE) setup as
well as in a recently introduced gas diffusion electrode (GDE) setup providing
high mass transport conditions. The ORR activity is determined, and the
degradation tested using accelerated degradation tests (ADTs). It is shown that with respect to the benchmark,
the Pt – Au nanocomposite
concept exhibits improved ORR activity as well as improved stability both in
the RDE and the GDE measurements. By comparison, the Pt – Ir nanocomposite
exhibits improved stability but lower ORR activity. Combining the GDE approach
with small angle X-ray scattering, it is shown that the improved stability of the Pt – Au nanocomposite can be assigned to a reduced Pt particle growth
due to the adjacent Au NPs. The results demonstrate that nanocomposites could
be an alternative catalyst design strategy complementing the state-of-the-art
alloying concepts.<br /> | Jia Du; Jonathan Quinson; Alessandro Zana; Matthias Arenz | Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c759514c89195df3ad4d46/original/elucidating-pt-based-nanocomposite-catalysts-for-the-oxygen-reduction-reaction-in-rotating-disk-electrode-and-gas-diffusion-electrode-measurements.pdf |
60c73dd3567dfe1fb3ec36ed | 10.26434/chemrxiv.5459617.v2 | First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers | <div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div> | Adrian Cernescu; Michał Szuwarzyński; Urszula Kwolek; Karol Wolski; Paweł Wydro; Mariusz Kepczynski; Magdalena Wytrwał-Sarna; Szczepan Zapotoczny; Maria Nowakowska; Luca Quaroni | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2018-02-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73dd3567dfe1fb3ec36ed/original/first-nano-infrared-spectroscopy-and-imaging-measurements-of-single-phospholipid-bilayers.pdf |
66599ffd418a5379b0bdd031 | 10.26434/chemrxiv-2024-rf0kh-v2 | One-step Hydrothermal Synthesis of Sn-doped Sb2Se3 for Solar Hydrogen Production | Antimony selenide (Sb2Se3) has recently been intensively investigated and has achieved significant advancement in photoelectrochemical (PEC) water splitting. In this work, a facile one-step hydrothermal method for the preparation of Sn-doped Sb2Se3 photocathodes with improved PEC performance was investigated. We present an in-depth study of the performance enhancement in Sn-doped Sb2Se3 photocathodes using capacitance-voltage (CV), drive level capacitance profiling (DLCP), and electrochemical impedance spectroscopy (EIS) techniques. The incorporation of Sn2+ into the Sb2Se3 results in increased carrier density, reduced surface defects, and improved charge separation, thereby leading to improved PEC performance. With a thin Sb2Se3 absorber layer (270 nm thickness), the Sn-doped Sb2Se3 photocathode exhibits an improved photocurrent density of 17.1 mA cm−2 at 0 V versus RHE (VRHE) compared to that of the undoped Sb2Se3 photocathode (14.4 mA cm−2). This work not only highlights the positive influence of Sn doping on Sb2Se3 photocathodes but also showcases a one-step method to synthesize doped Sb2Se3 with improved optoelectronic properties. | Zhenbin Wang; Sanghyun Bae; Miloš Baljozović; Pardis Adams; David Yong; Erin Service; Thomas Moehl; Wenzhe Niu; David Tilley | Catalysis; Energy; Electrocatalysis; Photocatalysis; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66599ffd418a5379b0bdd031/original/one-step-hydrothermal-synthesis-of-sn-doped-sb2se3-for-solar-hydrogen-production.pdf |
64680bb2a32ceeff2dec802c | 10.26434/chemrxiv-2022-3p4gx-v2 | Metric geometry tools for automatic structure phase map
generation | Extracting a phase map that provides a hierarchical summary of high-throughput experiments is a long-standing bottleneck for the modern goal of achieving automation and acceleration in material discovery. A phase map that underpins the inherent properties of materials is typically denoted using a composition-structure map but can be extended to other relevant parameters such as synthesis. This paper describes a computational statistical tool to efficiently obtain a phase map from multi-scale experimental measurement profiles obtained from high-throughput measurements. We motivate the construction of a phase map as the problem of learning the underlying metric geometry defined by a set of templates in infinite-dimensional function spaces. We provide a statistical analysis tool to obtain a phase map as an asymptotic of the diffusion of resulting distance functions on the composition. Using examples from small-angle X-ray scattering experiments of polymer blend systems, we show that learned metric geometry can efficiently differentiate ordered phase regions with shifted, missing, and broad Bragg peaks along with features related to non-Bragg behavior of soft-matter systems. The metric geometry allows us to define a shape distance between scattering profiles invariant to phase-independent transformations thus valuable for obtaining a phase map. We also apply the methodology to benchmark experimental diffraction data to showcase potential utility and broad applicability. | Kiran Vaddi; Karen Li; Lilo D Pozzo | Materials Science; Polymer Science; Energy; Conducting polymers; Polymer blends | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64680bb2a32ceeff2dec802c/original/metric-geometry-tools-for-automatic-structure-phase-map-generation.pdf |
632cdb57114b7e560f19c4ab | 10.26434/chemrxiv-2022-9nn82-v2 | Effects of temperature and storage time on bisphenol A migration from polycarbonate bottles into water: Analysis using UV-visible spectrophotometric method. | Endocrine-disrupting chemicals (EDCs) have received widespread attention over the years due to their deleterious effects on human health. Bisphenol A (BPA) - a monomer used globally in producing polycarbonate plastics and epoxy resins, is a prototypic EDC that has received widespread attention due to its estrogenic activity. BPA has been detected in human serum, urine, amniotic fluid, placenta tissues, and umbilical cord blood. Its presence in the human population has been ascribed to consuming BPA-contaminated food due to its migration from polycarbonate plastics. However, little is known about the inimical health hazard of BPA migrating from polycarbonate bottles into food or drinks in Nigeria and how temperature and storage duration can influence its migration into any contact media. To address this problem, we scrutinized the effect of storage time and temperature on BPA migration from 3 selected polycarbonate water bottles and a brand of polycarbonate baby feeding bottles into a mixture of methanol and water in Makurdi, Nigeria, using the UV-Visible spectrophotometric method. We measured detectable levels of BPA right from day 1 at room temperature, suggesting a positive correlation between BPA release and residual BPA in the PC bottles. The amount of BPA migrated was in the range of (0.030 ± 0.012) ng/mL (day 1 at room temperature) to (5.620 ± 0.650) ng/mL (day 10 at 60 °C) for the 3 brands of polycarbonate feeding bottles and (0.080 ± 0.010) ng/mL (day 1 at room temperature) to (4.300 ± 0.100) ng/mL (day 10 at 60 °C) for a brand of polycarbonate water bottles studied. Both temperature and duration of storage generously influenced the migration of BPA exponentially. However, our study identified temperature as the dominant significant factor that enhanced the migration of BPA from PC bottles into the water. Therefore, it is safer for consumers to store foods in BPA-free bottles to avert health risks related to ingestion of BPA. | Edor Uche Godwin; Ogbene Gillian Igbum | Polymer Science; Inorganic Polymers | CC BY 4.0 | CHEMRXIV | 2022-09-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632cdb57114b7e560f19c4ab/original/effects-of-temperature-and-storage-time-on-bisphenol-a-migration-from-polycarbonate-bottles-into-water-analysis-using-uv-visible-spectrophotometric-method.pdf |
66afbeb701103d79c5bcefbc | 10.26434/chemrxiv-2024-p6wg1 | Tunability in Heterobimetallic Complexes Featuring an Acyclic “Tiara” Polyether Motif | Both cyclic “crown” and acyclic “tiara” polyethers have been recognized as useful for binding of metal cations and enabling assembly of multimetallic complexes. However, the properties of heterobimetallic complexes built upon acyclic polyethers have received less attention than they deserve. Here, the synthesis and characterization of a family of eight redox-active heterobimetallic complexes that pair a nickel center with secondary redox-inactive cations (K+, Na+, Li+, Sr2+, Ca2+, Zn2+, La3+ and Lu3+) bound in acyclic polyether “tiara” moieties are reported. Structural studies with X-ray diffraction (XRD) analysis were carried out on the monometallic nickel precursor complex to the heterobimetallics and the adducts with K+, Li+, Sr2+, Zn2+, and Lu3+; the results confirm binding of the secondary cations in the tiara site, and demonstrate that the tiara moiety is more conformationally flexible than the analogous 18-crown-6-like moiety of a homologous macrocyclic ligand. Spectroscopic and electrochemical studies show, however, that the stability and cation-driven tunability of the tiara-based heterobimetallic species are quite similar to those previously measured for crown-based species. Consequently, the tiara motif appears to be at least as equally useful for constructing tunable multimetallic species as the more commonly encountered crown motif. As use of acyclic tiaras avoids the need for tedious and/or time-intensive syntheses of macrocyclic structures, these findings suggest tiara motifs could be broadly advantageous in design of ligands to support multimetallic chemistry. | Joseph Karnes; Allen Oliver; Cynthia Day; Victor Day; James Blakemore | Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66afbeb701103d79c5bcefbc/original/tunability-in-heterobimetallic-complexes-featuring-an-acyclic-tiara-polyether-motif.pdf |
60c73f1c842e6543efdb1a19 | 10.26434/chemrxiv.7243448.v1 | Modeling the Influence of Correlated Molecular Disorder on the Dynamics of Excitons in Organic Molecular Semiconductors | <div>In this Letter, we investigate the role of correlated molecular disorder on the dynamics of excitons in oligothiophene-based organic semiconductors. We simulate exciton dynamics using the Frenkel exciton model and we derive parameters for this model so that they reflect the specific characteristics of all-atom molecular systems. By systematically modifying the parameters of the Frenkel exciton model we isolate the influence of spatial and temporal molecular correlations on the dynamics of excitons in these systems. We find that the molecular fluctuations inherent to these systems exhibit long-lived memory effects, but that these effects do not significantly influence the dynamic properties of excitons. We also find that excitons can be sensitive to the molecular-scale spatial correlations, and that this sensitivity grows with the amount of energetic disorder within the material. We conclude that control over spatial correlations can mitigate the negative influence of disorder on exciton transport. </div> | Chee Kong Lee; Liang Shi; Adam Willard | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2018-10-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f1c842e6543efdb1a19/original/modeling-the-influence-of-correlated-molecular-disorder-on-the-dynamics-of-excitons-in-organic-molecular-semiconductors.pdf |
677f13d7fa469535b93e56cf | 10.26434/chemrxiv-2025-9cwx5 | Theory-guided design of Pd-catalysts for nondirected C-H functionalization governed by noncovalent interactions | The development of selective catalysts for nondirected C-H functionalization remains a critical challenge in organic synthesis. In this study, we present a computational framework for designing PdIV-based catalysts for nondirected meta-selective C-H activation of anisole, with a focus on ligand design for the Pd complex. Among the ligands surveyed, the pyrazolo naphthyridine (PzNPy) ligand was predicted to exhibit both higher reactivity and selectivity for meta-C-H activation compared to other ligands, as evidenced by its lower overall and relative (meta vs. para) Gibbs free energy barriers, respectively. Energy decomposition analysis (EDA) highlighted the importance of noncovalent interactions, particularly the frozen interaction components (permanent electrostatics, Pauli repulsion, and dispersion), in determining the selectivity trends. Systematic modification of the PzNPy ligand in silico by introducing various electron-donating or electron-withdrawing substituents revealed that while changes to substituents do not significantly affect the selectivity of the catalyst, they do have a pronounced effect on its reactivity. Furthermore, we observed a strong correlation between the Hammett sigma meta (σm) constant of the substituents and the enthalpic contributions to the free energy barrier (∆H‡meta), highlighting how the electronic effects of substituents influence reactivity. Further analysis also revealed a strong correlation between ∆H‡meta and the strength of electrostatic interaction evaluated at the intermediate reactant complex that forms prior to the transition state, providing insights into the enhanced reactivity associated with electron-withdrawing substituents on the PzNPy ligand. Our results demonstrate the potential to enhance both the reactivity and selectivity of catalysts for non-directed C-H functionalization through rational ligand design. | Kristen W. Romero; Yuezhi Mao | Organometallic Chemistry; Catalysis; Ligand Design; Theory - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677f13d7fa469535b93e56cf/original/theory-guided-design-of-pd-catalysts-for-nondirected-c-h-functionalization-governed-by-noncovalent-interactions.pdf |
6103c59a880443775ee48c80 | 10.26434/chemrxiv-2021-m14db | Affordable Ab Initio Path Integral for Thermodynamic Properties via Molecular Dynamics Simulations Using Semiempirical Reference Potential | Path integral molecular dynamics (PIMD) is becoming a routinely applied method for the incorporation of the nuclear quantum effect in computer simulations. However,
direct PIMD simulations at an ab initio level of theory are formidably expensive. Using the protonated 1,8-bis(dimethylamino)naphthalene molecule as an example, we show in this work that the computational expense for the intra-molecular proton transfer between the two nitrogen atoms can be remarkably reduced by implementing the idea of reference-potential methods. The simulation time can be easily extended to a scale of nanosecond while maintaining the accuracy on an ab initio level of theory
for thermodynamic properties. In addition, the post-processing can be carried out in parallel on massive computer nodes. A 545-fold reduction in the total CPU time can be achieved in this way as compared to a direct PIMD simulation at the same ab initio level of theory. | Yuanfei Xue; Jia-Ning Wang; Wenxin Hu; Jun Zheng; Yongle Li; Xiaoliang Pan; Yan Mo; Yihan Shao; Lu Wang; Ye Mei | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2021-08-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6103c59a880443775ee48c80/original/affordable-ab-initio-path-integral-for-thermodynamic-properties-via-molecular-dynamics-simulations-using-semiempirical-reference-potential.pdf |
61add2f9a02d166da8e5dd8f | 10.26434/chemrxiv-2021-846w3 | UV-Spectroscopic Detection of (Pyro-)Phosphate with the PUB module | Despite the prevalence of ortho- and pyrophosphate in biochemistry, operationally simple and versatile high-throughput methodologies for their quantification are lacking. We herein introduce PUB, a module for phosphate detection by continuous UV-spectroscopic monitoring of 5-bromouridine phosphorolysis. The PUB module employs cheaply available, bench-stable reagents and can be employed for continuous and discontinuous reaction monitoring in biochemical assays to detect (pyro-)phosphate concentrations spanning almost four orders of magnitude, as demonstrated with representative use-cases. | Lea Eilert; Anett Schallmey; Felix Kaspar | Catalysis; Analytical Chemistry; Biochemical Analysis; Spectroscopy (Anal. Chem.); Biocatalysis | CC BY 4.0 | CHEMRXIV | 2021-12-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61add2f9a02d166da8e5dd8f/original/uv-spectroscopic-detection-of-pyro-phosphate-with-the-pub-module.pdf |
6522bfd6bda59ceb9a1e3fd5 | 10.26434/chemrxiv-2023-f3b4l | Attraction Between Like Charged Ions in Ionic Liquids: Unveiling the Enigma of Tetracyanoborate Anions | Intermolecular interactions in ionic liquids are mainly governed by Coulomb forces. Attraction between cations has been previously observed and was attributed to dispersion interactions between non-polar moieties, hydrogen bonding, or π-stacking. In this study, we present the intriguing behaviour of tetracyanoborate anions in ionic liquids that, unlike their dicyanamide and tricyanomethanide counterparts, form dimers in both solid and liquid phases. A joint simulation and experimental study uncovers the origin of such anion-anion attraction: stabilisation by induction and dispersion forces between several cyano-groups, which is strong enough to overcome electrostatic repulsion. These findings open up new opportunities in the rational design of ionic liquids, where interactions between ions of the same charge can be controlled and fine-tuned by the presence of cyano-groups. | Kateryna Goloviznina; Eduards Bakis; Frederik Philippi; Nicolas Scaglione; Toms Rekis; Laura Laimina; Margarida Costa Gomes; Agilio Padua | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Structure; Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6522bfd6bda59ceb9a1e3fd5/original/attraction-between-like-charged-ions-in-ionic-liquids-unveiling-the-enigma-of-tetracyanoborate-anions.pdf |
60c75617bb8c1ae98b3dc55d | 10.26434/chemrxiv.14208206.v1 | A Convenient and Cost Efficient Route Suitable for “One-Pot” Synthesis of Molnupiravir | Herein,
we reported a convenient and cost efficient one-pot synthesis of molnupiravir
from cytidine. This method utilized N,N-dimethylformamide dimethyl acetal (DMF-DMA)
as an extraordinary protecting agent to achieve site specific esterification at 5’-hydroxyl group of the nucleoside easily, and afforded this promising drug
candidate (purity up to 99%, HPLC a/a) in 70% overall yield without
chromatography purification, which is superior to the existing methods in
aspect of the yield, the cost and the operation, and shows great potential
value for commercial production. Furthermore, this excellent protecting agent
was also successfully used in the synthesis of remdesivr from its parent
nucleoside with a high total yield (76%).<br /> | Tianwen Hu; Yuanchao Xie; Yin Liu; Haitao Xue; Fuqiang Zhu; Haji A. Aisa; Jingshan Shen | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75617bb8c1ae98b3dc55d/original/a-convenient-and-cost-efficient-route-suitable-for-one-pot-synthesis-of-molnupiravir.pdf |
65cdabece9ebbb4db96630cc | 10.26434/chemrxiv-2024-zjmnx-v2 | Blue organic long-persistent luminescence via upconversion from charge-transfer to locally excited singlet state | Long-persistent luminescence (LPL) materials have applications from safety signage to bioimaging; however, existing organic LPL (OLPL) systems do not align with human scotopic vision, which is sensitive to blue light. We reveal a ground-breaking strategy to blueshift the emissions in binary OLPL systems by upconverting the charge-transfer (CT) to a locally excited (LE) singlet state. Through rigorous steady-state and time-resolved photoluminescence spectroscopy and wavelength-resolved thermoluminescence measurements, we provide the direct experimental evidence for this upconversion in OLPL systems featuring small energy offsets between the lowest-energy CT and LE singlet states. These systems exhibited strong room temperature LPL, particularly when extrinsic electron traps are added. Importantly, the developed OLPL system achieved Class A (ISO 17398) LPL, matching well with human scotopic vision. The findings not only elucidate the role of small energy offsets in modulating LPL but also provide new avenues for enhancing the efficiency and applicability of OLPL materials. | Zesen Lin; Jinting Ye; Shin Shinohara; Yuya Tanaka; Rengo Yoshioka; Chin-Yiu Chan; Yi-Ting Lee; Xun Tang; Kirill Mitrofanov; Kai Wang; Hayato Ouchi; Yemineni S. L. V. Narayana; Hisao Ishii; Xiao-Hong Zhang; Chihaya Adachi; Xian-Kai Chen; Ryota Kabe | Physical Chemistry; Photochemistry (Physical Chem.); Physical and Chemical Properties; Spectroscopy (Physical Chem.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-02-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65cdabece9ebbb4db96630cc/original/blue-organic-long-persistent-luminescence-via-upconversion-from-charge-transfer-to-locally-excited-singlet-state.pdf |
60c74faf0f50db01a1397445 | 10.26434/chemrxiv.12173214.v2 | Persistent and Reversible Solid Iodine Electrodeposition in Nanoporous Carbons | Aqueous iodine based electrochemical energy storage is considered a potential candidate to improve sustainability and performance of current battery and supercapacitor technology. It harnesses the redox activity of iodide, iodine and polyiodide species in the confined geometry of nanoporous carbon electrodes. However, current descriptions of the electrochemical reaction mechanism to interconvert these species are elusive. Here we show that in nanoporous carbons electrochemical oxidation of iodide forms persistent solid iodine deposits. Confinement slows down dissolution into triiodide and pentaiodide, responsible for otherwise significant self-discharge via shuttling. The main tools for these insights are in situ Raman spectroscopy and in situ small and wide angle X-ray scattering (in situ SAXS/WAXS). In-situ Raman confirms the reversible formation of triiodide and pentaiodide. In situ SAXS/WAXS indicates remarkable amounts of solid iodine deposited in the carbon nanopores. Combined with stochastic modelling, in situ SAXS allows quantifying the solid iodine volume fraction and visualizing the iodine structure on 3D lattice models at the sub-nanometer scale. Based on the derived mechanism we demonstrate strategies for improved iodine pore filling capacity and prevention of self-discharge, applicable to hybrid supercapacitors and batteries.<br /> | Christian Prehal; Harald Fitzek; Gerald Kothleitner; Volker Presser; Bernhard Gollas; Stefan Freunberger; Qamar Abbas | Energy Storage | CC BY 4.0 | CHEMRXIV | 2020-09-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74faf0f50db01a1397445/original/persistent-and-reversible-solid-iodine-electrodeposition-in-nanoporous-carbons.pdf |
64e74a1079853bbd7853b129 | 10.26434/chemrxiv-2023-mtr4f | Harnessing Nanoreactors: Gelatin Nanogels for Human Therapeutic Protein Delivery | Nanogels, polymeric nano-hydrogels suspended in an aqueous solution, have emerged as potential vehicles for transporting therapeutic proteins. These systems offer high protein loading capacity and a tunable gel matrix for controlled protein encapsulation and release. In this study, we designed and fabricated nanogels via a nanoreactor method, followed by radical photopolymerization, and investigated the tunable swelling properties of the nanogels. Our results demonstrated that nanogels with less modified gelatin had a higher degree of swelling capacity and larger mesh size. Interestingly, we found that the initial size of the nanogels was solely dependent on the nanoreactor condition rather than the modified gelatin, the gelling biomaterial, signifying the importance of nanoreactor control in particle size determination. Nanogels showcased high protein loading capacity and rapid response to changes in salt condition, pH, and temperature, thereby accelerating the rates of protein release. This study demonstrated the tunable swelling properties, high protein loading and rapid release ability of nanogels triggered by internal/external modulators. Therefore, the nanogels developed in this study present a versatile platform for protein delivery, offering enhanced protein absorption and release capabilities. | Jeehye Kim; Caroline E. Copeland; Yong-Chan Kwon | Biological and Medicinal Chemistry; Bioengineering and Biotechnology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e74a1079853bbd7853b129/original/harnessing-nanoreactors-gelatin-nanogels-for-human-therapeutic-protein-delivery.pdf |
65d1caa69138d2316160a7ad | 10.26434/chemrxiv-2024-xtwlj | Iron-Catalyzed Aza-Annulative π-Extension with Alkynes via C–H Activation using an Oxidative Auxiliary | Abstract: Aza-annulative π-extension (AAPE) reactions offer a potent pathway to create novel donor-acceptor conjugated materials by integrating an imine moiety into the conjugated system, serving as an electron-accepting unit. However, the affinity of late-transition metals for conjugated π-systems, coupled with their elevated cost, has posed significant challenges, restricting efficient AAPE reactions on straightforward C–H substrates for developing conjugated new materials. In this study, we unveil an iron-catalyzed C–H activation methodology, facilitating AAPE with diverse internal alkynes and employing oxime ether as both a self-oxidizing auxiliary and nitrogen source, derived seamlessly from accessible carbonyl compounds. The AAPE reaction was enabled by using trisphosphine as a ligand, and isobutyl aluminum(III) catecholate as a base. By using the reaction, we discovered an aza-oxa[5]helicene from dixanthone as a potential circularly polarized luminescence material and two narrow-band-emissive molecules from easily accessible pentacene-6,13-dione and quinacridone, which emit blue and yellow light with high color purity and high fluorescence quantum yield. These findings emphasize the potential of iron-catalyzed C–H activation in expanding the range of donor-acceptor-type conjugated materials for organic electronics. | Yan Zhang; Shota Fukuma; Rui Shang; Eiichi Nakamura | Catalysis | CC BY 4.0 | CHEMRXIV | 2024-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d1caa69138d2316160a7ad/original/iron-catalyzed-aza-annulative-extension-with-alkynes-via-c-h-activation-using-an-oxidative-auxiliary.pdf |
60c751b29abda241b6f8dc84 | 10.26434/chemrxiv.13202849.v1 | A Broadly Accessible Liquid Chromatography Method for Quantification of Six Nitrosamine Compounds and N,N-Dimethylformamide in Metformin Drug Products Using High Resolution Mass Spectrometry | N-nitrosodimethylamine (NDMA) and the industrial solvent, N,N-dimethylformamide (DMF),
are both probable human carcinogens that have been detected in pharmaceutical drug products
like metformin, which is used to treat type II diabetes. Some lots of metformin drug products
have exceeded the United States Food and Drug Administration (FDA) daily allowable intake
limit for NDMA, while the presence of DMF has been detected at several orders of magnitude
higher than NDMA. A recent study found that a low abundance isotope of DMF interferes with
NDMA quantification by using a unique subset of LC-MS instruments capable of high mass
resolution. In this study, an LC-HRMS method is developed that chromatographically separates
NDMA from DMF in metformin drug products to eliminate interference. The method can detect
nitrosamines and DMF under the current regulatory guidance for industry and provides a
solution for simultaneously quantifying nitrosamines and DMF for a broad range of LC-MS
instruments. | Qian Wu; Evgenia Kvitko; Nicola Zenzola; Kaury Kucera; David Light | Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c751b29abda241b6f8dc84/original/a-broadly-accessible-liquid-chromatography-method-for-quantification-of-six-nitrosamine-compounds-and-n-n-dimethylformamide-in-metformin-drug-products-using-high-resolution-mass-spectrometry.pdf |
67226948f9980725cf9a2638 | 10.26434/chemrxiv-2024-zzjlx | Intramolecular Magnetic Exchange Interaction in Dichalcogenide Substituted Organic Diradical Dications | Organic diradical dications, due to reduced intermolecular interactions, exhibit a greater tendency to adopt high spin states in the solid phase compared to their neutral diradical counterparts. This characteristic makes them promising candidates for applications involving organic electronics. We present a theoretical study of a recently synthesized sulfur-based diradical dication, a unique system exhibiting a robust triplet ground state. Using a number of density functional theory (DFT) based methods (e.g. standard broken-symmetry DFT, constrained DFT, spin-flip TDDFT) and wavefunction-based multi-reference CASSCF+NEVPT2 methods, we investigate its magnetic properties and explore the influence of chalcogen substitution on the magnetic exchange coupling. An active space scanning method was adopted to overcome the difficulties in choosing the correct active space for multireference calculation. Our findings highlight the critical role of multi-reference methods in accurately capturing the magnetic behavior of highly pi-conjugated systems. The study reveals a surprising variation in magnetic properties among sulfur, selenium, and tellurium-based diradical dications, despite being elements of the same group. These results offer valuable insights into the design and tuning of magnetic properties in organic diradical dications. | Abhishek R Nath; Manish Kumar; Md. Ehesan Ali | Theoretical and Computational Chemistry; Organic Chemistry; Computational Chemistry and Modeling; Theory - Computational; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-11-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67226948f9980725cf9a2638/original/intramolecular-magnetic-exchange-interaction-in-dichalcogenide-substituted-organic-diradical-dications.pdf |
63f026f5fcfb27a31ff8949a | 10.26434/chemrxiv-2023-71kvg | Photochemically- and Thermally-Generated BN- and BNP-Doped Borafluorenate Heterocycles via Intramolecular Staudinger-Type Reactions | We report a series of BN- and BNP-borafluorenate heterocycles, bis(borafluorene-phosphinimine) (11-15), formed via intramolecular Staudinger-type reactions. The reactions were promoted by light or heat using monodentate phosphine-stabilized 9-azido-9-borafluorenes (R3P-BF-N3) (6-10) and involve the release of dinitrogen (N2), phosphine migration from boron to nitrogen, and oxidation of the phosphorus center (PIII to PV). Compounds 11-15 are blue emissive in the solution and solid states with solution phase absolute quantum yields ranging from 13-67%. Our studies were extended by comparing the reactivity of borafluorene azides supported by monodentate phosphorus ligands with those of bidentate phosphorus ligands, diphenyl-2-pyridylphosphine, trans-1,2-bis(diphenylphosphino)ethylene, and bis(diphenylphosphino)methane. A number of five-membered BNP-doped heterocycles were obtained which served as molecular precursors to access a new class of 4-membered BN-borafluorenate heterocycles via ring contraction and dimerization. All compounds discussed in this study have been fully characterized by single crystal X-ray diffraction and multinuclear NMR spectroscopy (1H, 13C, 11B, and 31P). | Bi Youan Tra; Andrew Molino; Kimberly Hollister; Samir Sarkar; Diane Dickie; David Wilson; Robert Gilliard | Organic Chemistry; Inorganic Chemistry; Organometallic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63f026f5fcfb27a31ff8949a/original/photochemically-and-thermally-generated-bn-and-bnp-doped-borafluorenate-heterocycles-via-intramolecular-staudinger-type-reactions.pdf |
60c74f3b9abda23dbff8d809 | 10.26434/chemrxiv.12867320.v1 | Metal Ammonium Phosphates Ion Exchangers for the Remediation of Low-Level Nuclear Wastes | The
nuclear industry generates large volumes of liquid wastes during
decommissioning and decontamination activities which require extensive clean-up
for recycle and/or disposal. The disposal of spent ion exchange materials used
to clean these decontamination liquors is challenging and costly for the
nuclear industry due to problematic end-of-life handling and low capacities of
these materials for most radionuclides. Certain mixed-metal phosphates could be
advantageous in this role due to their inherent vitrification properties and
potentially high capacities for cationic and/or anionic radionuclides. Similar ammonium-based
ion exchangers like the caesium-selective ammonium phosphomolybdate (AMP) are
well known in the nuclear industry, but outside of this, such materials remain
largely unexplored for this purpose. In this publication, we assess several
metal ammonium phosphates (MAPs) and related compounds prepared using a
continuous flow technique for their ability to act as ion exchangers for the
remediation of surrogate radionuclides from a model decontamination solution,
and discuss their possible implementation for the cleanup of low-level nuclear
wastes. | Alistair Holdsworth; Harry Eccles; Gary Bond | Separation Science; Coordination Chemistry (Inorg.); Kinetics and Mechanism - Inorganic Reactions; Nuclear Chemistry; Reaction (Inorg.); Transition Metal Complexes (Inorg.); Water Purification; Solution Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f3b9abda23dbff8d809/original/metal-ammonium-phosphates-ion-exchangers-for-the-remediation-of-low-level-nuclear-wastes.pdf |
64d62c59dfabaf06ff1a56b2 | 10.26434/chemrxiv-2023-0k7rg | On the Nonexistence of “InNCN” as an Indium Cyanamide for Industrial-Grade CO2 Electroreduction to Formic Acid | A recent paper in the field of chemical catalysis claims a new solid-state phase dubbed “InNCN” of which neither chemical analysis nor yield are known. Based on the chemical valence rules and the sparse published structural information, it is shown that there is no evidence for the existence of “InNCN”. | Richard Dronskowski | Inorganic Chemistry; Main Group Chemistry (Inorg.); Solid State Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64d62c59dfabaf06ff1a56b2/original/on-the-nonexistence-of-in-ncn-as-an-indium-cyanamide-for-industrial-grade-co2-electroreduction-to-formic-acid.pdf |
67bfa0556dde43c908a12e04 | 10.26434/chemrxiv-2025-pk16s | Production of high-value antibiotics by Teredinibacter turnerae using paper- and plant-based waste products | Cellulosic materials are commonly used in the production of biofuels and commodity chemicals. Here, we employ a cellulolytic bacterium to produce high-value antibiotics using paper and plant waste material as primary feedstocks. Teredinibacter turnerae is an intracellular symbiont of shipworms, marine bivalves of the family Teredinidae, where it contributes cellulases and other carbohydrate-active enzymes that help the animals digest wood. T. turnerae is also a prolific producer of antibiotic drug leads proposed to be integral to shipworm ecology. In the presence of waste cellulose as the sole carbon source, T. turnerae robustly produced potent antiparasitic and antibiotic agents. This suggests an inexpensive strategy to harness mixed waste materials for the synthesis of high-value compounds, such as pharmaceuticals. | Marina Gerton; Marvin Altamia; Daniel Distel; Bailey Miller; Eric Schmidt | Biological and Medicinal Chemistry; Analytical Chemistry; Chemical Engineering and Industrial Chemistry; Bioengineering and Biotechnology; Drug Discovery and Drug Delivery Systems; Natural Resource Recovery | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bfa0556dde43c908a12e04/original/production-of-high-value-antibiotics-by-teredinibacter-turnerae-using-paper-and-plant-based-waste-products.pdf |
60c75288bdbb893f0aa3a2c6 | 10.26434/chemrxiv.12698084.v3 | Negative Charge Management to Make Fragile Bonds No Longer Fragile towards Electrons for Robust Organic Optoelectronic Materials | <p>The
development of robust organic (opto)electronic devices is mainly depressed by
the poor intrinsic stability of organic materials on service. For organic light-emitting diode (OLED) materials, a key parameter for
intrinsic stability is the bond-dissociation energy of the most fragile bond
(BDE<sub>f</sub>). Although rarely concerned, many OLED molecules have the
lowest BDE<sub>f</sub> in anionic states (BDE<sub>f</sub>(−) ∼1.6−2.5
eV), which could be a fatal short-slab for device stability. Here, we confirmed
the clear relationship between BDE<sub>f</sub>(−), intrinsic material stability, and device lifetime, and further developed a general and effective strategy to promote BDE<sub>f</sub>(−) ~1 eV for various
fragile bonds by introducing appropriate negative charge manager within the
molecule. The manager can firmly confine negative-charge and protect fragile
bonds, which was verified in typical phosphine-oxide and carbazole derivatives,
and backed by newly-designed molecules. This
tactic provides a new perspective to reform the vulnerable building blocks for robust
organic (opto)electronic materials and devices.<br /></p> | Rui Wang; Qing-Yu Meng; Yi-Lei Wang; JUAN QIAO | Dyes and Chromophores; Optical Materials; Physical and Chemical Processes; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75288bdbb893f0aa3a2c6/original/negative-charge-management-to-make-fragile-bonds-no-longer-fragile-towards-electrons-for-robust-organic-optoelectronic-materials.pdf |
65b3f01be9ebbb4db90bca99 | 10.26434/chemrxiv-2024-5l0dx | De-epimerizing DyKAT of β-Lactones Generated by Isothiourea-Catalysed Enantioselective [2+2] Cycloaddition | Moderate diastereoselectivity (typically 70:30 dr) is observed in the isothiourea-catalysed [2+2]-cycloaddition of C(1)-ammonium enolates with pyrazol-4,5-diones to generate spirocyclic β lactones, but subsequent ring-opening with morpholine generatesβ hydroxyamide products with enhanced stereoselectivity (up to >95:5 dr). Stereoconvergence is observed in the ring-opening of diastereoisomeric β-lactones, leading to a single product (>95:5 dr, >99:1 er). Mechanistic studies and DFT analysis indicate a substrate controlled Dynamic Kinetic Asymmetric Transformation (DyKAT) involving epimerisation at C(3) of the β-lactone under the reaction conditions, coupled with a hydrogen bond-assisted nucleophilic addition to the Si face of the β-lactone and stereodetermining ring-opening. The scope and limitations of a one-pot protocol consisting of isothiourea-catalysed enantio-determining [2+2] cycloaddition followed by diastereo-determining ring-opening is subsequently developed. Variation within the anhydride ammonium enolate precursor, as well as N(1)- and C(3)- within the pyrazol-4,5-dione scaffold is demonstrated, giving a range of functionalised β hydroxyamides with high diastereo- and enantiocontrol (>20 examples, up to >95:5 dr and >99:1 er) via this DyKAT. | Aífe Conboy; Alister Goodfellow; Kevin Kasten; Joanne Dunne; David Cordes; Michael Buehl; Andrew Smith | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Stereochemistry; Organocatalysis | CC BY 4.0 | CHEMRXIV | 2024-01-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65b3f01be9ebbb4db90bca99/original/de-epimerizing-dy-kat-of-lactones-generated-by-isothiourea-catalysed-enantioselective-2-2-cycloaddition.pdf |
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