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60c74be94c8919e960ad3524 | 10.26434/chemrxiv.12389264.v1 | Photocatalytic Aided Removal of Nitrogen Oxides and VOCs from Outdoor Environment: Graphene as a Highway for Electron Mobility in TiO2 Nanoparticles | Outdoor and indoor air pollution is a global environmental concern in modern society. Although many policies and regulations on air quality have been promulgated worldwide over the past decades, airborne pollution still negatively affects health and therefore the life-style of human beings. One of the strategies to challenge this problem might be reducing the amount of airborne pollutant by mineralising them via photoinduced reactions. Photocatalytic oxidation of gaseous pollutants <i>via</i> titanium dioxide is one of the most investigated solar photochemical reactions. In this research work, by means of a green sol-gel procedure, we have coupled titania to graphene (0.5 and 1.0 wt%) aiming to increase the solar photocatalytic activity of the produced hybrid materials. The photocatalytic reactions were assessed by monitoring the removal of nitrogen oxides and two different volatile organic compounds (benzene and isopropanol). Photocatalytic mechanism was investigated by means of EPR
spin trapping experiments.Our results highlight the exceptional characteristics of the TiO2/graphene hybrid material (1.0 wt% graphene), and its suitability for multi-purpose applications in the field of environmental remediation. Compared to unmodified titania, the hybrid material with 1.0 wt% graphene shows a clear enhancement in the photocatalytic removal of those hazardous pollutants – corresponding to more than twice the photocatalytic degradation rate. In addition, the same material is highly stable and shows fully recyclability over repeated tests. Hybrid titania-graphene materials could thus be exploited to grant a safer outdoor and indoor environments, having a beneficial impact on public health and thus on the quality of our lives. | David Maria Tobaldi; Dana Dvoranova; Luc Lajaunie; nejc rozman; Bruno Figueiredo; Maria Paula Seabra; andrijana sever skapin; José Calvino; Vlasta Brezova; Joao Antonio Labrincha | Carbon-based Materials; Nanocatalysis - Catalysts & Materials; Heterogeneous Catalysis; Photocatalysis; Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74be94c8919e960ad3524/original/photocatalytic-aided-removal-of-nitrogen-oxides-and-vo-cs-from-outdoor-environment-graphene-as-a-highway-for-electron-mobility-in-ti-o2-nanoparticles.pdf |
60c753f6bb8c1aa04a3dc151 | 10.26434/chemrxiv.13599329.v1 | Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies | Abstract:
Hydroboration reaction of
alkynes is one of the most synthetically powerful tools to access organoboron
compounds, versatile precursors for cross coupling chemistry. This type of
reaction has traditionally been mediated by transition metal or main group catalysts.
Herein, we report a novel method using tropylium salts, typically known as organic
oxidants and Lewis acids, to efficiently promote the hydroboration reaction of
alkynes. A broad range of vinylboranes can be easily
accessed via this metal-free protocol. Similar hydroboration reactions of
alkenes and epoxides can also be efficiently catalyzed by the same tropylium
catalysts. Experimental studies and DFT calculations suggested that the
reaction follows an uncommon mechanistic paradigm, which is triggered by a
hydride abstraction of pinacolborane with tropylium ion. This is followed by a series
of <i>in situ</i> counterion-activated substituent
exchanges to generate boron intermediates that promote the hydroboration
reaction. | Nhan Nu Hong Ton; Binh Khanh Mai; Thanh Vinh Nguyen | Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753f6bb8c1aa04a3dc151/original/tropylium-salt-promoted-hydroboration-reactions-mechanistic-insights-via-experimental-and-computational-studies.pdf |
61bb9c71a53f1b65389e59e0 | 10.26434/chemrxiv-2021-4nmd7 | Deleterious Effects of Halides and Solvents on the Integrity of Copper Iodide Hole Extraction Layers in Hybrid Perovskite Photovoltaics | Copper iodide (CuI) is a promising material for use as a hole transport layer in perovskite solar cells due to its optical transparency, low-cost fabrication, and efficient electronic (hole) conductivity. Various reports of perovskite solar cells that utilize CuI have shown impressive solar cell performance and improved device stability. Despite these observations, we found no clear experimental evidence that the CuI hole transport layer is retained in perovskite p-i-n solar cells after device fabrication. Using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and impedance spectroscopy, we studied how each of the components present in the precursor solution for fabricating the perovskite active layer impacts the integrity of CuI films. Based on these data, we establish the deleterious effects of halide ions and solvents such as dimethyl sulfoxide (DMSO). We also show that we can fabricate stable CuI material in situ during perovskite deposition by taking advantage of a known redox chemistry of Cu(II)/Cu(I) and halides. | Emily Smith; D. Venkataraman | Inorganic Chemistry; Energy; Solid State Chemistry; Photovoltaics; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2021-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61bb9c71a53f1b65389e59e0/original/deleterious-effects-of-halides-and-solvents-on-the-integrity-of-copper-iodide-hole-extraction-layers-in-hybrid-perovskite-photovoltaics.pdf |
60c7481f567dfef681ec4972 | 10.26434/chemrxiv.11858346.v1 | Ab Initio Non-Covalent Crystal Field Theory for Lanthanide Complexes: A Multiconfigurational Non-Orthogonal Group Functions Approach | We present a non-orthogonal fragment ab initio methodology for the calculation of crystal field energy levels and magnetic properties in lanthanide complexes, implementing a systematic description of non-covalent contributions to metal-ligand bonding. The approach has two steps. In the first step, appropriate ab initio wavefunctions for the various ionic fragments (lanthanide ion and coordinating ligands) are separately optimized, accounting for the electrostatic influence of the surrounding environment, within various approximations. In the second and final step, the scalar relativistic (DKH2) electrostatic Hamiltonian of the whole molecule is represented on the basis of the optimized metal-ligand multiconfigurational non-orthogonal group functions (MC-NOGF), and reduced to an effective (2J+1)-dimensional non-orthogonal Configuration Interaction (CI) problem via L{\"o}wdin-partitioning. Within the proposed formalism, the projected Hamiltonian can be implemented to any desired order of perturbation theory in the fragment-localised excitations out of the degenerate space, and its eigenvalues and eigenfunctions are systematic approximations to the crystal field energies and wavefunctions. We present a preliminary implementation of the proposed MC-NOGF method to first-order degenerate perturbation theory within our own ab initio code CERES, and compare its performance both with the simpler non-covalent orthogonal ab initio approach Fragment Ab Initio Model Potential (FAIMP) approximation, and with the full CAHF/CASCI-SO method, accounting for metal-ligand covalency in a mean-field manner. We find that energies and magnetic properties for 44 complexes obtained via an iteratively optimized version of our MC-NOGF first-order non-covalent method, compare remarkably well to the full CAHF/CASCI-SO method including metal-ligand covalency, and are superior to the best purely electrostatic results achieved via an iteratively optimized version of the FAIMP approach.<br /> | Alessandro Soncini; MATTEO PICCARDO | Magnetic Materials; Lanthanides and Actinides; Magnetism; Computational Chemistry and Modeling; Theory - Computational | CC BY 4.0 | CHEMRXIV | 2020-02-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7481f567dfef681ec4972/original/ab-initio-non-covalent-crystal-field-theory-for-lanthanide-complexes-a-multiconfigurational-non-orthogonal-group-functions-approach.pdf |
632828020847009e1980ec64 | 10.26434/chemrxiv-2022-85wcl-v2 | Predicting RP-LC retention indices of structurally
unknown chemicals from mass spectrometry data | Non-target analysis combined with high resolution mass spectrometry is considered one of the most comprehensive strategies for the detection and identification of known and unknown chemicals in complex samples. However, many compounds remain unidentified due to data complexity and limited structures in chemical databases. In this work, we have developed and validated a novel machine learning algorithm to predict the retention index (ri) values for structurally (un)known chemicals based on their measured fragmentation pattern. The developed model, for the first time, enabled the predication of ri values without the need for the exact structure of the chemicals, with an R^2 of 0.91 and 0.77 and root mean squared error (RMSE) of 47 and 67 ri units for the NORMAN (n=3131) and amide (n=604) test sets, respectively. This fragment based model showed comparable accuracy in r_i prediction compared to conventional descriptor-based models that rely on known chemical structure, which obtained a R^2 of 0.85 with and RMSE of 67. | Jim Boelrijk; Denice van Herwerden; Saer Samanipour; Bernd Ensing; Patrick Forré | Analytical Chemistry; Chemoinformatics; Mass Spectrometry; Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632828020847009e1980ec64/original/predicting-rp-lc-retention-indices-of-structurally-unknown-chemicals-from-mass-spectrometry-data.pdf |
648b2daabe16ad5c57f865e4 | 10.26434/chemrxiv-2023-v6m0k | M5X4 - A Family of MXenes | MXenes are two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides typically synthesized from layered MAX-phase precursors. With over 50 experimentally reported MXenes and a near-infinite number of possible chemistries, MXenes are the fastest-growing family of 2D materials. They offer a wide range of properties, which can be altered by their chemistry (M, X, Tx) and the number of metal layers in the structure, ranging from two in M2XTx to five in M5X4. Only one M5X4Tx MXene, Mo4VC4, has been reported. Herein, we report the synthesis and characterization of two new phase-pure M5AX4 mixed transition metal MAX-phases, (TiTa)5AlC4 and (TiNb)5AlC4, and their successful topochemical transformation into (TiTa)5C4Tx and (TiNb)5C4Tx MXenes. The resulting MXenes were delaminated into single-layer flakes, analyzed structurally, and characterized for their thermal and optical properties. This establishes a family of M5AX4 MAX phases and their corresponding MXenes. These materials were experimentally produced based on guidance from theoretical predictions, opening the door to exciting new applications for MXenes. | Marley Downes; Christopher Shuck; Robert Lord; Mark Anayee; Mikhail Shekhirev; Ruocun Wang; Tetiana Hryhorchuk; Martin Dahlqvist; Johanna Rosen; Yury Gogotsi | Materials Science; Nanoscience; Carbon-based Materials; Ceramics; Nanostructured Materials - Materials; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-06-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/648b2daabe16ad5c57f865e4/original/m5x4-a-family-of-m-xenes.pdf |
61782f758acf7e1758cf8a56 | 10.26434/chemrxiv-2021-lfljk-v4 | Recommendation System to Predict Missing Adsorption Properties of Nanoporous Materials | Nanoporous materials (NPMs) selectively adsorb and concentrate gases into their pores, and thus could be used to store, capture, and sense many different gases. Modularly synthesized classes of NPMs, such as covalent organic frameworks (COFs), offer a large number of candidate structures for each adsorption task. A complete NPM-property table, containing measurements of the relevant adsorption properties in the candidate NPMs, would enable the matching of NPMs with adsorption tasks. However, in practice the NPM-property matrix is only partially observed (incomplete); (i) many properties of any given NPM have not been measured and (ii) any given property has not been measured for all NPMs.<br /><br />The idea in this work is to leverage the observed (NPM, property) values to impute the missing ones. Similarly, commercial recommendation systems impute missing entries in an incomplete item-customer ratings matrix to recommend items to customers. We demonstrate a COF recommendation system to match COFs with adsorption tasks by training a low rank model of an incomplete COF--adsorption-property matrix. A low rank model, trained on the observed (COF, adsorption property) values, provides (i) predictions of the missing (COF, adsorption property) values and (ii) a "map" of COFs, represented as points, wherein COFs with similar (dissimilar) adsorption properties congregate (separate). We find the performance of the COF recommendation system varies for different adsorption tasks and diminishes precipitously when the fraction of missing entries exceeds 60%. The concepts in our COF recommendation system can be applied broadly to many different materials and properties. <br /> | Arni Sturluson; Ali Raza; Grant D. McConachie; Daniel Siderius; Xiaoli Fern; Cory Simon | Theoretical and Computational Chemistry; Materials Science; Machine Learning; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2021-10-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61782f758acf7e1758cf8a56/original/recommendation-system-to-predict-missing-adsorption-properties-of-nanoporous-materials.pdf |
64ecb0463fdae147fa02bf66 | 10.26434/chemrxiv-2023-7d7tz | Disclosing the interfacial electrolyte structure at Na-insertion electrode materials: origins of desolvation phenomenon | Among a variety of promising cathode materials for Na-ion batteries, polyanionic Na-insertion compounds are among the preferred choice due to known fast sodium transfer through the ion channels along their framework structures. The most interesting representatives are Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF), which display large Na+ diffusion coefficients and high voltage plateaux (up to 4.2V for NVPF). While the diffusion in the solid material is well-known to be the rate-limiting step during charging, already being thoroughly discussed in the literature, liquid-state transport of sodium ions towards the electrode was recently shown to be important due to complex ion desolvation effects at the interface. In order to fill the blanks in the description of the electrode/electrolyte interface in Na-ion batteries, we performed a molecular dynamics study of the local nanostructure of a series of carbonate-based sodium electrolytes at the NVP and the NVPF interfaces along with the careful examination of the desolvation phenomenon. We show that the tightness of solvent packing at the electrode surface is a major factor determining the height of the free energy barrier associated with desolvation, which explains the differences between the NVP and the NVPF structures. To rationalize and emphasize the remarkable properties of this family of cathode materials, a complementary comparative analysis of the same electrolyte systems at the carbon electrode interface was also performed. | Kateryna Goloviznina; Ezzoubair Bendadesse; Ozlem Sel; Jean-Marie Tarascon; Mathieu Salanne | Theoretical and Computational Chemistry; Energy; Computational Chemistry and Modeling; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ecb0463fdae147fa02bf66/original/disclosing-the-interfacial-electrolyte-structure-at-na-insertion-electrode-materials-origins-of-desolvation-phenomenon.pdf |
60c7570f842e655d34db4614 | 10.26434/chemrxiv.14368982.v1 | The Use of Zeolite-Based Geopolymers as Adsorbent for Copper Removal from Aqueous Media | In this study the use of a natural zeolite-based geopolymer use in removal of copper from aqueous media has been presented for the first time. <div>Additionally, kinetics and isotherms of the adsorption have also been demonstrated. </div> | Haci Baykara; Maria de Lourdes Mendoza Solorzano; Jose Javier Delgado Echeverria; Mauricio H. Cornejo; Clotario V. Tapia-Bastidas | Inorganic Polymers; Separation Science; Chemical Kinetics; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7570f842e655d34db4614/original/the-use-of-zeolite-based-geopolymers-as-adsorbent-for-copper-removal-from-aqueous-media.pdf |
66e45cea51558a15efe0732b | 10.26434/chemrxiv-2024-jxsfc | Pd-Catalysed Migratory 1,1-Cycloannulation Reaction of Alkenes | One of the central goals of synthetic chemistry is to develop efficient methods for constructing heterocyclic architectures, given their broad distribution in a wide range of natural compounds, pharmaceuticals, agrochemicals, and materials. As a result, methods that allow for the modular and diverse synthesis of heterocyclic compounds via one single approach are in high demand. Here, we report a novel strategy for the preparation of diverse heterocycles via a Pd-catalysed migratory 1,1-cycloannulation reaction (MCAR) of alkenes. Starting from readily available alkenyl amines and alkenyl alcohols, this approach allows the formation of a wide range of heterocycles, including five to seven-membered azaheterocycles and oxaheterocycles with high efficiency and good functional group tolerance. The key to the realisation of this reaction is the use of 4-iodophenol or 2-iodophenol derivatives, where the phenolic hydroxyl group plays a critical role in controlling the direction of migration and the ring-size of the heterocycles through the formation of a quinone methide intermediate. The utility of this strategy in synthetic chemistry and medicinal chemistry were preliminarily demonstrated by the late-stage introduction of heterocycle scaffolds into complex drug molecules, and the efficient preparation of serval bioactive compounds. | Jin-Ping Wang; Tao Liu; Yichen Wu; Peng Wang | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2024-09-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66e45cea51558a15efe0732b/original/pd-catalysed-migratory-1-1-cycloannulation-reaction-of-alkenes.pdf |
67583040f9980725cf9a1634 | 10.26434/chemrxiv-2024-0r81w | Ru(II)-Catalyzed Late-Stage C-H Amidation of Medicinally Rele-vant Benzodiazepine Scaffold | A late-stage C-H functionalization of 1,4-benzodiazepines for direct C-H amidation has been developed via Ru-catalyzed C-H activation. This method efficiently generates medicinally relevant functionalized products using Ru-metal. Tosyl azide serves as a bench-stable amidating reagent. The amidated product is further converted to an aminated product through chemoselective hydrolysis of the sulfonamide bond. In mechanistic studies, ruthenacycle has been synthesized and charac-terized by NMR spectroscopy. | Shourabh Rav; Shiv Shankar Gupta; Sarthi -; Storm Hassell-Hart; John Spencer; Upendra Sharma | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67583040f9980725cf9a1634/original/ru-ii-catalyzed-late-stage-c-h-amidation-of-medicinally-rele-vant-benzodiazepine-scaffold.pdf |
6356980d55a081f737c32a86 | 10.26434/chemrxiv-2022-l7xbh | Aldehydes as O-Nucleophiles in Cobalt Hydride Catalysis: Overriding the Innate Somophilicity | In metal hydride-catalyzed alkene hydrofunctionalization reactions via hydrogen atom transfer (HAT), simple carbonyl groups have been well recognized as good somophiles at the carbon for C–C bond formation. Here we report an alternative pathway exploring the carbonyl as an O-nucleophile to make new C–O bonds during the CoH-catalyzed oxidative cyclization of alkenyl aldehydes. This reaction provides a rapid, mild, modular, and stereoselective (up to > 20:1) entry to saturated O-heterocycles via nucleophilic trapping of an in situ formed oxocarbenium intermediate. The key to overriding the carbonyl’s innate somophilicity was found to be promoting the formation of organocobalt species and suppressing degenerative transfer. | Yi-Chen Nie; Fan Yang; Yu-Hao Li; Rong Zhu | Organic Chemistry; Catalysis | CC BY NC 4.0 | CHEMRXIV | 2022-10-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6356980d55a081f737c32a86/original/aldehydes-as-o-nucleophiles-in-cobalt-hydride-catalysis-overriding-the-innate-somophilicity.pdf |
66fdcde551558a15efe29bcc | 10.26434/chemrxiv-2024-nwdvf | Tungsten Oxide Nanocrystals Doped with Interstitial Methylammonium Cations | Doping of semiconductor nanocrystals is a well-established process to impart new or enhanced functionalities to the host material. In this work we present the synthesis of colloidal WO3 nanocrystals doped with interstitial methylammonium cations. The organic cations are located within the voids of the WO3 cage and increase the charge carrier concentration. As a result, the nanocrystals exhibit intense surface plasmon resonances in the near infrared, comparable to those obtained for WO3 “bronzes” doped with alkali metals. We confirm the successful incorporation of these novel organic dopants through a combined experimental and theoretical study. Furthermore, we demonstrate the ability to dope the nanocrystals with even larger cations including formamidinium, providing a pathway to obtaining WO3 doped with bespoke organic cations that offer additional functionalities for use in optics, electronics and catalysis. | Owen Kendall; Lesly Melendez; Merve Nur Guven Bicer; Michael Wilms; Joel van Embden; Daniel Gomez; Arrigo Calzolari; Deborah Prezzi; Enrico Della Gaspera | Nanoscience; Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66fdcde551558a15efe29bcc/original/tungsten-oxide-nanocrystals-doped-with-interstitial-methylammonium-cations.pdf |
610add5245805d249f80eada | 10.26434/chemrxiv-2021-ddm5j | Synthesis of Azalurenone Alkaloids by Pd- mediated Intramolecular Oxidative Cyclisation Protocol | In this paper we present the synthesis of different substituted azafluorenone via oxidative intra-molecular Heck cyclization protocol. The Heck precursor alcohols were synthesised via reaction of the Grignard reagents of corresponding iodides upon 2-bromopyridine-3-carboxaldehyde The Grignard reagents were easily prepared from fresh magnesium turnings activated by pinch of iodine and their corresponding halides (iodide or bromide) in refluxing dry ether medium. Then these freshly prepared Grignard reagents were added drop wise into an ice-cold ethereal solution of 2-bromoprydine-3-carboxaldehyde , which gave our desired Heck precursor alcohols in quantitative yields | Jayanta Kumar Ray | Organic Chemistry; Organometallic Chemistry; Natural Products; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2021-08-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/610add5245805d249f80eada/original/synthesis-of-azalurenone-alkaloids-by-pd-mediated-intramolecular-oxidative-cyclisation-protocol.pdf |
67caf92181d2151a0280c94c | 10.26434/chemrxiv-2025-h1cdq | Nonpolar C-H Bond Activation by Multi-Site Concerted Electron-Proton Transfer for Electrochemical Dimerization of β-Ketoester | Dimerized β-ketoesters are crucial intermediate organic molecules for the synthesis of natural products and pharmaceutically essential molecules. Herein, we present a direct electro-oxidation of α-C-H bond of β-ketoesters on graphite electrode surface in acetonitrile solvent with NH4PF6 electrolyte and sodium hydride base employing a constant potential (1.8 V) methodology in a two-electrodes setup for the synthesis of dimerized β-ketoesters eliminating the need for toxic oxidants or metal-based expensive catalysts. Cyclic voltammetry, UV-Vis spectroscopy, kinetic isotopic effects, and other control experiments suggested multi-site concerted electron-proton transfer (MS-CEPT) was operational for the α-C-H bond activation towards the generation of a neutral radical intermediate on α-carbon, which enabled C(sp³)−C(sp³) bond formation. This study is the first example of activation of a nonpolar C-H bond employing MS-CEPT in a direct electro-oxidative methodology. Twenty-one examples of dimerization of β-ketoesters having diverse substituents have been provided with excellent yields (average yield of 73%). The methodology has been further utilized for the total syntheses of naturally occurring dimeric aromatic propanoids, such as dihydrocubebin and epi-dihydrocubebin. | Salman Ahsan; Monosij Nandy; Shivani Ahlawat; Souvik Pal; Alakesh Bisai; Amit Paul | Physical Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Physical Organic Chemistry; Electrochemistry - Mechanisms, Theory & Study | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67caf92181d2151a0280c94c/original/nonpolar-c-h-bond-activation-by-multi-site-concerted-electron-proton-transfer-for-electrochemical-dimerization-of-ketoester.pdf |
670e98b751558a15ef2a57d2 | 10.26434/chemrxiv-2024-f9zm0 | Hypoxia-Responsive Polymersomes for Stemness Reduction in Patient-Derived Solid Tumor Spheroids | Aggressive solid tumors are associated with rapid growth, early hypoxia, the lack of targeted therapies, and a poor prognosis. The hypoxic niches within the rapidly growing solid tumors give rise to a stem cell-like phenotype with higher metastasis and drug resistance. To overcome the drug resistance of these regions, we used hypoxia-responsive polymersomes with an encapsulated anticancer drug (doxorubicin, Dox) and a stemness modulator (all-trans-retinoic acid, ATRA). Reductase enzymes overexpressed in the hypoxia reduce the azobenzene linker of the polymers, disrupt the bilayer structure of the polymersomes, and release the encapsulated drugs. We used triple-negative breast cancer (TNBC) as a representative of aggressive and hypoxic solid tumors. We observed that ATRA synergistically enhanced the efficacy of Dox in killing the cancer cells. A synergistic combination of the two drug-encapsulated polymersomes reduced volumes of patient-derived TNBC spheroids by 90%. In contrast, Dox alone decreased the spheroid volumes by 70% and encapsulated Dox by 19%. Mechanistic studies revealed that ATRA inhibited the efflux pumps, leading to a higher concentration of doxorubicin within the TNBC cells. In addition, the combination of encapsulated Dox and ATRA significantly decreased stemness expression of the TNBC cells in hypoxia compared to Dox alone. | Connor Edvall; Narendra Kale; Sakurako Tani; Shubhashri Ambhore; Rayat Hossain; Chukwuebuka Ozoude; Karl Van Horsen; jiyan Mohammad; Daniel Tuvin; Santo Kalathingal; Jagadish Loganathan; Yongki Choi; Venkatachalem Sathish; James Brown; Sanku Mallik | Biological and Medicinal Chemistry; Materials Science; Nanoscience; Cell and Molecular Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670e98b751558a15ef2a57d2/original/hypoxia-responsive-polymersomes-for-stemness-reduction-in-patient-derived-solid-tumor-spheroids.pdf |
60c745bfee301ca559c793b1 | 10.26434/chemrxiv.10247813.v1 | Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism | <div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div> | Shiori Date; Kensei Hamasaki; Karen Sunagawa; Hiroki Koyama; Chikayoshi Sebe; Kou Hiroya; Hiroki Shigehisa | Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-11-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745bfee301ca559c793b1/original/direct-cyclization-of-alkenyl-thioester-via-transition-metal-hydrogen-atom-transfer-radical-polar-crossover-mechanism.pdf |
67605bd281d2151a02f5ddc1 | 10.26434/chemrxiv-2024-gfg95 | Cyclic IMS-MS evidence for potential ring opening in collisionally activated sodiated cyclodextrins | Current tandem mass spectrometry-based methods for cyclodextrin characterization rely on exact mass and fragmentation patterns. In general, orthogonal methods provide additional information, which increases confidence in characterization. Ion mobility spectrometry (IMS) and mass spectrometry (MS) provide two dimensions of analysis based on molecular weight and size. Here, we report new gas phase behavior of sodiated cyclodextrins revealed by Cyclic IMS coupled to tandem MS. Gas phase ion activation prior to IMS separation on sodiated α-, β-, and γ-cyclodextrins generates isomeric species with different mobilities. Fragmentation studies on all isomers following gas phase separation showed a greater degree of fragmentation than was observed for the original sodiated cyclodextrins. These findings suggest that sodiated cyclodextrins undergo structural changes upon activation, with the newly formed isomers significantly contributing to fragmentation. To our knowledge this is the first report on separation of isomeric ions generated upon collisional activation of sodiated cyclodextrins in the gas phase. Results of this study can be used for better understanding of cyclodextrin fragmentation. Additionally, these findings can be used to develop more specific methodologies for cyclodextrin characterization. | Sudam S. Mane; Easton K. Cox; Cole D. Warner; David V. Dearden; Kenneth W. Lee | Analytical Chemistry; Mass Spectrometry; Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67605bd281d2151a02f5ddc1/original/cyclic-ims-ms-evidence-for-potential-ring-opening-in-collisionally-activated-sodiated-cyclodextrins.pdf |
6333fcca2984c9665e6fc78c | 10.26434/chemrxiv-2022-3p6cf-v2 | Bottom-up design of porous electrode by combining a genetic algorithm and a pore network model | The microstructure of porous electrodes determines multiple performance-defining properties, such as the available reactive surface area, mass transfer rates, and hydraulic resistance. Thus, optimizing the electrode architecture is a powerful approach to enhance the performance and cost-competitiveness of electrochemical technologies. To expand our current arsenal of electrode materials, we need to build predictive frameworks that can screen a large geometrical design space while being physically representative. Here, we present a novel approach for the optimization of porous electrode microstructures from the bottom-up that couples a genetic algorithm with a previously validated electrochemical pore network model. In this first demonstration, we focus on optimizing redox flow battery electrodes. The genetic algorithm manipulates the pore and throat size distributions of an artificially generated microstructure with fixed pore positions by selecting the best-performing networks, based on the hydraulic and electrochemical performance computed by the model. For the studied VO2+/VO2+ electrolyte, we find an increase in the fitness of 75% compared to the initial configuration by minimizing the pumping power and maximizing the electrochemical power of the system. The algorithm generates structures with improved fluid distribution through the formation of a bimodal pore size distribution containing preferential longitudinal flow pathways, resulting in a decrease of 73% for the required pumping power. Furthermore, the optimization yielded an 47% increase in surface area resulting in an electrochemical performance improvement of 42%. Our results show the potential of using genetic algorithms combined with pore network models to optimize porous electrode microstructures for a wide range of electrolyte composition and operation conditions. | Rik van Gorp; Maxime van der Heijden; Mohammad Amin Sadeghi; Jeffrey Gostick; Antoni Forner Cuenca | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6333fcca2984c9665e6fc78c/original/bottom-up-design-of-porous-electrode-by-combining-a-genetic-algorithm-and-a-pore-network-model.pdf |
60c73d934c891975c5ad1c49 | 10.26434/chemrxiv.5995078.v1 | Quantum Mechanical Interpretation of the Ultra-Low Energy Methyl-Rotation Dynamics in Porous Metal-Organic Frameworks Probed by Low-Frequency Vibrational Spectroscopy and ab initio Simulations | <div>Understanding the nature of the interatomic interactions present within the pores of metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 and its cobalt analogue</div><div>ZIF-67, the imidazolate methyl-groups, which point directly</div><div>into the void space, have been shown to freely rotate - even</div><div>down to cryogenic temperatures. Using a combination of ex-</div><div>perimental terahertz time-domain spectroscopy, low-frequency</div><div>Raman spectroscopy, and state-of-the-art ab initio simulations,</div><div>the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully charac-</div><div>terized within the context of a quantum-mechanical hindered-</div><div>rotor model. The results lend insight into the fundamental</div><div>origins of the experimentally observed methyl-rotor dynamics,</div><div>and provide valuable insight into the nature of the weak inter-</div><div>actions present within this important class of materials.</div> | Qi Li; Adam J. Zaczek; Timothy M. Korter; J. Axel Zeitler; Michael
T. Ruggiero | Theory - Computational; Clusters; Physical and Chemical Properties; Quantum Mechanics; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d934c891975c5ad1c49/original/quantum-mechanical-interpretation-of-the-ultra-low-energy-methyl-rotation-dynamics-in-porous-metal-organic-frameworks-probed-by-low-frequency-vibrational-spectroscopy-and-ab-initio-simulations.pdf |
61c2da03f52bc4027ec95864 | 10.26434/chemrxiv-2021-dt5b2 | Gemini-Mediated Self-Disinfecting Surfaces to
Address Contact Transmission of Infectious
Diseases | According to both the Center for Disease Control (CDC) and the World Health Organization (WHO), contact-transmission (contact between host tissues and a contaminated surface) is the primary transmission route of infectious diseases worldwide. Usually this is mitigated by adherence to a schedule of repeated regular sanitization, yet this approach is inherently limited by sanitization frequency; conventional disinfectants/methods are only germicidal during the period of application, and surfaces are easily re-contaminated in the interim between cleanings. One solution to this problem is to use agents/coatings that impart self-disinfecting properties onto the existing surfaces such that they display sustained virucidal/antimicrobial properties against pathogens that settle upon them. Quaternary-ammonium organosilicon compounds are ideal candidates to achieve this; cationic surfactants are safe and well-established surface disinfectants while organosilanes are used broadly to form durable coatings with altered surface properties on many different materials. Despite their potential to circumvent disadvantages of traditional disinfection methods, extant commercially available quaternary-ammonium silanes do not display comparable efficacy to standard surface disinfectants, nor have their respective coatings been demonstrated to meet the Environmental Protection Agency’s guidelines for residual/extended efficacy. Inspired by powerful surface activity of double-headed “gemini” surfactants, here we present gemini-diquaternary (GQ) silanes with robust residual germicidal efficacy on various surfaces by incorporating a second cationic “head” to the structure of an conventional mono-quaternary-ammonium silane. Aqueous solutions of GQs were tested in suspension- and surface-antimicrobial assays against an array of pathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). GQ performance was benchmarked against the common disinfectants, ethanol, hydrogen peroxide and hypochlorite, as well as against a common antimicrobial mono-quaternary (MQ) silane. Solutions of GQ silanes were efficacious when used for immediate disinfection, showing comparable activity to common disinfectants (>106 fold reduction in 15 seconds). Additionally GQ solutions were demonstrated to impart durable self-disinfecting properties to a variety of porous and nonporous surfaces, efficacious after repeated cycles of abrasion and repeated contaminations, and with superior coating ability and activity (>108 higher activity) than that of the popular MQ silane. GQ solutions as surface treatments show great promise to overcome the limitations of traditional disinfectants in preventing the spread of infectious diseases. | Kollbe Ahn Ando; Roscoe Lisntadt; Jinsoo Ahn; Minju Kim | Materials Science; Coating Materials | CC BY NC ND 4.0 | CHEMRXIV | 2021-12-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61c2da03f52bc4027ec95864/original/gemini-mediated-self-disinfecting-surfaces-to-address-contact-transmission-of-infectious-diseases.pdf |
63b3542081e4ba1d09625acb | 10.26434/chemrxiv-2023-fpf1n | The Magic of Triisopropyl-1,4,7-Triazacyclononane: Probing the Role of Ni(III) and Ni(I) Centers in Cross-Coupling Catalysis | The last two decades have experienced a dramatic development of nickel-catalyzed cross-coupling reactions involving alkyl substrates, including a wide range of stereoselective transformations. In these reactions, nickel complexes supported by N-donor ligands have been proposed to involve paramagnetic Ni(I) and Ni(III) species as the active intermediates during catalysis. Herein, we report the use of a bulky 1,4,7-triisopropyl-1,4,7-triazacyclononane (iPr3TACN) ligand that allowed the detection and isolation of uncommon organometallic Ni(I) and Ni(III) complexes, which are involved in well-defined oxidative addition, transmetallation, and reductive elimination steps of the proposed catalytic cycle. Moreover, (iPr3TACN)Ni(II) complexes were shown to be efficient catalysts for the alkyl-alkyl Kumada cross-coupling, while a beneficial effect of acetonitrile on the yield of the desired cross-coupled products was observed, likely due to the stabilization of transient Ni(I) species. Overall, these studies provide unambiguous evidence for the involvement of both Ni(III) and Ni(I) organometallic species in Ni-catalyzed alkyl-alkyl cross-coupling reactions. | Leonel Griego; Ju Byeong Chae; Liviu Mirica | Organic Chemistry; Inorganic Chemistry; Organometallic Chemistry; Organic Synthesis and Reactions; Organometallic Compounds; Kinetics and Mechanism - Organometallic Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63b3542081e4ba1d09625acb/original/the-magic-of-triisopropyl-1-4-7-triazacyclononane-probing-the-role-of-ni-iii-and-ni-i-centers-in-cross-coupling-catalysis.pdf |
6508af1f99918fe537317b0d | 10.26434/chemrxiv-2023-lkndx | Modular Preparation of Cationic Bipyridines and Azaarenes via C–H Activation | Bipyridines are ubiquitous in organic and inorganic chemistry because of their redox and photochemical properties and their utility as ligands to transition metals. Cationic substituents on bipyridines and azaarenes are valuable as powerful electron-withdrawing functionalities that also enhance solubility in polar solvents, but there are no general methods for direct functionalization. A versatile method for the preparation of trimethylammonium- and triarylphosphonium-substituted bipyridines and azaheterocycles is disclosed. This methodology showcases a C–H activation of pyridine N-oxides that enables a highly modular and scalable synthesis of a diverse array of cationically charged azaarenes. The addition of trimethylammonium functionalities on bipyridine derivatives resulted in more anodic reduction potentials (up to 700 mV) and increased electrochemical reversibility compared to the neutral unfunctionalized bipyridine. Additonally, metallation of 4-triphenylphosphinated biquinoline to make the corresponding Re(CO)3Cl complex resulted in reduction potentials 400 mV more anodic than the neutral derivative. | Ryan King; Jenny Yang | Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6508af1f99918fe537317b0d/original/modular-preparation-of-cationic-bipyridines-and-azaarenes-via-c-h-activation.pdf |
67c062fdfa469535b9297fcd | 10.26434/chemrxiv-2025-zjxth | Interplay of structural and electronic properties and their impact on thin films of metal-free organic radicals (Final report on DFG funded projects, reference number: CA852/11-1 and CA852/11-3, Project number: 394233453) | The project and its extension concentrate on radical thin films. I have identified and refined the growth protocols for various radicals and multi-radicals, enabling their evaporation while pre-serving their radical nature. Additionally, I have explored the influence of different functional groups on thin film properties. During these years, I have addressed a variety of aspects, demonstrating the feasibility of using radicals in fields ranging from quantum technologies to spintronics. By using primarily X-ray-based techniques, including at synchrotron facilities, I have linked structural, electronic, and magnetic properties. I have also examined how the interaction strength between the (multi-)radicals and the substrate affects the interface formation, growth modes, and film processes of the radical thin films. Furthermore, I have focused on evaluating film stability, which is crucial for understanding their chemistry when exposed to air prior to performing electron spin resonance (ESR) spectroscopy—a traditional (ex-situ) technique used for radicals—and for determining film stability in environments simulating working devic-es. I have developed a protocol to study the effects of air exposure on radical thin films and utilized this method. Finally, I have conducted and interpreted X-ray magnetic circular dichro-ism (XMCD) investigations, revealing the interplay between structure and magnetic behavior in radical thin films. | Maria Benedetta Casu | Physical Chemistry; Materials Science; Nanoscience; Carbon-based Materials; Thin Films; Interfaces | CC BY 4.0 | CHEMRXIV | 2025-03-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c062fdfa469535b9297fcd/original/interplay-of-structural-and-electronic-properties-and-their-impact-on-thin-films-of-metal-free-organic-radicals-final-report-on-dfg-funded-projects-reference-number-ca852-11-1-and-ca852-11-3-project-number-394233453.pdf |
673bf46e7be152b1d08fde8e | 10.26434/chemrxiv-2024-mnf3b | A Novel Fe-doped Metal Oxide Electrode Material for High Energy Densities Within Intercalated Pseudo Supercapacitors | The current lithium-ion battery technology is expensive and not environmentally sustainable. While supercapacitors are an alternative they have very low energy densities making them impractical to use. Therefore, this project aimed to create an energy source that solved the problems batteries had while improving the super-capacitor technology. This would be achieved by creating a cost-effective pseudo-super-capacitor. This project hence synthesized a novel electrode material. To ensure the faradaic redox reaction occurred the oxide MnO2 was used. This MnO2 was synthesized with the sol-gel process to create 1D nano-rods. It was then doped with Fe to weaken the hydrogen bonds in the MnO2 to create oxygen vacancies. These oxygen vacancies and 1D nano-rods improve mobility, conductivity, and structural stability. The novel electrode material was combined with the binder solution and current collector to make the final pseudo-super-capacitor. This not only allowed for the overall capacitance to be higher than commercial products with a capacitance of 0.90F but also allowed for the energy density to be 5x higher with around 5.337(Wh/kg). The power density was also not compromised being 2456.163 (W/kg). The prototype has the potential to store 900 watts at the mere cost of $10.03. Future studies include increasing capacitance and energy density but also experimenting with nano synthesization techniques. With a power source as potent as this many science fields will gain flexibility and low-income communities can gain access to a reliable power source. This prototype will have a transformative impact on society. | Arya Gurumukhi | Materials Science; Nanoscience; Energy; Nanostructured Materials - Materials; Nanofabrication; Energy Storage | CC BY 4.0 | CHEMRXIV | 2024-11-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673bf46e7be152b1d08fde8e/original/a-novel-fe-doped-metal-oxide-electrode-material-for-high-energy-densities-within-intercalated-pseudo-supercapacitors.pdf |
618a485b9b583aa54cf150f9 | 10.26434/chemrxiv-2021-g54hd | Deconvoluting the Impacts of the Active Material Skeleton and the Inactive Phase Morphology on the Performance of Lithium Ion Battery Electrodes | In order to extract the most capacity out of Li-ion battery (LIB) active materials, the optimization of the electrodes architectures at the mesoscale is essential. This work focuses on the morphology of the inactive phase (carbon additives and binder) through a 3-D modeling approach based on stochastic generation with realistic LiNi1/3Mn1/3Co1/3O2 particle size distributions. It was found that having the inactive phase as a film spread on the active material results in poorer performance in part due to the loss of active surface area when compared to an agglomerates morphology. | Mehdi Chouchane; Alejandro A. Franco | Theoretical and Computational Chemistry; Energy; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2021-11-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/618a485b9b583aa54cf150f9/original/deconvoluting-the-impacts-of-the-active-material-skeleton-and-the-inactive-phase-morphology-on-the-performance-of-lithium-ion-battery-electrodes.pdf |
643d416808c86922ff297ab9 | 10.26434/chemrxiv-2023-08cj4 | Pharmacophore-based ML model to predict ligand selectivity for E3 ligase binders | E3 ligases are enzymes that play a critical role in ubiquitin-mediated protein degradation and are involved in various cellular processes. Pharmacophore analysis is a useful approach for predicting E3 ligase binding selectivity, which involves identifying key chemical features necessary for a ligand to interact with a specific protein target cavity. While pharmacophore analysis is not always sufficient to accurately predict ligand binding affinity, it can be a valuable tool for filtering and/or designing focused libraries for screening campaigns. In this study, we present a fast and inexpensive approach using a pharmacophore fingerprinting scheme known as ErG, which is used in a multiclass machine learning classification model. This model can assign the correct E3 ligase binder to its known E3 ligase and predict the probability of each molecule to bind to different E3 ligases. Practical applications of this approach are demonstrated on commercial libraries for rational design of E3 ligase binders. | Reagon Karki; Yojana Gadiya; Philip Gribbon; Andrea Zaliani | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-04-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643d416808c86922ff297ab9/original/pharmacophore-based-ml-model-to-predict-ligand-selectivity-for-e3-ligase-binders.pdf |
60c741670f50db61dc395af1 | 10.26434/chemrxiv.7480103.v2 | How Do Size and Aggregation of Ice-binding Proteins Control their Ice Nucleation Efficiency | <p>Organisms that thrive at cold temperatures produce ice-binding proteins to manage the nucleation and growth of ice. Bacterial ice-nucleating proteins (INP) are typically large and form aggregates in the cell membrane, while insect hyperactive antifreeze proteins (AFP) are soluble and generally small. Experiments indicate that larger ice-binding proteins and their aggregates nucleate ice at warmer temperatures. Nevertheless, a quantitative understanding of how do size and aggregation of ice-binding proteins determine the temperature Thet at which proteins nucleate ice is still lacking. Here we address this question using molecular simulations and nucleation theory. The simulations indicate that the 2.5 nm long antifreeze protein TmAFP nucleates ice at 2±1 °C above the homogeneous nucleation temperature, in good agreement with recent experiments. We predict that the addition of ice-binding loops to TmAFP increases Thet until the length of the binding-site becomes ~4 times its width, beyond which Thet plateaus. We implement an accurate procedure to determine Thet of surfaces of finite size using classical nucleation theory and, after validating the theory against Thet of the proteins in molecular simulations, we use it to predict Thet of the INP of Ps. syringae as a function of the length and number of proteins in the aggregates. We conclude that assemblies with at most 34 INP already reach the Thet = -2 °C characteristic of this bacterium. Interestingly, we find that Thet is a strongly varying non-monotonic function of the distance between proteins in the aggregates. This indicates that to achieve maximum freezing efficiency, bacteria must exert exquisite, sub-angstrom control of the distance between INP in their membrane</p> | Yuqing Qiu; Arpa Hudait; Valeria Molinero | Biophysical Chemistry; Interfaces; Self-Assembly; Statistical Mechanics; Structure; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2019-04-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741670f50db61dc395af1/original/how-do-size-and-aggregation-of-ice-binding-proteins-control-their-ice-nucleation-efficiency.pdf |
64ba769eb605c6803b1d017b | 10.26434/chemrxiv-2023-bxsbh-v2 | Synthetic DNA-based nanoswimmers driven by enzyme catalysis | We report here DNA-based synthetic nanostructures decorated with enzymes (hereafter referred to as DNA enzyme nanoswimmers) that self-propel by converting the enzymatic substrate into the product in solution. The DNA enzyme nanoswimmers are obtained from tubular DNA structures that self-assemble spontaneously by hybridization of DNA tiles. We have functionalized these DNA structures with two different enzymes, urease and catalase, and show that upon addition of the enzymatic substrate (i.e., urea and H2O2), they exhibit concentration-dependent motion and different motion dynamics, including enhanced diffusion and ballistic motion. These results pave the way for the development of synthetic enzyme-driven nanoswimmers that can self-propel in fluids and have the potential to provide new insights into biological motion dynamics at the micro-nanoscale. | Tania Patiño; Serena Gentile; Lorena Baranda; Erica Del Grosso; Rafael Mestre; Samuel Sanchez; Francesco Ricci | Physical Chemistry; Analytical Chemistry; Nanoscience; Nanodevices; Nanostructured Materials - Nanoscience; Self-Assembly | CC BY 4.0 | CHEMRXIV | 2023-07-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ba769eb605c6803b1d017b/original/synthetic-dna-based-nanoswimmers-driven-by-enzyme-catalysis.pdf |
65a796cf9138d231611c2449 | 10.26434/chemrxiv-2024-tfkhh | Composition effects of electrodeposited Cu-Ag nanostructured electrocatalysts for CO2 reduction | The electrochemical reduction of carbon dioxide (CO2RR) to valuable C2+ liquid fuels and oxygenates, such as ethanol and propanol, is a promising strategy to minimize the carbon footprint and store renewable electricity. In this study, we investigate the CO2RR on electrodeposited Cu-Ag nanostructures obtained using a green choline chloride and urea deep eutectic solvent (DES). We show that Cu-Ag nanostructured electrocatalysts with tunable composition, loadings, and size can be simply prepared in one step, without adding other additives or surfactant agents. We investigate the intrinsic activity and selectivity of the CO2RR by determining the electrochemically active surface area (ECSA) using lead underpotential deposition (UPD). The analysis of the partial current densities normalized by the ECSA shows that the addition of Ag on electrodeposited Cu primarily suppresses the production of hydrogen and methane with respect to Cu nanostructures. At the same time, the production of carbon monoxide (CO) slightly increases but, the partial current of the total C2+ products does not considerably increase. Despite that the production rate of C2+ is similar on Cu and CuAg, the addition of Ag enhances the formation of alcohols and oxygenates over ethylene, in line with previous reports. We highlight the potential of metal electrodeposition from DES as a sustainable and inexpensive strategy for the development of bimetallic Cu-based nanocatalysts towards CO2RR. | Elena Plaza-Mayoral; Valery Okatenko; Kim Nicole Dalby; Hanne Falsig; Ib Chorkendorff; Paula Sebastian-Pascual; Maria Escudero-Escribano | Catalysis; Nanoscience; Energy; Nanostructured Materials - Nanoscience; Electrocatalysis; Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2024-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a796cf9138d231611c2449/original/composition-effects-of-electrodeposited-cu-ag-nanostructured-electrocatalysts-for-co2-reduction.pdf |
60c75230842e6573cddb3cb1 | 10.26434/chemrxiv.13262603.v1 | Target2drug : A Novel Programmatic Workflow to Automate in Silico Drug Discovery | As the Big Data and Artificial Intelligence (AI) revolution continues to affect every area of our lives, it’s influence is also exerted in the areas of bioinformatics, computational biology and drug discovery. Machine/Deep Learning tools have been developed to predict compounds-drug target interactions and the vice-versa process of predicting target interactions for an compound. In our presented work, we report a programmatic tool, which incorporates many features of the bioinformatics, computational biology and AI-driven drug discovery revolutions into a single workflow assembly. When a user is required to identify drugs against a new drug target, the user provides target signatures in the form of amino acid sequence of the target or it’s corresponding nucleotide sequence as input to the tool and the tool carries out a BLAST protocol to identify known protein drug targets that are similar to the new target submitted by the user and collects data linked to the target involving, active compounds against the target, the activity value and molecular descriptors of active compounds to perform QSAR modelling and to generate drug leads with predictions from the validated QSAR model. The tool performs an In-Silico modelling to generate In-Silico interaction profiles of compounds generated as drug leads and the target and stores the results in the working folder of the user. To demonstrate the use of the tool, we have carried out a demonstration with the target signatures of the current pandemic causing virus, SARS-CoV 2. However the tool can be used against any target and is expected to help in growing our knowledge graph of targets and interacting compounds. <br /> | Ben Geoffrey A S; Rafal Madaj; Akhil Sanker; Pavan Preetham Valluri; Judith Gracia; Harshmeet Singh | Computational Chemistry and Modeling; Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75230842e6573cddb3cb1/original/target2drug-a-novel-programmatic-workflow-to-automate-in-silico-drug-discovery.pdf |
66723603c9c6a5c07acbf83a | 10.26434/chemrxiv-2024-t5m4d-v2 | Investigation of the non-radiative photo-processes of unnatural DNA base: 7-(2-thienyl)-imidazo[4,5-b]pyridine (Ds) - A computational study | 7-(2-thienyl)-imidazo[4,5-b]pyridine (Ds) is an unnatural nucleic acid which forms stable pair with Pyrrole-2-carbaldehyde (Pa) in DNA. This Ds-Pa pair gets stabilized via van der Waals interaction and shape fitting. In our previous study,\cite{ghosh2021radiationless} we investigated the non-radiative photo-processes of unnatural DNA base Pa and also there are some studies on its stability and reactivity in the ground state. But to form a good unnatural base pair, one has to understand its stability not only in the ground state but also in the excited states after absorbing UV radiation. Therefore, in this study, the excited state photo-processes of Ds on UV irradiation and it's non-radiative decay channels have been investigated. It is shown using state of the art multi reference methods and this investigation finally leads the molecule to access minimum energy crossing point (MECP) via a downhill pathway. | Paulami Ghosh | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2024-06-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66723603c9c6a5c07acbf83a/original/investigation-of-the-non-radiative-photo-processes-of-unnatural-dna-base-7-2-thienyl-imidazo-4-5-b-pyridine-ds-a-computational-study.pdf |
62c577a1d66f683ed4be8210 | 10.26434/chemrxiv-2022-g19mw-v2 | Why do sulfone-containing polymer photocatalysts work so well for sacrificial hydrogen evolution from water? | In recent years, many of the highest performing polymer photocatalysts for hydrogen evolution from water have contained dibenzo[b,d]thiophene sulfone units in their polymer backbones. However, the reasons behind the dominance of this building block are not well understood. We use a new set of processable materials, in which the sulfone content is systematically controlled, to understand how the sulfone unit affects the three key processes involved in photocatalytic hydrogen generation in this system: light absorption; transfer of the photogenerated hole to the hole scavenger triethylamine (TEA); and transfer of the photogenerated electron to the palladium metal co-catalyst that remains in the polymer from synthesis. Using transient absorption spectroscopy and electrochemical measurements, and combined with molecular dynamics and density functional theory simulations, we find that the sulfone unit has two primary effects. On the picosecond timescale, it dictates the thermodynamics of hole transfer out of the polymer. The sulfone unit attracts water molecules such that the average permittivity experienced by the solvated polymer is increased, and we demonstrate here that TEA oxidation is only thermodynamically favourable above a certain permittivity threshold. On the microsecond timescale, we present experimental evidence that the sulfone unit acts as the electron transfer site out of the polymer, with the kinetics of electron extraction to palladium dictated by the ratio of photogenerated electrons to the number of sulfone units. For the highest performing, sulfone-rich material, hydrogen evolution appears to be limited by the photogeneration rate of electrons rather than their extraction from the polymer. | Sam A. J. Hillman; Reiner Sebastian Sprick; Drew Pearce; Duncan Woods; Wai-Yu Sit; Xingyuan Shi; Andrew I. Cooper; James R. Durrant; Jenny Nelson | Catalysis; Polymer Science; Energy; Conducting polymers; Photocatalysis; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c577a1d66f683ed4be8210/original/why-do-sulfone-containing-polymer-photocatalysts-work-so-well-for-sacrificial-hydrogen-evolution-from-water.pdf |
628cd23259f0d6af819bc104 | 10.26434/chemrxiv-2022-93cks | Intermolecular Dearomative [4+2] Cycloaddition of Naphthalenes via Visible-Light Energy-Transfer-Catalysis | Dearomative cycloaddition reaction serves as a blueprint for creating three-dimensional molecular topology from flat-aromatic compounds. However, severe reactivity and selectivity issues make this process challenging. Herein, we describe visible-light energy-transfer catalysis for the intermolecular dearomative [4+2] cycloaddition reaction of feed-stock naphthalene molecules with vinyl benzenes. Tolerating a wide range of functional groups, a variety of structurally diverse 2-acyl naphthalenes and styrenes could easily be converted to a diverse range of bicyclo[2.2.2]octa-2,5-diene scaffolds in high yields and selectivities. The late-stage modification of pharmaceutical agents further demonstrated the broad potentiality of this methodology. The efficacy of the introduced methods was further highlighted by the post-synthetic diversification of the products. Furthermore, photoluminescence, electrochemical, kinetic, and control experiments support the energy transfer catalysis | Pramod Rai; Kakoli Maji; Sayan K. Jana; Biplab Maji | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/628cd23259f0d6af819bc104/original/intermolecular-dearomative-4-2-cycloaddition-of-naphthalenes-via-visible-light-energy-transfer-catalysis.pdf |
640b1563b5d5dbe9e8064f48 | 10.26434/chemrxiv-2023-zmh4f | Discovery of a Drug-like, Natural Product-Inspired DCAF11 Ligand Chemotype | Targeted proteasomal and autophagic protein degradation, often employing bifunctional modalities, is a new paradigm for modulation of protein function. In an attempt to explore protein degradation by means of autophagy we combined arylidene-indolinones reported to bind the autophagy related LC3B-protein and ligands of the PDE lipoprotein chaperone, the BRD2/3/4-bromodomain containing proteins and the BTK- and BLK kinases. Unexpectedly, the resulting bifunctional degraders do not induce protein degradation by means of macroautophagy, but instead direct their targets to the ubiquitin-proteasome system. Target and mechanism identification revealed that the arylidene-indolinones covalently bind DCAF11, a substrate receptor in the CUL4A-RBX1-DDB1-DCAF11 E3 ligase. The tempered -unsaturated indolinone electrophiles define a novel drug-like DCAF11-ligand class that enables exploration of this E3 ligase in chemical biology and medicinal chemistry programs. The arylidene-indolinone scaffold frequently occurs in natural products which raises the question whether novel E3 ligand classes can be found more widely among natural products and related compounds. | Gang Xue; Jianing Xie; Matthias Hinterndorfer; Marko Cigler; Hana Imrichova; Soheila Adariani; Lara Dötsch; Georg Winter; Herbert Waldmann | Biological and Medicinal Chemistry; Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY 4.0 | CHEMRXIV | 2023-03-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/640b1563b5d5dbe9e8064f48/original/discovery-of-a-drug-like-natural-product-inspired-dcaf11-ligand-chemotype.pdf |
6758cd7af9980725cfa9eec8 | 10.26434/chemrxiv-2024-g0cx2 | Single point mutations in disordered proteins: linking sequence, ensemble, and function | Mutations in genomic DNA often result in single-point missense mutations in proteins. For most folded proteins, the functional effect of these missense mutations can be understood by their impact on structure. However, missense mutations in intrinsically disordered protein regions (IDRs) remain poorly understood. In IDRs, function can depend on the structural ensemble - the collection of accessible, interchanging conformations that is encoded in their amino acid sequence. We argue that, analogously to folded proteins, single point mutations in IDRs can alter their structural ensemble, and consequently alter their biological function. To make this argument, we first provide experimental evidence from the literature showcasing how single point missense mutations in IDRs affect their ensemble dimensions. Then, we use genomic data from patients to show that disease-linked missense mutations occurring in IDRs can, in many cases, affect the IDR ensembles. We hope this analysis prompts further study of disease-linked, single-point mutations in IDRs. | Eduardo Flores; Nirbhik Acharya; Carlos Castaneda; Shahar Sukenik | Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Biophysics | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6758cd7af9980725cfa9eec8/original/single-point-mutations-in-disordered-proteins-linking-sequence-ensemble-and-function.pdf |
648b1c874f8b1884b7557693 | 10.26434/chemrxiv-2023-0b2kz | Results from the operation of an efficient and flexible large-scale biogas methanation system | This study reports the design and operation of a power-to-gas system producing 240 kW of synthetic natural gas (SNG) from biogas and PV electricity. The system is composed of a solar field, an electrolyser, a plate-type heat exchanger methanation reactor and the required ancillary units. Biogas pre-treatment is not needed, as the cleaning is performed in the system and the raw gas is directly processed in the reactor. The process consumes biogas and renewable electricity to produce SNG and high-pressure steam from the methanation waste heat. The process efficiency in this configuration is 76 %. The methanation reactor produces grid compliant SNG in all the load cases tested and in all the verified biogas composition cases. The reactor shows an excellent flexibility at the start-up, as grid-compliant SNG is produced in less than 10 minutes from feed start in hot-standby. Additionally, the reactor adapts in few minutes to load changes. The reactor is modelled to better understand the origin of the excellent performance in the biogas methanation reaction. It was found that the plate-type heat exchanger operated with boiling water as cooling is an ideal solution for the methanation reaction as it approximates well the optimal reaction pathway in terms of temperature and conversion profile. Large cooling is available where needed, preventing the operation at too high temperature. Isothermal conditions are established at the end of the reactor, allowing reaching the required high conversion. | Emanuele Moioli; Patrick Senn; Simon Oestrup; Christoph Hütter | Catalysis; Chemical Engineering and Industrial Chemistry; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/648b1c874f8b1884b7557693/original/results-from-the-operation-of-an-efficient-and-flexible-large-scale-biogas-methanation-system.pdf |
67d0920881d2151a02067a64 | 10.26434/chemrxiv-2025-wrbzk | Quantum Interference in a Molecular Analog of the Crystalline Silicon Unit Cell | This manuscript describes the emergence of destructive σ-quantum interference (σ-DQI) in sila-adamantane, a molecule whose cluster core is isostructural with the crystalline silicon unit cell. To reveal these σ-DQI effects, we take a bridge-cutting approach where we conceptually excise the bridging paths of a sila-adamantane molecular wire, paring the cluster down to its bicyclic [3.3.1] and linear oligosilane forms. Scanning tunneling microscopy break-junction (STM-BJ) measurements reveal that conductance in single-molecule junctions of the tricyclic sila-adamantane is 2.7-times lower than their bicyclic Si[3.3.1] analog. The only structural difference between their cluster cores is a remote dimethylsilylene bridge that is present in sila-adamantane yet absent in Si[3.3.1]. Density functional theory calculations reveal that this dimethylsilylene bridge enforces C₃ steric symmetry at the sila-diamondoid bridgehead positions, allowing each electrode to couple into the three cluster bridge dimensions equally. Though each bridge alignment is sterically equivalent, they have profound electronic differences: when electrodes align with the long branches of sila-adamantane, strong σ-DQI interactions occur between the key frontier molecular orbitals implicated in charge transport that suppress electronic transmission across the molecular junction. We can exploit these alignment-dependent σ-DQI effects to create new forms of stereoelectronic conductance switches, where a reversible mechanical stimulus controls which pathway through the diamondoid framework the electrodes align through. This represents the first example of dynamic modulation of σ-DQI and enables us to achieve switching ratios (average on/off ~ 5.6) higher than previously reported σ-stereoelectronic switches. Ultimately, these studies reveal how the dimensionality and symmetry of crystalline silicon influence charge transport at its most fundamental level, and how these principles can be harnessed to control σ-quantum interference in single-molecule electronic applications. | Matthew Hight; Ashley Pimentel; Timothy Siu; Joshua Wong; Jennifer Nguyen; Veronica Carta; Timothy Su | Inorganic Chemistry; Nanoscience; Nanodevices; Main Group Chemistry (Inorg.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d0920881d2151a02067a64/original/quantum-interference-in-a-molecular-analog-of-the-crystalline-silicon-unit-cell.pdf |
60c74523469df40728f43460 | 10.26434/chemrxiv.9974687.v1 | Electrochemical Vicinal Difluorination of Alkenes: Sustainable, Scalable, and Amenable to Electron-rich Substrates | Fluorinated alkyl groups are important motifs in bioactive compounds, positively influencing pharmacokinetics, potency and F conformation. The oxidative difluorination of alkenes represents an H important strategy for their preparation, yet current methods are limited in their alkene-types and tolerance of electron-rich, readily oxidized functionalities, as well as in their scalability. Herein, we report a method for the difluorination of a number of unactivated alkene-types that is tolerant of electron-rich functionality, giving products that are otherwise unattainable. Key to success is the electrochemical generation of a hypervalent iodine mediator (in the presence of nucleophilic fluoride and HFIP) using an ‘ex-cell’ approach, which avoids the oxidative decomposition of the substrate. The more sustainable conditions give good to excellent yields of product in up to decagram scales<br /> | Sayad Doobary; Alexi Sedikides; Henry caldora; Darren poole; Alastair Lennox | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74523469df40728f43460/original/electrochemical-vicinal-difluorination-of-alkenes-sustainable-scalable-and-amenable-to-electron-rich-substrates.pdf |
632a21640e3c6a33d6220ace | 10.26434/chemrxiv-2022-j329q | DNA crosslinked alginate hydrogels: Characterization, microparticle development and applications in forensic science | DNA-based hydrogels are attractive materials due to the integration of highly specific DNA sequences that can perform targeted functions for multiple fields. In this work we present a suite of materials with covalently bound ssDNA to an alginate-based hydrogel for targeted forensic applications. These crosslinked materials not only promote a more stable 3D polymeric network, but also achieve localization of functional ssDNA, a more desirable feature compared to previous DNA encapsulated versions. Specifically, dual amine terminated ssDNA (N-DNA-N) of three different concentrations was bound to alginate using carbodiimide chemistry. Rheological characterization showed that each DNA-crosslinked material forms similar structures, but the higher DNA concentration behaved like a dynamic viscoelastic material. FTIR analysis confirmed the formation of amide bonds, indicative of successful crosslinking between the N-DNA-N and alginate. SEM visualization also showed that each material had distinct topographies, where the covalent crosslinked alginate-DNA materials had more ordered particles and networked structures. We also investigated ssDNA with three different amine functionalities to understand the amine reactivity, which revealed that the N-DNA-N attaches primarily from the terminal primary amines on the DNA strands. From this, microparticles (MPs) using the DNA-crosslinked materials were developed, and the particle morphology and sizes were measured. It was determined that MPs made using DNA-crosslinked materials had larger particle diameters compared to the non-DNA controls, which is ideal for the generation of white blood cell (WBC) mimetics in forensic materials. In addition, these MPs could be successfully processed in a relevant forensic scenario through extraction, amplification, and genotyping, demonstrating the functionality of these materials to forensic blood simulants. | Amanda Orr; Paul Wilson; Theresa Stotesbury | Materials Science; Biological Materials | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632a21640e3c6a33d6220ace/original/dna-crosslinked-alginate-hydrogels-characterization-microparticle-development-and-applications-in-forensic-science.pdf |
673d9919f9980725cfe77b49 | 10.26434/chemrxiv-2024-gw8l0 | Biomimetic Synthesis of Cucurbalsaminone A | Cucurbalsaminones, notable for their unique 5/6/3/6/5-fused pentacyclic triterpenoid structure, are potent inhibitors of P-glycoprotein. In this study, we propose a biosynthetic pathway starting from lanosterol, aiming to elucidate how these types of complex structures are synthesized by nature. Based on that, we present the first synthesis of cucurbalsaminone A in biomimetic fashion. This synthesis emphasizes key steps including oxidative olefin transposition, Lewis acid-mediated sequential migration of Me and H, and the oxa-di-π-methane rearrangement. This work provides valuable insights into synthesis of complex triterpenoid structures which have potential biological applications. | DATTATRAYA DETHE; Chirantan Singha; Salman A. Siddiqui | Organic Chemistry; Natural Products; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673d9919f9980725cfe77b49/original/biomimetic-synthesis-of-cucurbalsaminone-a.pdf |
632b0881ba8a6dae2f577e95 | 10.26434/chemrxiv-2022-9pl01 | Discovery of a Simple Iron Catalyst Reveals the Intimate Steps of C–H Amination to Form C–N Bonds | Formation of ubiquitous C–N bonds traditionally uses prefunctionalized carbon precursors. Recently, metal-catalyzed amination of unfunctionalized C–H bonds with azides has become an attractive and atom-economic strategy for C–N bond formation, though all catalysts contain sophisticated ligands. Here, we report Fe(HMDS)2 (HMDS = –N(SiMe3)2) as an easy-to-prepare catalyst for intramolecular C–H amination. The catalyst shows unprecedented turnover frequencies (110 h–1 vs 70 h–1 reported to date) and requires no additives. Amination is successful for benzylic and aliphatic C–H bonds (>80% yield) and occurs already at room temperature. The catalyst simplicity enabled for the first time comprehensive mechanistic investigations. Kinetic, stoichiometric, and computational studies unveiled the intimate steps of the C–H amination process, including catalyst resting state and turnover-limiting N2 loss of the coordinated azide, The high reactivity of the iron imido intermediate is rationalized by its complex spin system revealing imidyl and nitrene character. | Wowa Stroek; martin albrecht | Catalysis; Homogeneous Catalysis | CC BY 4.0 | CHEMRXIV | 2022-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632b0881ba8a6dae2f577e95/original/discovery-of-a-simple-iron-catalyst-reveals-the-intimate-steps-of-c-h-amination-to-form-c-n-bonds.pdf |
60c73f5c337d6ce8fae26511 | 10.26434/chemrxiv.7326719.v1 | Label-Free Impedimetric Nanoband Sensor for Detection of Both Bovine Viral Diarrhoea Virus (BVDV) and Antibody (BVDAb) in Serum | <p>In veterinary
medicine, diagnostic tools enabling early detection of infectious disease in cattle
could play a pivotal role in the control and eradication of bovine viral
diarrhoea (BVD). Early identification of
cattle persistently infected with bovine viral diarrhoea virus (BVDV) is
critical for early diagnosis and isolation of the animal from a susceptible herd.
The immediate availability of electronic test results to a veterinarian on-farm,
would eliminate the need to submit samples to a commercial laboratory thereby
improving animal therapeutic outcomes considerably. An impedimetric silicon chip-based biosensor
platform, containing six gold nanoband electrodes as six individual sensors,
was developed in this study for detection of BVD disease target molecules.
Gold nanoband electrodes were first coated with an electrodeposited polymer and
then modified with either monoclonal antibodies or Erns protein, for the
subsequent detection of BVD virus and antibodies in whole serum,
respectively. We demonstrate that the
nanoband sensors have sufficient sensitivity and specificity for serological
detection of both targets, with a low time-to-result (20 minutes). All serological samples were benchmarked against,
and in complete agreement with, gold standard commercial ELISA methods.
These initial proof-of-concept findings are of particular significance for
potential on-farm point of use applications, where rapid analysis times and
specificity are required to permit early diagnostics by veterinarians. </p> | Niamh Creedon; Riona sayers; Benjamin O'sullivan; emer kennedy; Pierre Lovera; Alan O'Riordan | Biochemical Analysis; Electrochemical Analysis; Nanodevices; Nanofabrication; Biochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5c337d6ce8fae26511/original/label-free-impedimetric-nanoband-sensor-for-detection-of-both-bovine-viral-diarrhoea-virus-bvdv-and-antibody-bvd-ab-in-serum.pdf |
60c757090f50db06033981be | 10.26434/chemrxiv.14363471.v1 | Hydrothermal Water Enabling One-Pot Transformation of Amines to Alcohols | While the amination of primary alcohols to amines is quite normal, the reverse reaction, deamination of amines to alcohols is rare. Recent advances achieve the transformation by catalytic multistep processes. We report a one-pot method that enables water nucleophilic attack of amines through the unique catalytic role of hydrothermal water. By achieving dehydrogenation of amines or building targeting group, we fulfilled amines transformation by subsequent reduction or direct deamination, which could further link to the utilization of naturally abundant glutamic acid. The method avoids oxidants, catalysts or multistep, thus achieves simple, green and selective transformation of primary amines. | Lanxin Wu; Jiong Cheng; Xiaoguang Wang; Yang Yang | Organic Compounds and Functional Groups | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757090f50db06033981be/original/hydrothermal-water-enabling-one-pot-transformation-of-amines-to-alcohols.pdf |
673f5032f9980725cf51bd1a | 10.26434/chemrxiv-2024-b97rz | A Fully Light-Driven Approach to Separate Carbon Dioxide from Emission Streams | Carbon capture from industrial point sources is an essential component of the global effort to mitigate climate risks. However, traditional approaches require significant energy input—often provided, counterproductively, by fossil fuel combustion. Using sunlight directly as the energy source would significantly improve the energy efficiency of carbon capture processes. Herein, we report the first fully visible light-driven CO2 separation system, in which carbon capture is achieved via the photoenolization/cycloaddition reaction of inexpensive 2-methylbenzophenone with CO2, and CO2 release is realized through an intramolecular photodecarboxylation reaction. This system operates isothermally, works with natural sunlight, and facilitates CO2 removal from natural gas flue emissions, providing a blueprint for other non-thermal chemical separations. | Bayu Ahmad; Kiser Colley; Andrew Musser; Phillip Milner | Organic Chemistry; Earth, Space, and Environmental Chemistry; Photochemistry (Org.); Environmental Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/673f5032f9980725cf51bd1a/original/a-fully-light-driven-approach-to-separate-carbon-dioxide-from-emission-streams.pdf |
64d64be6dfabaf06ff1bb441 | 10.26434/chemrxiv-2023-xdglp | Direct Arylation Polymerization of Degradable Imine-based
Conjugated Polymers | The development and optimization of reliable polymerization methods are needed for the synthesis of degradable
imine-based conjugated polymers, which are attractive materials for transient electronics. Direct arylation polymerization
(DArP) has emerged as a sustainable and atom-economical synthetic method for the preparation of well-defined conjugated
polymers. Compared to polymerization methods such as imine polycondensation or Stille cross-coupling polymerization
which require monomer functionalization, direct arylation proceeds via C-H activation and thereby reduces synthetic complexities
and toxic by-products. Here we report the first use of DArP for the synthesis of an imine-based indacenodithiophene
(IDT) copolymer, p(IDT-TIT). Polymers prepared via DArP can result in branched or cross-linked polymer chains due to the
reactivity of C-H bonds in the monomers. In this report, we demonstrate a systematic study focusing on the reaction conditions
needed to prepare p(IDT-TIT) via DArP with tetramethylethylenediamine as a co-ligand. The degradable polymer is
characterized via nuclear magnetic resonance spectroscopy, high-temperature gel permeation chromatography, and ultraviolet-
visible-near-infrared spectroscopy. With the simplicity of monomer preparation and reaction conditions, we anticipate
this efficient synthetic protocol will lead to higher synthetic adoption in the research community to aid the exploration of
high-performance imine-based degradable materials. | Nathan Sung Yuan Hsu; Angela Lin; Azalea Uva; Shine Huang; Helen Tran | Polymer Science; Conducting polymers; Polymerization (Polymers); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64d64be6dfabaf06ff1bb441/original/direct-arylation-polymerization-of-degradable-imine-based-conjugated-polymers.pdf |
60c742290f50db2209395c51 | 10.26434/chemrxiv.8224148.v1 | Chemical Synthesis of (+)-Brevianamide a Supports a Diels–Alderase-Free Biosynthesis | <div>
<div>
<div>
<p>The fungal-derived bicyclo[2.2.2]diazaoctane alkaloids are of significant interest to the
scientific community for their potent and varied biological activities. Within this large
and diverse family of natural products the insecticidal metabolite (+)-brevianamide A is
particularly noteworthy for its synthetic intractability and inexplicable biogenesis.
Despite five decades of research, this alkaloid has never succumbed to chemical
synthesis. It has been suggested that a proposed Diels–Alder reaction in the biosynthesis
of (+)-brevianamide A requires a Diels–Alderase enzyme. We herein report the first
chemical synthesis of (+)-brevianamide A (7 steps, 8.0% overall yield, 750 mg scale),
which provides compelling evidence in support of a Diels–Alderase-free biosynthesis; a
significant departure from the established biosynthesis of related alkaloids.
</p>
</div>
</div>
</div> | Robert Godfrey; Nicholas Green; Gary Nichol; Andrew Lawrence | Bioorganic Chemistry; Natural Products; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c742290f50db2209395c51/original/chemical-synthesis-of-brevianamide-a-supports-a-diels-alderase-free-biosynthesis.pdf |
60c743fb702a9b50dc18a723 | 10.26434/chemrxiv.8061839.v2 | Tuning the Magnetic Alignment of Cellulose Nanocrystals from Perpendicular to Parallel Using Lepidocrocite Nanoparticles | The magnetic alignment of cellulose nanocrystals (CNC) and lepidocrocite nanorods (LpN), pristine and in hybrid suspensions has been investigated using contrast-matched small-angle neutron scattering (SANS) under in situ magnetic fields (0 – 6.8 T) and polarized optical microscopy. The pristine CNC (diamagnetic) and pristine LpN (paramagnetic) align perpendicular and parallel to the direction of field, respectively. The alignment of both the nanoparticles in their hybrid suspensions depends on the relative amount of the two components (CNC and LpN) and strength of the applied magnetic field. In the presence of 10 wt% LpN and fields < 1.0 T, the CNC align parallel to the field. In the hybrid containing lower amount of LpN (1 wt%), the ordering of CNC is partially frustrated in all range of magnetic field. At the same time, the LpN shows both perpendicular and parallel orientation, in the presence of CNC. This study highlights that the natural perpendicular ordering of CNC can be switched to parallel by weak magnetic fields and the incorporation of paramagnetic nanoparticle as LpN, as well it gives a method to influence the orientation of LpN.<br /> | Valentina Guccini; Sugam Kumar; Yulia Trushkina; Gergely Nagy; Christina Schütz; Germán Salazar-Alvarez | Magnetic Materials; Nanostructured Materials - Nanoscience; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743fb702a9b50dc18a723/original/tuning-the-magnetic-alignment-of-cellulose-nanocrystals-from-perpendicular-to-parallel-using-lepidocrocite-nanoparticles.pdf |
67a91838fa469535b9aacc4c | 10.26434/chemrxiv-2024-0xd0x-v4 | Organozinc reagents in solution: insights from ab initio molecular dynamics and X-ray absorption spectroscopy | Organozinc reagents play a critical role in synthesis, yet our comprehension of their structure-reactivity relationships is limited by a lack of information about their structures in solution. This study introduces a computational workflow, validated by X-ray absorption spectroscopy, to investigate organozinc reagents in solution. The solvation states of ZnCl2, ZnMeCl and ZnMe2 were explored using ab initio molecular dynamics (metadynamics and Blue Moon sampling) within an explicit solvent cage. The study revealed the existence of various solvation states at room temperature, providing clarity on the previously debated structure of ZnMe2 in THF solution. These findings were confirmed by near- edge X-ray absorption spectroscopy (XANES) interpreted using time-dependent density functional theory (TD-DFT) calculations. | Jordan RIO; Quentin PESSEMESSE; Michele CASCELLA; Pierre-Adrien PAYARD; Marie-Eve L. PERRIN | Theoretical and Computational Chemistry; Analytical Chemistry; Organometallic Chemistry; Computational Chemistry and Modeling; Main Group Chemistry (Organomet.); Spectroscopy (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a91838fa469535b9aacc4c/original/organozinc-reagents-in-solution-insights-from-ab-initio-molecular-dynamics-and-x-ray-absorption-spectroscopy.pdf |
60d443b7fca4905c94c8d670 | 10.26434/chemrxiv-2021-05zhj | Structural requirements for photo-induced RNA-protein cross-linking | Understanding structure-function relationships of RNA-binding proteins requires knowledge of how they bind RNAs in vivo. RNA-protein interactions are studied using light-induced cross-linking at “zero-distance”, yielding nucleotide/amino-acid adducts for mass-spectrometry (MS)-based characterization. However, prerequisites for cross-linking are poorly understood, limiting interpretation of cross-linking data. Here, we report novel insights on cross-linking requirements from studying RBFOX-RRM domain bound to 13C-labeled variants of its heptaribonucleotide binding element as a model. We probed the influence of nucleotide identity, sequence position and amino-acid composition using tandem-MS to assign cross-links at site-specific resolution. We observed cross-linking at three nucleotides, which were stacked onto phenylalanines. Surprisingly, this stacking was required for neighbouring amino-acids to cross-link, and is apparent in published RNA-protein datasets. We hypothesize that π-stacking activates cross-linking via electron transfer, whereafter nucleotide- and peptide radicals, possibly stabilized by capto-dative effects, recombine. These findings should facilitate interpretation of cross-linking data from structural studies and genome-wide datasets. | Anna Knörlein; Chris Sarnowski; Tebbe de Vries; Moritz Stoltz; Michael Götze; Ruedi Aebersold; Frédéric Allain; Alexander Leitner; Jonathan Hall | Biological and Medicinal Chemistry; Chemical Biology | CC BY 4.0 | CHEMRXIV | 2021-06-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60d443b7fca4905c94c8d670/original/structural-requirements-for-photo-induced-rna-protein-cross-linking.pdf |
612f944866dedd1780013640 | 10.26434/chemrxiv-2021-773t6-v2 | Development of Specially Reinforced Magnesium Composites Prepared by Squeeze Casting Process | A wide range of opportunities in the field of automotive and structural applications are being offered by Magnesium matrix composites because of their enhanced mechanical properties. Magnesium alloys based Metal Matrix Composites (MMCs) are the best candidates for lightweight structural applications due to their improved creep properties. In the present study, three specimens of specially reinforced magnesium composites were manufactured by using the squeeze casting process. Specimen 1 has a composition of 7 % aluminum alloy in addition to 1% zinc and the composition of reinforcement is Titanium Carbide 0.3 % in addition to 1.5% Carbon nanotubes. Specimen 2 has a composition of 12 % aluminum alloy in addition to 1 % zinc and the composition of reinforcement is 2% B_4 C in addition to 2 % Carbon nanotubes. Specimen 3 has a composition of 14 % aluminum alloy in addition to 1 % zinc and the composition of reinforcement is 2 % B_4 C in addition to 2 % Carbon nanotubes. The mechanical properties analysis showed that specimen 2 has a higher hardness value in comparison to other manufactured specimens and it was also observed that specimen 2 possesses a higher tensile strength value in comparison to the other two specimens. Microstructure analysis shows that there was a uniform distribution of the reinforcements in the matrix. So it can be inferred that this uniform distribution causes higher hardness and higher tensile strength in the manufactured specimens. | Akshansh Mishra; Devarrishi Dixit; Raheem Al-Sabur | Materials Science; Composites | CC BY NC 4.0 | CHEMRXIV | 2021-09-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/612f944866dedd1780013640/original/development-of-specially-reinforced-magnesium-composites-prepared-by-squeeze-casting-process.pdf |
6668425112188379d8d83bb5 | 10.26434/chemrxiv-2024-f301n | Polyhydroxy Fullerene, Fullerol, Fullerenol or Polyoxy Fullerene? A Combined Experimental and Theoretical Interrogation | Hydroxylated fullerenes have gained attention for their broad range of applications ranging from laser activated transformations to healthspan extension. However, hydroxylated fullerenes are often assumed to contain only hydroxyl groups appended to fullerene cage and lack sufficient characterization. Previous attempts at using theoretical quantum chemical calculations to predict the vibrational spectrum of C60(OH)X has failed to reproduce experimental FTIR peaks. Here, we use density functional theory calculations to predict the vibrational spectra of a model C60(OH)12 molecule with systematic replacement of hydroxyl groups with carbonyl, and hemiketal groups. We demonstrate the role of charge and counterions on calculated vibrational spectrum and develop a combined model to accurately predict FTIR peaks. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. | Yue Xu; Martina Stella; Stefan Knecht; Fabijan Pavosevic; Vijay Krishna | Theoretical and Computational Chemistry; Analytical Chemistry; Nanoscience; Spectroscopy (Anal. Chem.); Nanostructured Materials - Nanoscience; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6668425112188379d8d83bb5/original/polyhydroxy-fullerene-fullerol-fullerenol-or-polyoxy-fullerene-a-combined-experimental-and-theoretical-interrogation.pdf |
632b7026fee74e4492454476 | 10.26434/chemrxiv-2022-r3w01-v2 | In situ Study of Au Nanoparticle Growth in a Mechanochemical-Aging-Based Synthesis | As we strive to perform chemical transformations in a more sustainable fashion, inducing reactions through the absorption of mechanical energy has emerged as a highly successful approach. Due to the wide-ranging applications of gold nanoparticles (AuNPs), mechanochemical strategies have already been employed for their synthesis. However, we do not yet fully understand the underlying processes surrounding the gold salt reduction, nucleation and growth of AuNPs in the solid state. Herein, we present a mechanically activated aging synthesis of AuNPs, through a solid-state Turkevich reaction. Solid reactants are only briefly exposed to mechanical energy before being aged statically for a period of six weeks at different temperatures. The aging step grants a greater period of time to analyze the initial reduction and subsequent nanoparticle formation processes. During the aging period the reaction was monitored using a combination of X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) to gain meaningful insights into the solid-state formation of gold nanoparticles. | Austin Richard; Michael Ferguson; Blaine Fiss; Hatem Titi; Jesus Valdez; Nikolas Provatas; Tomislav Friscic; Audrey Moores | Materials Science; Inorganic Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Solid State Chemistry; Supramolecular Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632b7026fee74e4492454476/original/in-situ-study-of-au-nanoparticle-growth-in-a-mechanochemical-aging-based-synthesis.pdf |
67c9436381d2151a024942eb | 10.26434/chemrxiv-2024-2s6kk-v3 | A Rapid-heating Copper Block Reactor System for Improved Isothermal Kinetics of Polyethylene Pyrolysis | Developing continuous-flow pyrolysis reactor systems is essential to meet the increasing demand for plastic pyrolysis oil. Most literature polymer pyrolysis kinetic studies use non-isothermal thermal gravimetric (TG) equipment or batch systems. Most systems are characterized by having a prolonged heating times which may lead to a significant polymer conversion before reaching the isothermal temperature, affecting the kinetic measurements. We present a novel, affordable, copper-block semi-batch reactor system that reaches the desired reaction temperature in less than four minutes. Through simulation, we demonstrate the superiority of this system over the commonly used stainless-steel reactors. We utilized this system to measure the isothermal kinetics of PE pyrolysis at temperatures between 411 and 449 °C. Employing a discrete lump methodology, we identified a five-lump reaction model: three polymer chains with descending molecular weights (S1, S2, S3), liquid (L), and gas (G), with reactions progressing in series and then in parallel. The initial decomposition steps exhibited similar activation energies of 360±17 and 357±06 kJ/mol, indicating that molecular weight has little effect on the initial PE pyrolysis rate. The parallel paths producing liquid and gas had activation energies of 288±02 and 179±13 kJ/mol. The proposed system facilitates accurate isothermal kinetic data measurement, enabling the design of improved continuous-flow reactor systems for plastics pyrolysis, ultimately contributing to global sustainability goals. | Abdulrahman Alzailaie; Ibrahim Alshankiti; Mohammed Babkoor; Jason Loiland; Robert Schucker | Chemical Engineering and Industrial Chemistry; Reaction Engineering | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c9436381d2151a024942eb/original/a-rapid-heating-copper-block-reactor-system-for-improved-isothermal-kinetics-of-polyethylene-pyrolysis.pdf |
60c7422c469df4ed1bf42f5e | 10.26434/chemrxiv.8241107.v1 | Ultra-High to Ultra-Low Drug Loaded Micelles: Probing Host-Guest Interactions by Fluorescence Spectroscopy | Polymer micelles are an attractive means to solubilize water insoluble compounds such as drugs. Drug loading, formulations stability and control over drug release are crucial factors for drug loaded polymer micelles. The interactions between the polymeric host and the guest molecules are considered critical to control these factors but typically barely understood. Here, we compare two isomeric polymer micelles, one of which enables ultra-high curcumin loading exceeding 50 wt.%, while the other only allows a drug loading of only 25 wt.%. In the low capacity micelles, steady-state fluorescence revealed a very unusual feature of curcumin fluorescence, a high energy emission at 510 nm. Time-resolved fluorescence upconversion showed that the fluorescence life time of the corresponding species is too short in the high-capacity micelles, preventing an observable emission in steady-state. Therefore, contrary to common perception, stronger interactions between host and guest can be detrimental to the drug loading in polymer micelles. | Michael M Lübtow; Henning Marciniak; Alexander Schmiedel; Markus Roos; Christoph Lambert; Robert Luxenhofer | Drug delivery systems; Organic Polymers; Spectroscopy (Anal. Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7422c469df4ed1bf42f5e/original/ultra-high-to-ultra-low-drug-loaded-micelles-probing-host-guest-interactions-by-fluorescence-spectroscopy.pdf |
60c74fafee301c8425c7a732 | 10.26434/chemrxiv.12931445.v1 | A Concise Route to MK-4482 (EIDD-2801) from Cytidine: Part 2 | A new route to MK-4482 (<b>1</b>) was developed. The route
replaces uridine with the more available and less expensive cytidine. Low cost, simple reagents are used for the
chemical transformations and the yield is improved from 17% to 44%. A step is removed from the longest linear
sequence, and these advancements are expected to expand access to MK-4482
should it become a viable drug substance. | Vijayagopal Gopalsamuthiram; Corshai Williams; Jeffrey Noble; Timothy F. Jamison; B. Frank Gupton; David Snead | Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Process Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fafee301c8425c7a732/original/a-concise-route-to-mk-4482-eidd-2801-from-cytidine-part-2.pdf |
64b6a128ae3d1a7b0deb8f3c | 10.26434/chemrxiv-2023-zxldx | Convergence of Time-Derivative Non-Adiabatic Couplings in Plane-Wave DFT Calculations | Accurate prediction of charge carrier relaxation rates is essential to design molecules and materials with the desired photochemical properties for applications like photocatalysis and solar energy conversion. Non-adiabatic molecular dynamics allows one to simulate the relaxation process of excited charge carriers. Plane-wave density functional theory (DFT) calculations make the time-derivative non-adiabatic couplings (TNACs) simple to compute because the basis is independent of the atomic positions. However, the effect of the kinetic energy cutoff for the plane-wave basis on the accuracy of the dynamics has not been studied. Here, we examine the effect of the kinetic energy cutoff on the TNACs and decay time scales for the prototypical model system of tetracene. These calculations show that the choice of kinetic energy cutoff can change the relaxation time by up to 30%. The relaxation times of states that have small TNACs to other states or are far from degenerate are more sensitive to the kinetic energy cutoff than those of states with large TNACs or near degeneracies. A kinetic energy cutoff of 60 Ry is sufficient for all states to reach qualitative agreement (absolute error < 10%) our reference decay time with our 110 Ry reference data, and a cutoff of 80 Ry is required for all states to reach quantitative agreement (absolute error < 2%). | Alva Dillon; Rebecca Gieseking | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Photochemistry (Physical Chem.); Quantum Mechanics | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b6a128ae3d1a7b0deb8f3c/original/convergence-of-time-derivative-non-adiabatic-couplings-in-plane-wave-dft-calculations.pdf |
62bf071e25302151b8862423 | 10.26434/chemrxiv-2022-w2lhd | Enzyme-Graphene Nanometal biohybrid Architectures as Highly Efficient Multifunctional Catalysts for Cascade Reactions | The development of new catalytic systems with different chemo- and biocatalytic functionalities for sustainable one-pot multistep transformations represents a big challenge in modern chemistry. Here, we have designed and synthesized novel enzyme-graphene nanometal hybrids of palladium and copper as multiactive heterogeneous catalysts. The in-situ formation of metallic nanoparticles of different size and species on enzymes (C. antartica lipase, CALB and and T. lanuginosus lipase), TLL) immobilized on multilayer graphene-anchored enzymes (G@CALB and G@TLL preparations) at room temperature and aqueous media allowed to create different kind of enzyme-metal nanoarchitectures, containing up to two enzymes and metallic nanoparticles of two different metals in the same compartment. The metallic nanoparticles were synthesized exclusively induced by the enzyme, homogeneously distributed on the enzymatic structure used as scaffold. The cooperative and synergistic participation of different chemo and biocatalytic components in the reduction process and especially in different cascade reactions was demonstrated. Domino cascade in aqueous media (enzymatic hydrolysis, metal reduction, and metal oxidation) was successfully performed from the different hybrid systems. The synthesis of glycoderivatives, transforming selectively peracetylated glucal to novel disaccharides, using G@CALB-Cu3(PO4)2NPs and G@CALB-Cu(0)NPs or α-peracetylated glucose to diacetyl-gluconic acid by G@TLL@CRL-Cu3(PO4)2NPs was successfully performed. Finally, the successful application in the dynamic kinetic resolution of racemic arylamine (>99% conversion and ee) in organic solvent catalyzed by G@CALB-Pd(0)NPs-Cu3(PO4)2NPs demonstrated the potential effect in synthetic chemistry, and the synergistic effect of catalysis between enzyme and metals. Furthermore, recycling studies demonstrated the high robustness of them. | Noelia Losada-Garcia; Esteban Urriolabeitia; Jose M. Palomo | Catalysis; Nanoscience; Nanocatalysis - Catalysts & Materials; Biocatalysis; Heterogeneous Catalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62bf071e25302151b8862423/original/enzyme-graphene-nanometal-biohybrid-architectures-as-highly-efficient-multifunctional-catalysts-for-cascade-reactions.pdf |
668a79b95101a2ffa8a6c39f | 10.26434/chemrxiv-2024-7bbmh | Sustainable, precious metal-free C-N cross coupling through photocatalysis | Photoredox catalysis has evolved out as one of the sustainable ways of constructing C-N bond. Herein, reported a visible-light organic photoredox catalyzed method that enables C-N cross coupling under mild and sustainable reaction condition. This catalytic system worked for both activated, unactivated amines and electron rich or deficient aryl bromides with broad range of functional group tolerance in good to excellent yields. The noteworthy aspects, milder reaction condition at room temperature without addition of any additional ligand make the procedure attractive. | Mohammad Hassam; Samuel Mamidipalli; Akhila Ailaveni; Pankaj Kumar Singh; Shambabu Joseph Maddirala | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Photochemistry (Org.); Photocatalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668a79b95101a2ffa8a6c39f/original/sustainable-precious-metal-free-c-n-cross-coupling-through-photocatalysis.pdf |
6740e3885a82cea2fa709bc3 | 10.26434/chemrxiv-2024-2hg7l | Exploring Atom-Pairwise and Many-Body Dispersion Corrections for the BEEF-vdW Functional | The Bayesian error estimation functional (BEEF-vdW) is widely used in surface science and catalysis, because it provides a balanced description of molecular, surface and solid state systems, along with reliable error estimates. However, the nonlocal van-der-Waals density functional (vdW-DF2) employed in BEEF-vdW {can be computationally costly and displays relatively low accuracy for molecular systems.} Therefore, this work explores whether atom-pairwise and many-body dispersion treatments represent viable alternatives to using the vdW-DF2 functional with BEEF-vdW. To this end, we investigate the performance of commonly used atom-pairwise corrections (\emph{i.e.} the Tkatchenko-Scheffler, TS, and the exchange-hole dipole moment, XDM, approaches) and many-body dispersion (MBD) treatments for molecular, surface and solid-state systems. The results indicate that atom pairwise methods such as TS and particularly XDM provide a good balance of cost and accuracy across all systems. | Elisabeth Keller; Volker Blum; Karsten Reuter; Johannes T. Margraf | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6740e3885a82cea2fa709bc3/original/exploring-atom-pairwise-and-many-body-dispersion-corrections-for-the-beef-vd-w-functional.pdf |
60c74fae4c8919e7a2ad3c22 | 10.26434/chemrxiv.12931226.v1 | A Quantitative Evaluation of Computational Methods to Accelerate the Study of Alloxazine-Derived Electroactive Compounds for Energy Storage | Alloxazines are a promising class of organic electroactive molecules for application in aqueous redox flow batteries. Preliminary studies show that structural modifications of alloxazines with electron-donating and/or -withdrawing functional groups help in tuning of their redox properties. High-throughput computational screening enables rational and time-efficient discovery of functional compounds. The effectiveness of high-throughput computational screening efforts is strongly dependent on the accuracy and speed at which the performance descriptors are estimated for a large pool of candidate compounds. Here, we performed a quantitative study to assess the performance of computational methods, including the forcefield based molecular mechanics, semi-empirical quantum mechanics, density functional based tight binding, and density functional theory, on the basis of their accuracy and computational cost in predicting the redox potentials of electroactive alloxazines. We compared the performances of various energy-based descriptors, including the redox reaction energy and the frontier orbital energies of the reactant and product molecules. We found that the lowest unoccupied molecular orbital energy of the reactant molecules is the best performing descriptor for the alloxazines, which is in contrast to other classes of molecules, such as quinones that we reported earlier. Importantly, we present a flexible<i> in silico</i> approach to accelerate both the singly and the high-throughput computational screening studies, therewithal considering the level of accuracy <i>vs</i> measured electrochemical data, that is principally applicable for the discovery of efficient, alloxazine-derived organic compounds for energy storage in aqueous redox flow batteries. | Qi Zhang; Abhishek Khetan; Süleyman Er | Energy Storage; Fuels - Energy Science | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fae4c8919e7a2ad3c22/original/a-quantitative-evaluation-of-computational-methods-to-accelerate-the-study-of-alloxazine-derived-electroactive-compounds-for-energy-storage.pdf |
629a123fd18cdf0a0e4dd0ff | 10.26434/chemrxiv-2022-jl00l-v2 | Effect of Surface Roughness of Carbon Nanotube-based Catalyst Layer for Polymer Electrolyte Membrane Fuel Cell Performance | The effect of surface roughness of the catalyst layer (CL) based on carbon-nanotube (CNTs) in contact with polymer electrolyte membrane (PEM) in polymer electrolyte membrane fuel cell (PEMFC) was studied. The surface roughness of vacuum-filtrated CL sheets were evaluated using laser microscope and the surface of CL sheet contacting the filter membrane was found to be smoother compared to the surface exposed to the air. When a smoother surface of the CL sheet was laminated with PEM to fabricate membrane-electrode-assembly (MEA), power density of the single cell was 604.6 mW cm-2 at 80 °C under 100%R.H., which was greater than the MEA having a rougher CL surface (542.4 mW cm-2). | Tsuyohiko Fujigaya; Yin Kan Phua; Don Terrence Weerathunga; Dan Wu; Chaerin Kim; Samindi Jayawickrama; Naoki Tanaka | Catalysis; Energy; Electrocatalysis; Fuel Cells; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629a123fd18cdf0a0e4dd0ff/original/effect-of-surface-roughness-of-carbon-nanotube-based-catalyst-layer-for-polymer-electrolyte-membrane-fuel-cell-performance.pdf |
64a76e9d6e1c4c986bf0f88b | 10.26434/chemrxiv-2023-jvfqq | Designing electrodes and electrolytes for batteries by leveraging deep learning | High-performance batteries are poised for electrification of vehicles and therefore mitigate greenhouse gas emissions, which, in turn, promote a sustainable future. However, the design of optimized batteries is challenging due to the nonlinear governing physics and electrochemistry. Recent advancements have demonstrated the potential of deep learning techniques in efficiently designing batteries, particularly in optimizing electrodes and electrolytes. This review provides comprehensive concepts and principles of deep learning and its application in solving battery-related electrochemical problems, which bridges the gap between artificial intelligence and electrochemistry. We also examine the potential challenges and opportunities associated with different deep learning approaches, tailoring them to specific battery requirements. Ultimately, we aim to inspire future advancements in both fundamental scientific understanding and practical engineering in the field of battery technology. Furthermore, we highlight the potential challenges and opportunities for different deep learning methods according to the specific battery demand to inspire future advancement in fundamental science and practical engineering. | Chenxi Sui; Ziyang Jiang; Genesis Higueros; David Carlson; Po-Chun Hsu | Theoretical and Computational Chemistry; Materials Science; Energy | CC BY 4.0 | CHEMRXIV | 2023-07-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64a76e9d6e1c4c986bf0f88b/original/designing-electrodes-and-electrolytes-for-batteries-by-leveraging-deep-learning.pdf |
60c74d6ff96a00111c287939 | 10.26434/chemrxiv.12616793.v1 | In Operando Detection of the Physical Properties Change of the Interfacial Electrolyte during Li-Metal Electrode Reaction by Atomic Force Microscopy | This manuscript propose the operando detection technique of the physical properties change of electrolyte during Li-metal battery operation.The physical properties of electrolyte solution such as viscosity (η) and mass densities (ρ) highly affect the feature of electrochemical Li-metal deposition on the Li-metal electrode surface. Therefore, the operando technique for detection these properties change near the electrode surface is highly needed to investigate the true reaction of Li-metal electrode. Here, this study proved that one of the atomic force microscopy based analysis, energy dissipation analysis of cantilever during force curve motion, was really promising for the direct investigation of that. The solution drag of electrolyte, which is controlled by the physical properties, is directly concern the energy dissipation of cantilever motion. In the experiment, increasing the energy dissipation was really observed during the Li-metal dissolution (discharge) reaction, understanding as the increment of η and ρ of electrolyte via increasing of Li-ion concentration. Further, the dissipation energy change was well synchronized to the charge-discharge reaction of Li-metal electrode.This study is the first report for direct observation of the physical properties change of electrolyte on Li-metal electrode reaction, and proposed technique should be widely interesting to the basic interfacial electrochemistry, fundamental researches of solid-liquid interface, as well as the battery researches. | Mitsunori Kitta | Electrochemical Analysis; Microscopy; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74d6ff96a00111c287939/original/in-operando-detection-of-the-physical-properties-change-of-the-interfacial-electrolyte-during-li-metal-electrode-reaction-by-atomic-force-microscopy.pdf |
60c73ec0bb8c1a72ca3d998d | 10.26434/chemrxiv.7090526.v1 | Structure, Synthesis of Hierridin C and Discovery of Prevalent Alkylresorcinol Biosynthesis in Picocyanobacteria | Small, single-celled planktonic cyanobacteria are ubiquitous in the world’s oceans yet tend not to to be perceived as biosynthetically-prolific organisms. Here we report the isolation and structure elucidation of hierridin C, an antiplasmodial halogenated alkylresorcinol produced in very low amounts by the picocyanobacterium <i>Cyanobium</i>sp. LEGE 06113. We describe a simple, straightforward synthetic route to the scarcely-produced hierridins that relies on a key, highly regioselective halogenation step. In addition, we show that these compounds originate from a type III PKS pathway and that similar biosynthetic gene clusters are found in a variety of bacterial genomes, most notably those of the globally-distributed picocyanobacteria genera <i>Prochlorococcus</i>, <i>Cyanobium</i>and <i>Synechococcus</i>. | Margarida Costa; Ivo E. Sampaio-Dias; Raquel Castelo-Branco; Hugo Scharfenstein; Roberta Rezende de Castro; Artur Silva; Maria Paula Cruz Schneider; Maria João Araújo; Rosário Martins; Valentina F. Domingues; Fatima Nogueira; Vera Camões; Vitor M. Vasconcelos; Pedro Leao | Natural Products; Biochemistry; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2018-09-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73ec0bb8c1a72ca3d998d/original/structure-synthesis-of-hierridin-c-and-discovery-of-prevalent-alkylresorcinol-biosynthesis-in-picocyanobacteria.pdf |
65333accc3693ca993c4ce95 | 10.26434/chemrxiv-2023-949dk | A multiple-fidelity Method for Accurate Simulation of MoS 2 Properties Using JAX-ReaxFF and Neural Network Potentials | Reactive force field (ReaxFF) is one of the most commonly used force field to model the chemical reactions on atomic level. Recently, JAX-ReaxFF, combined with auto- matic differentiation, has been used to efficiently parameterize ReaxFF. However, pre- dicted properties using parameterized ReaxFF may be inaccurate due to the inductive bias of its analytical formula. While neural network-based potentials (NNPs) trained on density functional theory (DFT)-labeled data offer a more accurate method, it re- quires a large amount of training data to be trained from scratch. To overcome these issues, we present a multiple-fidelity method that combines JAX-ReaxFF and NNP, and apply the method on MoS 2 , a promising two-dimensional (2D) semiconductor for flexible electronics due to its excellent mechanical, optical, and electronic properties. By optimizing ReaxFF for MoS 2 and incorporating implicit prior physical information in the functional forms, we show that ReaxFF can serve as a cost-effective way to generate pretraining data, facilitating more accurate simulations of MoS 2 properties, such as the convex hull diagram, sulfur vacancy formation, and interaction with S 8 using SchNet. Moreover, in the Mo-S-H multi-element system, the pretraining strat- egy can reduce root-mean-square errors(RMSE) of energy by 20%. This approach can be extended to a wide variety of material systems, accelerating their computational research. | Kehan Wang; Longkun Xu; Wei Shao; Haishun Jin; Qiang Wang; Ming Ma | Materials Science | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65333accc3693ca993c4ce95/original/a-multiple-fidelity-method-for-accurate-simulation-of-mo-s-2-properties-using-jax-reax-ff-and-neural-network-potentials.pdf |
66bc60d820ac769e5f8b8d24 | 10.26434/chemrxiv-2024-zscz6 | Harnessing competitive interactions to regulate supramolecular “micelle-droplet-fiber” transition and reversibility in water | Supramolecular assembly of proteins into irreversible fibrils is often associated with diseases where aberrant phase transitions occur. Due to the complexity of biological systems and their surrounding environments, the mechanism underlying phase separation-mediated supramolecular assembly is poorly understood, making the reversal of so-called irreversible fibrillization a significant challenge. Therefore, it is crucial to develop simple model systems that provide insights into the mechanistic process of monomers to phase-separated droplets to ordered supramolecular assemblies. Such models can help in investigating strategies to either reverse or modulate these states. Herein, we present a simple synthetic model system composed of three components, including a benzene-1,3,5-tricarboxamide-based supramolecular monomer, a surfactant, and water, to mimic the condensate pathway observed in biological systems. This highly dynamic system can undergo “micelle-droplet-fiber” transition over time and space with a gradient field, regulated by competitive interactions. Importantly, manipulating these competitive interactions through guest molecules, temperature changes, and co-solvent can reverse the ordered fibers back into a disordered liquid or micellar state. Our model system provides new insights into the critical balance between various interactions among the three components that determine the pathway and reversibility of the process. Extending this ‘competitive-interactions’ approach from a simple model system to complex macromolecules, e.g., proteins, could open new avenues for biomedical applications, such as condensate-modifying therapeutics. | Heleen Duijs; Shikha Dhiman; Lu Su | Polymer Science; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66bc60d820ac769e5f8b8d24/original/harnessing-competitive-interactions-to-regulate-supramolecular-micelle-droplet-fiber-transition-and-reversibility-in-water.pdf |
60c758d9842e654ea3db48ef | 10.26434/chemrxiv.14579259.v1 | In Situ Probing Potassium-ion Intercalation-induced Amorphization in Crystalline Iron Phosphate Cathode Materials | <p>Na-ion and K-ion batteries are promising alternatives for large-scale energy storage applications due to their abundancy and lower cost. However, designing an electrode structure to reversibly accommodate these large alkali-ions is the remaining challenge before their commercialization. Intercalation of these large ions could cause irreversible structural deformations and amorphization in the crystalline electrodes. The designing of new amorphous electrodes is another route to develop electrodes to store these ions reversibly. Lack of understanding of dynamic changes in the amorphous nanostructures during battery operation is the bottleneck for further developments. Here, we report the utilization of in situ digital image correlation and in-operando X-ray diffraction (XRD) techniques to probe dynamic changes in the amorphous phase of iron phosphate during potassium intercalation. In-operando XRD demonstrates amorphization in the electrode’s nanostructure during the first charge / discharge cycle. In situ strain analysis detects the reversible deformations associated with redox reactions in the amorphous phases. This method offers new insights to study mechanics of ion intercalation in the amorphous nanostructures.</p> | bertan ozdogru; Younghwan Cha; Vijay Murugesan; Min-Kyu Song; ozgur capraz | Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758d9842e654ea3db48ef/original/in-situ-probing-potassium-ion-intercalation-induced-amorphization-in-crystalline-iron-phosphate-cathode-materials.pdf |
60c752514c89192194ad40f2 | 10.26434/chemrxiv.13285712.v1 | Measuring the Concentration of Protein Nanoparticles Synthesized by Desolvation Method: Comparison of Bradford Assay, BCA Assay, hydrolysis/UV Spectroscopy and Gravimetric Analysis | Research paper on sunthesis of protein nanoparticles<div><br /><div><b>Abstract</b></div><div>The desolvation
technique is one of the most popular methods for preparing protein
nanoparticles for medicine, biotechnology, and food applications. We fabricated
11 batches of BSA nanoparticles and 2 batches of gelatin nanoparticles by
desolvation method. BSA nanoparticles from 2 batches were cross-linked by
heating at +70 °C for 2 h; other nanoparticles were stabilized by
glutaraldehyde. We compared several analytical approaches to measuring their
concentration: gravimetric analysis, bicinchoninic acid assay, Bradford assay,
and alkaline hydrolysis combined with UV spectroscopy. We revealed that the
cross-linking degree and method of cross-linking affect both Bradford and BCA
assay. Direct measurement of protein concentration in the suspension of purified
nanoparticles by dye-binding assays can lead to significant (up to 50-60%)
underestimation of nanoparticle concentration. Quantification of non-desolvated
protein (indirect method) is affected by the presence of small nanoparticles in
supernatants and can be inaccurate when the yield of desolvation is low. The
reaction of cross-linker with protein changes UV absorbance of the latter.
Therefore pure protein solution is an inappropriate calibrator when applying UV
spectroscopy for the determination of nanoparticle concentration. Our
recommendation is to determine the concentration of protein nanoparticles by at
least two different methods, including gravimetric analysis.<div><br /></div></div></div> | Pavel Khramtsov; Tatyana Kalashnikova; Maria Bochkova; Maria Kropaneva; Valeria Timganova; Svetlana A. Zamorina; Mikhail B. Rayev | Biodegradable Materials; Biopolymers; Drug delivery systems; Nanostructured Materials - Nanoscience; Bioengineering and Biotechnology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752514c89192194ad40f2/original/measuring-the-concentration-of-protein-nanoparticles-synthesized-by-desolvation-method-comparison-of-bradford-assay-bca-assay-hydrolysis-uv-spectroscopy-and-gravimetric-analysis.pdf |
678c2e176dde43c9081b2c87 | 10.26434/chemrxiv-2025-dbzgk | Photocatalytic Hydrophosphination Using Calcium Precatalysts | Hydrophosphination using calcium compounds as catalysts under irradiation is described as a foray into s-block photocatalysis. Transition-metal compounds have been highly successful hydrophosphination catalysts under photochemical conditions, utilizing substrates previously considered inaccessible. A calcium hydrophosphination precatalyst, Ca(nacnac)(THF)(N(SiMe3)2) (1, nacnac = HC[(C(Me)N-2,6-iPr2C6H3)]2), reported by Barrett and Hill, as well as the presumed intermediate, Ca(nacnac)(THF)(PPh2) (2), and the Schlenk equilibrium product, Ca[N(SiMe3)2]2(THF)2 (3) were screened under photochemical conditions with a range of unsaturated substrates including styrenic alkenes, Michael acceptors, and dienes with modest to excellent conversions, though unactivated alkenes were in accessible. All compounds exhibit enhanced catalysis under irradiation by LED-generated blue light. Nacnac-supported compounds generate radicals as evidenced by EPR spectroscopy and radical trapping reactions, whereas unsupported calcium compounds are EPR silent and appear to undergo insertion-based hydrophosphination akin to thermal reactions based. These results buttress the notion that photoactivation of -basic ligands is a broad phenomenon, extending beyond the d-block, but like d-block metals, consideration of ancillary ligands is essential to avoid radical reactivity. | Moniruzzaman Moniruzzaman; Nai-Yuan Jheng; Rory Waterman | Inorganic Chemistry; Catalysis; Organometallic Chemistry; Photocatalysis; Main Group Chemistry (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678c2e176dde43c9081b2c87/original/photocatalytic-hydrophosphination-using-calcium-precatalysts.pdf |
60c74dc3bdbb891ca7a39a56 | 10.26434/chemrxiv.12661502.v1 | On-Demand Detachment of Maleimide Derivatives on Cysteine to Facilitate (Semi)Synthesis of Challenging Proteins | <p>The maleimide group is a widely used reagent for bio-conjugation of peptides, proteins and oligonucleotides employing Michael addition and Diels-Alder cycloaddition reactions. However, the utility of this functionality in chemical synthesis of peptides and proteins remains unexplored. We report, for the first time that Pd<sup>II </sup>complexes can mediate the efficient removal of various maleimide derivatives in aqueous conditions. Maleimide removal by Pd<sup>II</sup> was applied for the synthesis of two ubiquitin activity-based probes (Ub-ABPs) employing solid phase chemical ligation (SPCL). SPCL was achieved through a sequential three segments ligation on a polymer support <i>via</i> a maleimide anchor. The obtained probes successfully formed the expected covalent complexes with deubiquitinating enzymes (DUBs) USP2 and USP7, highlighting the use of our new method for efficient preparation of unique synthetic proteins. Importantly, we demonstrate the advantages of our newly developed method for the protection and deprotection of native cysteine with a maleimide group in a peptide fragment derived from thioredoxin-1 (Trx-1) obtained <i>via</i> intein based expression to enable ligation/desulfurization and subsequent disulfide bond formation in a one-pot process.</p> | Ganga B. Vamisetti; satish gandhesiri; Prasad Sulkshane; Guy Mann; Michael H. Glickman; ashraf brik | Bioorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dc3bdbb891ca7a39a56/original/on-demand-detachment-of-maleimide-derivatives-on-cysteine-to-facilitate-semi-synthesis-of-challenging-proteins.pdf |
64649acffb40f6b3eeb9ed54 | 10.26434/chemrxiv-2023-cj9fb | Direct Monitoring of the Potassium Charge Carrier in Prussian Blue Cathodes using Potassium K-edge X-ray Absorption Spectroscopy | Prussian Blue is widely utilized as a cathode material in batteries, due to its ability to intercalate alkaline metal ions, including potassium. However, the exact location of potassium or other cations within the complex structure, and how it changes as a function of cycling, is unclear. Herein, we report direct insight into the nature of potassium speciation within Prussian Blue during cyclic voltammetry, via oper-ando potassium K-edge X-ray Absorption Near Edge Structure (XANES) analysis. Clear and identifiable spectra are experimentally differen-tiated for the fully intercalated (fully reduced Fe2+FeII Prussian White), partially intercalated (Prussian Blue; Fe3+FeII), and free KNO3(aq) elec-trolyte. Comparison of the experiment with simulated XANES of theoretical structures indicates that potassium lies within the channels of the Prussian blue structure, but is displaced towards the periphery of the channels by occluded water and/or structural water present resulting from [Fe(CN)6]4- vacancies. The structural composition from the charge carrier perspective was monitored for two samples of differing crystallinity and electrochemical stability. Reproducible potassium XANES spectral sequences were observed for crystalline Prus-sian blue, in agreement with retention of capacity; in contrast, the capacity of the poorly crystalline sample declined as the potassium became trapped within the partially intercalated poorly-crystalline Prussian blue. The cause of degradation could be attributed to a signif-icant loss of [Fe(CN)6]-[Fe(NC)6] ordering and the formation of a potassium-free non-conducting ferrihydrite phase. These findings demonstrate the potential of XANES to directly study the nature and evolution of potassium species during an electrochemical process. | Alexander Mayer; Owain Beynon; Andrew Logsdail; Upul Wijayantha; Sandra Dann; José Marco; Joshua Elliot; Matteo Aramini; Giannantonio Cibin; SIMON KONDRAT | Physical Chemistry; Energy; Energy Storage; Physical and Chemical Properties; Spectroscopy (Physical Chem.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-05-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64649acffb40f6b3eeb9ed54/original/direct-monitoring-of-the-potassium-charge-carrier-in-prussian-blue-cathodes-using-potassium-k-edge-x-ray-absorption-spectroscopy.pdf |
62d15a54a7d17edb505c4692 | 10.26434/chemrxiv-2022-s48dt | Undirected, Pd-catalysed deuteration of indoles with programmable regioselectivity | Methods for selective deuterium-incorporation into drug-like molecules have become extremely valuable due to the commercial and biological importance of deuterated compounds. Selective C2-deuteration of indoles currently requires the installation of directing groups on nitrogen. Herein, we report the directing group free, Pd(OAc)2 catalysed, C2-selective deuteration of indoles with CD3CO2D in high yields and selectivity. Slight modification of the reaction conditions also allows selective access to C3- as well as C2-and-C3-deuterated indoles, providing a user-friendly, programmable deuteration scaffold. | Liam Fitzgerald; Rachael McNulty; Andrew Greener; Miriam O'Duill | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY 4.0 | CHEMRXIV | 2022-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62d15a54a7d17edb505c4692/original/undirected-pd-catalysed-deuteration-of-indoles-with-programmable-regioselectivity.pdf |
65fd5e1be9ebbb4db94195f0 | 10.26434/chemrxiv-2024-jqd66-v2 | Inducible protein expression in stably transfected cells paves the way toward in-cell NMR studies in defined physiological states and 3D tissue cultures. | In-cell NMR spectroscopy is the sole technique for characterizing protein structure, dynamics, and interactions in living human cells at atomic resolution. However, its applications have been restricted to asynchronous single-cell suspensions. We developed a strategy based on target protein inducible overexpression in stably transfected cells, allowing the acquisition of high-resolution in-cell NMR spectra in physiologically defined cellular states and 3D tissue models. | Lukas Trantirek; Silvie Foldynova-Trantirkova; Jan Rynes; Eva Istvankova; Michaela Krafcikova; Enrico Luchinat; Letizia Barbieri; Lucia Banci; Kristyna Kamarytova; Tomas Loja; Bohumil Fafilek; Gustavo Rico-Llanos; Pavel Krejci; Libor Macurek | Biological and Medicinal Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65fd5e1be9ebbb4db94195f0/original/inducible-protein-expression-in-stably-transfected-cells-paves-the-way-toward-in-cell-nmr-studies-in-defined-physiological-states-and-3d-tissue-cultures.pdf |
634e6139e3f3ee94805e7c5c | 10.26434/chemrxiv-2022-r1f7k | Beam damage in operando X-ray diffraction studies of Li-ion batteries | Operando powder X-ray diffraction (PXRD) is a widely employed method for investigation of structural evolution and phase transitions in electrodes for rechargeable batteries. Due to the advantages of high brilliance and high X-ray energies, the experiments are often carried out at synchrotron facilities. It is known that the X-ray exposure can cause beam damage in the battery cell resulting in hindrance of the electrochemical reaction. In this study, we investigate the extent of X-ray beam damage during operando powder X-ray diffraction synchrotron experiments of battery materials with varying X-ray energies, amount of X-ray exposure and battery cell chemistries. Battery cells were exposed to 15, 25, or 35 keV X-rays (with varying dose) during charge or discharge in a battery tests cell specially designed for operando experiments. The observed beam damage was probed by µPXRD mapping of the electrodes recovered from the operando battery cell after charge/discharge. Our investigation reveals that beam damage depends strongly both on X-ray energy, amount of exposure and that it depends strongly on the cell chemistry, i.e. the chemical composition of the electrode. | Christian Kolle Christensen; Martin Aaskov Karlsen; Andreas Østergaard Drejer; Bettina Pilgaard Andersen; Christian Lund Jakobsen; Morten Johansen; Daniel Risskov Sørensen; Innokenty Kantor; Mads Ry Vogel Jørgensen; Dorthe Bomholdt Ravnsbæk | Materials Science; Energy; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/634e6139e3f3ee94805e7c5c/original/beam-damage-in-operando-x-ray-diffraction-studies-of-li-ion-batteries.pdf |
65c082f5e9ebbb4db9b2979b | 10.26434/chemrxiv-2024-qqq0k-v2 | Rationalizing Defective Biomimetic Ceria: In vitro Demonstration of a Potential “Trojan horse” Nanozyme Based-Platform Leveraging Photo-Redox Activities for Minimally Invasive Therapy | Metal oxide nanostructures with surface-defect mediated chemistry have garnered pronounced interest due to the influence of these defects in tuning the photo-induced intracellular bio-catalytic (enzyme-mimicking) responses. However, designing defective nanozymes with pH-responsive multi-bio-catalytic functions without any dopants is challenging. Herein, oxygen-deficient “trojan horse-like” folate-functionalized, L-arginine-coated ceria (FA-L-arg-CeO2) nanozymes with synergistic multi-enzyme-mimicking and anti-cancer potential are introduced. The nanozymes possessed enhanced surface oxygen vacancies (VO●), strategically created under kinetically favourable synthesis conditions. Increased surface VO● promoted band structure reconstruction and amplified photochemical-response efficacy under single laser irradiation (808 nm), outperforming the defect-free commercial nano-CeO2 in rapid anti-tumorigenic activities. Through folate receptor-mediated endocytosis, these biostable nanozymes localized in MDA-MB-231 cells (84% in 48 h) and demonstrated NIR-accelerated enzymatic functions depending on the pH of the biological milieu. The reduced band gap energy facilitated effective electron-hole separation, up-regulating in vitro photo-redox reactions that impart exceptional therapeutic potential and inhibit 62% cell metastasis within only 12 h. By perturbing intratumoural redox homeostasis, VO●-rich FA-L-arg-CeO2 nanozymes unanimously killed 86% of MDA-MB-231 cancer cells while preferentially shielding benign L929 cells. Unlike conventional drug-loaded or dopant-incorporated CeO2 nanoplatforms, these defective multi-modal nanozymes unravel a new avenue for developing smart, low-cost, bio-active agents with enhanced efficacy and bio-safety. | Sayoni Sarkar; Diksha Malhotra; Monalisha Debnath; Gopal Kundu; Rohit Srivastava; Ajit Kulkarni | Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c082f5e9ebbb4db9b2979b/original/rationalizing-defective-biomimetic-ceria-in-vitro-demonstration-of-a-potential-trojan-horse-nanozyme-based-platform-leveraging-photo-redox-activities-for-minimally-invasive-therapy.pdf |
64268c07647e3dca99ccb1af | 10.26434/chemrxiv-2023-cj9p9 | Computational Discovery of Stable Metal-Organic Frameworks for Methane-to-Methanol Catalysis | The challenge of direct partial oxidation of methane to methanol has motivated the targeted search of metal-organic frameworks (MOFs) as a promising class of materials for this transformation because of their site-isolated metals with tunable ligand environments. Thousands of MOFs have been synthesized, yet relatively few have been screened for their promise in methane conversion. We developed a high-throughput virtual screening (HTVS) workflow that identifies MOFs from a diverse space of experimental MOFs that have not been studied for catalysis, yet are thermally stable, synthesizable, and have promising unsaturated metal sites for C–H activation via a terminal metal-oxo species. We carried out density functional theory (DFT) calculations on the radical rebound mechanism for methane to methanol conversion on models of the secondary building units (SBUs) from 87 selected MOFs. While we showed that oxo formation favorability decreases with increasing 3d filling, consistent with prior work, previously observed scaling relations between oxo formation and hydrogen atom transfer (HAT) are disrupted by the greater diversity in our MOF set. Accordingly, we focused on Mn MOFs, which favor oxo intermediates without disfavoring HAT or leading to high methanol release energies—a key feature for methane hydroxylation activity. We identified three Mn MOFs comprising unsaturated Mn centers bound to weak-field carboxylate ligands in planar or bent geometries with promising methane to methanol kinetics and thermodynamics. The energetic spans of these MOFs are indicative of promising turnover frequencies for methane to methanol that warrant further experimental catalytic studies. | Husain Adamji; Aditya Nandy; Ilia Kevlishvili; Yuriy Roman-Leshkov; Heather Kulik | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Machine Learning; Heterogeneous Catalysis; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-03-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64268c07647e3dca99ccb1af/original/computational-discovery-of-stable-metal-organic-frameworks-for-methane-to-methanol-catalysis.pdf |
6706d6f712ff75c3a1fcae36 | 10.26434/chemrxiv-2024-rz1j4 | Site-selective copper(I) catalyzed hydrogenation of amides | We present a bifunctional catalyst consisting of a copper(I)/N-heterocyclic carbene and an organocatalytic guanidine moiety that enables for the first time a copper(I) catalyzed reduction of amides with H2 as the terminal reducing agent. The guanidine allows for reactivity tuning of the originally weakly nucleophilic copper(I) hydrides – formed in situ –to be able to reacting with diffi-cult-to-reduce amides. Additionally, the guanidine moiety is key for the selective recognition of “privileged” amides based on simple and readily available heterocycles in the presence of other amides within one molecule to give rise to a hitherto unknown site-selective catalytic amide hydrogenation. A substrate scope, mechanistic investigations as well as a working hypothesis, supported by computational analysis for the site-selectivity is presented. | Dimitrios-Ioannis Tzaras; Thomas Jacquemin; Mahadeb Gorai; Thiemo Arndt; Birte Zimmermann; Martin Breugst; Teichert Johannes | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Supramolecular Chemistry (Org.); Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6706d6f712ff75c3a1fcae36/original/site-selective-copper-i-catalyzed-hydrogenation-of-amides.pdf |
669507d901103d79c510d0d0 | 10.26434/chemrxiv-2024-qnwgv | Paper-based electrochemical device for the determination of H2S in murine lysates for liquid biopsy application | Hydrogen Sulfide (H₂S) is a biologically active endogenous gas, produced in mammalian tissues, which plays a critical role in several pathophysiological processes, including oncogenesis. Recent studies have indicated that this gas-transmitter may exert diametrically opposite effects on neoplastic cell proliferation, depending on the duration and concentration of H₂S exposure. Due to this dual role, antineoplastic drugs, aimed at modulating H₂S levels, are attracting considerable interest in both research and clinical settings. Furthermore, H₂S could serve as a diagnostic marker, potentially indicating the presence of tumors in various body fluids. Traditionally, H₂S is detected using spectrophotometric, chromatography, and fluorometric methods. However, the use of electrochemical sensors is a promising strategy to speed up and simplify operations. In this context, an electrochemical sensor, screen-printed on filter paper, and then modified with Prussian blue, was developed. After the optimization of various experimental parameters, such as the concentration of Prussian Blue to be used for the electrode modification and the constant potential applied during the chronoamperometric measurements, the sensor was analytically characterized in standard solution, achieving a good repeatability and a detection limit of 3 μM. The sensor was then applied to determine H₂S in several biological samples, including a murine skin lysate, two pharmacologically treated neoplastic murine lysates, and an untreated neoplastic murine lysate, obtaining results in agreement with those observed with the standard H2S determination method, demonstrating the applicability of the developed electroanalytical method for liquid biopsy. | Alessandra Glovi; Antonella Miglione; Daniela Claudia Maresca; Fabio Somma; Antonio Giordano; Stefano Cinti | Analytical Chemistry; Electrochemical Analysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669507d901103d79c510d0d0/original/paper-based-electrochemical-device-for-the-determination-of-h2s-in-murine-lysates-for-liquid-biopsy-application.pdf |
66e3c4e6cec5d6c142ebe00e | 10.26434/chemrxiv-2024-zfvb1 | Redox dye-mediated fluorescence energy transfer of carbon nanotube based nanosensors | Single-walled carbon nanotubes (SWCNTs) exhibit non-photobleaching, near-infrared (NIR) fluorescence suitable for bioimaging applications. In particular, SWCNT fluorescence quenching induced by biopolymer dispersants facilitates flexible design of molecular nanosensors, yet challenges remain in analyte selectivity and lack of rational design strategies. A sought-after alternative to haphazard molecular modulation of SWCNT-based fluorescence is to couple the movement of a quencher to the SWCNT surface, enabling fluorescence energy transfer to modulate molecular recognition with high selectivity. This study presents the rational design of SWCNT-based nanosensors that leverages the unique properties of methylene blue (MB)-proximity mediated fluorescence quenching. MB-SWCNT based nanosensors exhibit 1- stability in redox environments and 2- analyte-specific displacement-driven fluorescence modulation. By designing hybridization-induced displacement of MB-conjugated ssDNA from the SWCNT surface, we calculate that SWCNT fluorescence modulation can occur within a 6.8 nm fluorescence resonance energy transfer distance from the SWCNT surface, and develop a robust and versatile platform to synthesize oligonucleotide nanosensors with tunable ΔF/F0 of up to 150%. Building upon this strategy, we developed four distinct nanosensors capable of selectively detecting tobacco mosaic virus (TMV) viral RNA fragments, which successfully differentiated TMV-infected plants from mock controls. Finally, we demonstrate the potential expansion of our design to target a wider scope of biomolecules using the biotin-avidin system as a model. By attaching biotin to MB-conjugated ssDNA, we enabled selective and robust responses to biotin-binding proteins through the same MB displacement mechanism as our oligonucleotide nanosensors. Therefore, we herein present a generalizable platform that enables rational engineering of SWCNT NIR fluorescence intensity through MB distance-dependent fluorescence energy transfer, overcoming the intrinsic selectivity challenges of current SWCNT nanosensors. | Shoichi Nishitani; Kevin Ao; Amad Jalil; Octavio I. Arias-Soto; Ava Moudi; Feiyang Chen; Ankita Biyani; Padma N. Muppirala; Markita P. Landry | Materials Science; Analytical Chemistry; Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66e3c4e6cec5d6c142ebe00e/original/redox-dye-mediated-fluorescence-energy-transfer-of-carbon-nanotube-based-nanosensors.pdf |
60c74937bdbb89a2b9a39121 | 10.26434/chemrxiv.12044106.v1 | A computational thermochemical value for Cr-Cu bond dissociation energy: using crystal field theory to understand the chemical bond in metal clusters | <div>
<p>Semi-empirical (PM6) approach was employed to
modelling Cr-Cu dimmer. The obtained bond dissociation energy for such specie
agrees very well with experimental/reference values. It was verified that in the Cr-Cu dimmer,
chromium has only one unpaired electron, meaning that copper behaves, in such
dimmer, as a strong field ligand. Such
results strongly suggest that 1:1 Cr-Cu bronzes must behave as a one unpaired
electron compound and not a five
unpaired electrons one, with, of course, remarkable influences on their
magnetic properties.</p>
</div> | Robson de Farias | Theory - Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74937bdbb89a2b9a39121/original/a-computational-thermochemical-value-for-cr-cu-bond-dissociation-energy-using-crystal-field-theory-to-understand-the-chemical-bond-in-metal-clusters.pdf |
6324c8122984c9adb661ef44 | 10.26434/chemrxiv-2022-b3f72-v5 | Comparing corrosion control treatments for drinking water using a robust Bayesian generalized additive model | Pipe loop studies are used to evaluate corrosion control treatment, and updated regulatory guidance will ensure that they remain important for water quality management. But the data they generate are difficult to analyze: non-linear time-trends, non-detects, extreme values, and autocorrelation are common attributes that make popular methods, such as the t- or rank-sum tests, poor descriptive models. Here, we propose a model for pipe loop data that accommodates many of these difficult-to-model attributes: a robust Bayesian generalized additive model with continuous-time autoregressive errors. Our approach facilitates corrosion control treatment comparisons without the need for imputing non-detects or special handling of outliers. It is well-suited to describing nonlinear trends without overfitting, and it accounts for the reduced information content in autocorrelated time series. We demonstrate it using a four-year pipe loop study, with multiple pipe configurations and orthophosphate dosing protocols, finding that an initially high dose of orthophosphate (2 mg P L-1) that is subsequently lowered (0.75 mg P L-1) can yield lower lead release than an intermediate dose (1 mg P L-1) in the long term. Water utilities face difficult tradeoffs in applying orthophosphate for corrosion control, and better models of pipe loop data can help inform the decision-making process. | Benjamin F Trueman; Wendell James; Trevor Shu; Evelyne Doré; Graham A Gagnon | Earth, Space, and Environmental Chemistry; Environmental Science | CC BY NC 4.0 | CHEMRXIV | 2022-09-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6324c8122984c9adb661ef44/original/comparing-corrosion-control-treatments-for-drinking-water-using-a-robust-bayesian-generalized-additive-model.pdf |
6728bc777be152b1d0f13fc4 | 10.26434/chemrxiv-2024-zfqv5 | RNA Binding and Coacervation Promotes Preservation of Peptide Form and Function Across the Heterochiral-Homochiral Divide | Recent evidence suggests that peptide-RNA coacervates may have buffered the emergence of folded domains from flexible peptides. As primitive peptides were likely composed of both L- and D-amino acids, we hypothesized that coacervates may have also supported the emergence of chiral control. To test this hypothesis, we compared the coacervation propensities of an isotactic (homochiral) peptide and a syndiotactic (alternating chirality) peptide, both with an identical sequence derived from the ancient helix-hairpin-helix (HhH) motif. Using electron paramagnetic resonance (EPR) spectroscopy and molecular dynamics (MD) simulations, we found that the syndiotactic peptide does not form stable dimers with high α-helicity in solution, unlike the isotactic peptide. However, both peptides do coacervate with RNA, albeit with distinct reentrant phase behaviors. Coacervation in each case is facilitated by oligomer formation, likely dimerization, upon RNA binding that promotes RNA cross-linking. Additionally, RNA cross-linking and coacervation of the syndiotactic peptide seems to involve α-helical conformations. We attribute differences in reentrant phase behavior to differences in dimer flexibility and stability that alter the effectiveness of RNA cross-linking. These results illustrate how RNA-binding and/or coacervation by early protein forms could have promoted the transition of flexible, heterochiral peptides into folded, homochiral domains. | Daniella Goldfarb; Manas Seal; Ilan Edelstein; Orit Weil-Ktorza; Norman Metanis; Yaakov Levy; Liam Longo | Physical Chemistry; Biophysical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6728bc777be152b1d0f13fc4/original/rna-binding-and-coacervation-promotes-preservation-of-peptide-form-and-function-across-the-heterochiral-homochiral-divide.pdf |
67dbceee6dde43c9088cbc90 | 10.26434/chemrxiv-2025-1scrm | A 3D-Bioprinted Dermal-Like Scaffold Incorporating
Fibroblasts and DRG Neurons to investigate Peripheral
Nerve Regeneration | Peripheral nervous system (PNS) regeneration is a rapidly advancing field with critical implications for addressing sensory
impairments and neuropathic conditions. Dorsal root ganglion (DRG) neurons, essential for sensory transmission, exhibit
regenerative potential through axonal regeneration. However, the mechanisms driving these processes are not yet
understood. This study introduces an innovative 3D-bioprinted fibroblasts/DRG co-culture construct, specifically designed
to investigate and characterize PNS regeneration and wiring mechanisms under both physiological and pathophysiological
conditions. By characterizing bioink rheology and optimizing bioprinting parameters, we created a stable, biocompatible
derma-like construct supporting cell adhesion and growth. Bioprinted 3T3 fibroblasts demonstrate high viability and
proliferation, while DRG neurons exhibit enhanced neurite outgrowth and complex branching patterns within the co-culture
system. These findings highlight the role of fibroblasts in promoting axonal regeneration and provide a robust in-vitro
platform for studying sensory system reinnervation. This model lays the foundation for developing personalized therapies
for neuropathic pain and sensory dysfunction, advancing both fundamental neuroscience and translational medicine. | Simone Bonetti; Francesco Formaggio; Emanuela Saracino; Eva Clemente; Marianna Barbalinardo; Franco Corticelli; Sara Buoso | Biological and Medicinal Chemistry; Materials Science; Biocompatible Materials; Bioengineering and Biotechnology | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67dbceee6dde43c9088cbc90/original/a-3d-bioprinted-dermal-like-scaffold-incorporating-fibroblasts-and-drg-neurons-to-investigate-peripheral-nerve-regeneration.pdf |
65f3c0199138d231617c9383 | 10.26434/chemrxiv-2024-vgzp3 | Electrocatalytic hydrogen evolution performance of mesoporous Ni/NiO/carbon composites fabricated from carbon dots | Mesoporous Ni/NiO/carbon composites were successfully prepared from the tri-component self-assembly of carbon dots, nickel precursors and surfactant F127. The functional groups of carbon dots can chelate with the metal and then further assemble with the surfactant to prepare mesoporous metals/carbon materials (Ni-NC/MC), which are applied to the electrolysis of water to produce hydrogen. The results show that the interaction between Ni/NiO heterostructures is the active component of the catalyst. The carbon dots show a certain confinement effect, which hinders the further growth of metal particles. Moreover, large specific surface area and suitable Ni/NiO ratio are beneficial to the HER catalytic activity and operational stability of the catalyst. | Yan Yang; Ruihan Liu; Weiruo Liu; Lexuan Ji; Mengjie Gao; Yunpu Zhai | Catalysis; Nanoscience; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Electrocatalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f3c0199138d231617c9383/original/electrocatalytic-hydrogen-evolution-performance-of-mesoporous-ni-ni-o-carbon-composites-fabricated-from-carbon-dots.pdf |
6404fdcf63e8d44e596c9f0d | 10.26434/chemrxiv-2023-860zh | DFT and TDDFT Studies of Silicon Analogs of Fluorescein Derivatives | Fluorescein derivatives play an important role in the field of biological and fluorescent sensors. To tune the spectroscopic properties many attempts have been made including extending conjugation, substituting the central carbon by nitrogen or introducing electron withdrawing groups and replace the oxygen bridge atom by other elements such as N, C, S, Se, and Te. In this paper we report density functional theory (DFT) and time-dependent DFT (TDDFT) studies of silicon analog of fluorescein derivatives with oxygen replaced by Si, C, and Ge. Among the different silicon analogs, the most conjugated molecule 4 showed red shift in absorption wavelength (495 nm). The OH position of molecule 2 has a significant effect on the spectral properties of the silicon analogs of the fluorescein. Since aggregation is very common in most of the fluorescein and it is interesting to study the effect of aggregation, we also studied dimerization of molecule 1 in silicon analog of fluorescein derivative and the results show that two absorption bands are formed with red shift compared to monomer. | Krishanthi Weerasinghe; Lichang Wang | Theoretical and Computational Chemistry; Physical Chemistry; Physical and Chemical Properties; Spectroscopy (Physical Chem.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6404fdcf63e8d44e596c9f0d/original/dft-and-tddft-studies-of-silicon-analogs-of-fluorescein-derivatives.pdf |
66cb6d6620ac769e5fd36102 | 10.26434/chemrxiv-2024-fsk3r | Visible-Light-Assisted the Metal-Free 1,2-Carboimination of Alkenes to Synthesize Complex 1,6-Amino Alcohols | Herein, we report a visible-light-mediated synthesis of highly complex 1,6-amino alcohols through the 1,2-carboimination of alkenes leading by an energy transfer (EnT) mechanism. This protocol successfully achieved the simultaneous formation of C(sp3)–C(sp3) and C(sp3)–N bonds after several cascade steps: homolysis of the O-N bond, carbon dioxide and acetonitrile extrusion, 1,5-hydrogen atom transfer (HAT), Giese-type and radical additions. This additive and metal-free method presented a broad functional tolerance, and its value was proved with the late-stage installation of the 1,6-amino alcohol motif in biomolecules and pharmaceuticals. Finally, the versatility of the 1,6-iminyl alcohols products is showcased through their conversion to a variety of useful intermediates applicable to target-directed synthesis. | Aida Jaafar; Christian Cristobal; Javier Adrio; Maria Ribagorda; María Jesús Cabrera-Afonso | Organic Chemistry; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66cb6d6620ac769e5fd36102/original/visible-light-assisted-the-metal-free-1-2-carboimination-of-alkenes-to-synthesize-complex-1-6-amino-alcohols.pdf |
676455026dde43c908a47b3a | 10.26434/chemrxiv-2024-3c396 | Surface state of NiOOH under oxidative conditions: Can dopants induce surface oxidation? | Nickel oxyhydroxide (NiOOH), featuring redox-active NiIII, is a one of the best non-noble electro- oxidation catalyst in alkaline solution. However, NiOOH is only stable at potentials ≥ 1.5V vs RHE, with Ni(OH)2 being the stable reduced form at lower potentials. The potential of the phase transition from inactive Ni(OH)2 to active NiOOH can be tuned by doping. Lowering the potential for reaching the phase-transition is thought to be beneficial for lowering the overpotential of oxidation reactions catalysed by NiOOH. Here, we investigate which first row transition metals are most plausible for this purpose: First, the doped structure should be more stable than the phase-segregated system and second the potential for reaching the NiOOH-like phase should be lower compared to the pure Ni compound. Substitutional doping of NiOOH is found to be plausible for many dopants, but only V can be incorporated exothermically compared to their pure oxyhydroxides. Furthermore, dopants lead to a substantial lowering in the potential necessary to reach the phase transition. Since catalysis is more a surface than a bulk process, we then investigate the surface state of NiOOH and the impact of substitutional doping on it. To address this question, we apply grand-canonical density functional theory (GC-DFT) in order to explicitly account for the electrochemical potential. We find that the stoichiometric surface (50% hydrogen coverage) is the most stable one over a large range of relevant potentials at pH 14. Oxidizing the surface lowers the hydrogen coverage and occurs at about 1.7 V vs RHE, i.e.,∼0.2 V less positive compared to the potential of the phase transition. At a doping level of 25%, only V and Cr allow to stabilize NiIII at significantly lower potentials compared to pure NiOOH (down to 1.1 V vs RHE) in the bulk. Furthermore, vanadium, chromium and manganese might be suitable choices as these metal centers, which remain in the +III or +IV state at lower potentials compared to Ni, could also act as active sites in electro-oxidation reactions. | Laureline Treps; Tony Ermacora; Andrea Giacomelli; Carine Michel; Stephan N. Steinmann | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Electrocatalysis | CC BY NC 4.0 | CHEMRXIV | 2024-12-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/676455026dde43c908a47b3a/original/surface-state-of-ni-ooh-under-oxidative-conditions-can-dopants-induce-surface-oxidation.pdf |
60c75603469df44d0df45250 | 10.26434/chemrxiv.14188679.v1 | Functional Group Identification for FTIR Spectra Using Image-Based Machine Learning Models | <p>Fourier Transform Infrared Spectroscopy (FTIR) is a ubiquitous spectroscopic technique. Spectral interpretation is a time-consuming process, but it yields important information about functional groups present in compounds and in complex substances. We develop a generalizable model via a machine learning (ML) algorithm using Convolutional Neural Networks (CNNs) to identify the presence of functional groups in gas phase FTIR spectra. The ML models will reduce the amount of time required to analyze functional groups and facilitate interpretation of FTIR spectra. Through web scraping, we acquire intensity-frequency data from 8728 gas phase organic molecules within the NIST spectral database and transform the data into images. We successfully train models for 15 of the most common organic functional groups, which we then determine via identification from previously untrained spectra. These models serve to expand the application of FTIR measurements for facile analysis of organic samples. Our approach was done such that we have broad functional group models that inference in tandem to provide full interpretation of a spectrum. We present the first implementation of ML using image-based CNNs for predicting functional groups from a spectroscopic method.</p> | Abigail Enders; Nicole North; Chase Fensore; Juan Velez-Alvarez; Heather Allen | Analytical Chemistry - General; Spectroscopy (Anal. Chem.); Machine Learning; Artificial Intelligence | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75603469df44d0df45250/original/functional-group-identification-for-ftir-spectra-using-image-based-machine-learning-models.pdf |
678b0839fa469535b974e78d | 10.26434/chemrxiv-2025-mtljf | Using Yield Fingerprints to Study Reaction Mechanism | Understanding reaction mechanisms can help to optimize efficiency, which allows industrially important molecules to be synthesized less expensively and more sustainably. Determining mechanisms, however, can be time consuming and resource-intensive. In this work, we outline an expeditious method to differentiate reaction mechanisms by means of unsupervised learning. With this technique, reaction “fingerprints” are created from the yields of a set of substrates subjected to several different reaction conditions. The resultant fingerprints are clustered by similarity to reveal mechanistic relationships. We have benchmarked this method with elimination reaction mechanisms, and used it to explore mechanistic relationships among C–H activation, phenol cross coupling, and amination catalysts. We determined that our method successfully categorizes elimination reaction mechanisms, as well as C–H activation reaction mechanisms between eCMD, CMD, and SEAr. Additionally, we found that due to the swift progress and discovery of new mechanisms in the C–H activation field, much of the C–H activation literature contains outdated mechanistic labels. Our method was able to correct these labels, and can be used to quickly hypothesize a mechanism for new C–H activation or amination catalysts with only 4-6 experiments. We also predicted potential similarities in phenol oxidative cross coupling catalysts that are mechanistically not well understood. Overall, this method has the potential to simplify the study of reaction mechanism for many types of reactions. | Kalyana B. Duggal; Emmanuel Moya Cruz; Adriana L. Jemison; Yaning Liu; Grace O. DeCostanza; Cameron B. Berlin; Paige E. Piszel; Weihao Zhu; Madeline E. Rotella; Marisa C. Kozlowski | Theoretical and Computational Chemistry; Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Physical Organic Chemistry; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678b0839fa469535b974e78d/original/using-yield-fingerprints-to-study-reaction-mechanism.pdf |
672242fe5a82cea2fa866390 | 10.26434/chemrxiv-2024-msn1r | Perfluoro(2-ethoxy-2-fluoroethoxy)-acetic acid (EEA) and other target and suspect PFAS in the vicinity of a fluoropolymer production plant | Multiple target and suspect per- and polyfluoroalkyl substances (PFAS), including the replacement fluoropolymer processing aid perfluoro(2-ethoxy-2-fluoroethoxy)-acetic acid (“EEA”), were measured in both air and surface water in the vicinity of a fluoropolymer production plant (FPP) in Thornton-Cleveleys (United Kingdom) during sampling campaigns in 2021 and 2023, respectively. Targeted and suspect screening methods were conducted using ultra-high-performance liquid chromatography (UHPLC) coupled with Q-Exactive HF Orbitrap high-resolution mass spectrometry (HRMS). Summed PFAS levels in water nearby the plant ranged from 30 ng/L to 22.5 μg/L and were dominated by perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs), most notably perfluorooctanoic acid (PFOA; up to 20.6 μg/L), EEA (up to 1.7 μg/L) and perfluorohexanoic acid (PFHxA; up to 650 ng/L). Additionally, various homologous series of PFAS suspects, such as hydrogen-substituted PFCAs (H-PFCAs), chlorine-substituted PFCAs (Cl-PFCAs) and monoether perfluoroether alkyl carboxylic acids (ME-PFECAs) were identified, some for the first time in Europe. In air, PFOA was detected in all but one sample collected 20 km from the plant at concentrations ranging from 0.51 to 2.50 pg/m3. The three air samples that showed detectable EEA concentrations also displayed evidence of long-chained targets and suspects and were associated with high wind speeds from a southwesterly direction. Overall, this study shows that this site continues to be a source of a complex mixture of legacy and scarcely monitored PFAS that occur in multiple environmental media. This highlights the importance of further research that assesses the toxicity of these substances and resulting impacts on humans and wildlife. | Joost Dalmijn; Jonathan Benskin; Matthew Salter; Andrew Sweetman; Crispin Halsall; Jack Garnett; Ian Cousins | Earth, Space, and Environmental Chemistry; Environmental Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672242fe5a82cea2fa866390/original/perfluoro-2-ethoxy-2-fluoroethoxy-acetic-acid-eea-and-other-target-and-suspect-pfas-in-the-vicinity-of-a-fluoropolymer-production-plant.pdf |
65480243c573f893f1df7dc3 | 10.26434/chemrxiv-2023-p4rvg | Chronological Molecular Fingerprint of Wetland Soil by Sensitivity-Enhanced Solid-State NMR | Soil organic matter (SOM) plays a major role in mitigating greenhouse gas emission and thereby regulating Earth’s climate, carbon and water cycles, and biodiversity. Wetland soils contain the highest stores of soil carbon on the planet on an areal basis, accounting for one-third of all the SOM, yet our understanding of carbon sequestration within wetlands lags behind that of upland soils. Here we show the molecular-level fingerprints of wetland soils spanning eleven centuries using advanced solid-state nuclear magnetic resonance (ssNMR) spectroscopy. Remarkably, combining dynamic nuclear polarization (DNP) with SOM enrichment allowed up to an 8,000-fold time-saving over conventional NMR approaches. This innovative approach for SOM characterization revealed that the parent herbaceous plant core molecular structures are preserved, with the aromatic and carbohydrate motifs becoming tightly packed, even after a millennium. Such preserved cores occur alongside molecules from the decomposition of loosely packed parent biopolymers and biogeochemical processing driven by geological global and anthropogenic changes, adding to the chemical diversity of SOM. These findings reveal that particulate organic matter (POM) should be a major focus for wetlands, and other soils with high organic matter content, especially when considering the fate of coastal wetland SOM when exposed to oxygenated water due to erosion. | Wancheng Zhao; Elizabeth C Thomas; Debkumar Debnath; Faith Scott; Frederic Mentink-Vigier; John R. White; Robert L. Cook; Tuo Wang | Earth, Space, and Environmental Chemistry; Geochemistry; Soil Science | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65480243c573f893f1df7dc3/original/chronological-molecular-fingerprint-of-wetland-soil-by-sensitivity-enhanced-solid-state-nmr.pdf |
60c73f5dee301c2d78c788b9 | 10.26434/chemrxiv.7335935.v1 | Convenient Synthesis of the Immunogenic Glycolipid BbGL1 | A simple and efficient method to synthesize the immunogenic glycolipid BbGL1 is introduced. Two simple steps were required to obtain the desired product in good yield. First, a highly efficient glycosylation of cholesterol using galactosyl trichloroacetimidate as a donor was performed to produce cholesteryl--D-galactoside. Finally, an efficient palmitoylation on the C6–OH of the galactose of the synthesized saponin using sym-collidine and acyl chloride under microwave heating that produced BbGL1 in good yield. The procedure is a convenient and cheaper alternative to the reported procedures allowing a rapid preparation of multiple analogs and conjugates. | Sebastián N. Jäger; Exequiel O. J. Porta; Guillermo Labadie | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2018-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5dee301c2d78c788b9/original/convenient-synthesis-of-the-immunogenic-glycolipid-bb-gl1.pdf |
61f2632571868d166bc01e0f | 10.26434/chemrxiv-2022-53ghb-v2 | Dielectric Response of 1,1-Difluorosumanene Caused by an In-Plane Motion | We have designed and synthesized a new curved π-conjugated molecule, 1,1-difluorosumanene (1), which possesses two fluorine atoms on the same benzylic carbon of unsubstituted sumanene, producing a large dipole moment along the in-plane direction. Thermal analyses, variable-temperature X-ray diffraction, and IR measurements indicated a 120° in-plane motion of 1 in the stacking columns, which did not cause any phase transition in the crystalline state. Indeed, dielectric measurements on powder and single-crystal forms of 1 showed that both the real (ε1) and imaginary (ε2) parts of the dielectric constant were enhanced above ~360 K at 1 MHz with a Debye-type dielectric relaxation, confirming that 1 underwent a pendulum fluctuation induced by the external electric field. | Yumi Yakiyama; Minghong Li; JianYun Wu; Kohei Sambe; Tomoyuki Akutagawa; Takashi Kajitani; Takanori Fukushima; Kazunari Matsuda; Hidehiro Sakurai | Organic Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-01-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61f2632571868d166bc01e0f/original/dielectric-response-of-1-1-difluorosumanene-caused-by-an-in-plane-motion.pdf |
65b2831f9138d23161bafd58 | 10.26434/chemrxiv-2024-dxd4w | Efficient defect-driven cation exchange beyond the nanoscale semiconductors toward antibacterial functionalization | Defect engineering is an exciting tool for customizing semiconductors' structural and optoelectronic properties. Elaborating programmable methodologies to circumvent energy constraints in multievent inversions expands our understanding of mechanisms governing the functionalization of nanomaterials. Herein, we introduce a novel strategy based on defect incorporation and solution rationalization, which triggers energetically unfavorable cation exchange reactions in extended solids. Using Sb2X3 + Ag (I) → Ag: Sb2X3 (X = S, Se) as a system to model, we demonstrate that incorporating chalcogen vacancies and AgSbVX complex defects into initial thin films (TFs) is crucial for activating long-range solid-state ion diffusion. Additional regulation of the Lewis acidity of auxiliary chemicals provides exceptional conversion yield of the Ag precursor into a solid-state product up to 90%, simultaneously transforming upper matrix layers into AgSbX2. The proposed strategy enables tailoring radiative recombination processes, offers efficiency to invert TFs at moderate temperatures quickly, and yields structures of large areas with substantial antibacterial activity in visible light for a particular system considered. Similar customization can be applied to most sulfides and selenides with controlled reaction yields. | Svetlana Polivtseva; Olga Volobujeva; Ivan Kuznietsov; Reelika Kaupmees; Mati Danilson; Jüri Krustok; Palanivel Molaiyan; Tao Hu; Ulla Lassi; Mihhail Klopov; Heleen van Gog; Marijn A. van Huis; Harleen Kaur; Angela Ivask; Merilin Rosenberg; Nicholas Gathergood; Chaoying Ni; Maarja Grossberg-Kuusk | Materials Science; Inorganic Chemistry; Thin Films; Reaction (Inorg.); Solid State Chemistry; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2024-01-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65b2831f9138d23161bafd58/original/efficient-defect-driven-cation-exchange-beyond-the-nanoscale-semiconductors-toward-antibacterial-functionalization.pdf |
60c74ff40f50dbcd103974db | 10.26434/chemrxiv.12925511.v2 | MicroED Elucidation of Diverse Solid-State Packing in a Family of Electron-Deficient Expanded Helicenes | Solid-state packing plays a defining role in the properties
of a molecular organic material, but it is difficult to elucidate in the
absence of single crystals that are suitable for X-ray diffraction. Here, we
demonstrate the coupling of divergent synthesis with microcrystal electron
diffraction (MicroED) for rapid assessment of solid-state packing motifs, using
a class of chiral nanocarbons – expanded helicenes – as a proof of concept. Two
highly selective oxidative dearomatizations of a readily-accessible helicene
provided a divergent route to four electron-deficient analogues containing
quinone or quinoxaline units. Crystallization efforts consistently yielded microcrystals that were unsuitable for single
crystal X-ray diffraction, but ideal for MicroED. This technique facilitated
the elucidation of solid-state structures of all five compounds with
<1.1 Å resolution. The otherwise-inaccessible data revealed a range of notable
packing behavior, including four
different space groups, homochirality in a crystal for a helicene with an
extremely low enantiomerization barrier, and nanometer scale cavities. The
results of this study suggest that MicroED will soon become an indispensable tool for high-throughput investigations in
pursuit of next-generation organic materials. | Adrian Samkian; Gavin R. Kiel; Christopher G. Jones; Harrison Bergman; Julia Oktawiec; Hosea Nelson; T. Don Tilley | Organic Synthesis and Reactions; Supramolecular Chemistry (Org.); Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ff40f50dbcd103974db/original/micro-ed-elucidation-of-diverse-solid-state-packing-in-a-family-of-electron-deficient-expanded-helicenes.pdf |
60c746c5bb8c1a121f3da960 | 10.26434/chemrxiv.11362520.v1 | Metallic Nanodimers as Phototactic Thermoplasmonic Nanoswimmers | We assess the potentiality of several geometries of metallic nanodimers (one of the simplest thermoplasmonic systems) as candidates for active particles (nanoswimmers) propelled and controlled by light (phototaxis).<br />The studied nanodimers are formed by two spherical nanoparticles of gold, silver, or copper with radii ranging from 20 to 100 nm. Contrary to most proposals, which assume the asymmetry of the systems as a requirement for self-propulsion, our results show that nanodimers made of identical nanoparticles are excellent candidates for phototactic self-thermophoretic systems. Nonsymmetrical nanodimers, although having a tunable effective diffusion, possess much lower or null average thermophoretic forces. We show that the effective diffusion and the net thermophoretic force in both types of systems depend strongly on the wavelength of the incident light, which makes these properties highly tunable. Our study may result useful for the design of simple-to-make but controllable self-propelled nanoparticles, which can find numerous applications. | Andres Bertoni; Nicolas Passarelli; Raúl Bustos-Marún | Nanodevices; Plasmonic and Photonic Structures and Devices | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746c5bb8c1a121f3da960/original/metallic-nanodimers-as-phototactic-thermoplasmonic-nanoswimmers.pdf |
60c74980f96a00352b28727c | 10.26434/chemrxiv.11871402.v4 | Repurposing Therapeutics for COVID-19: Supercomputer-Based Docking to the SARS-CoV-2 Viral Spike Protein and Viral Spike Protein-Human ACE2 Interface | The novel Wuhan coronavirus (SARS-CoV-2) has been sequenced, and the virus shares substantial similarity with SARS-CoV. Here, using a computational model of the spike protein (S-protein) of SARS-CoV-2 interacting with the human ACE2 receptor, we make use of the world's most powerful supercomputer, SUMMIT, to enact an ensemble docking virtual high-throughput screening campaign and identify small-molecules which bind to either the isolated Viral S-protein at its host receptor region or to the S protein-human ACE2 interface. We hypothesize the identified small-molecules may be repurposed to limit viral recognition of host cells and/or disrupt host-virus interactions. A ranked list of compounds is given that can be tested experimentally.<br /> | Micholas Smith; Jeremy C. Smith | Biophysics; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74980f96a00352b28727c/original/repurposing-therapeutics-for-covid-19-supercomputer-based-docking-to-the-sars-co-v-2-viral-spike-protein-and-viral-spike-protein-human-ace2-interface.pdf |
625f595cef2adee2073656be | 10.26434/chemrxiv-2021-lplvt-v2 | Homogeneous Electrocatalytic Reduction of CO2 by a CrN3O Complex: Electronic Coupling with Redox-Active Terpyridine Fragment Favors Selectivity for CO | Electrocatalyst design and optimization strategies continue to be an active area of research interest for the applied use of renewable energy resources. The electrocatalytic conversion of CO2 is an attractive approach in this context, because of the added potential benefit of addressing its rising atmospheric concentrations. In previous experimental and computational studies, we have described the mechanism of the first molecular Cr complex capable of electrocatalytically reducing CO2 to CO in the presence of an added proton donor, which contained a redox-active 2,2'-bipyridine (bpy) fragment, CrN2O2. The high selectivity for CO in the bpy-based system was dependent on a delocalized Cr(II)(bpy•−) active state. Subsequently, we became interested in exploring how expanding the polypyridyl ligand core would impact selectivity and activity during electrocatalytic CO2 reduction. Here, we report a new CrN3O catalyst, Cr(tpytbupho)Cl2 1, where 2-([2,2':6',2''-terpyridin]-6-yl)-4,6-di-tert-butylphenolate = [tpytbupho]–, which reduces CO2 to CO with almost quantitative selectivity via a different mechanism than our previously reported Cr(tbudhbpy)Cl(H2O) catalyst. Computational analyses indicate that although the stoichiometry of both reactions is identical, changes in the observed rate law are the combined result of a decrease in intrinsic ligand charge (L3X vs L2X2) and an increase in ligand redox activity, which result in increased electronic coupling between the doubly reduced tpy fragment of the ligand and the Cr(II) center. The strong electronic coupling enhances the rate of protonation and subsequent C–OH bond cleavage, resulting in CO2 binding becoming the rate-determining step, which is an uncommon mechanism during protic CO2 reduction. | Amelia Reid; Shelby Hooe; Juan Moreno; Diane Dickie; Charles Machan | Inorganic Chemistry; Catalysis; Energy; Electrochemistry; Electrocatalysis; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/625f595cef2adee2073656be/original/homogeneous-electrocatalytic-reduction-of-co2-by-a-cr-n3o-complex-electronic-coupling-with-redox-active-terpyridine-fragment-favors-selectivity-for-co.pdf |
62448b013b5f99d0a2c9fa88 | 10.26434/chemrxiv-2022-w14dp-v3 | Substituent Control of Tribofilm Growth under Mechanochemical Conditions | Mechanochemistry is known to play a key role in the function of some lubricant additives, such as the tribofilm growth of zinc dialkyldithiophosphate (ZDDP). This raises the intriguing possibility of tailoring the mechanochemical reactivity of additives by modifying their alkyl substituents. Here, we study the tribofilm formation rate of ZDDPs containing several different alkyl groups on steel surfaces from a high-friction base oil. We use macroscale tribometer experiments under full-film elastohydrodynamic lubrication conditions to ensure that the temperature and stress are carefully controlled. We show how the chain length and the presence of branches or bulky cycloaliphatic groups can lead to large differences in the temperature− and stress−dependencies of the tribofilm formation rate, which can be explained through changes to the packing density, steric hindrance, and stress transmission efficiency. Our rate data are successfully fitted using the Bell model; a simple modification of the Arrhenius equation that is commonly employed to model the kinetics of mechanochemical processes. Using this model, we observe large differences in the activation energy, pre-exponential factor, and activation volume for the various ZDDPs. Our findings show how structure−performance relationships can be identified for lubricant additives, which can be used to optimise their molecular structure. | Jie Zhang; James Ewen; Hugh Spikes | Physical Chemistry; Chemical Kinetics; Interfaces | CC BY 4.0 | CHEMRXIV | 2022-03-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62448b013b5f99d0a2c9fa88/original/substituent-control-of-tribofilm-growth-under-mechanochemical-conditions.pdf |
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