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60c73d0d9abda22efef8b65f | 10.26434/chemrxiv.5358079.v1 | Degradation of high molar mass poly(ethylene glycol), poly(2-ethyl-2-oxazoline) and poly(vinyl pyrrolidone) by reactive oxygen species | The development of the apparent molar mass of different poly(ethylene glycol), poly(2-ethyl-2-oxazoline) and poly(vinyl pyrrolidone) upon incubation with hydrogen peroxide and different concentrations and catalytic amounts of CuSO4 was followed used gel permeation chromatography. | Robert Luxenhofer; Juliane Ulbricht; Moritz Faust | Organic Polymers | CC BY NC ND 4.0 | CHEMRXIV | 2017-08-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d0d9abda22efef8b65f/original/degradation-of-high-molar-mass-poly-ethylene-glycol-poly-2-ethyl-2-oxazoline-and-poly-vinyl-pyrrolidone-by-reactive-oxygen-species.pdf |
60c74f13842e6577a5db3797 | 10.26434/chemrxiv.12844820.v1 | Carborane Guests for Cucurbit[7]uril Facilitate Strong Binding and on Demand Removal | High affinity guest have been reported for the macrocyclic host cucurbit[7]uril (CB[7]), enabling widespread applications, but preventing CB[7] materials from being returned to their guest-free state for reuse. Here we present polyhedral boron clusters (carboranes) as strongly-binding, yet easily removable, guests for CB[7]. Aided by a Pd-catalyzed coupling of an azide anion, we prepared boron-functionalized 9<i>-</i>amino and 9-ammonium modified <i>ortho-</i>carboranes that bind to CB[7] with a <i>K<sub>a</sub></i>=10<sup>10</sup> M<sup>-1</sup>. Upon treatment with base, the <i>ortho</i>-carboranes<i> </i>readily undergo deboronation to yield anionic <i>nido</i>-carborane, a poor guest of CB[7], facilitating recovery of guest-free CB[7]. We showcase the utility of the modified <i>ortho</i>-carborane guest by recycling a CB[7]-functionalized resin. With this report, we introduce stimuli-responsive decomplexation as an additional consideration in the design of high affinity host-guest complexes. | Anna Kataki-Anastasakou; Jonathan C. Axtell; Selena Hernandez; RafalM. Dziedzic; Gary J. Balaich; Arnold L. Rheingold; Alexander Spokoyny; Ellen Sletten | Bioorganic Chemistry; Supramolecular Chemistry (Org.); Main Group Chemistry (Inorg.); Supramolecular Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f13842e6577a5db3797/original/carborane-guests-for-cucurbit-7-uril-facilitate-strong-binding-and-on-demand-removal.pdf |
639231820fd99261d73dc526 | 10.26434/chemrxiv-2022-kq456 | A Comparison of Key Features in Melting Point Prediction Models for Quinones and Hydroquinones | Quinones and hydroquinones are small organic molecules with numerous applications: battery electrolytes, pharmaceuticals, sensors, to name a few. An understanding of their fundamental properties, such as melting points, is essential to incorporate these compounds into relevant technologies. In this study, two different approaches were investigated to predict the melting points of quinone and hydroquinone-based molecules. In the first approach, molecular features were calculated with the Mordred molecular descriptor calculator and used to train a ridge regression and a random forest machine learning (ML) model. In the second, a simpler featurization that captures key enthalpic and entropic descriptors was applied in three model variants - a thermodynamic model, a ridge regression model, and a random forest model. The Mordred-calculated features in the ridge regression model outperformed the thermodynamic features across all models for the quinone dataset (average absolute errors (AAE): 29.5 °C), but the thermodynamic features in the thermodynamic model resulted in lower prediction errors for the hydroquinone dataset (AAE: 35.4 °C). These results emphasize the importance of including intermolecular interaction descriptors, especially for classes of molecules in which these interactions are expected to be strong (e.g. hydrogen bonding in hydroquinones). As a byproduct of this study, we also consolidate (from previously published data) four new datasets with quinone and hydroquinone melting points and other key features. | Devi Ganapathi; Wunmi Akinlemibola; Antonio Baclig; Emily Penn; William Chueh | Theoretical and Computational Chemistry; Organic Chemistry; Computational Chemistry and Modeling; Machine Learning; Chemoinformatics - Computational Chemistry; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-12-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/639231820fd99261d73dc526/original/a-comparison-of-key-features-in-melting-point-prediction-models-for-quinones-and-hydroquinones.pdf |
60c75350f96a0057fc288418 | 10.26434/chemrxiv.13474659.v1 | On the Relationship Between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water | The split of the 1<i>b</i><sub>1</sub> peak observed in the X-ray emission (XE) spectrum of liquid water has been the focus of intense research over the last two decades. Although several hypotheses have been proposed to explain the origin of the 1<i>b</i><sub>1</sub> splitting, a general consensus has not yet been reached. In this study, we introduce a novel theoretical/computational approach which, combining path-integral molecular dynamics (PIMD) simulations carried out with the MB-pol potential energy function and time-dependent density functional theory (TD-DFT) calculations, correctly predicts the split of the 1<i>b</i><sub>1</sub> peak in liquid water and not in crystalline ice. A systematic analysis in terms of the underlying local structure of liquid water at ambient conditions indicates that several different hydrogen-bonding motifs contribute to the overall XE lineshape in the energy range corresponding to emissions from the 1<i>b</i><sub>1</sub> orbitals, which suggests that it is not possible to unambiguously attribute the split of the 1<i>b</i><sub>1</sub> peak to only two specific structural arrangements of the underlying hydrogen-bonding network. | Vinicius Cruzeiro; Andrew Wildman; Xiasong Li; Paesani Lab | Computational Chemistry and Modeling; Theory - Computational; Physical and Chemical Properties; Spectroscopy (Physical Chem.); Statistical Mechanics; Structure; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75350f96a0057fc288418/original/on-the-relationship-between-hydrogen-bonding-motifs-and-the-1b1-splitting-in-the-x-ray-emission-spectrum-of-liquid-water.pdf |
66e062cd12ff75c3a1f3a4df | 10.26434/chemrxiv-2024-t91vx | Unraveling the Mechanistic Insights of Electrochemical PFAS Substrate Degradation | Electrochemical per- and polyfluoroalkyl substances (PFAS) degradation is a promising and sustainable approach for the removal of persistent organic pollutants from aqueous environments. The use of molecular catalyst in degrading PFAS electrochemically has been rarely explored. Herein, we used a molecular Cu(I) electrocatalyst bearing triazole based ligands, [CuT2]•ClO4, that could cleave the C−F bonds under mild conditions. This work demonstrated the applicability to different PFAS substrates with variable chain lengths and different backbones by studying their behavior under controlled-current electrolysis. Additionally, we used mass spectrometry to identify the possible electrochemical degradation products. To get some kinetic insights, the [CuT2]+-PFAS interaction was studied using cyclic voltammetry and showed a slow e– transfer event with [CuT2]+ and PFAS binding. Moreover, it was observed that that the rate-limiting step is independent of the -CF2- functionalities present in the PFAS backbones. The electrochemical degradation of PFAS can offer potential for scalability and adaptability in wastewater treatment systems. | Ashwin Chaturvedi; Pramod Tiwari; Soumalya Sinha; Jianbing Jiang | Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66e062cd12ff75c3a1f3a4df/original/unraveling-the-mechanistic-insights-of-electrochemical-pfas-substrate-degradation.pdf |
63efb90dfcfb27a31ff39b08 | 10.26434/chemrxiv-2023-xhcx9 | DECIMER.ai - An open platform for automated optical chemical structure identification, segmentation and recognition in scientific publications | The number of publications describing chemical structures has increased steadily over the last decades. However, the majority of published chemical information is currently not available in machine-readable form in public databases. It remains a challenge to automate the process of information extraction in a way that requires less manual intervention - especially the mining of chemical structure depictions. As an open-source platform that leverages recent advancements in deep learning, computer vision, and natural language processing, DECIMER.ai (Deep lEarning for Chemical ImagE Recognition) strives to automatically segment, classify, and translate chemical structure depictions from the printed literature. The segmentation and classification tools are the only openly available packages of their kind, and the optical chemical structure recognition (OCSR) core application yields outstanding performance on all benchmark datasets. The source code, the trained models and the datasets developed in this work have been published under permissive licences. An instance of the DECIMER web application is available at https://decimer.ai. | Kohulan Rajan; Henning Otto Brinkhaus; M. Isabel Agea; Achim Zielesny; Christoph Steinbeck | Theoretical and Computational Chemistry; Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63efb90dfcfb27a31ff39b08/original/decimer-ai-an-open-platform-for-automated-optical-chemical-structure-identification-segmentation-and-recognition-in-scientific-publications.pdf |
67bfa4da6dde43c908a184c8 | 10.26434/chemrxiv-2025-s1r54 | Polariton Mediated Electron Transfer under the Collective Molecule-Cavity Coupling Regime | We investigate polariton-mediated electron transfer (PMET) under the collective molecule-cavity coupling regime, with the presence of dark state transfer, cavity loss, and continuous-wave (CW) laser driving using quantum dynamics simulations and analytic rate constant theories. We demonstrate how the PMET rate constant can be enhanced by the collective coupling effect, that is, light-matter coupling strength is small, but there are many molecules collectively coupled to the cavity. We demonstrate how the delocalized light-matter interactions, together with the local electronic donor-acceptor couplings can be used to enhance the rate constant of the charge transfer reactions. We further show that the PMET rate constant is affected by dark states and cavity loss which are often regarded as obstacles, and how to overcome them to provide a significant cavity-induced rate constant enhancement under the collective coupling regime. We first show how reactions initialized in the collective upper polariton (UP) state can significantly enhance the PMET rate constant by increasing the reaction driving force of an otherwise uphill ET reaction with collective strong coupling and positive detuning. We then show that by driving the UP state with a CW laser in a positively detuned cavity, the effective PMET rate constant can be several orders of magnitude larger than outside the cavity even with significant molecular disorder and cavity loss. These results reveal a promising approach to realize photochemical rate enhancement with collective strong coupling in disordered and lossy polariton systems as well as enable otherwise impractical uphill ET reactions. | Eric Koessler; Arkajit Mandal; Andrew Musser; Todd Krauss; Pengfei Huo | Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Chemical Kinetics; Photochemistry (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2025-02-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bfa4da6dde43c908a184c8/original/polariton-mediated-electron-transfer-under-the-collective-molecule-cavity-coupling-regime.pdf |
629486c2cd6c1c4473207c1f | 10.26434/chemrxiv-2022-mw2kb | PDTAC: Targeted photodegradation of GPX4 triggers Ferroptosis and potent antitumor immunity | Targeted degradation of proteins, especially those regarded as ‘undruggable’, attracts wide attention to develop novel potential therapeutic strategy. GPX4, a key enzyme regulating ferroptosis, is such a target whose inhibition is currently limited to molecules acting through covalently binding. Here, we have developed a targeted photolysis approach to achieve the efficiently degradation of GPX4. The Photo-Degradation TArgeting Chimeras (PDTACs) were synthesized by conjugating a clinically approved photosensitizer Verteporfin to GPX4-targeting peptides. Although the ligands themselves exhibit neither inhibitory nor degrading activity towards GPX4, these chimeras degraded selectively the target protein in living cells upon red-light irradiation. In contrast to the application of Verteporfin alone, the targeted photolysis of GPX4 resulted in dominant ferroptotic cell death in malignant cancer cells of different origins. Moreover, the dying cells resulted from our chimeras exhibited potent immunogenicity in vitro, and elicited more efficiently anti-tumor immunity in vivo in comparison with those dying from Verteporfin. Our approach therefore provides a novel method to dysfunction GPX4 based on noncovalent binding and specifically trigger immunogenic ferroptosis, which may boost the development of triggering ferroptosis as a potential strategy in cancer immunotherapy. | Sijin Liu; Xi Zhao; Sufang Shui; Biao Wang; Yingxian Cui; Tairan Yuwen; Suwei Dong; Guoquan Liu | Biological and Medicinal Chemistry; Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/629486c2cd6c1c4473207c1f/original/pdtac-targeted-photodegradation-of-gpx4-triggers-ferroptosis-and-potent-antitumor-immunity.pdf |
66a3175d01103d79c5b70f54 | 10.26434/chemrxiv-2024-r809t | Xanthopinacol Boronate: A Robust, Photochemically Assembled and Cleavable Boronic Ester for Orthogonal Chemistry | Organoboronic acids impact numerous fields of application from organic synthesis to materials science and drug discovery. However, their highly polar nature makes them challenging to handle, purify, and characterize. Boronic esters help overcome these issues, and pinacol esters (Bpin) have become the dominant boronic acid surrogate in organic synthesis. Despite its popularity, Bpin is not without drawbacks as it is intrinsically reversible in the presence of water or alcohols, which may cause issues of premature release leading to losses during reactions and purification. This reversibility complicates the hydrolytic regeneration of free boronic acids, which often requires additional steps to destroy the pinacol by-product. Although other boronyl protecting groups exist, their cleavage to afford the boronic acid tends to require harsh pH conditions. To address these issues, we developed xanthopinacol boronates (Bxpin), a robust protecting group for boronic acids with excellent orthogonality in various chemical reactions and mild irreversible removal. Xpin boronates can be obtained directly by irradiation of a mixture of free boronic acid and xanthone with UV light, causing an in-situ dimerization of xanthone to the required xanthopinacol. The unique attributes of xpin boronates were further studied by UV-Vis spectrophotometry, X-ray crystallography, cyclic voltammetry, and various stability tests. | David Heard; Martin Lessard; Dennis Hall | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66a3175d01103d79c5b70f54/original/xanthopinacol-boronate-a-robust-photochemically-assembled-and-cleavable-boronic-ester-for-orthogonal-chemistry.pdf |
678a84c381d2151a028a576f | 10.26434/chemrxiv-2025-xt9vs | Homochiral versus Racemic 2D Covalent Organic Frameworks | The synthesis of homochiral two-dimensional Covalent Organic Frameworks (2D COFs) from chiral pi-conjugated building blocks is challenging, as chiral units often lead to misaligned stacking interactions. In this work, we introduce helical chirality into 2D COFs using configurationally stable enantiopure and racemic [5]helicenes as linkers in the backbone of 2D [5]HeliCOFs. Through condensation with 1,3,5-triformylbenzene (TFB) or 1,3,5-triformylphloroglucinol (TFP), our approach enables the efficient formation of a set of homochiral and racemic 2D [5]HeliCOFs. The resulting carbon-based crystalline and porous frameworks exhibit distinct structural features and different properties between homochiral and their racemic counterparts. Propagation of helical chirality into the backbone of the crystalline frameworks leads to the observation of extended chiroptical properties in the far-red visible spectrum, along with a less compact structure compared to the racemic frameworks. The present study offers insight into general chiral framework formation and extends the Liebisch–Wallach rule to 2D COFs. | José del Refugio Monroy; Joel Schlecht; Clara Douglas; Robbie Stirling; Glen Smales; Zdravko Kochovski; Oliver Dumele | Organic Chemistry; Organic Synthesis and Reactions; Physical Organic Chemistry; Stereochemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678a84c381d2151a028a576f/original/homochiral-versus-racemic-2d-covalent-organic-frameworks.pdf |
60c745f9702a9b750918aaca | 10.26434/chemrxiv.10284266.v1 | Correlation Length in Concentrated Electrolytes: Insights from All-Atom Molecular Dynamics Simulations | <div><p>We study the correlations length of
the charge-charge pair correlations in concentrated electrolyte solutions by
means of all-atom, explicit-solvent molecular dynamics simulations. We
investigate LiCl and NaI in water, which constitute highly soluble, prototypical
salts for experiments, as well as two more complex, molecular electrolyte
systems of lithium bis(trifluoromethane)sulfonimide (LiTFSI), commonly employed
in electrochemical storage systems, in water and in an organic solvent mixture
of dimethoxyethane (DME) and dioxolane (DOL). Our simulations support the
recent experimental observations as well as theoretical predictions of a
non-monotonic behavior of the correlation length with increasing salt
concentration. We observe a Debye-Hückel like regime at low concentration,
followed by a minimum reached when <i>d/λ<sub>D</sub></i> = 1, where <i>λ<sub>D</sub></i> is the Debye
correlation length and d the effective ionic diameter, and an increasing
correlation length with salt concentration in very concentrated electrolytes.
As in the experiments, we find that the screening length in the concentrated
regime follows a universal scaling law as a function <i>d/λ<sub>D</sub></i> for all
studied salts. However, the scaling exponent is significantly lower than the
experimentally measured one, and lies in the range of the theoretical
predictions based on much simpler electrolyte models.</p>
</div> | Samuel Coles; Chanbum Park; Rohit Nikam; Matej Kanduč; Joachim Dzubiella; Benjamin Rotenberg | Computational Chemistry and Modeling; Theory - Computational; Electrochemistry - Mechanisms, Theory & Study; Statistical Mechanics | CC BY NC ND 4.0 | CHEMRXIV | 2019-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745f9702a9b750918aaca/original/correlation-length-in-concentrated-electrolytes-insights-from-all-atom-molecular-dynamics-simulations.pdf |
66595c1621291e5d1db6d407 | 10.26434/chemrxiv-2024-n5dl2 | Tunable Interlayer Interactions in 2D van der Waals Frameworks
| Two-dimensional materials can be isolated as monolayer sheets when interlayer interactions involve weak van der Waals forces. These rigorously atomically thin structures enable novel topological physics and open chemical questions of how to tune the structure and properties of the sheets while maintaining the sheets as isolated monolayers. Interactions between sheets and the properties they generate remain relatively neglected, as a consequence of this focus on their properties as monolayers. Here, we investigate two-dimensional porous sheets that exfoliate into isolated monolayers, but aggregate upon oxidation, giving rise to tunable interlayer charge transfer absorption and Stokes-shifted photoluminescence. This optical behavior resembles interlayer excitons, now intensely studied due to their long-lived emission, but which remain difficult to tune through synthetic chemistry. Instead, the interlayer excitons of these framework sheets can be modulated through control of solvent, electrolyte, oxidation state, and the composition of the framework building blocks. In comparison to other two-dimensional materials, these framework sheets display the largest known interlayer binding strengths, attributable to interactions between specific components within the sheets. Taken together, these results provide a microscopic basis for manipulating long-range opto-electronic behavior in van der Waals materials through molecular synthetic chemistry. | Jacob McKenzie; Doran Pennington; Kentaro Kadota; Thomas Ericson; Elana Cope; Anthony Cozzolino; Christopher Hendon; Carl Brozek | Inorganic Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Coordination Chemistry (Inorg.); Solid State Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66595c1621291e5d1db6d407/original/tunable-interlayer-interactions-in-2d-van-der-waals-frameworks.pdf |
6583785e66c1381729ac86f5 | 10.26434/chemrxiv-2023-z3t3b | Machine Learning Guided AQFEP: A Fast & Efficient Absolute Free Energy Perturbation Solution for Virtual Screening | Structure-based methods in drug discovery have become an integral part of the modern drug discovery process. The power of virtual screening lies in its ability to rapidly and cost-effectively explore enormous chemical spaces to select promising ligands for further experimental investigation. Relative Free Energy Perturbation (RFEP) and similar methods are the gold standard for binding affinity prediction in drug discovery hit-to-lead and lead optimization phases, but have high computational cost and the requirement of a structural analog with a known activity. Without a reference molecule requirement, Absolute FEP (AFEP) has, in theory, better accuracy for hit ID, but in practice, the slow throughput is not compatible with VS, where fast docking and unreliable scoring functions are still the standard. Here, we present an integrated workflow to virtually screen large and diverse chemical libraries efficiently, combining active learning with a physics-based scoring function based on a fast absolute free energy perturbation method. We validated the performance of the approach in the ranking of structurally related ligands, virtual screening hit rate enrichment, and active learning chemical space exploration; disclosing the largest reported collection of free energy simulations to date. | Jordan E. Crivelli-Decker; Zane Beckwith; Gary Tom; Ly Le; Sheenam Khuttan; Romelia Salomon-Ferrer; Jackson Beall; Rafael Gomez-Bombarelli; Andrea Bortolato | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Computational Chemistry and Modeling; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2023-12-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6583785e66c1381729ac86f5/original/machine-learning-guided-aqfep-a-fast-efficient-absolute-free-energy-perturbation-solution-for-virtual-screening.pdf |
62fc97417cdc05dc339f83f4 | 10.26434/chemrxiv-2022-695rj | Accelerated discovery of multi-elemental reverse water-gas shift catalysts using extrapolative machine learning approach | Designing novel catalysts is key to solving many energy and environmental challenges. Despite the promise that data science approaches, including machine learning (ML), can accelerate the development of catalysts, truly novel catalysts have rarely been discovered by ML because of one of its most common limitations and criticisms—the assumed inability of the models to extrapolate and identify extraordinary materials beyond those present in the training data set. Herein, we demonstrate an extrapolative ML approach to develop new multi-elemental catalysts based on supported Pt as an active metal and TiO2 as a support for the low-temperature reverse water-gas shift (RWGS) reaction. Using 45 catalysts as the initial data points and performing 44 cycles of the closed loop discovery system (ML prediction + experiment), we experimentally tested a total of 300 catalysts and identified more than 100 catalysts with superior activity as compared to the previously reported high-performance catalysts. The composition of the optimal catalyst discovered by this approach was Pt(3)/Rb(1)-Ba(1)-Mo(0.6)-Nb(0.2)/TiO2. Notably, Nb was not included in the original dataset, and the catalyst composition identified was unpredictable even by human experts. | Gang Wang; Shinya Mine; Duotian Chen; Yuan Jing; Kah Wei Ting; Taichi Yamaguchi; Motoshi Takao; Zen Maeno; Ichigaku Takigawa; Koichi Matsushita; Ken-ichi Shimizu; Takashi Toyao | Theoretical and Computational Chemistry; Materials Science; Catalysis; Chemoinformatics - Computational Chemistry; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62fc97417cdc05dc339f83f4/original/accelerated-discovery-of-multi-elemental-reverse-water-gas-shift-catalysts-using-extrapolative-machine-learning-approach.pdf |
67a22cff6dde43c90892089f | 10.26434/chemrxiv-2025-f37vv | A Zirconium-based Metal–Organic Framework as an Effective Green Catalyst for the Synthesis of Biodiesel | CAU-28 (CAU = Christian-Albrechts-University) is a zirconium-based metal–organic framework (MOF) that was first dis-covered in 2017. In addition to its biorenewable linker and green synthesis, which uses a microwave for only 2 hours, this MOF also features high thermal and chemical stability, surface area, and porosity. The hexanuclear zirconium clusters in CAU-28 are connected to only eight furan-2,5-dicarboxylic acid linkers, resulting in four open metal sites per cluster. These open metal sites display Lewis acidic properties and can be taken advantage of for many applications, including catalysis. In this work, we demonstrate the high potential of CAU-28 as a green catalyst to produce biodiesel through esterification reactions. Under optimized catalytic conditions, CAU-28 is able to convert oleic acid to its fatty acid methyl ester counterpart with high selectivity, using a catalyst loading of only 5 wt.% and 1:24 molar ratio of oleic acid:methanol, at 90 °C for 90 min. Furthermore, the catalyst also shows high stability, maintaining its activity for three reaction cycles. | Michelle P. Duarte; Clara V. Diniz; Hudson A. Bicalho; Rafik Naccache; Ashlee J. Howarth | Inorganic Chemistry; Catalysis; Coordination Chemistry (Inorg.); Acid Catalysis; Heterogeneous Catalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a22cff6dde43c90892089f/original/a-zirconium-based-metal-organic-framework-as-an-effective-green-catalyst-for-the-synthesis-of-biodiesel.pdf |
66847b5e01103d79c5d4b3c2 | 10.26434/chemrxiv-2024-b9kv2 | Pathways to Biorenewable Circularity in Crosslinked Cycloolefin Resins | Here, we show how to redesign cycloolefin resins for biorenewable circularity by addressing how bio-derived polar functionality influences ring strain, ring–chain equilibria, and likelihood for catalyst poisoning. These bio-based cycloolefin resins (bioCOR) are thermally and photochemically polymerizable, resulting in high-modulus thermosets with excellent thermal stability. Most notably, we found that the efficacy of thermoset deconstruction to the original crosslinker depended strongly on the ring-closing depolymerization catalyst. | Zhen Xu; Zi Wang; Maxwell Venetos; Sarah Klass; Pawan Khanal; Christopher Chan; Mutian Hua; Jay Keasling; Kristin Persson; Brett Helms | Organometallic Chemistry; Polymer Science; Biopolymers; Polymerization (Organomet.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66847b5e01103d79c5d4b3c2/original/pathways-to-biorenewable-circularity-in-crosslinked-cycloolefin-resins.pdf |
63b02547a2da4b3a72166f96 | 10.26434/chemrxiv-2022-rt0tw-v2 | Folding double-stranded DNA into designed shapes with triplex-forming oligonucleotides | The folding of double-stranded DNA around histones is a central mechanism in eukaryotic cells for compacting the genetic information into chromosomes. Very few artificial methods are available for controlling the shape of dsDNA at any level, whereas several artificial methods have been developed to efficiently organize single-stranded DNA and RNA into a variety of well-defined nanostructures by programmed self-assembly. Here, we show how long double-stranded DNA sequences can be spatially organized by triplex-forming oligonucleotides (TFOs), which bridge two or more encoded polypurine domains. The linearized or plasmid dsDNA is compacted into antiparallel folds, which enables the formation of raster-filled 2D shapes and 3D structures with either square or hexagonal organizations. Contrary to ssDNA, dsDNA has inherent rigidity which alleviates the requirement to saturate a structure with TFO strands, yet the TFOs are still able to bend the dsDNA controllably and steeply up to 180° over 6 bp. The majority of structures investigated here are formed by Hoogsteen interactions which require pH = 5-6, however, the methodology is also applied with reverse Hoogsteen interactions at physiological pH. In both cases, the DNA triplexes render pure polypurine scaffolded structures resistant to DNase I. | Cindy Ng; Anirban Samanta; Ole Aalund Mandrup; Emily Tsang; Sarah Youssef; Lasse Hyldgaard Klausen; Mingdong Dong; Minke Anne Door Nijenhuis; Kurt Vesterager Gothelf | Nanoscience; Nanostructured Materials - Nanoscience | CC BY 4.0 | CHEMRXIV | 2023-01-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63b02547a2da4b3a72166f96/original/folding-double-stranded-dna-into-designed-shapes-with-triplex-forming-oligonucleotides.pdf |
60c749f3337d6c09cae277bf | 10.26434/chemrxiv.12058929.v2 | Synthesis of Multilamellar Walls Vesicles (MLWV) Polyelectrolyte Surfactant Complexes (PESCs) from pH-Stimulated Phase Transition Using Microbial Biosurfactants | Multilamellar wall vesicles (MLWV) are an interest class of polyelectrolyte-surfactant complexes (PESCs) for the wide applications ranging from house-care to biomedical products. If MLWV are generally obtained by a polyelectrolyte-driven vesicle agglutination under pseudoequilibrium conditions, the resulting phase is often a mixture of more than one structure. In this work, we show that MLWV can be massively and reproductively prepared from a recentlydeveloped method involving a pH-stimulated phase transition from a complex coacervate phase (Co). We employ a biobased pH-sensitive microbial glucolipid biosurfactant in the presence of a natural, or synthetic, polyamine (chitosan, poly-L-Lysine, polyethylene imine, polyallylamine). In situ small angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) show a systematic isostructural and isodimensional transition from the Co to the MLWV phase, while optical microscopy under polarized light experiments and cryo-TEM reveal a massive, virtually quantitative, presence of MLWV. Finally, the multilamellar wall structure is not perturbed by filtration and sonication, two typical methods employed to control size distribution in vesicles. In summary, this work highlights a new, robust, non-equilibrium phase-change method to develop biobased multilamellar wall vesicles, promising soft colloids with applications in the field of personal care, cosmetics and pharmaceutics among many others. | Chloé Seyrig; Patrick Le Griel; Nathan Cowieson; Javier PErez; Niki Baccile | Aggregates and Assemblies; Biocompatible Materials; Polyelectrolytes - Materials; Surfactants; Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749f3337d6c09cae277bf/original/synthesis-of-multilamellar-walls-vesicles-mlwv-polyelectrolyte-surfactant-complexes-pes-cs-from-p-h-stimulated-phase-transition-using-microbial-biosurfactants.pdf |
617c5d98f9f05b636ee59728 | 10.26434/chemrxiv-2021-19l62 | Freeze-Float System for High-throughput Measurement of Ice Nucleation | In this publication, we developed the high throughput screening implementation of freeze-float selection platform system we established in the previous publication. The goal of this publication is to expand the system to higher throughput and accuracy. In the following sections, we describe the steps for automated droplets generations, adaptation of freeze-float selection using controlled and uniform temperature cooling system, and semi-automated droplets detection program. We aimed to improve previously published system to add functional advantages, such as; a) increased efficiency of the screening with fewer manipulation steps; b) increased accuracy of measurement due to the increased sample size; c) increased uniformity of temperature distribution by incorporating the controlled-rate freezer. In the following sections, we describe the steps for automated droplets generations, freeze-float system adaptations using controlled and uniform temperature cooling system, and semi-automated droplets detection program. | Yuki Kamijo; Ratmir Derda | Physical Chemistry; Interfaces | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/617c5d98f9f05b636ee59728/original/freeze-float-system-for-high-throughput-measurement-of-ice-nucleation.pdf |
62272bc2c45c0ba26d294f9f | 10.26434/chemrxiv-2022-8ssqx | Accelerated Synthesis and Discovery of Covalent Organic Framework Photocatalysts for Hydrogen Peroxide Production | A high-throughput sonochemical synthesis and testing strategy was developed to discover covalent organic frameworks (COFs) for photocatalysis. In total, 76 conjugated polymers were synthesized, including 60 crystalline COFs of which 18 were previously unreported. These COFs were then screened for photocatalytic hydrogen peroxide (H2O2) production using water and oxygen. One of these COFs, sonoCOF-F2, was found to be an excellent photocatalyst for photocatalytic H2O2 production even in the absence of sacrificial donors. However, after long-term photocatalytic tests (96 h), the imine sonoCOF-F2 transformed into an amide-linked COF with reduced crystallinity and loss of electronic conjugation, decreasing the photocatalytic activity. When benzyl alcohol was introduced to form a two-phase catalytic system, the photo-stability of sonoCOF-F2 was greatly enhanced, leading to stable H2O2 production for at least one week. | Wei Zhao; Peiyao Yan; Boyu Li; Mounib Bahri; Lunjie Liu; Xiang Zhou; Rob Clowes; Nigel D. Browning; Yue Wu; John W. Ward; Andrew I. Cooper | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62272bc2c45c0ba26d294f9f/original/accelerated-synthesis-and-discovery-of-covalent-organic-framework-photocatalysts-for-hydrogen-peroxide-production.pdf |
65df9c0c9138d2316141d526 | 10.26434/chemrxiv-2024-sdwfr | Mixed host co-assembled systems for broad-scope analyte sensing | Here we report a systems-oriented approach to developing information-rich mixed host chemosensors. We show that co-assembling macro-cyclic hosts from different classes, DimerDye sulfonatocalix[4]arenes and cucurbit[n]urils, effectively increases the scope of analyte binding interactions and therefore, sensory outputs. This simple dynamic strategy exploits cross-reactive noncovalent host-host complexation interactions while integrating a reporter dye, thereby producing emergent photophysical responses when an analyte interacts with either host. We first demonstrate the advantages of mixed host co-assembled chemosensors through an increased detection range of hydrophobic, cationic, neutral, and anionic drugs. We then implement mixed host sensors in an array-based platform for the differentiation of illicit drugs, including cannabinoids, benzodiazepine analogs, opiates, anesthetics, amphetamine, and common adulterating substances. Finally, the potential of this approach is applied to profiling real-world multi-component illicit street drug samples, proving to be more effective than classical sensor arrays. | Allison Selinger; Joana Krämer; Eric Poarch; Dennis Hore; Frank Biedermann; Fraser Hof | Organic Chemistry; Analytical Chemistry; Supramolecular Chemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65df9c0c9138d2316141d526/original/mixed-host-co-assembled-systems-for-broad-scope-analyte-sensing.pdf |
675c6c297be152b1d0e291d9 | 10.26434/chemrxiv-2024-gzvbj | A manganese(I) complex with a 190 ns metal-to-ligand charge transfer lifetime | The successful application of transition metal based photoactive complexes in lighting, imaging, sensing, and photocatalysis is usually based on the triplet metal-to-ligand charge transfer (3MLCT) excited state of precious metal complexes with 4d6 and 5d6 valence electron configuration. These photocatalysts exhibit excited state lifetimes exceeding hundreds of nanoseconds. Simple transition metal complexes with 3d6 valence electron configuration containing abundant metals exhibit lifetimes of less than 1-2 nanoseconds and they require multistep ligand syntheses mitigating large-scale implementation. We report that a commercially available bis(imidazolium) pyridine pro-ligand [H2pbmi]2+ and a manganese(II) salt give access to the tetracarbene manganese(I) complex [Mn(pbmi)2]+. This purple colored complex phosphoresces at room temperature in fluid solution. Its 3MLCT excited state lifetime of 190 ns exceeds those of simple 3MLCT photoactive 3d6 complexes by more than one to two orders of magnitude. In combination with its reversible ground state MnII/I redox chemistry, this translates to a 3MLCT excited state capable of reducing an organic substrate by bimolecular quenching. The combination of manganese(I) with rigid carbene and pyridine chelate ligands expands key strategies for photoactive 3d6 metal complexes of earth-abundant metals with 3MLCT lifetimes rivalling those of precious metals and providing a conceptual starting point for a sustainable photochemistry. | Sandra Kronenberger; Robert Naumann; Christoph Förster; Nathan East; Jan Klett; Katja Heinze | Physical Chemistry; Inorganic Chemistry; Transition Metal Complexes (Inorg.); Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675c6c297be152b1d0e291d9/original/a-manganese-i-complex-with-a-190-ns-metal-to-ligand-charge-transfer-lifetime.pdf |
60c74f71842e650abbdb3836 | 10.26434/chemrxiv.12905873.v1 | Formation of Corrugated 2D Tin Iodide Perovskites and Their Use as Lead-Free Solar Absorbers | Major strides have
been made in the development of materials and devices based around
low-dimensional hybrid group 14 metal halide perovskites. Thus far, this work
has mostly focused upon compounds containing highly toxic Pb, with the
analogous less toxic Sn materials being comparatively poorly evolved. In
response, the study herein aims to (i) provide insight into the impact of
templating cation upon the structure of 2D tin iodide perovskites, and (ii)
examine their potential as light absorbers for photovoltaic (PV) cells. It was
discovered through systematic tuning of organic dications, that imidazolium
rings are able to induce formation of (110)-oriented materials, including the
first examples of “3 × 3” corrugated Sn-I perovskites. This structural outcome
is a consequence of a combination of supramolecular interactions of the two
endocyclic N-atoms in the imidazolium functionalities with the Sn-I framework
and the higher tendency of Sn<sup>2+</sup> ions to stereochemically express their
5s<sup>2</sup> lone pairs relative to the 6s<sup>2</sup> electrons of Pb<sup>2+</sup>.
More importantly, the resulting materials feature very short separations
between their 2D inorganic layers with iodide–iodide (I···I) contacts as small
as 4.174 Å,
which is amongst the shortest ever recorded for 2D tin iodide perovskites. The
proximate inorganic distances, combined with the polarizable nature of the
imidazolium moiety, eases the separation of photogenerated charge within the
materials. This is evident from the excitonic activation energies as low as
83(10) meV, measured for ImEA[SnI<sub>4</sub>]. When combined with superior
light absorption capabilities relative to their lead congeners, this allowed
fabrication of lead-free solar cells with incident photon-to-current and power conversion
efficiencies of up to 70 % and 2.26 %, respectively, which are amongst the
highest values reported for pure 2D group 14 metal halide perovskites. In fact,
these values are superior to the corresponding lead iodide material, which
demonstrates that 2D Sn-based materials have significant potential as less
toxic alternatives to their Pb counterparts. | Benny Febriansyah; Yulia Lekina; Jagjit Kaur; Thomas J. N. Hooper; Padinhare Cholakkal Harikesh; Ming Hui Lim; Teck Ming Koh; Sudip Chakraborty; Ze Xiang Shen; Nripan Mathews; Jason England | Hybrid Organic-Inorganic Materials; Photovoltaics | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f71842e650abbdb3836/original/formation-of-corrugated-2d-tin-iodide-perovskites-and-their-use-as-lead-free-solar-absorbers.pdf |
60c7481c0f50db0b0239671a | 10.26434/chemrxiv.11858013.v1 | Bifunctional Activation of Methane by Bioinspired Transition Metal Complexes. A Simple Methane Protease Model | Bifunctional methane activation by M(II)-N2S motif. | Mary E. Anderson; Michael B. Marks; Thomas Cundari | Acid Catalysis; Base Catalysis; Biocatalysis; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7481c0f50db0b0239671a/original/bifunctional-activation-of-methane-by-bioinspired-transition-metal-complexes-a-simple-methane-protease-model.pdf |
63d8141de136d9bc55208310 | 10.26434/chemrxiv-2023-kxwvp | Bipolar membrane capacitive deionization for pH-assisted ionic separations | Selective ionic separations represent an increasingly important technical area for the strategic interests of the U.S. economy - e.g., securing critical minerals and materials and circular economy aspirations that include recovering organic acids from processed biomass. This work disseminates bipolar membrane (BPM) capacitive deionization for selective ionic separations from multi-component, ionic species mixtures. The selective separations are guided by the Pourbaix diagram and acid-base equilibria principles. BPM capacitive deionization was demonstrated to generate alkaline or acidic process streams depending upon the location of the BPM in the electrochemical cell. Prior to assessing BPM-membrane capacitive deionization (BPM-MCDI) for selective ionic separations, the role of system operating parameters on effluent stream pH was studied. pH adjustment in BPM-CDI/MCDI was more sensitive to cell voltage when compared to process stream residence time and salt feed concentration. The BPM-MCDI gave about 6x or greater higher copper(II) removal efficiency when compared to sodium ion removal efficiency from brine mixtures. Finally, BPM-MCDI demonstrated over 1.4x greater removal efficiency for copper ions from brine mixtures and 5x greater removal efficiency for itaconic acid from brine mixtures when benchmarked against a traditional flow-by-MCDI setup. | Tanmay Kulkarni; Aliya Muhammad; Christopher Arges | Chemical Engineering and Industrial Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63d8141de136d9bc55208310/original/bipolar-membrane-capacitive-deionization-for-p-h-assisted-ionic-separations.pdf |
643dd39f08c86922ff2f80bc | 10.26434/chemrxiv-2023-h05hr | INSPIRE: Development of an Interdisciplinary Summer Program in Research and Entrepreneurship | We developed the Interdisciplinary Science Program in Research and Entrepreneurship (INSPIRE) to address the changing career landscape that students with an interest in Physical Chemistry, Biophysics and Biochemistry face. Third and fourth-year undergraduate Chemistry and Physics students participated in a 4-week, hands-on program that introduced applications of biophysical and biochemical techniques to drug discovery, while simultaneously engaging in a crash course on entrepreneurship and pharma. The principal objective of the program was to introduce students to the interdisciplinary nature of Chemistry and Physics research in the Life Sciences while simultaneously introducing the idea of translating their future graduate work into a career in biotechnology. | Abootaleb Sedighi; Tudor Radu; Qirat Ashraf; Balmiki Kumar; Erica Quilates; Rima Rahmatullah; Joshua N. Milstein | Chemical Education; Chemical Education - General | CC BY 4.0 | CHEMRXIV | 2023-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643dd39f08c86922ff2f80bc/original/inspire-development-of-an-interdisciplinary-summer-program-in-research-and-entrepreneurship.pdf |
60c756229abda26718f8e4ba | 10.26434/chemrxiv.14152655.v1 | Strong Binding of Noble Gases to [B12X11]˗: A Theoretical Study | We systematically explore the stability and properties
of [B<sub>12</sub>X<sub>11</sub>Ng]<sup>−</sup> adducts resulting
from the capture reaction of noble gas atoms (Ng) by anionic [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> clusters in the ion
trap. [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> can be obtained by
stripping one X<sup>−</sup> ligand
off the icosahedral <i>closo</i>-dodecaborate
dianion [B<sub>12</sub>X<sub>12</sub>]<sup>2</sup><sup>−</sup>. We study the
binding of the noble gas atoms He, Ne, Kr, Ar and Xe to [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> with ligands X =
F, Cl, Br, I, CN. While He cannot be captured by these clusters and Ne only
binds at low temperatures, the complexes with the heavier Kr, Ar and Xe show
appreciable complexation energies and exceed 1 eV at room temperature in
the case of [B<sub>12</sub>(CN)<sub>11</sub>Xe]<sup>−</sup>. For the latter
three noble gases, we observe a significant charge transfer from the Ng to the icosahedral
B<sub>12</sub> cage. | Kevin Wöhner; Toshiki Wulf; Nina Vankova; Thomas Heine | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c756229abda26718f8e4ba/original/strong-binding-of-noble-gases-to-b12x11-a-theoretical-study.pdf |
61893bc28ac7a24f676c8d1b | 10.26434/chemrxiv-2021-fhtqz | Sustainable Production of Reduced Phosphorus Compounds: Mechanochemical Hydride Phosphorylation Using Condensed Phosphates as a Route to Phosphite | Phosphorus removal and recovery technologies have been implemented to tackle the anthropogenic eutrophication caused by phosphate runoff into waterways. In pursuit of a better utilization of the phosphates recovered from waste water treatment, we herein report that condensed phosphates can be employed to phosphorylate hydride reagents under solvent-free mechanochemical conditions to furnish phosphite (HPO3)2−, a versatile chemical with phosphorus in the +3 oxidation state. Hydride phosphorylation, as a two-electron one-proton reduction of a main group element oxide, constitutes a direct parallel with CO2 reduction to formate. Using potassium hydride as the hydride source, sodium trimetaphosphate (Na3P3O9 ), triphosphate (Na5P3O10), and pyrophosphate (Na4P2O7) engendered phosphite in 44, 58, and 44% yields based on total P content, respectively, under their optimal conditions. Formation of overreduced products including hypophosphite (H2PO2−) was identified as a competing process, and mechanistic investigation revealed that hydride attack on in situ generated phosphorylated phosphite species is a potent pathway for overreduction. The phosphite generated from our method could be easily isolated in the form of barium phosphite, a useful intermediate for production of phosphorous acid. This method circumvents the need to pass through white phosphorus (P4) as a high energy intermediate and mitigates involvement of environmentally hazardous chemicals. A bioproduced polyphosphate from baker’s yeast was demonstrated to be a viable starting material for the production of phosphite. This example demonstrates the possibility of accessing reduced phosphorus compounds in a more sustainable manner, and more importantly, closing the modern phosphorus cycle. | Feng Zhai; Tiansi Xin; Michael Geeson; Christopher Cummins | Biological and Medicinal Chemistry; Inorganic Chemistry; Agriculture and Food Chemistry; Food; Kinetics and Mechanism - Inorganic Reactions; Main Group Chemistry (Inorg.) | CC BY 4.0 | CHEMRXIV | 2021-11-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61893bc28ac7a24f676c8d1b/original/sustainable-production-of-reduced-phosphorus-compounds-mechanochemical-hydride-phosphorylation-using-condensed-phosphates-as-a-route-to-phosphite.pdf |
669f4b3301103d79c55418d6 | 10.26434/chemrxiv-2024-df783 | Chiral Symmetry Breaking in Colloidal Metal Nanoparticle Solutions by Circularly Polarized Light | Shape symmetry breaking in the formation of inorganic nanostructures is of large current interest. It was typically achieved through growth of colloidal nanoparticles with adsorbed chiral molecules. Photochemical processes induced through asymmetric plasmon excitation by circularly polarized light in surface immobilized nanostructures also led to symmetry breaking. Here we show that chiral symmetry breaking can be achieved on randomly rotating gold@silver core-shell nanobars in colloidal solution, by means of circularly polarized illumination, where orientational averaging does not eliminate the symmetry breaking of an asymmetric plasmon-induced galvanic replacement reaction. Different morphological effects that are produced by circularly vs. linearly polarized light illumination demonstrate the intricate effect of light polarization on the localized plasmonic-induced photochemical response. The symmetry breaking becomes smaller in more symmetric geometrical shapes such as triangular nanoprisms and nanocubes, down to zero in spherical ones. The symmetry breaking rises when the nanobars are immobilized on a substrate and illuminated from a single direction. | Monika Ghalawat; Daniel Feferman; Lucas Besteiro; Wanting He; Artur Movsesyan; Jesus Valdez; Audrey Moores; Zhiming Wang; Dongling Ma; Alexander Govorov; Gil Markovich | Nanoscience; Nanofabrication; Nanostructured Materials - Nanoscience; Plasmonic and Photonic Structures and Devices; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669f4b3301103d79c55418d6/original/chiral-symmetry-breaking-in-colloidal-metal-nanoparticle-solutions-by-circularly-polarized-light.pdf |
626d6340ef2ade173b434225 | 10.26434/chemrxiv-2022-zpl7n | Active states during the reduction of CO2 by an MoS2 electrocatalyst | Transition-metal dichalcogenides (TMDCs) such as MoS2 are earth-abundant catalysts that are attractive for many chemical processes, including the carbon dioxide reduction reaction (CO2RR). While many studies have correlated synthetic preparation and architectures with macroscopic electrocatalytic performance, not much is known about the state of MoS2 under functional conditions, particularly its interactions with target molecules like CO2. Here, we combine operando Mo K- and S K-edge X-ray absorption spectroscopy (XAS) with first-principles simulations to track changes in the electronic structure of MoS2 nanosheets during CO2RR. Comparison of the simulated and measured XAS discerned the existence of Mo-CO2 binding in the active state. This state perturbs hybridized Mo 4d-S 3p states and is critically mediated by sulfur vacancies induced electrochemically. The study sheds new light into the underpinnings of the excellent performance of MoS2 in CO2RR. The electronic signatures we reveal could be a screening criterion toward further gains in activity and selectivity of TMDCs in general. | Khagesh Kumar; Sasawat Jamnuch; Leily Majidi; Saurabh Misal; Alireza Ahmadiparidari; Michael Dato; George Sterbinsky; Tianpin Wu; Amin Salehi-Khojin; Tod Pascal; Jordi Cabana | Inorganic Chemistry; Catalysis; Energy; Spectroscopy (Inorg.); Electrocatalysis; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2022-05-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626d6340ef2ade173b434225/original/active-states-during-the-reduction-of-co2-by-an-mo-s2-electrocatalyst.pdf |
63c80dd53e865614b886e156 | 10.26434/chemrxiv-2023-bf0l3 | Calculation of the ELF in the excited state with single determinant methods | Since its first definition, back in 1990, the Electron Localization Function (ELF) has settled as one of the most commonly employed techniques to characterize the nature of the chemical bond in real space. Although most of the work using the ELF has been focused on the study of ground-state chemical reactivity, a growing interest has blossomed to apply these techniques to the nearly unexplored realm of excited states and photochemistry. Since accurate excited electronic states usually require to account appropriately for electron correlation, the standard single-determinant ELF formulation cannot be blindly applied to them, and it is necessary to turn to correlated ELF descriptions based on the two-particle density matrix (2-PDM). The latter require costly wavefunction approaches, unaffordable for most of the systems of current photochemical interest. Here, we compare exact, 2-PDM-based ELF results with those of approximate 2-PDM reconstructions taken from Reduced Density Matrix Functional Theory (RDMFT). Our approach is put to the test in a wide variety of representative scenarios, such as those provided by the lowest-lying excited electronic states of simple diatomic and polyatomic molecules. Altogether, our results suggest that even approximate 2-PDMs are able to accurately reproduce, on a general basis, the topological and statistical features of the ELF scalar field, paving the way toward the application of cost-effective methodologies, such as TD-HF or TD-DFT, in the accurate description of the chemical bonding in excited states of photochemical relevance. | Andrea Echeverri; Miguel Gallegos; Tatiana Gómez; Angél Martín Pendás; Carlos Cárdenas | Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Photochemistry (Physical Chem.); Structure | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63c80dd53e865614b886e156/original/calculation-of-the-elf-in-the-excited-state-with-single-determinant-methods.pdf |
623d89be74104fd471b18e45 | 10.26434/chemrxiv-2022-3w7gt-v2 | Circular Geometry in Molecular Stream Separation to Facilitate Non-Orthogonal Field-to-Flow Orientation | Molecular stream separation (MSS) is a promising complement for continuous-flow synthesis. MSS is driven by forces exerted on molecules by a field applied at an angle to the stream-carrying flow. MSS has only been performed with a 90 field-to-flow angle because of a rectangular geometry of canonic MSS; the second-order rotational symmetry of a rectangle prevents any other angle. Here, we propose a non-canonic circular geometry for MSS, which allows changing the field-to-flow angle. We conducted in silico and experimental studies of circular geometry for continuous-flow electrophoresis (CFE, an MSS method). Counterintuitively, circular CFE was found to support better flow and electric-field uniformity than rectangular CFE. We proved that the nonorthogonal field-to-flow orientation can result in a higher stream resolution than the orthogonal one. We foresee that circular CFE will serve as a new testbed for the investigation and creation of new CFE modalities. | Sven Kochmann; Nikita A. Ivanov; J.C. Yves Le Blanc; Boris I. Gorin; Sergey N. Krylov | Theoretical and Computational Chemistry; Physical Chemistry; Analytical Chemistry; Separation Science; Computational Chemistry and Modeling; Transport phenomena (Physical Chem.) | CC BY NC 4.0 | CHEMRXIV | 2022-03-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/623d89be74104fd471b18e45/original/circular-geometry-in-molecular-stream-separation-to-facilitate-non-orthogonal-field-to-flow-orientation.pdf |
6734e0327be152b1d0f9f875 | 10.26434/chemrxiv-2024-9m3pc-v3 | Association Kinetics for Perfluorinated n-Alkyl
Radicals | Radical-radical reaction channels are important in the pyrolysis and oxidation chemistry of perfluoroalkyl substances. In particular, unimolecular dissociation reactions within unbranched n-perfluoroalkyl chains, and their corresponding reverse barrierless association reactions, are expected to be significant contributors to the gas-phase thermal decomposition of families of species such as perfluorinated carboxylic acids and perfluorinated sulfonic acids. Unfortunately, experimental data for these reactions are scarce and uncertain. Furthermore, obtaining reliable theoretical predictions for such reactions is a laborious and computationally intensive task. In this work, we present state-of-the-art ab initio transition-state-theory-based master-equation calculations examining the chemical kinetics of the various association/decomposition reactions producing/decomposing the C2 − C4 series of unbranched n-perfluoroalkanes (C2F6, C3F8, and C4F10). The variable-reaction-coordinate transition-state theory (VRCTST) formalism is employed in computing the microcanonical and canonical rates for the association reactions. Reaction thermochemistry is obtained via composite quantum chemistry calculations and the laddering of error-cancelling reaction schemes via a connectivity-based hierarchy approach employing ANL1/ANL0-style reference energies. Lennard-Jones collision model parameters for the considered systems were estimated by a direct dynamics approach, and collisional energy transfer parameters were obtained from analogies to systems of similar size and heavy-atom connectivity. A one-dimensional master equation approach was used to convert the microcanonical rate coefficients from the VRC-TST analysis into temperature- and pressure-dependent rate constants for the association reactions and the reverse dissociation reactions. The data are reported in standardized formats for usage in comprehensive chemical kinetic models for PFAS thermal destruction. | Hrishikesh Ram; Yuri Georgievskii; Sarah Elliott; Stephen Klippenstein | Theoretical and Computational Chemistry; Physical Chemistry; Earth, Space, and Environmental Chemistry; Computational Chemistry and Modeling; Chemical Kinetics; Thermodynamics (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2024-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6734e0327be152b1d0f9f875/original/association-kinetics-for-perfluorinated-n-alkyl-radicals.pdf |
674432bc7be152b1d0af6d13 | 10.26434/chemrxiv-2024-h62w7 | Trapping crystallinity in highly crosslinked thermosets by light-based 3D printing from the liquid crystalline phase | We propel photopolymerizable liquid crystalline (LC) shape memory materials from solely elastomeric performance to the thermomechanical performance of tough, yielding thermosets. LC elastomers are at the forefront of smart, stimuli-responsive materials development. To apply their properties to mechanically superior thermosets, we demonstrate main-chain incorporation of high quantities of preordered LC motifs into a densely crosslinked network via thiol-ene photopolymerization to achieve a new material class hybridizing the advantages of LC elastomers and liquid crystalline networks. A terminal alkene mesogen with a robust LC phase is combined with multiple trithiol comonomers and selected based on resulting polymer crystallinities (13-37%). The bulk materials exhibit high strength, stiffness and pronounced yielding under stress with elongations around 200%. Their excellent thermomechanical properties were explained by phase separation observed in atomic force microscopy. Furthermore, we demonstrate shape memory of these materials with fast, near-perfect shape imprinting (99%) and recovery (97%) over at least 20 cycles, and their light-based 3D printing at high temperature. | Michael Göschl; Dominik Laa; Mojtaba Ahmadi; Thomas Koch; Jürgen Stampfl; Katharina Ehrmann; Robert Liska | Materials Science; Polymer Science; Liquid Crystals; Materials Processing; Polymerization (Polymers); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-11-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674432bc7be152b1d0af6d13/original/trapping-crystallinity-in-highly-crosslinked-thermosets-by-light-based-3d-printing-from-the-liquid-crystalline-phase.pdf |
67a9a4b2fa469535b9b5ba7d | 10.26434/chemrxiv-2025-jcdht | Direct Carbonate Reduction on Sn Oxide Surface | Direct reduction of carbonate (CO32‒) to value-added chemicals presents several advantages for integrating CO2 capture from air with electrochemical conversion at near-unity efficiency. However, a critical challenge lies in effectively adsorbing CO32‒ as a reactive intermediate for sequential reduction. Density functional theory calculations indicate that the presence of oxygen vacancies (xVO) on a SnO2 surface significantly enhances its reactivity toward CO32‒ adsorption, with the resulting adsorbed species (*CO3) detectable by Raman spectroscopy. Operando electrochemical Raman spectra have confirmed the formation of *CO3 on the partially reduced SnO2-xVO surface. Pulse electrolysis has successfully converted CO32‒ to CO at a constant flow rate in an electrolyzer featuring a gas diffusion electrode configuration. A reaction cycle, encompassing SnO2 partial reduction, CO32‒ adsorption and reduction, and SnO2 regeneration, has been proposed as a viable approach for continuous direct CO32‒ reduction. | Jun Wang; Lijuan Chen; Lan Huang; Tengfei Chen; Juqin Zeng; Wenbo Ju | Physical Chemistry; Catalysis; Energy; Electrocatalysis; Physical and Chemical Processes; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a9a4b2fa469535b9b5ba7d/original/direct-carbonate-reduction-on-sn-oxide-surface.pdf |
635d1711aa2784657a51a1e0 | 10.26434/chemrxiv-2022-kwj88 | Mechanical Evaluation of Hydrogel-Elastomer Interfaces Generated Through Thiol-Ene Coupling | The formation of hybrid hydrogel-elastomer scaffolds is an attractive strategy for the formation of tissue engineering constructs and microfabricated platforms for advanced in vitro models. The emergence of thiol-ene coupling, in particular radical-based, for the engineering of cell-instructive hydrogels and the design of elastomers raises the possibility of mechanically integrating these structures, without relying on the introduction of additional chemical moieties. However, the bonding of hydrogels (thiol-ene radical or more classic acrylate/methacrylate radical-based) to thiol-ene elastomers and alkene-functional elastomers has not been characterised in detail. In this study, we quantify the tensile mechanical properties of hybrid hydrogel samples formed of two elastomers bonded to a hydrogel material. We examine the impact of radical thiol-ene coupling on the crosslinking of both elastomers (silicone or polyesters) and hydrogels (based on thiol-ene crosslinking or diacrylate chemistry), and on the mechanics and failure behaviour of resulting hybrids. This study demonstrates the strong bonding of thiol-ene hydrogels to alkene-presenting elastomers with a range of chemistries, including silicones and polyesters. Overall, thiol-ene coupling appears as an attractive tool for the generation of strong, mechanically integrated, hybrid structures for a broad range of applications. | Khai Nguyen; Stéphane Dejean; Benjamin Nottelet; Julien Gautrot | Materials Science; Polymer Science; Biocompatible Materials; Elastic Materials; Hydrogels; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-10-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/635d1711aa2784657a51a1e0/original/mechanical-evaluation-of-hydrogel-elastomer-interfaces-generated-through-thiol-ene-coupling.pdf |
64e8160b79853bbd785d064b | 10.26434/chemrxiv-2024-zqbjt | On the Entanglement of Chromophore and Solvent Orbitals | Among various types of chromophore-solvent interactions, the entanglement of chromophore and solvent orbitals, when significant, can cause the chromophore frontier orbitals to spread over to nearby solvent molecules, introducing partial charge-transfer character to the lowest excitations of the chromophore and lowering the excitation energies. While highly intuitive, the physical details of such orbital entanglement effects on the excitation energies of chromophore have yet to be fully explored. Here, using two well-known biochromophores (oxyluciferin and p-hydroxybenzyledene imidazolinone) as examples, we show that the chromophore-solvent orbital entanglements can be elucidated using two quantum mechanical embedding schemes: density matrix embedding theory (DMET) and absolutely localized molecular orbitals analysis (ALMO). However, there remains a great challenge to incorporate the orbital entanglement effect in combined quantum mechanical molecular mechanical (QM/MM) calculations, and we hope that our findings will stimulate development of new methods in that direction | Xinwei Ji; Zheng Pei; Kim Ngan Huynh; Junjie Yang; Xiaoliang Pan; Binju Wang; Yuezhi Mao; Yihan Shao | Theoretical and Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2024-10-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e8160b79853bbd785d064b/original/on-the-entanglement-of-chromophore-and-solvent-orbitals.pdf |
659fbda79138d23161abddae | 10.26434/chemrxiv-2023-j6mvr-v3 | Pulse Dipolar Electron Paramagnetic Resonance Spectroscopy Distance Measurements at Low Nanomolar Concentrations: the Copper(II)-Trityl Case | Recent sensitivity enhancements in pulse dipolar EPR spectroscopy (PDS) have afforded distance measurements at submicromolar spin concentrations. This development opens the path for new science, as more biomolecular systems can be investigated at their respective physiological concentrations. Here, we demonstrate that the combination of orthogonal spin labelling using copper(II) ions and trityl yields a more than 3-fold sensitivity increase compared to the established copper(II)-nitroxide labelling strategy. Application of the recently developed variable-time RIDME method yields a further approximately 2.5-fold increase compared to the commonly used constant-time RIDME. This overall increase in sensitivity of almost an order of magnitude makes distance measurements in the range of 3 nm with protein concentrations as low as 10 nM feasible, more than two times lower than previously reported. We expect that experiments at single digit nanomolar concentrations are imminent, which has the potential to transform biological PDS applications. | Katrin Ackermann; Caspar Heubach; Olav Schiemann; Bela Bode | Physical Chemistry; Biological and Medicinal Chemistry; Biophysics; Biophysical Chemistry; Spectroscopy (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2024-01-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/659fbda79138d23161abddae/original/pulse-dipolar-electron-paramagnetic-resonance-spectroscopy-distance-measurements-at-low-nanomolar-concentrations-the-copper-ii-trityl-case.pdf |
60c75639337d6cfb00e28dc7 | 10.26434/chemrxiv.14217263.v1 | The Synthesis Properties and Reactivity of Lewis Acidic Aminoboranes | <div>
<p>The evolution of frustrated Lewis
pair chemistry has led to significant research into the development of new
Lewis acidic boranes. Much of this has focused on modifying aryl substituents
rather than introducing heteroatoms bound to boron. We recently reported unique
Lewis acidic behaviour from bis(pentafluorophenyl)phenothiazylborane (<b>1</b>)
for the heterolytic dehydrocoupling of stannanes. In this work, we synthesize and characterize a
family of Lewis acidic aminoboranes and explored their reactivity with various
Lewis bases as well as their efficacy as catalysts for stannane dehydrocoupling
and hydrosilylation. Quantum chemical caluclations were undertaken to
understand the origins of the Lewis acidity and the most Lewis acidic
aminoborane (<b>5</b>) was found to be an effective catalyst even in coordinating
solvents such as water or acetonitrile, suggesting the amino substituent
provides a level of protection against competing donors. </p>
</div>
<br /> | Jordan
N. Bentley; Selvyn A. Simoes; Ekadashi Pradhan; Tao Zeng; Chris Caputo | Main Group Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75639337d6cfb00e28dc7/original/the-synthesis-properties-and-reactivity-of-lewis-acidic-aminoboranes.pdf |
60c74aae702a9b8dd218b2ee | 10.26434/chemrxiv.12241193.v1 | An Unexpected Oxidative C-O Bond Formation: 11,17a-Dihydrobenzo[4,5]oxazolo[3,2-A]dinaphtho[2,1- C:1',2'-E]azepine | Phosphoric acids bound to 3,3’-subsituted 1,1’-binaphthalene-2,2’-diol (BINOL) have found wide application as effective asymmetric catalysts. In this work, we describe our attempt to construct a new binaphthalene-based phosphoric acid <b>6</b>. We found that both the key precursor <b>2</b> and the desired product <b>6 </b>decay rapidly and quantitatively to a stable dihydrooxazole <b>3</b> via an O<sub>2</sub>-driven oxidative C-O bond formation. | Michael Abraham; Philipp Honegger | Organic Synthesis and Reactions | CC BY 4.0 | CHEMRXIV | 2020-05-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74aae702a9b8dd218b2ee/original/an-unexpected-oxidative-c-o-bond-formation-11-17a-dihydrobenzo-4-5-oxazolo-3-2-a-dinaphtho-2-1-c-1-2-e-azepine.pdf |
648b636d4f8b1884b757d8a2 | 10.26434/chemrxiv-2023-hbrd6-v2 | Activation of N–O σ Bonds with Transition Metals: A Versatile Platform for Organic Synthesis and C–N Bonds Formation | N–O σ bonds containing compounds are versatile substrates for organic synthesis under transition metal catalysis. Their ability to react through both polar (oxidative addition, formation of metallanitrene, nucleophilic substitution) and radical pathways (single electron transfer, homolytic bond scission) have triggered the development of various synthetic methodologies, particularly toward synthesizing nitrogen-containing compounds. In this review, we discuss the different modes of activation of N–O bonds in the presence of transition metal catalysts, emphasizing the experimental and computational mechanistic proofs in the literature to help to design new synthetic pathways toward the synthesis of C–N bonds. | Uroš Todorović; R. Martin Romero; Lucile Anthore-Dalion | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/648b636d4f8b1884b757d8a2/original/activation-of-n-o-bonds-with-transition-metals-a-versatile-platform-for-organic-synthesis-and-c-n-bonds-formation.pdf |
64ecf53cdd1a73847fb7654c | 10.26434/chemrxiv-2023-pxlxb | Minimizing the environmental impacts of plastic through eco-design | While plastic pollution threatens ecosystems and human health, the use of plastic products continues to increase. Limiting its harm requires strategies when designing plastic products informed by the threats plastics pose to the environment. Thus, we developed a sustainability metric for the eco-design of plastic products with low environmental persistence and uncompromised performance. To do this, we integrated the environmental degradation rate of plastic into established material selection strategies, deriving material indices for environmental persistence. By comparing indices for the environmental impact of on-the-market plastics and proposed alternatives, we show that accounting for environmental persistence in design could translate to societal benefits of hundreds of millions of dollars for an individual consumer product. Our analysis identifies which materials deserve adoption and investment to create functional and less environmentally impactful products. | Bryan James; Collin Ward; Mark Hahn; Steven Thorpe; Christopher Reddy | Materials Science; Polymer Science; Earth, Space, and Environmental Chemistry; Biodegradable Materials; Cellulosic materials; Environmental Science | CC BY 4.0 | CHEMRXIV | 2023-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ecf53cdd1a73847fb7654c/original/minimizing-the-environmental-impacts-of-plastic-through-eco-design.pdf |
656eeddbcf8b3c3cd7d1d06d | 10.26434/chemrxiv-2023-brkl9 | Continuous Direct Mechanocatalytic Suzuki-Miyaura Coupling via Twin-Screw Extrusion | This work establishes the first direct mechanocatalytic reaction protocol within an extruder, focusing on the Suzuki-Miyaura reaction. Through the coating of either the extruder screws or barrel with Pd, we executed the cross-coupling reaction without the reliance on molecular catalyst compounds or powders, and solvents continuously. We identified the influence and interplay of crucial reaction parameters such as temperature, mechanical energy input, residence time, rheology, and catalyst contact time and finally obtained 36% and 75% of the reaction product after one and four reactor passes respectively. | Viviene Chantrain; Tilo Rensch; Wilm Pickhardt; Sven Graetz; Lars Borchardt | Organic Chemistry; Catalysis; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2023-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/656eeddbcf8b3c3cd7d1d06d/original/continuous-direct-mechanocatalytic-suzuki-miyaura-coupling-via-twin-screw-extrusion.pdf |
64b28daeb053dad33a4ad216 | 10.26434/chemrxiv-2023-dz9l7 | Rapid PROTAC discovery platform: nanomole scale array synthesis and direct screening of reaction mixtures to facilitate the expedited discovery and follow-up of PROTAC hits. | Precise linker length, shape and linker attachment point are all integral components to designing efficacious PROTACs. Due to the increased synthetic complexity of these heterobifunctional degraders and the difficulty of computational modelling to aid PROTAC design, the exploration of structure-activity-relationship (SAR) remains mostly empirical, which requires a significant time and resource investment. To facilitate rapid hit finding we developed capabilities for PROTAC parallel synthesis and purification by harnessing an array of pre-formed E3-ligand linker intermediates. In the next iteration of this approach, we developed a rapid, nanomole-scale PROTAC synthesis methodology using amide coupling that enables direct screening of non-purified reaction mixtures in cell-based degradation assays, as well as logD and EPSA measurements. This approach greatly expands and accelerates PROTAC SAR exploration (5 days instead of several weeks) while using nanomole amounts of reagents. Lastly, it avoids laborious and solvent-demanding purification of the reaction mixtures, thus making it an economical and more sustainable methodology for PROTAC hit finding. | Mateusz Plesniak; Emilia K. Taylor; Frederik Eisele; Christopher M. B. K. Kourra; Iacovos Michaelides; Alice Oram; Johan Wernevik; Zulma Santisteban-Valencia; Hannah Rowbottom; Nadia Mann; Linda Fredlund; Valentyna Pivnytska; Anna Noven; Mohammad Pirmoradian; Thomas Lundback; R. Ian Storer; Mariell Pettersson; Gian Marco De Donatis; Marie Rehnstrom | Biological and Medicinal Chemistry; Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64b28daeb053dad33a4ad216/original/rapid-protac-discovery-platform-nanomole-scale-array-synthesis-and-direct-screening-of-reaction-mixtures-to-facilitate-the-expedited-discovery-and-follow-up-of-protac-hits.pdf |
60c741a70f50dbf08b395b66 | 10.26434/chemrxiv.8080043.v1 | Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes | <p>Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length or strength of the resultant nanotubes. Imine-linked macrocycles were recently found to assemble into high-aspect ratio (>10<sup>3</sup>), lyotropic nanotubes in the presence of excess acid. Yet these harsh conditions are incompatible with many functional groups and processing methods, and lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine-2,6-diimine-linked macrocycles that assemble into high-aspect ratio nanotubes in the presence of less than 1 equiv of CF<sub>3</sub>CO<sub>2</sub>H per macrocycle. Analysis by gel permeation chromatography and fluorescence spectroscopy revealed a cooperative self-assembly mechanism. Nanofibers obtained by touch-spinning the pyridinium-based nanotubes exhibit Young’s moduli of 1.48 GPa, which exceeds that of many synthetic polymers and biological filaments. These findings will enable the design of structurally diverse nanotubes from synthetically accessible macrocycles. </p> | Michael J. Strauss; Darya Asheghali; Austin Evans; Rebecca Li; Anton Chavez; Chao Sun; Matthew Becker; William Dichtel | Supramolecular Chemistry (Org.); Liquid Crystals; Nanostructured Materials - Nanoscience; Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741a70f50dbf08b395b66/original/cooperative-self-assembly-of-pyridine-2-6-diimine-linked-macrocycles-into-mechanically-robust-nanotubes.pdf |
6176d099ac379fcd35be0138 | 10.26434/chemrxiv-2021-w6h5m | Flipping the switch: reverse-demand voltage-sensitive fluorophores | Fluorescence microscopy with fluorescent reporters that respond to environmental cues are a powerful method for interrogating biochemistry and biophysics in living systems. Photoinduced electron transfer (PeT) is commonly used as a trigger to modulate fluorescence in response to changes in the biological environment. PeT based indicators rely either on PeT into the excited state (acceptor PeT) or out of the excited state (donor PeT). Our group has been developing voltage-sensitive fluorophores (VF dyes) that respond to changes in biological membrane potential. We hypothesize that the mechanism of voltage sensitivity arises from acceptor PeT (a-PeT) from an electron-rich aniline-containing molecular wire into the excited state fluorophore, resulting in decreased fluorescence at negative membrane potentials. Here, we can reverse the direction of electron flow to access donor-excited PeT (d-PeT) VF dyes by introducing electron-withdrawing (EWG), rather than electron-rich molecular wires. Similar to first-generation aniline containing VF dyes, EWG-containing VF dyes show voltage-sensitive fluorescence, but with the opposite polarity: hyperpolarizing membrane potentials now give fluorescence increases. We use a combination of computation and experiment to estimate a ΔE of ~0.6 eV for voltage sensitivity in d-PeT indicators, show that two of the new reverse VF dyes are voltage sensitive, and provide the first example, to our knowledge, of a molecular sensor that can be tuned across energy regimes to access bi-directional electron flow for fluorescence sensing in living systems. | Jack McCann; Brittany Benlian; Isaac Knudson; Evan Miller | Biological and Medicinal Chemistry; Organic Chemistry; Photochemistry (Org.); Physical Organic Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6176d099ac379fcd35be0138/original/flipping-the-switch-reverse-demand-voltage-sensitive-fluorophores.pdf |
60c74cde0f50dbd7da396f17 | 10.26434/chemrxiv.12505187.v1 | Molecular Docking and Dynamic Simulation of UDP-N-Acetylenolpyruvoylglucosamine Reductase (MurB) Obtained from Mycobacterium Tuberculosis Using in Silico Approach | <p>The
UDP-N-acetylenolpyruvoylglucosamine reductase (MurB) catalyze the final steps
of the UDP-N-acetylmuramic acid (UDPMurNAc) formation in the peptidoglycan
biosynthesis pathway. The absence of this pathway in mammal made it an
attractive target for drug development in <i>Mycobacterium
tuberculosis</i> (MTB). In this study, the crystal structure of MurB from MTB (PDB
Code: 5JZX and resolution of 2.2 Å) bound to FAD and K<sup>+</sup> was obtained
from Protein Data Bank (PDB). A total of 2157 compounds with best binding
conformations obtained from zinc database through virtual screening. These
compounds further screened for drug-likeness, pharmacokinetic properties, physicochemical
properties (Lipinski rule of five), and molecular docking analysis to obtained
compounds with desirable therapeutic properties and good binding energies
against MurB. Seven compounds (7) with minimum binding energies ranged between
─11.80 and ─10.39kcal/mol were selected, lower than the binding energy of FAD
(─10.06kcal/mol). Four compounds with best binding energies (ZINC19837204 =
─11.80kcal/mol, ZINC11839554 = ─11.47kcal/mol, ZINC14976552 = ─10.77kcal/mol)
and ability to interact with the residues (ZINC12242812 = ─10.39kcal/mol) of
the substrate binding site further selected for the molecular dynamic (MD)
simulation analysis. The result of the MD simulation showed that all the four
ligands formed stable complexes in the binding site of the MurB, during the
50ns MD simulation, when compared with the cofactor (FAD). Therefore, these
compounds were proposed to be novel inhibitors of MTB after <i>in vivo</i> and <i>in vitro</i> validation.</p> | Mustafa Alhaji Isa; Mohammed Mustapha Mohammed | Bioinformatics and Computational Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74cde0f50dbd7da396f17/original/molecular-docking-and-dynamic-simulation-of-udp-n-acetylenolpyruvoylglucosamine-reductase-mur-b-obtained-from-mycobacterium-tuberculosis-using-in-silico-approach.pdf |
63cfaa151fb2a86691dece44 | 10.26434/chemrxiv-2023-d0gpc | The promotional role of Mn in CO2 hydrogenation over Rh-based catalysts from a surface organometallic chemistry approach | Rh-based catalysts modified by transition metals have been intensely studied for CO2 hydrogenation due to their high activity. However, understanding the role of promoters at the molecular-level remains challenging due to the ill-defined structure of heterogeneous catalysts. Here, we constructed well-defined RhMn@SiO2 and Rh@SiO2 model catalysts via surface organometallic chemistry combined with thermolytic molecular precursors (SOMC/TMP) approach to rationalize the promotional effect of Mn in CO2 hydrogenation. We found that the addition of Mn shifts the products from almost pure CH4 to a mixture of methane and oxygenates (CO, CH3OH, and CH3CH2OH) upon going from Rh@SiO2 to RhMn@SiO2. In situ X-ray absorption spectroscopy (XAS) confirms that the MnII is atomically dispersed in the vicinity of metallic Rh nanoparticles, and enables to induce the oxidation of Rh to form Mn-O-Rh interface under reaction conditions. The formed interface is key to maintain Rh+ site to promote the formation of CO, CH3OH and CH3CH2OH. | Wei Zhou; Scott R. Docherty; Christian Ehinger; Xiaoyu Zhou; Christophe Copéret | Catalysis; Heterogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2023-01-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63cfaa151fb2a86691dece44/original/the-promotional-role-of-mn-in-co2-hydrogenation-over-rh-based-catalysts-from-a-surface-organometallic-chemistry-approach.pdf |
62c5480fe60d982003f94933 | 10.26434/chemrxiv-2022-glxvs | Assessing Deep Generative Models in Chemical Composition Space | The computational discovery of novel materials has been one of the main motivations behind research in theoretical chemistry for several decades. Despite much effort, this is far from a solved problem, however. Among other reasons, this is due to the enormous space of possible structures and compositions that could potentially be of interest. In the case of inorganic materials, this is exacerbated by the combinatorics of the periodic table, since even a single crystal structure can in principle display millions of compositions. Consequently, there is a need for tools that enable a more guided exploration of the materials design space. Here, generative machine learning (ML) models have recently emerged as a promising technology. In this work, we assess the performance of a range of deep generative models based on Reinforcement Learning (RL), Variational Autoencoders (VAE) and Generative Adversarial Networks (GAN) for the prototypical case of designing Elpasolite compositions with low formation energies. By relying on the fully enumerated space of 2~million main group Elpasolites, the precision, coverage and diversity of the generated materials is rigorously assessed. Additionally, a hyperparameter selection scheme for generative models in chemical composition space is developed. | Hanna Türk; Elisabetta Landini; Christian Kunkel; Johannes T. Margraf; Karsten Reuter | Theoretical and Computational Chemistry; Machine Learning | CC BY NC 4.0 | CHEMRXIV | 2022-07-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c5480fe60d982003f94933/original/assessing-deep-generative-models-in-chemical-composition-space.pdf |
60c7487dbb8c1a27bb3dac8c | 10.26434/chemrxiv.11914239.v1 | Apparent Phototaxis Enabled by Brownian Motion | Biomimetic behaviour in artificially created active matter that allow deterministic and controlled motility has become of growing interest in recent years. It is well known that phototrophic bacteria optimize their position with respect to light by phototaxis. Here, we describe how our magnetic, photocatalytic microswimmers apparently undergo phototactic behaviour. Since there is no obvious reason for the particles to do so, we analyze different influences and elucidate through experiments and theoretical considerations from which physical circumstances this behaviour originates. | Lukas Niese; Linlin Wang; Sayan Das; Juliane Simmchen | Nanodevices; Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7487dbb8c1a27bb3dac8c/original/apparent-phototaxis-enabled-by-brownian-motion.pdf |
63e2559c1f23f0032d479094 | 10.26434/chemrxiv-2023-hfqxb | Data-Mining Unveils Structure-Property-Activity Correlation of Viral Infectivity Enhancing Self-Assembling Peptides | Gene therapy via retroviral vectors holds great promise for treating a variety of serious diseases. It requires the use of additives to boost infectivity. Amyloid-like peptide nanofibers (PNFs) were shown to efficiently enhance retroviral gene transfer. However, the underlying mode of action of these peptides remains largely unknown. This data-mining study elucidates the multi-scale structure-property-activity relationship of transduction enhancing peptides for retroviral gene transfer. In contrast to previous reports, we find that not the amyloid fibrils themselves, but rather m-sized -sheet rich aggregates enhance infectivity. Specifically, microscopic aggregation of -sheet rich amyloid structures with a hydrophobic surface pattern and positive surface charge were identified as key material properties. We validate the reliability of the amphiphilic sequence pattern and the general applicability of the key properties by rationally creating new active sequences and identifying short amyloidal peptides from various pathogenic and functional origin. Data-mining - even for small datasets - enables the development of new efficient retroviral transduction enhancers and provides important insights into the diverse bioactivity of the functional material class of amyloids. | Kübra Kaygisiz; Lena Rauch-Wirth; Arghya Dutta; Xiaoqing Yu; Yuki Nagata; Tristan Bereau; Jan Münch; Christopher V. Synatschke ; Tanja Weil | Materials Science; Polymer Science; Nanoscience; Aggregates and Assemblies; Fibers; Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63e2559c1f23f0032d479094/original/data-mining-unveils-structure-property-activity-correlation-of-viral-infectivity-enhancing-self-assembling-peptides.pdf |
652ff5ec2431cc1dacd1cac2 | 10.26434/chemrxiv-2023-rknf4 | Cobalt Catalyzed Enantioselective Reductive Coupling of Imines and Internal Alkynes | Chiral allylic amines hold significant importance as structural components in natural products, pharmaceuticals, and chiral catalysts. In this study, we have delved into cobalt-catalyzed enantioselective reductive coupling of imines with internal alkynes. The key to our success lies in developing a cobalt bisphosphine conglomerate catalyst and utilizing zinc as the electron donor. Our investigations have indicated that an in-situ cobalt(I) catalyst orchestrates the oxidative cyclization of alkynes and imines. Zinc plays a pivotal role in facilitating the transmetallation of the resulting azacobaltacycle. Subsequently, the organozinc intermediate is captured by a proton. Remarkably, the reaction proceeds under mild conditions and accommodates a wide range of substrates. Both symmetric and asymmetric alkyl and aryl alkynes have been successfully coupled with various imines. We have isolated tri- and tetrasubstituted allyl amines in exceptional yields exceeding 89%, with enantiomeric excess surpassing >99% and regioselectivities exceeding >20:1. These chiral allylic amines can serve as versatile platform molecules for subsequent transformations while preserving their stereochemical integrity to a high degree. | Kakoli Maji; Angshuman Palai; Biplab Maji | Organic Chemistry; Catalysis; Organometallic Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-10-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652ff5ec2431cc1dacd1cac2/original/cobalt-catalyzed-enantioselective-reductive-coupling-of-imines-and-internal-alkynes.pdf |
66ecde2b51558a15ef85ccb0 | 10.26434/chemrxiv-2024-86tvm | Extrudable and highly creep-resistant covalent adaptable networks made from polyethylene and ethylene/1-octene copolymers by reactive processing with aromatic disulfide cross-links | Polyolefins like polyethylene (PE) and ethylene-based copolymers are widely used in consumer and industrial applications due to their versatility, the diversity and tunability of their properties, and their theoretical recyclability at elevated temperatures. However, their recycling rates are markedly low, and, though the cross-linking of PE enhances its properties through the creation of a networked architecture, the resulting thermoset known as PEX is rendered completely unrecyclable. Incorporating associative or dissociative dynamic covalent bonds as cross-links into plastics like PE is a promising route both to make use of spent plastics (via “upcycling” them) and to generate recyclable alternatives to unrecyclable thermosets like PEX. Such materials are known as covalent adaptable networks or CANs (also called vitrimers if the cross-links are exclusively associative). Here, we present a method for imbuing ethylene-based polymers with aromatic disulfide dynamic covalent cross-links, resulting in robust, reprocessable CANs. Radical-based reactive processing of PE and ethylene/1-octene-based copolymers with 1 wt% dicumyl peroxide and 5 wt% bis(4-methacryloyloxyphenyl) disulfide (BiPheS methacrylate or BPMA) successfully resulted in CANs which fully recovered their cross-link densities and associated thermomechanical properties after multiple reprocessing cycles. These CANs demonstrate remarkable elevated-temperature creep resistance due to the high-temperature thermal stability and high temperatures required for exchanges of the BiPheS-based cross-links. BiPheS-based cross-links in PE and ethylene-based copolymer CANs also enable their (re)processability via extrusion at elevated temperatures, with property recovery demonstrated with extrusion temperatures as high as 260 °C, thereby indicating the feasibility of extending our approach to industrial scales and processes as well as other rigorous applications. | Mathew Suazo; Logan Fenimore; Stephanie Barbon; Hayley Brown; Evelyn Auyeung; Gerardo Cespedes; Colin Li Pi Shan; John Torkelson | Materials Science; Polymer Science; Chemical Engineering and Industrial Chemistry; Elastic Materials; Materials Processing; Polymer chains | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ecde2b51558a15ef85ccb0/original/extrudable-and-highly-creep-resistant-covalent-adaptable-networks-made-from-polyethylene-and-ethylene-1-octene-copolymers-by-reactive-processing-with-aromatic-disulfide-cross-links.pdf |
6191ab9b47f47d7288a1a442 | 10.26434/chemrxiv-2021-gqq59 | Multigram Scale Total Synthesis of Piperarborenines C-E | We report the development of a multigram scale total synthesis of heterodimeric β-truxinic imides piperarborenines C-E using a catechol-mediated diastereoselective intramolecular [2+2] photocycloaddition. Key innovations lie in the use of (1) catechol as a highly selective auxiliary for the robust and scalable synthesis of homo- and heterodimeric β-truxinates, (2) UV LEDs for direct excitation in the [2+2] cycloaddition step, and (3) a bis pentafluorophenyl ester and LDA for the challenging installation of the syn dihydropyridinone imides. This approach is exceptionally scalable – requiring minimal chromatography, no photocatalysts, and no cryogenic conditions - and will enable thorough evaluation of the biological properties and anticancer profiles of piperaborenines C-E and derivatives thereof. | Jason Lenihan; Matthew Mailloux; Aaron Beeler | Organic Chemistry; Organic Synthesis and Reactions; Photochemistry (Org.); Process Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6191ab9b47f47d7288a1a442/original/multigram-scale-total-synthesis-of-piperarborenines-c-e.pdf |
650c9935ed7d0eccc3f9dc68 | 10.26434/chemrxiv-2023-tj7m0 | Orientation of Cobalt-Phthalocyanines on Molybdenum disulfide: Distinguishing between Single Crystals and Small Flakes | Heterostructures consisting of transition metal dichalcogenides (TMDCs) and organic molecules are currently of enormous interest for a variety of applications. Comparably weakly interacting molecules like phthalocyanines exhibit a high potential for the tuning of electronic properties of TMDCs. Knowledge of the molecular orientation is a prerequisite for the understanding of the nature and strength of the interfacial interaction. We study the molecular orientation of cobalt phthalocyanine (CoPc) and perfluorinated (CoPcF16) on both large molybdenum disulfide (MoS2) single crystals and small MoS2 flakes using synchrotron-based techniques: X-ray absorption spectroscopy (XAS) at the Co L3 edge and spectromicroscopy in a photoemission electron microscope (PEEM). We show that the orientation can be radically different on both substrates. Whereas on large crystals an almost flat-lying orientation is observed, significant tilt angles were found on smaller flakes. The orientation depends crucially on the number of MoS2 layers and/or the size of flat terraces. | Philipp Haizmann; Eric Juriatti; Maren Klein; Katharina Greulich; Peter Nagel; Michael Merz; Stefan Schuppler; Amir Ghiami; Ruslan Ovsyannikov; Erika Giangrisostomi; Thomas Chassé; Marcus Scheele; Heiko Peisert | Physical Chemistry; Materials Science; Nanoscience; Thin Films; Interfaces; Surface | CC BY 4.0 | CHEMRXIV | 2023-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/650c9935ed7d0eccc3f9dc68/original/orientation-of-cobalt-phthalocyanines-on-molybdenum-disulfide-distinguishing-between-single-crystals-and-small-flakes.pdf |
66afbed401103d79c5bcf1ec | 10.26434/chemrxiv-2023-njjmp-v2 | Redox Properties of [Cp*Rh] Complexes Supported by Mono-substituted 2,2′-Bipyridyl Ligands | The redox properties of half-sandwich rhodium complexes supported by 2,2′-bipyridyl (bpy) ligands can be readily tuned by selection of an appropriately substituted derivative of bpy, but the influences of single substituents on the properties of such complexes are not well documented, as disubstituted bpy variants are much more common. Here, the synthesis, characterization, and redox properties of two new [Cp*Rh] complexes (where Cp* is η5-1,2,3,4,5-pentamethylcyclopentadienyl) supported by the uncommon mono-substituted ligands 4-chloro-2,2′-bipyridyl (mcbpy) and 4-nitro-2,2′-bipyridyl (mnbpy) are reported. Single-crystal X-ray diffraction studies and related spectroscopic experiments confirm installation of the single substituents (–Cl and –NO2, respectively) on the bipyridyl ligands; the precursor monosubstituted ligands were prepared via a divergent route from unsubstituted bpy. Electrochemical studies reveal that each of the complexes undergoes an initial net-two-electron reduction at potentials more positive than that associated with the parent unsubstituted complex of bpy, and that the complex supported by mnbpy can undergo a third, chemically reversible reduction at –1.62 V vs. ferrocenium/ferrocene. This redox behavior is consistent with inductive influences from the substituent groups on the supporting ligands, although the nitro group uniquely enables addition of a third electron. Spectrochemical studies carried out with UV-visible detection confirm the redox stoichiometry accessible to these platforms, highlighting the rich redox chemistry and tunable behavior of [Cp*Rh] complexes supported by bpy-type ligands. | Jonah Stiel; Wade Henke; William Moore; Nathaniel Barker; Allen Oliver; Victor Day; James Blakemore | Inorganic Chemistry; Electrochemistry; Transition Metal Complexes (Inorg.); Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66afbed401103d79c5bcf1ec/original/redox-properties-of-cp-rh-complexes-supported-by-mono-substituted-2-2-bipyridyl-ligands.pdf |
6758bbdff9980725cfa8e479 | 10.26434/chemrxiv-2024-7c6g7-v2 | Imine-Oxazoline (ImOx): A C1-Symmetric N,N-Bidentate Ligand for Asymmetric Catalysis | Asymmetric catalysis relies on the design of chiral ligands, but the variety of nitrogen-based ligands remains limited To address this gap, we have developed a class of C1-symmetric N,N-bidentate ligand, imine-oxazoline (ImOx), derived from amino acids through a four-step synthesis. ImOx features an imine moiety conjugated with a chiral oxazoline ring, as a hybrid of α-diimine (ADI) and pyridine oxazoline (PyOx) ligands. Its low symmetry allows for independent optimization at both coordination sites. ImOx improves the enantioselectivity of palladium-catalyzed conjugate addition reactions, demonstrating a strong correlation between ee and the steric effects on both the imine and oxazoline sites. Studies on well-defined organopalladium intermediates reveal that the steric bulk of ImOx necessitates a cationic pathway to promote alkene insertion. Structural characterization if ImOx suggests a stronger trans-influence compared to PyOx. Moreover, ImOx demonstrates excellent redox activity, promoting the reduction of nickel complexes and stabilizing nickel radical complexes. We anticipate that ImOx will expand the toolkit of chiral N-ligands for asymmetric catalysis. | Elliot Silk; Alexander Shtukenberg; Tianning Diao | Organometallic Chemistry; Ligand Design | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6758bbdff9980725cfa8e479/original/imine-oxazoline-im-ox-a-c1-symmetric-n-n-bidentate-ligand-for-asymmetric-catalysis.pdf |
6417a2ad2bfb3dc25108d31c | 10.26434/chemrxiv-2023-443cj | Near-Infrared-Light-Activatable Proximity Labeling of Bead-Binding Proteins | Photocatalytic proximity labeling has recently undergone significant advances as a valuable tool for understanding protein–protein and cell–cell interactions. This paper reports the first photocatalytic protein-labeling approach in which the reaction can be controlled using near-infrared (NIR) light (810 nm). Magnetic affinity beads with encapsulated sulfur-substituted silicon (IV) phthalocyanine, which produces singlet oxygen upon NIR irradiation, were prepared. We have developed a method in which the histidine residues of proteins bound to the ligands on the beads are selectively oxidized and labeled by the nucleophilic labeling reagent while minimizing nonspecific adsorption to the dye. Beads with aryl sulfamide, lactose, or CZC-8004 ligands immobilized on their surface can be used to label proteins that bind these ligands, as well as their protein–protein interaction partners. | Shinichi Sato; Keita Nakane; Yuki Hoshino; Kosuke Dodo; Shusuke Tomoshige; Minoru Ishikawa; Taniyuki Furuyama | Biological and Medicinal Chemistry; Catalysis; Chemical Biology; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6417a2ad2bfb3dc25108d31c/original/near-infrared-light-activatable-proximity-labeling-of-bead-binding-proteins.pdf |
60c74f28337d6cac3de280ac | 10.26434/chemrxiv.12855551.v1 | Integral Mass Balance (IMB) Method for Measuring Multicomponent Gas Adsorption Equilibria in Nanoporous Material | Multicomponent gas adsorption equilibria must be determined in order to assess the performance
of an adsorbent for a particular gas separation and for process design. The experimental
techniques commonly used for this purpose, however, are time-consuming and typically require
large samples. In this article, we describe a new approach, called the Integral Mass Balance
(IMB) method, which combines the controlled flow of a gas mixture with in-situ gravimetric
measurement and gas composition analysis using quadrupole mass spectrometry. The IMB
method allows very rapid equilibrium multicomponent gas adsorption measurements to be
performed on samples weighing only a few grams. The method is demonstrated and validated by
performing binary O2/N2 adsorption measurements on a commercial 5A zeolite, at ambient temperature and a total pressure of 0.915 MPa. Excellent agreement with previously published
data was found, using a 3.5 g sample, with a measurement time of only four hours for a twenty
point isotherm. In contrast, other techniques of equivalent accuracy would require around twenty
days of experimental effort to collect a comparable amount of data. Selectivities were also
calculated and shown to agree with previously published results. In principle, the technique
could readily be extended to measure gas adsorption from ternary or higher mixtures.
<br /> | Darren Broom; Orhan Talu; Michael J. Benham | Thermodynamics (Chem. Eng.); Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f28337d6cac3de280ac/original/integral-mass-balance-imb-method-for-measuring-multicomponent-gas-adsorption-equilibria-in-nanoporous-material.pdf |
6115d8153b558f4d27fc67a4 | 10.26434/chemrxiv-2021-kmfr5-v3 | Lewis acid-mediated Suzuki–Miyaura Cross-Coupling Reaction | The palladium-catalysed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organoborons is a reliable method for carbon–carbon bond formation. This reaction involves a base-mediated transmetalation process, but the presence of a base also promotes competitive protodeborylation, which reduces the efficiency. Herein, we established an SMC reaction via Lewis acid-mediated transmetalation of an organopalladium(II) intermediate with organoborons. Experimental and theoretical investigations indicate that the controlled release of the transmetalation-active intermediate enabled base-independent transmetalation under heating conditions and enhanced the applicable scope of this process. This system enabled us to avoid the addition of a base, and thus, rendered substrates with base-sensitive moieties available. Results from this research further expand the overall utility of cross-coupling chemistry. | Takashi Niwa; Yuta Uetake; Motoyuki Isoda; Tadashi Takimoto; Miki Nakaoka; Daisuke Hashizume; Hidehiro Sakurai; Takamitsu Hosoya | Organic Chemistry; Catalysis; Organometallic Chemistry; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6115d8153b558f4d27fc67a4/original/lewis-acid-mediated-suzuki-miyaura-cross-coupling-reaction.pdf |
6720aaa35a82cea2fa2fa00e | 10.26434/chemrxiv-2024-99gt2-v2 | Elucidation of the activity and pH stability limits of polyoxometalate-intercalated layered double hydroxide nanocomposites towards water oxidation catalysis | The inclusion of water oxidation active polyoxometalates (POMs) inside layered materials is a promising strategy to increase their catalytic efficiency while overcoming their fragility under homogeneous conditions. In this sense, intercalation of POMs in the interlaminar space of layered double hydroxides (LDHs), formed by positively charged brucite-type inorganic layers, is a very interesting strategy that is gaining attention in the field. Despite their huge potential, there is a lack of accurate characterization of the materials, especially after their use as water oxidation catalysts in pH conditions in which the POM counterpart has been demonstrated to be unstable (strong alkali media). For this reason and as a proof-of-concept, we have intercalated the well-known [Co4(H2O)2(PW9O34)2]10- POM (Co4-POM) in the lamellar space of the Mg2Al-LDH layered double hydroxide, to study its catalytical capabilities and stability. Remarkably, the nanocomposites show improved water oxidation efficiencies with excellent stability in close-to-neutral media compared to the water-insoluble cesium salt of Co4-POM or commercial Co3O4. However, thorough post-catalytic characterization of the nanocomposites demonstrates that the polyoxotungstate framework of the POM suffers from hydrolytic instability in strong alkali conditions, leading to the formation of a mixed-valence cobalt(II/III) oxide in the interlayer space of Mg2Al-LDH. This work highlights the importance of accurately assessing the fate of the catalytical POM after the catalytic reaction, especially when employing conditions outside the pH stability window of the POM, which can lead to erroneous conclusions and mistaken catalytic activities. | Joaquín Soriano-López; Javier Quirós-Huerta; Álvaro Seijas-Da Silva; Ramón Torres-Cavanillas; Eduardo Andres-Garcia; Gonzalo Abellán; Eugenio Coronado | Catalysis; Energy; Electrocatalysis; Heterogeneous Catalysis; Fuels - Energy Science; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6720aaa35a82cea2fa2fa00e/original/elucidation-of-the-activity-and-p-h-stability-limits-of-polyoxometalate-intercalated-layered-double-hydroxide-nanocomposites-towards-water-oxidation-catalysis.pdf |
660155b066c1381729c4d24a | 10.26434/chemrxiv-2024-tkd72 | Development of a novel class of CBP/EP300 bromodomain inhibitors which block TNF-α induced NFκB signaling | Tumor Necrosis Factor α (TNF-α) is an inflammatory cytokine that is a key mediator in autoimmune disorders such as Crohn’s disease and rheumatoid arthritis (RA). Targeting epigenetic regulators of cytokine transcription and signaling is a promising therapeutic approach. However, the specific mechanisms by which they contribute to the immune response are not well established yet. Here, we present a new class of selective CBP/EP300-bromodomain (BRD) inhibitors comprising a 3-methylcinnoline as acetyl-lysine mimic discovered by high-throughput docking of a fragment library. These compounds inhibit NFκB signaling in THP-1 cells, reducing TNF-α-induced cytokine expression in vitro. Furthermore, when tested in vivo, BRD inhibitors reduced the pro-inflammatory response by decreasing the secretion of IL-1β, MCP-1, IL-1α, and IL-6 from TNF-α-stimulated animals and inhibiting the migration of innate immune cells towards the draining lymph node. The results of this study confirmed CBP/EP300-BRD as valid therapeutic targets for autoimmune diseases and our inhibitors represent a promising new class of non-cytotoxic therapeutic agents for treating RA. | Katherine Gosselé; Irene Latino; Eleen Laul; Mariia Kirillova; Vlad Pascanu; Emanuele Carloni; Rajiv Bedi; Amedeo Caflisch; Santiago Gonzalez; Cristina Nevado | Biological and Medicinal Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/660155b066c1381729c4d24a/original/development-of-a-novel-class-of-cbp-ep300-bromodomain-inhibitors-which-block-tnf-induced-nf-b-signaling.pdf |
671e8e7698c8527d9e8c9ab0 | 10.26434/chemrxiv-2024-sp5jg | Synthesis and Redox Properties of Nickel Pincer Complexes Featuring an X-type Bismuth Ligand | This communication reports the synthesis of a new neutral and a cationic Ni(II) complex featuring a PBiP pincer ligand (BiNiCl and BiNiAcN) through oxidative addition of a Ni(0) precursor. Crystal structures revealed that the sigma-donating bismuthane exerts insignificant trans influence on the nickel. Cyclic voltammetry and orbital analysis highlight the redox-noninnocence of the PBiP ligand and potential redox-induced structural decomposition of the complexes. | Kim Gates; Yuka Aoyama; Hang Cao; Gongfang Hu | Organometallic Chemistry; Electrochemistry - Organometallic; Main Group Chemistry (Organomet.); Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671e8e7698c8527d9e8c9ab0/original/synthesis-and-redox-properties-of-nickel-pincer-complexes-featuring-an-x-type-bismuth-ligand.pdf |
6113ca8f03182fab861de3b7 | 10.26434/chemrxiv-2021-sbpbk | Targeted positioning of quantum dots inside 3D silicon photonic crystals revealed by synchrotron X-ray fluorescence tomography | It is a major outstanding goal in nanotechnology to precisely position functional nanoparticles, such as quantum dots, inside a three-dimensional (3D) nanostructure in order to realize novel functions.
Once the 3D positioning is performed, the challenge arises how to non-destructively verify where the nanoparticles reside in the 3D nanostructure.
Here, we study 3D photonic band gap crystals made of Si that are infiltrated with PbS nanocrystal quantum dots.
The nanocrystals are covalently bonded to polymer brush layers that are grafted to the Si-air interfaces inside the 3D nanostructure using surface-initiated atom transfer radical polymerization (SI-ATRP).
The functionalized 3D nanostructures are probed by synchrotron X-ray fluorescence (SXRF) tomography that is performed at 17 keV photon energy to obtain large penetration depths and efficient excitation of the elements of interest.
Spatial projection maps were obtained followed by tomographic reconstruction to obtain the 3D atom density distribution with 50 nm voxel size for all chemical elements probed: Cl, Cr, Cu, Ga, Br, Pb.
The quantum dots are found to be positioned inside the 3D nanostructure, and their positions correlate with the positions of elements characteristic of the polymer brush layer and the ATRP initiator.
We conclude that X-ray fluorescence tomography is very well suited to non-destructively characterize 3D nanomaterials with photonic and other functionalities. | Andreas S. Schulz; Cornelis A. M. Harteveld; G. Julius Vancso; Jurriaan Huskens; Peter Cloetens; Willem L. Vos | Materials Science; Polymer Science; Nanoscience; Optical Materials; Polymer brushes; Nanofabrication | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6113ca8f03182fab861de3b7/original/targeted-positioning-of-quantum-dots-inside-3d-silicon-photonic-crystals-revealed-by-synchrotron-x-ray-fluorescence-tomography.pdf |
65a9927de9ebbb4db979e1d8 | 10.26434/chemrxiv-2024-ql0bc | Organic semiconductor-BiVO4 tandems for solar-driven H2O and CO2 splitting | Photoelectrochemical (PEC) systems offer a promising platform towards direct solar light harvesting and chemical storage. However, most prototypes employ wide bandgap semiconductors, moisture-sensitive inorganic light absorbers, or corrosive electrolytes. Here, we introduce PEC devices based on an organic donor-acceptor bulk heterojunction (BHJ), which demonstrate long-term H2 evolution and CO2 reduction in benign aqueous media using a carbon-based encapsulant. Accordingly, PCE10:EH-IDTBR photocathodes display long-term H2 production for 300 h in a near-neutral pH solution, whereas photocathodes with a molecular CO2 reduction catalyst attain a CO:H2 selectivity of 5.41±0.53 under 0.1 sun irradiation. Their early onset potentials enable the assembly of PCE10:EH-IDTBR - BiVO4 artificial leaves, which couple unassisted syngas production with O2 evolution, sustaining a 1:1 ratio of CO to H2 over 96 h of operation. | Celine Yeung; Virgil Andrei; Tack Ho Lee; James Durrant; Erwin Reisner | Catalysis; Energy | CC BY 4.0 | CHEMRXIV | 2024-01-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a9927de9ebbb4db979e1d8/original/organic-semiconductor-bi-vo4-tandems-for-solar-driven-h2o-and-co2-splitting.pdf |
67d2a06b6dde43c908a0d57b | 10.26434/chemrxiv-2025-1hcft | Structural Transformations within the Solvate Ionic Liquid [Li(Triglyme)][NTf2]: Implications for Self-Diffusion, Viscosity, and Ionic Conductivity | Solvate ionic liquids (SILs) are a promising new class of electrolytes for lithium-ion batteries. Prominent SIL candidates are equimolar mixtures of lithium salts with weakly interacting anions and glyme. In particular, the equimolar mixture of lithium ([Li]+)(bis(trifluoromethanesulfonyl)imide ([NTf2]-) and triglyme (G3) is of great interest. It has been suggested that this mixture exhibits a behavior similar to ionic liquids due to the formation of stable 1:1 complexes of [Li]+ with G3 molecules. We use up to multi-mocrosecond molecular dynamics (MD) simulations to better understand the structure and dynamics of the mixtures for varying mixing ratios and temperatures and to characterize the typical coordination patterns of the [Li]+ complexes. We find that at low [Li][NTf2] content, each [Li]+ cation is, on average, coordinated by two G3 molecules. For nearly equimolar mixtures, the complex changes to a one-fold G3-coordinated cation plus one additional anion. For higher than equimolar salt concentrations, cations are increasingly surrounded by their counterions, forming lithium bridges between adjacent anions. We observe that the structure primarily depends on the mixture composition while it is remarkably temperature-insensitive. The latter suggests that cluster equilibria in the SIL are subject to only small entropy differences, retaining the SIL-like structural features up to more than 200 degrees Celsius. We demonstrate that the structural changes have a major impact on the transport properties of the system: For the investigated temperatures, the self-diffusion coefficients of all components decrease by several orders of magnitude with increasing [Li][NTf2] content, while the viscosity strongly increases. For mole fractions between 0.4 and 0.5, both [Li]+ and G3 move concertedly and exhibit similar self-diffusion coefficients, indicating the formation of stable 1:1 complexes. We conclude that these mixtures can be categorized as highly temperature-stable SILs with possible implications for battery technology. | Jule Kristin Philipp; Lennart Kruse; Dietmar Paschek; Ralf Ludwig | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Theory - Computational; Transport phenomena (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2025-03-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d2a06b6dde43c908a0d57b/original/structural-transformations-within-the-solvate-ionic-liquid-li-triglyme-n-tf2-implications-for-self-diffusion-viscosity-and-ionic-conductivity.pdf |
60c74576bdbb89930ca38a24 | 10.26434/chemrxiv.10028348.v1 | Sequential Immobilization of Ansa-Hafnocene Complexes for Propene Polymerization | We report the immobilization of the ultrarigid <i>ansa</i>-hafnocene complexes [Me<sub>2</sub>Si(Ind*)<sub>2</sub>HfCl<sub>2</sub>] (Ind* = 7,(3',5'-Di-<i>tert</i>-butylphenyl)-4-methoxy-2-methylindenyl) on silica as heteregeneous catalysts for propene polymerization. A sequential three-step synthesis on the siliceous surface led to pre-catalysts of the generalized structure SiO<sub>2</sub>-Si(Ind*)<sub>2</sub>HfCl<sub>2</sub>, which possess the silylene bridge of the substituted bis(indenyl) ligand directly attached to the surface. The immobilized pre-catalysts show very poor performance in the polymerization of propene, independent on the reaction conditions and the employed silica. Based on the results, we suggest that the close proximity of the catalyst to the surface combined with the steric congestion provoked by the ligand prevents a continuous polymerization, most likely due to a blockage of the catalytically active sites with growing polymer.<br /> | Marius Arz; Tim Kratky; Sebastian Günther; Katia Rodewald; Thomas Burger; Manfred Heuberger; Bernhard Rieger | Heterogeneous Catalysis; Polymerization (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74576bdbb89930ca38a24/original/sequential-immobilization-of-ansa-hafnocene-complexes-for-propene-polymerization.pdf |
6761076f6dde43c90865b1f5 | 10.26434/chemrxiv-2024-s6w35 | Imaging of guest molecule adsorption onto 2D covalent organic frameworks by scanning tunneling microscopy | Porous materials play an important role in molecular adsorption and separation. However, understanding the mechanisms of molecular adsorption and separation into the pores remains a challenge. Herein, the adsorption of 1,3,5-tris(4-iodophenyl) benzene (TIPB) molecules onto a 2D covalent organic framework (COF) monolayer is studied by low-temperature scanning tunneling microscopy (LT-STM) and density functional theory (DFT) calculations. The COF monolayers are synthesized via the on-surface Ullmann reaction. The COF films have six types of porous morphology with different pore sizes, namely tetragon, pentagon, hexagon, heptagon, octagon, and nonagon lattices. The adsorption behavior of guest TIPB molecules into the host COF’s pores is in-situ probed by high-resolution LT-STM. Our results reveal that the in-plane adsorption of TIPB molecules is pore-size-dependent and influenced by the interaction with substrate, with tetragon and pentagon lattices showing no molecule adsorption due to their small pore size. Hexagon and heptagon lattices can adsorb one TIPB molecule through I-H bonding, while octagon and nonagon lattices are able to accommodate two TIPB molecules through both I-H & I-I bonding. The substrate affects the in-plane adsorption. After annealing, the adsorbed molecules can form new covalent bonds with the COF lattice, resulting in the pore-size-dependent grafting of TIPB molecules at the COF branched chains. These findings help to understand the pore-size-dependent adsorption mechanisms and the covalent grafting of guest molecules onto 2D COFs. | Dingguan Wang; Jinwei Fan; Jingyu He; Zhuoqun Wang; Dong Nie; Jianyu Zhu; Hafiza Saima Batool; Ming Yang; Qingchun Deng; Andrew Wee | Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6761076f6dde43c90865b1f5/original/imaging-of-guest-molecule-adsorption-onto-2d-covalent-organic-frameworks-by-scanning-tunneling-microscopy.pdf |
60eb1c64338e927a0b0a04b7 | 10.26434/chemrxiv-2021-2j98p | Probing the Edges between Stability and Degradation of a Series of ZnSe-Based Layered Hybrid Semiconductors | The discovery of layered materials with potentially unique electrical and chemical properties has become a major focus of materials research in the past decade. II-VI layered hybrids (LHs) are a family of ligand-protected layered materials capable of isolation in few-layer form and possess emissive and electronic properties of potential relevance to semiconductor device technologies. We showed previously that, akin to black phosphorus (BP) and transition metal dichalcogenides (TMDCs), II-VI LHs are sensitive to ambient atmospheric conditions. However, the causes for degradation of these ligand-protected materials remain unclear. Using ZnSe-based LHs, we show herein that the stability of these materials is related to the length and chemistry of the organic ligands coordinated to the LH surfaces. Furthermore, exposure to isotopically enriched H218O and 18O2 reveals that H2O and O2 are both reactants contributing to ZnSe-LH degradation. An H2O-initiated degradation pathway is proposed and is supported by density functional theory (DFT) calculations. Our findings contribute to the discovery of protection strategies for layered materials and elucidate a degradation pathway that may also be applicable to other layered materials. | Mengwen Yan; Jeremy Feldblyum; Alan Chen; Christopher Myers; Gregory John; Vincent Meyers | Materials Science; Inorganic Chemistry; Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials; Ligands (Inorg.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2021-07-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60eb1c64338e927a0b0a04b7/original/probing-the-edges-between-stability-and-degradation-of-a-series-of-zn-se-based-layered-hybrid-semiconductors.pdf |
67b4cae8fa469535b9e1c32d | 10.26434/chemrxiv-2025-g6zh3 | Synthesis and biological characterization of 4,4-difluoro-3-(phenoxymethyl)piperidine scaffold as dopamine 4 receptor (D4R) antagonist in vitro tool compounds | We report the discovery and characterization of a novel series of 4,4-difluoropiperidine ether-based dopamine D4 receptor antagonists. Structure-activity relationship studies led to the identification of compound 14a, which displays exceptional binding affinity for the D4 receptor (Ki = 0.3 nM) and remarkable selectivity over other dopamine receptor subtypes (>2000-fold versus D1, D2, D3, and D5). However, compounds in this series were shown to have poor microsomal stability and high plasma protein binding. Despite these limitations, the exceptional selectivity profile of these compounds makes them valuable tool compounds for investigating D4 receptor signaling in cellular models of L-DOPA-induced dyskinesias. These findings provide important structural insights for the future development of metabolically stable D4 receptor antagonists for therapeutic applications. | Saeedeh Saeedi; Anish Vadukoot; Corey Hopkins | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67b4cae8fa469535b9e1c32d/original/synthesis-and-biological-characterization-of-4-4-difluoro-3-phenoxymethyl-piperidine-scaffold-as-dopamine-4-receptor-d4r-antagonist-in-vitro-tool-compounds.pdf |
6711a4d851558a15ef636fbb | 10.26434/chemrxiv-2024-vf00b | Synthetic reactions using a 3-D printed acid-catalyst | A 3-D printed cartridge was fabricated using acrylonitrile-butadiene-styrene (ABS) printer filament. The cartridge was printed with an internal helical honeycomb channel pattern - providing a high surface area suitable for flow chemistry. The internal chamber of the cartridge was treated with fuming sulfuric acid to anneal the surface and functionalize the material with sulfonic acid groups. The 3-D printed catalyst was then used in a variety acid-catalyzed organic reactions, with conversions in 52-97% yields. | Jacob Hood; Niechen Chen; Douglas Klumpp | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Acid Catalysis | CC BY 4.0 | CHEMRXIV | 2024-10-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6711a4d851558a15ef636fbb/original/synthetic-reactions-using-a-3-d-printed-acid-catalyst.pdf |
60c74ed19abda226eff8d724 | 10.26434/chemrxiv.12805280.v1 | Modified MAX Phase Synthesis for Environmentally Stable and Highly Conductive Ti3C2 MXene | One of the primary factors limiting further research and the commercial use of the two-dimensional (2D)
MXene titanium carbide (Ti3C2), as well as MXenes in general, is the rate at which freshly made samples oxidize and degrade
when stored as aqueous suspensions. Here, we show that including excess aluminum during synthesis of the Ti3AlC2 MAX
phase precursor leads to the creation of Ti3AlC2 grains with improved stoichiometry and crystallinity. Ti3C2 nanosheets
produced from the improved Ti3AlC2 are of higher quality, as evidenced by their increased resistance to oxidation and an
increase in their electrical conductivity to 20,000 S/cm. Our results indicate that defects created during the synthesis of
Ti3C2 (and by inference, other MXenes) lead to the previously observed instability. We show that by eliminating those
defects results in Ti3C2 that is highly stable in aqueous solutions and in air. Aqueous suspensions of single- to few-layer
Ti3C2 flakes produced from the modified Ti3AlC2 have a shelf life of over ten months, compared to one to two weeks for
Ti3C2 produced from conventional Ti3AlC2, even when stored in ambient conditions. Freestanding films made from Ti3C2
suspensions stored for ten months show minimal decreases in electrical conductivity and negligible oxidation. Oxidation
of the improved Ti3C2 in air initiates at temperatures that are 100-150°C higher than conventional Ti3C2. The observed improvements in both the shelf life and properties of Ti3C2 will facilitate the widespread use of this material.
<br /> | Tyler Mathis; Kathleen Maleski; Adam Goad; Asia Sarycheva; Mark Anayee; Alexandre C. Foucher; Kanit Hantanasirisakul; Eric Stach; Yury Gogotsi | Ceramics; Nanostructured Materials - Materials | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ed19abda226eff8d724/original/modified-max-phase-synthesis-for-environmentally-stable-and-highly-conductive-ti3c2-m-xene.pdf |
63bd6477a68d7b9914330210 | 10.26434/chemrxiv-2023-m3k16 | Rational Synthesis of Elusive Organic-Inorganic Hybrid Metal-oxo Clusters: Formation and Post-functionalization of Hexavanadates | Paving the way towards new functional materials relies increasingly on the challenging task of forming organic-inorganic hybrid compounds. In that regard, discrete atomically-precise metal-oxo nanoclusters have received increasing attention due to the wide range of organic moieties that can be attached onto them through functionalization reactions. The Lindqvist hexavanadate family of clusters ([V6O13{(OCH2)3C-R}2]2-; V6-R) is particularly interesting due to its magnetic, redox, and catalytic properties. However, compared to other metal-oxo cluster types it has been less extensively explored, which is mainly due to poorly understood synthetic challenges and the limited number of viable post-functionalization strategies. In this work, we present an in-depth investigation of the factors that influence the formation of hybrid hexavanadates (V6-R HPOMs) and leverage this knowledge to develop [V6O13{(OCH2)3CNHCOCH2Cl}2]2- (V6-Cl) as a new and tunable platform for the facile formation of discrete hybrid structures based on metal-oxo clusters in high yields. Moreover, we showcase the versatility of the V6-Cl platform through its facile post-functionalization via nucleophilic substitution with various carboxylic acids of differing complexity and with functionalities that are relevant in multiple disciplines of chemistry, such as supramolecular chemistry and biochemistry. Hence, V6-Cl was shown to be a straightforward and versatile starting point for the formation of functional supramolecular structures or other hybrid materials, thereby enabling their exploration in various fields. | David E. Salazar Marcano; Givi Kalandia; Mhamad Aly Moussawi; Kristof Van Hecke; Tatjana N. Parac-Vogt | Inorganic Chemistry; Coordination Chemistry (Inorg.); Spectroscopy (Inorg.); Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63bd6477a68d7b9914330210/original/rational-synthesis-of-elusive-organic-inorganic-hybrid-metal-oxo-clusters-formation-and-post-functionalization-of-hexavanadates.pdf |
67336ba45a82cea2fae3d19f | 10.26434/chemrxiv-2024-rbbcl | Development of a Highly Selective Synthesis of 4-Substituted Tetrahydroquinolines: Substrate Scope and Mechanistic Study | Herein, we describe a general and selective deprotonation functionalization reaction of tetrahydroquinolines at the 4–position using organolithiums and phosphoramide ligands. In addition to the development of a direct deprotonation alkylation reaction with primary and secondary alkyl halides, a Negishi cross–coupling protocol was realized to afford products with a range of aromatic halides. These methods were applied to the late-stage installation of tetrahydroquinolines into a variety of substrates including pharmaceuticals as well as natural product analogues. The use of thorough mechanistic investigations revealed the aggregation state of the newly formed tetrahydroquinoline anion to be a separated ion pair, which proved critical to optimizing the reaction conditions. | Jeanette Piña; Lupita Aguirre; Levi Litwiller; Hai Ly; Michael Crockett; Andy Thomas | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Physical Organic Chemistry; Kinetics and Mechanism - Organometallic Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67336ba45a82cea2fae3d19f/original/development-of-a-highly-selective-synthesis-of-4-substituted-tetrahydroquinolines-substrate-scope-and-mechanistic-study.pdf |
60c7408a469df47297f42c47 | 10.26434/chemrxiv.7500617.v2 | Native Ion Mobility Mass Spectrometry: when Gas Phase Ion Structures Depend on the Electrospray Charging Process | Ion mobility spectrometry (IMS) has become popular to characterize biomolecule folding. Numerous studies have shown that proteins that are folded in solution remain folded in the gas phase, whereas proteins that are unfolded in solution adopt more extended conformations in the gas phase. Here, we discuss how general this tenet is. We studied single-stranded DNAs (human telomeric cytosine-rich sequences with CCCTAA repeats), which fold into an intercalated motif (i-motif) structure in a pH-dependent manner, thanks to the formation of C‒H+‒C base pairs. As i-motif formation is favored at low ionic strength, we could investigate the ESI-IMS-MS behavior of i-motif structures at pH ~5.5 over a wide range of ammonium acetate concentrations (15 mM to 100 mM). The control experiments consisted of either the same sequence at pH ~7.5, wherein the sequence is unfolded, or sequence variants that cannot form i-motifs (CTCTAA repeats). The surprising results came from the control experiments. We found that the ionic strength of the solution had a greater effect on the compactness of the gas-phase structures than the solution folding state. This means that electrosprayed ions keep a memory of the charging process, which is influenced by the electrolyte concentration. We discuss these results in light of the analyte partitioning between the droplet interior and droplet surface, which in turn influences the probability of being ionized via a charged residue pathway or a chain extrusion pathway.<br /> | Nina A. Khristenko; Jussara Amato; Sandrine Livet; Bruno Pagano; Antonio Randazzo; Valerie Gabelica | Mass Spectrometry; Biophysics; Biophysical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-02-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7408a469df47297f42c47/original/native-ion-mobility-mass-spectrometry-when-gas-phase-ion-structures-depend-on-the-electrospray-charging-process.pdf |
60c741a9567dfe223aec3e09 | 10.26434/chemrxiv.8097818.v1 | Quasi-Harmonic Lattice Dynamics of a Prototypical Metal-Organic Framework | Quasi-harmonic lattice-dynamical calculations are performed to investigate the combined effect of temperature and pressure on the structural and mechanical properties of a prototypical metal-organic framework material: MOF-5. The softening upon compression of an A2g phonon mode at the gamma point in the high-symmetry Fm3m structure is identified, which leads to a symmetry reduction and a group subgroup phase transition to a low-symmetry Fm3 phase for compressions larger than 0.8%. The effect of the symmetry reduction on the equation-of-state of MOF-5 is investigated, which provides a static bulk modulus K reducing from 17 to 14 GPa and a corresponding change of K0 (pressure derivative of K) from positive to negative. The effect of pressure on the negative thermal expansion of the framework and on its mechanical response is analysed. The evolution of the mechanical anisotropy of MOF-5 as a function of pressure is also determined, which allows us to identify the occurrence of a shear-induced mechanical instability at 0.45 GPa.<br /> | Matthew R. Ryder; Jefferson Maul; Bartolomeo Civalleri; Alessandro Erba | Hybrid Organic-Inorganic Materials; Computational Chemistry and Modeling; Theory - Computational; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-05-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741a9567dfe223aec3e09/original/quasi-harmonic-lattice-dynamics-of-a-prototypical-metal-organic-framework.pdf |
60c7495f702a9bbe0418b120 | 10.26434/chemrxiv.12056178.v1 | Machine-Learning Coupled Cluster Properties through a Density Tensor Representation | <div>
<div>
<div>
<p>The introduction of machine-learning (ML) algorithms to quantum mechanics enables rapid
evaluation of otherwise intractable expressions at the cost of prior training on appropriate benchmarks. Many computational bottlenecks in the evaluation of accurate electronic
structure theory could potentially benefit from the application of such models, from reducing the complexity of the underlying wave function parameter space to circumventing the
complications of solving the electronic Schrödinger equation entirely. Applications of ML to
electronic structure have thus far been focused on learning molecular properties (mainly the
energy) from geometric representations. While this line of study has been quite successful,
highly accurate models typically require a “big data” approach with thousands of train-
ing data points. Herein, we propose a general, systematically improvable scheme for wave
function-based ML of arbitrary molecular properties, inspired by the underlying equations
that govern the canonical approach to computing the properties. To this end, we combine
the established ML machinery of the t-amplitude tensor representation with a new reduced
density matrix representation. The resulting model provides quantitative accuracy in both
the electronic energy and dipoles of small molecules using only a few dozen training points
per system.
</p>
</div>
</div>
</div> | Benjamin Peyton; Connor Briggs; Ruhee D'Cunha; Johannes T. Margraf; Thomas Crawford | Theory - Computational; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7495f702a9bbe0418b120/original/machine-learning-coupled-cluster-properties-through-a-density-tensor-representation.pdf |
64e41845694bf1540cc11726 | 10.26434/chemrxiv-2023-k6m24 | High-accuracy chemical structure restoration from molecular descriptors and its application to chemical design | Molecular descriptors are essential tools for analyzing compounds in drug discovery, but descriptors have a drawback - it is difficult to reconstruct the original compound using only descriptor data. To overcome this drawback, we used a deep learning Transformer model to restore the molecular structure from Morgan fingerprint (MF) data. We also explored compound optimization using numerical operations on the fingerprint vector. | Chiaki Nakamori; Tore Eriksson | Theoretical and Computational Chemistry; Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e41845694bf1540cc11726/original/high-accuracy-chemical-structure-restoration-from-molecular-descriptors-and-its-application-to-chemical-design.pdf |
60c75708bb8c1a56c33dc70c | 10.26434/chemrxiv.14347145.v1 | Multimodule Assembly Strategy for Diverted Total Synthesis and Stereochemical Determination of Laingolide A and Laingolide | Diverted total synthesis of diastereomers of
laingolide A and laingolide has been accomplished and the stereochemistry of
both (<i>E</i>)-enamide-containing 15-membered
macrolides has been assigned. Laingolide A and laingolide have 3 and 4
stereogenic centers, respectively, and only their planar structures were reported.
The former has 4 possible diastereomers while the latter has up to 8
diastereomers. A multimodule assembly (MMA) strategy was utilized to disconnect
both target molecules into 5 small structural modules among which only one
stereochemically varied module (stereo-module) needed to be prepared with other
4 modules available commercially. A sequence of ring-closing metathesis (RCM)
and alkene isomerization was used for construction of the macrocyclic skeleton
and installation of the (<i>E</i>)-enamide
moiety. Four each diastereomers of laingolide A and laingolide have been
synthesized, leading to assignment of (2<i>R</i>*,7<i>R</i>*,9<i>S</i>*)
and (2<i>R</i>*,4<i>R</i>*,7<i>R</i>*,9<i>S</i>*) relative stereochemistry for
laingolide A and laingolide, respectively. Moreover, according to the (2<i>S</i>,9<i>R</i>)
absolute configuration of the congener, laingolide B, the (2<i>S</i>,7<i>S</i>,9<i>R</i>) and (2<i>S</i>,4<i>S</i>,7<i>S</i>,9<i>R</i>)
absolute configurations are suggested for laingolide A and laingolide,
respectively. The current synthetic efforts reveal, for the first time, that
both laingolide A and laingolide possess the 7,9-<i>syn</i>-Me/<i>t</i>-Bu subunit. | Chengsen Cui; Yecai Lai; Wei-Min Dai | Natural Products; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75708bb8c1a56c33dc70c/original/multimodule-assembly-strategy-for-diverted-total-synthesis-and-stereochemical-determination-of-laingolide-a-and-laingolide.pdf |
60c73e58702a9bad65189d52 | 10.26434/chemrxiv.5787984.v2 | Elucidating the Role of Isotopically Chiral Initiators in the Soai Asymmetric Autocatalytic Reaction | A mechanistic rationalization is given for how asymmetric amplification is induced with fidelity in the Soai autocatalytic reaction by chiral initiators that are enantiomeric only by virtue of an isotope, e.g. – CH3 vs.CD3. A transient <i>inhibition</i> of the autocatalytic pathway at the outset of the reaction implicates an interaction between initiator and product initially formed in the uncatalyzed background reaction. Selectivity in formation of the product-initiator complex ultimately induces a slight enantioenrichment in the active dimer catalysts that trigger and direct the autocatalytic pathway.<br /> | Neil Hawbaker; Donna Blackmond | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2018-06-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e58702a9bad65189d52/original/elucidating-the-role-of-isotopically-chiral-initiators-in-the-soai-asymmetric-autocatalytic-reaction.pdf |
651a3302ade1178b247ee6d1 | 10.26434/chemrxiv-2023-tz7x8-v3 | A database of molecular properties integrated in the Materials Project | Advanced chemical research is increasingly reliant on large computed datasets of molecules and reactions to discover new functional molecules, understand chemical trends, train machine learning models, and more. To be of greatest use to the scientific community, such datasets should follow FAIR principles (i.e. be findable, accessible, interoperable, and reusable). In this work, we present a FAIR expansion of the Materials Project database ("MPcules") that adds more than 170,000 molecules studied using density functional theory (DFT) to the existing data, which comprises crystalline solids. MPcules is a diverse collection of DFT-calculated molecular properties, with an emphasis on reactive, open-shell, and charged species - relevant for studying reaction pathways - and a wide array of structural, electronic, vibrational, and thermodynamic properties. This database can be queried through an OpenAPI-compliant application programming interface and a featureful web application. We continue to expand the data available on MPcules and encourage contributions from the community. | Evan Walter Clark Spotte-Smith; Orion Archer Cohen; Samuel Blau; Jason Munro; Ruoxi Yang; Rishabh Guha; Hetal Patel; Sudarshan Vijay; Patrick Huck; Ryan Kingsbury; Matthew Horton; Kristin Persson | Theoretical and Computational Chemistry; Energy; Computational Chemistry and Modeling; Machine Learning; Chemoinformatics - Computational Chemistry; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-10-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651a3302ade1178b247ee6d1/original/a-database-of-molecular-properties-integrated-in-the-materials-project.pdf |
60c75250ee301ceaf0c7ab91 | 10.26434/chemrxiv.13283930.v1 | STopTox: An In-Silico Alternative to Animal Testing for Acute Systemic and TOPical TOXicity | <p><a>Since 2009, animal testing for cosmetic products has
been prohibited in Europe, and in 2016, US EPA announced their intent to
modernize the so-called "6-pack" of acute toxicity tests (acute oral
toxicity, acute dermal toxicity, acute inhalation toxicity, skin irritation and
corrosion, eye irritation and corrosion, and skin sensitization) and expand
acceptance of alternative methods to reduce animal testing of pesticides. We
have compiled, curated, and integrated the largest publicly available dataset and
developed an ensemble of QSAR models for all six endpoints. All models were
validated according to the OECD QSAR principles and tested using newly
identified data on compounds not included in the training sets. We have
established a publicly accessible Systemic and Topical chemical Toxicity (STopTox)
web portal (https://stoptox.mml.unc.edu/) integrating all developed models for “6-pack”
assays. This portal can be used by
scientists and regulators to identify putative toxicants or non-toxicants in
chemical libraries of interest.</a></p> | Joyce V. V. B. Borba; Vinicius Alves; Rodolpho Braga; Daniel Korn; Kirsten Overdahl; Arthur C. Silva; Steven Hall; Erik Overdahl; Judy Strickland; DAvid Allen; Nicole Kleinstreuer; Carolina Andrade; Eugene Muratov; Alexander Tropsha | Bioinformatics and Computational Biology; Computational Chemistry and Modeling; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75250ee301ceaf0c7ab91/original/s-top-tox-an-in-silico-alternative-to-animal-testing-for-acute-systemic-and-to-pical-to-xicity.pdf |
630c5c7e0187d98ab6a52213 | 10.26434/chemrxiv-2022-5lw1l | 3-Position-Selective C–H Trifluoromethylation of Pyridine Rings Based on Nucleophilic Activation | The first example of the 3-position-selective C(sp2)–H trifluoromethylation of pyridine rings was established. 3-Position-selective trifluoromethylation was achieved by the nucleophilic activation of pyridine and quinoline derivatives through hydrosilylation and successive electrophilic trifluoromethylation of the enamine intermediate. This reaction was applicable to perfluoroalkylation at the 3-position of the pyridine rings and late-stage trifluoromethylation of a bioactive molecule. Mechanistic studies indicated that the reaction proceeds via the formation of N-silyl enamine and trifluoromethylated enamine intermediates. | Ryuhei Muta; Takeru Torigoe; Yoichiro Kuninobu | Organic Chemistry; Organic Synthesis and Reactions | CC BY 4.0 | CHEMRXIV | 2022-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/630c5c7e0187d98ab6a52213/original/3-position-selective-c-h-trifluoromethylation-of-pyridine-rings-based-on-nucleophilic-activation.pdf |
60c7423f702a9b4a7f18a405 | 10.26434/chemrxiv.8246975.v1 | DNA and RNA Telomeric G-Quadruplexes: What Topology Features Can be Inferred from Ion Mobility Mass Spectrometry? | Maintenance of the telomeres is key to chromosome integrity and cell proliferation. The G-quadruplex structures formed by telomeric DNA and RNA (TTAGGG and UUAGGG repeats, respectively) are key to this process. However, because these sequences are particularly polymorphic, solving high-resolution structures is not always possible, and there is a need for new methodologies to characterize the multiple structures coexisting in solution. In this context, we evaluated whether ion mobility spectrometry coupled to native mass spectrometry could help separate and assign the G-quadruplex topologies. We explored the circular dichroism spectra, multimer formation, cation binding, and ion mobility spectra of several 4-repeat and 8-repeat telomeric DNA and RNA sequences, both in NH<sub>4</sub><sup>+</sup> and in K<sup>+</sup>. In 1 mM K<sup>+</sup> and 100 mM trimethylammonium acetate, all RNAs fold intramolecularly (no multimer). In 8-repeat sequences, the subunits are not independent: in DNA the first subunit disfavors the folding of the second one, whereas in RNA the two subunits fold cooperatively via cation-mediated stacking. Ion mobility spectrometry shows that gas-phase structures keep a memory of the solution ones, but not identical. At the native charge states, the loops can rearrange in a variety of ways (unless they are constrained by pre-formed hydrogen bonds), thereby wrapping the core and masking the strand arrangements. Our study highlights that, to progress towards structural assignment from IM-MS experiments, deeper understanding of the solution-to-gas-phase rearrangement mechanisms is warranted. <br /> | Valentina D’Atri; Valerie Gabelica | Analytical Chemistry - General; Mass Spectrometry; Biochemistry; Biophysics; Biophysical Chemistry; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7423f702a9b4a7f18a405/original/dna-and-rna-telomeric-g-quadruplexes-what-topology-features-can-be-inferred-from-ion-mobility-mass-spectrometry.pdf |
60c744e3bb8c1a83343da59d | 10.26434/chemrxiv.9920504.v1 | Cycloparaphenylene-Norbornene Monomers Afford Access to Carbon Nanohoop-Based Polymers | Although impressive strides have been made toward achieving precise polymer architectures, the pursuit of monomers with diverse structures and functions remains a critical challenge for polymer design. Herein we disclose the first polymers constructed from cycloparaphenylenes (CPPs), a family of strained, pi-rich macrocycles. Poly-CPPs were prepared via ring-opening metathesis polymerization (ROMP) of benzonorbornene-embedded CPPs. The distinctive size-dependent properties of CPPs, including fluorescence and host-guest chemistry, are preserved in poly-CPPs, offering a means to capitalize on these properties in polymeric materials. Moreover, copolymerizing CPPs of two different diameters results in polymers with emergent photophysical and supramolecular properties not achievable with small molecule CPP units. This work sets the stage for CPP derivatives to serve as molecular building blocks for the next generation of functional polymers. | Ruth Maust; Penghao Li; Lev N. Zakharov; Ramesh Jasti | Organic Polymers | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744e3bb8c1a83343da59d/original/cycloparaphenylene-norbornene-monomers-afford-access-to-carbon-nanohoop-based-polymers.pdf |
6414775d2bfb3dc251ed04bc | 10.26434/chemrxiv-2023-mhr4t | Hirshfeld atom refinement of metal-organic frameworks for accurate positioning of hydrogen atoms and disorder analysis | The application of Hirshfeld atom refinement (HAR) fragmentation method is demonstrated for the refinement of metal-organic framework (MOF) crystal structures. The presented method enables anisotropic refinement of imidazolate hydrogen atoms, as well as complex analysis of solvent disorder within MOF pores. The data used were derived from standard resolution in-house single crystal X-ray diffraction measurements, demonstrating that high quality structural analysis of MOFs no longer requires access to neutron or synchrotron facilities. | Yizhi Xu; Michał L. Chodkiewicz; Damian Trzybiński; Ivana Brekalo; Filip Topić; Krzysztof Wożniak; Mihails Arhangelskis | Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Structure; Materials Chemistry; Crystallography | CC BY 4.0 | CHEMRXIV | 2023-03-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6414775d2bfb3dc251ed04bc/original/hirshfeld-atom-refinement-of-metal-organic-frameworks-for-accurate-positioning-of-hydrogen-atoms-and-disorder-analysis.pdf |
67ac76abfa469535b902553d | 10.26434/chemrxiv-2025-m3mpv-v2 | Rationalized synthetic access to benzimidazoline based n-type dopant precursors | 1H-benzimidazoline based molecular n-dopant precursors, such as 4-(2,3-Dihydro-1,3-dimethyl-1H-benzimid-azol-2-yl)-N,N-dimethylbenzenamine (N-DMBI-H), enable efficient doping of n-dopable organic semiconductors. Chemical modification of the molecular structure of such compounds proved to be a fundamental tool to tune their properties and doping efficiencies, according to the desired application. Versatile and efficient synthetic strategies, giving access to the widest range of substitution motifs, could help improve the access to known derivatives and enable the preparation of new and improved ones. Literature reports several syn-thetic approaches but due to lack of rationalization and a comprehen-sive analysis, the selection of that best suited for a specific target deriv-ative still mostly relies on a trial and error approach. In this work, we compare the features of the two most popular synthetic strategies in the preparation of a wide variety of benzimidazoline dopants having diverse substitution patterns and electronic features. We thus propose guidelines for the selection of the best synthetic approach depending on the characteristics of the target dopant, known as well as original. | Francesca Pallini; Giulia Garavaglia; Gabriele Paoli; Giuseppe Mattioli; Francesco Porcelli; Lorenzo Mezzomo; Domenico Antonio Florenzano; Riccardo Ruffo; Mauro Sassi; SARA MATTIELLO | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67ac76abfa469535b902553d/original/rationalized-synthetic-access-to-benzimidazoline-based-n-type-dopant-precursors.pdf |
60c744a80f50db9c50396118 | 10.26434/chemrxiv.9876524.v1 | An Ultrafast Vibrational Study of Dynamical Heterogeneity in the Protic Ionic Liquid Ethyl-Ammonium Nitrate | <p>Using ultrafast two-dimensional infrared spectroscopy (2D-IR), a vibrational probe (thiocyanate, SCN<sup>-</sup>) was used to investigate the hydrogen bonding network of a molten salt (ethyl-ammonium nitrate, EAN) compared to that of H2O. The 2D-IR experiments were performed in both parallel () and perpendicular () conditions along with temperature dependence for both EAN (14-130 ˚C) and H2O (5-89 ˚C). With polarization control, the frequency fluctuation correlation function can be separated into structural and rotational components. An Arrhenius analysis lead to independent activation energies for the isotropic, and anisotropic signals, structural spectral diffusion, and rotational induced spectral diffusion. The rotational E<sub>a</sub>s were similar for both EAN and H2O suggesting that SCN<sup>-</sup> is experiencing a similar jump model, i.e. where hydrogen bond reorientation is dominated by large angular jumps stemming from molecular rotation dynamics. The frequency pre-factors, however, were different where the more rigid and vicious EAN had a slower rate. Furthermore, the 2D-IR anisotropy and vibrational relaxation rates of EAN are frequency dependent, revealing that SCN<sup>-</sup> experiences two subensembles. We suggest that the sub-ensemble with a faster rotational timescale correlates to SCN<sup>-</sup> with more, weaker hydrogen bonds, and the sub-ensemble with a slower rotational timescale correlates to SCN<sup>-</sup> with a stronger, more directional hydrogen bond.</p> | Clinton Johnson; Anthony W. Parker; Paul M. Donaldson; Sean Garrett-Roe | Physical and Chemical Processes; Solution Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744a80f50db9c50396118/original/an-ultrafast-vibrational-study-of-dynamical-heterogeneity-in-the-protic-ionic-liquid-ethyl-ammonium-nitrate.pdf |
67a5f57d6dde43c908ebe2a8 | 10.26434/chemrxiv-2025-3mzhb | A Kβ valence to core X-ray emission approach for fluorine and oxygen differentiation in Zr compounds | Distinguishing between neighbouring atomic number elements in the vicinity of a probed metal centre is challenging when using X-ray spectroscopies. This study shows the suitability of X-ray emission spectroscopy (XES) to probe a ligand (ns, np) – Zr (4d) to Zr (1s) valence to core (VtC) emission line in Zr based compounds. We sucessully demonstrate the differentiation between fluorine and oxygen environments around Zr. These findings were directly applied to compounds that have been reported for catalytic activity in C-F bond activation or oxygen evolution reactions. The results show different contributions of the respective precursors , oxygen, and fluorine in the local environment of the compounds. | Christian Heinekamp; Cafer-Tufan Cakir; Ana Guilherme Buzanich; Konstantin Klementiev; Michael Römelt; Thomas Braun; Franziska Emmerling | Physical Chemistry; Materials Science; Inorganic Chemistry; Solid State Chemistry; Spectroscopy (Inorg.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a5f57d6dde43c908ebe2a8/original/a-k-valence-to-core-x-ray-emission-approach-for-fluorine-and-oxygen-differentiation-in-zr-compounds.pdf |
67acb0d9fa469535b90b1260 | 10.26434/chemrxiv-2025-f1l90 | Access to nitrogen-nitrogen bond-containing heterocycles through substrate promiscuity of piperazate synthases | The nitrogen-nitrogen (N-N) bond motif comprises an important class of compounds for drug discovery. Synthetic methods are primarily based on the modification of N-N or N=N precursors, whereas selective methods for direct N-N coupling offer advantages in terms of atom economy and sustainability. In this context, enzymes such as piperazate synthases (PZSs), which naturally catalyze the N-N cyclization of L-N5-hydroxyornithine to the cyclic hydrazine L-piperazate, may allow an expansion of the current narrow range of chemical approaches for N-N coupling. In this study, we demonstrate that PZSs are able to catalyze the conversion of various N-hydroxylated diamines, which are different from the natural substrate. The N-hydroxylated diamines were obtained in situ using N-hydroxylating monooxygenases (NMOs), allowing subsequent cyclization by PZS, ultimately forming the N-N bond to yield various N-N bond-containing heterocycles. Using bioinformatic tools, we identified novel NMO and PZS homologs that exhibit distinct activity and stereoselectivity profiles. The screened panel yielded 17 hydroxylated diamines and new promiscuous NMOs, thereby expanding the substrate range of NMOs resulting in the formation of previously poorly accessible N-hydroxylated products as substrates for PZS. The subsequently investigated PZSs led to a series of 5- and 6-membered N-N bond-containing heterocycles, and the most promiscuous catalysts were used to scale up and optimize the synthesis, yielding the desired N-N bond-containing heterocycles with up to 45% isolated yield. Overall, our data provides essential insights into the substrate promiscuity and activity of NMOs and PZSs, further enhancing the potential of these biocatalysts for an expanded range of N-N coupling reactions. | Yongxin Li; Angelina Osipyan; Niels A.W. de Kok; Simon Schröder; Maria Founti; Peter Fodran; Ronald van Merkerk; Artur Maier; Dirk Tischler; Sandy Schmidt | Biological and Medicinal Chemistry; Catalysis; Biochemistry; Biocatalysis | CC BY NC 4.0 | CHEMRXIV | 2025-02-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67acb0d9fa469535b90b1260/original/access-to-nitrogen-nitrogen-bond-containing-heterocycles-through-substrate-promiscuity-of-piperazate-synthases.pdf |
668681f201103d79c5fc8d4e | 10.26434/chemrxiv-2024-h40w6 | Tellurium Empowered Catalysis for Enantioselective Seleno-Michael Addition Reaction | The development of a new catalyst, which has not been explored before, not only provides an alternative to
the existing organocatalysts but also leads to a distinct chemical reactivity. Here, an organotellurium catalyst consisting of a chiral quinine auxiliary displays remarkable activity for the enantioselective delivery of reactive arylselenols as a Michael donor in common solvents such as dichloromethane and acetonitrile. The developed chiral organotellurium-catalyzed arylselenol addition to alkenes shows a broad substrate scope as electron-rich and deficient arylselenols and diversely substituted enones are amenable to the reaction conditions. Control experiments, 77Se, and 125Te NMR, suggest that non-bonded Te...Se interaction between catalyst and arylselenol seems responsible for accelerated and highly enantioselective delivery of arylselenol to enone. The practically synthesized chiral organoselenides have also been readily post-derivatized by taking advantage of the leaving group ability and recyclability of arylselenium. | Saket Jain; Raviraj Ananda Thorat; Shinu Shaleela P P; Deeksha Chaurasia; SANGIT KUMAR | Organic Chemistry; Inorganic Chemistry; Catalysis; Bonding; Main Group Chemistry (Inorg.); Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668681f201103d79c5fc8d4e/original/tellurium-empowered-catalysis-for-enantioselective-seleno-michael-addition-reaction.pdf |
66c6c09320ac769e5f6ba59e | 10.26434/chemrxiv-2024-5rg72 | Synthesis, Characterizations and Chemometric Analysis Approach of Nitrile Functionalized Asymmetrical Dinuclear Silver(I) Di-N¬-Heterocyclic Carbene Complexes | A series of novel asymmetrical bis-benzimidazolium salts were synthesized via a two-step alkylation process, yielding the benzimidazolium salts of N,N'-(ethane/propane/butane-1,2/3/4-diyl)-1-benzylbenzimidazolium-1'-(n-benzonitrile)benzimidazolium dibromide (n = 2,3,4) (1Br – 9Br). These salts served as carbene precursors for the subsequent formation of nitrile-functionalized asymmetrical silver(I) di-NHC complexes (Ag1 – Ag9) (NHC = N-heterocyclic carbene) through an in-situ deprotonation method using Ag2O. Comprehensive characterization of the bis-benzimidazolium salts and their corresponding dinuclear silver(I) di-NHC complexes was performed using melting point determination, CHN elemental analyses, FTIR, and 1H- and 13C-NMR spectroscopy. The successful complexation of nitrile-functionalized NHC ligands with silver(I) ions was evidenced by the disappearance of the acidic-carbene proton peak (δ 9.69 – 10.23 ppm) in the 1H-NMR spectra of the complexes. Furthermore, the formation of Ag-Ccarbene bonds was confirmed by the appearance of characteristic peaks in the 13C-NMR spectra of Ag1 – Ag9 (δ 170.89 – 195.90 ppm). To elucidate structure-property relationships, the Principal Component Analysis (PCA) was applied to the NMR spectroscopic data. The Principal Component Analysis (PCA) of the 1H-NMR data revealed distinct clustering of bis-benzimidazolium salts and their respective silver(I) di-NHC complexes, with the first two principal components accounting for 71.40% of the total variance. Similarly, the PCA of the 13C-NMR data explained 72.08% of the total variance through the first two principal components. These results demonstrate the efficacy of PCA in differentiating and classifying the compounds based on their structural features and functional groups. Moreover, this study highlights the synergistic application of advanced spectroscopic techniques and chemometric analysis in inorganic synthesis chemistry subject and the insights gained from this approach contribute to a deeper understanding of the structural properties and potential applications of these novel NHC complexes, paving the way for future developments in organometallic chemistry and catalysis. | Muhammad Zulhelmi Nazri; Mohd Rizal Razali; Sunusi Yahya Hussaini; Norazah Basar | Inorganic Chemistry; Coordination Chemistry (Inorg.); Organometallic Compounds | CC BY NC 4.0 | CHEMRXIV | 2025-01-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c6c09320ac769e5f6ba59e/original/synthesis-characterizations-and-chemometric-analysis-approach-of-nitrile-functionalized-asymmetrical-dinuclear-silver-i-di-n-heterocyclic-carbene-complexes.pdf |
6422896a647e3dca99a1cb39 | 10.26434/chemrxiv-2023-26rl0 | Atomic Tailoring of Ubiquitin Side Chains Influences
E2-Mediated Ubiquitin Chain Formation
| Ubiquitin (Ub) is a small, highly conserved protein essential for eukaryotic biology, and is unique in its formation of polyubiquitin chains by conjugation to one of its seven lysine side chains. Here we report that atomic tailoring of Ub side chains – i.e. the insertion, deletion, or replacement of specific atoms – has significant and unexpected consequences on the enzymatic conjugation of Ub oligomers by isopeptide bond formation mediated by E2 conjugating enzymes. These studies employed chemical synthesis and ligation methods to prepare numerous specifically tailored Ub monomers on multi-milligram scales. While some modifications including N-terminal acylation and methionine replacement did not affect protein folding or Ub chain formation with Ube2K, other modifications had a pronounced effect of oligomerization with Ubc13/Mms2. We observed that Ala46Hse mutation obliterates the ability of this Ub monomer to accept another Ub at Lys63 in Ubc13-mediated conjugations. Exhaustive replacement of all seven lysines with shorter surrogates Orn, Dab, or Dap essentially blocks Ub chain formation, and in the case of Dap, precludes proper folding of the Ub protein. | Haewon Song; Toshiki Mikami; Sohei Majima; Jeffrey Bode | Biological and Medicinal Chemistry; Biochemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6422896a647e3dca99a1cb39/original/atomic-tailoring-of-ubiquitin-side-chains-influences-e2-mediated-ubiquitin-chain-formation.pdf |
65d76c9ee9ebbb4db9f6e658 | 10.26434/chemrxiv-2024-fqgr8 | Transition Metal-Free Catalytic C−H Zincation and C−H Alumination | C−H metalation is the most efficient method to prepare aryl–zinc and –aluminum complexes that are highly useful nucleophiles. Virtually all C–H metalation routes to form Al or Zn organometallic reagents require stoichiometric, strong Brønsted bases with no base-catalyzed reactions reported, to our knowledge. Herein we present a catalytic C–H metalation process to form aryl-zinc and aryl-aluminum complexes that uses only simple amine bases (e.g., Et3N) in sub-stoichiometric quantity (10 mol%). Key to this approach is coupling an endergonic C–H metalation step using a [(-diketiminate)MNR3]+ (M = Zn or Al–Me) electrophile with a sufficiently exergonic dehydrocoupling step between the acidic ammonium salt by-product of C–H metalation ([(R3N)H]+) and a Zn–H or Al–Me containing complex. This step, forming H2/MeH, makes the overall cycle exergonic while also generating more of the key cationic metal electrophile. Mechanistic studies supported by DFT calculations revealed metal-specific dehydrocoupling pathways, with the divergent reactivity shown to be due to the different metal valency (which impacts the accessibility of amine-free cationic complexes) and steric environment. Notably, dehydrocoupling in the zinc system proceeds through a ligand-mediated pathway involving protonation of the -diketiminate C position. In this step the magnitude of the key barrier is dependent on the steric bulk of the spectator ligand, with bulkier ligands actually affording lower barriers. This catalytic approach to arene C−H metalation has the potential to be applicable to other main group metals and ligands, thus will facilitate the synthesis of these important organometallic compounds. | Milan Bisai; Justyna Losiewicz; Lia Sotorrios; Gary Nichol; Andrew Dominey; Michael Cowley; Stephen Thomas; Stuart Macgregor; Michael Ingleson | Theoretical and Computational Chemistry; Catalysis; Organometallic Chemistry; Computational Chemistry and Modeling; Homogeneous Catalysis; Main Group Chemistry (Organomet.) | CC BY 4.0 | CHEMRXIV | 2024-02-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d76c9ee9ebbb4db9f6e658/original/transition-metal-free-catalytic-c-h-zincation-and-c-h-alumination.pdf |
67c5c47e81d2151a02e19610 | 10.26434/chemrxiv-2025-2950c | Vibrational Partition Functions from Bond Order and Populations Relationships | We present a novel method that computes harmonic vibrational partition functions from bond orders and popu- lation relationships (QBOP). The QBOP model first computes ZPEs and net vibrational bond energies from our earlier zero-point energies from bond orders and populations (ZPE-BOP) model and then maps these variables to calcu- late the harmonic vibrational partition function. Combined with traditional rotational, translational, and electronic partition function approximations, our method allows the approximate calculation of finite temperature thermal effects without a Hessian calculation. The method uses a total of 12 parameters that have been fitted to B3LYP/cc-pVTZ+1d data for first-row elements: H, Li, Be, B, C, N, O, and F. We benchmark our model to traditional SQM models (i.e., AM1, PM6, PM7, and XTB-2) and found QBOP-1 provides similar results. This work shows a novel way to obtain useful thermal energy calculations without a costly Hessian calculation, and thereby shifting standard bottle-necks in computational chemistry applications. | Barbaro Zulueta; John Keith | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67c5c47e81d2151a02e19610/original/vibrational-partition-functions-from-bond-order-and-populations-relationships.pdf |
643a95b51d262d40ea86c6b7 | 10.26434/chemrxiv-2023-gxzqw | Spontaneous crystal fluctuation in hydrocarbon polymer–coated monolayer MoS2, MoSe2, WS2, and WSe2 with strong photoluminescence enhancement | A large number of experimental results have been published on the improvement of optical properties in monolayer transition metal dichalcogenides (TMDCs) by probing with photoluminescence (PL) intensity. Remarkable improvement in PL intensity in sulfur-based compounds, such as MoS2 and WS2, has almost been established by chemical treatment methods, such as p-type dopants and superacids; in contrast, selenium-based compounds of MoSe2, especially WSe2, have a very limited strategy. One potential strategy for improving PL intensity in all compounds would be to remove the substrate effect by mechanical floating of the monolayers from the underneath substrate material. However, floating the monolayer is difficult; it is possible if the monolayer does transfer to the trenches of substrates, and a post-preparation method has not been established. In this paper, we developed a universal post-preparation method for removing the substrate effect by a spontaneous fluctuation of monolayer TMDCs via coating with a simple hydrocarbon, paraffin. Because of the large thermal coefficient of paraffin, the stain is effectively applied to the TMDCs in the coating process. The paraffin-coated monolayer TMDCs show spontaneous fluctuation; and in an extreme case, the fluctuation forms the shape of a bundle. During the fluctuation and deformation, the substrate effect was removed; as a result, PL intensity improved remarkably in both sulfur- and selenium-based compounds of MoS2, WS2, MoSe2, and WSe2. This work suggests a universal strategy for improving the optical property of monolayer TMDCs by removing the substrate effect. It also extends the design of applying TMDCs as optoelectronics material due to the transparency, flexibility, and biocompatibility of the paraffin. | Takahiro Nakahara; Takashi Kobayashi; Tetsuji Dohi; Takeshi Yoshimura; Norifumi Fujimura; Daisuke Kiriya | Materials Science; Nanoscience; Hybrid Organic-Inorganic Materials; Thin Films; Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-04-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643a95b51d262d40ea86c6b7/original/spontaneous-crystal-fluctuation-in-hydrocarbon-polymer-coated-monolayer-mo-s2-mo-se2-ws2-and-w-se2-with-strong-photoluminescence-enhancement.pdf |
624d62a37ffb638afef68527 | 10.26434/chemrxiv-2022-kpq9c | Enantioselective Synthesis of N-Alkylindoles Enabled by Nickel-Catalyzed Modular, Unified C-C Coupling | Enantioenriched N-alkylindole compounds, in which nitrogen is bound to a stereogenic sp3 carbon, are an important entity of target molecules in the fields of biological, medicinal, and organic chemistry. Despite considerable efforts aimed at inventing methods for stereoselective indole functionalization, straightforward access to a diverse range of chiral N-alkylindoles in an intermolecular catalytic fashion from readily available indole substrates remains an ongoing challenge. In sharp contrast to existing C-N bond-forming strategies, here, we describe a modular, unified, nickel-catalyzed C-C coupling protocol that couples a broad array of N-indolyl-substituted alkenes with aryl/alkenyl/alkynyl bromides to produce chiral N-alkylindole adducts in single regioisomeric form, in up to 91% yield and 97% ee. The process is amenable to proceed under mild conditions and exhibit broad scope and high functional group compatibility. Utility is highlighted through late-stage functionalization of natural products and drug molecules, preparation of chiral building blocks. | Lun Li; Jiangtao Ren; Jingjie Zhou; Xiaomei Wu; Zhihui Shao; Xiaodong Yang; Deyun Qian | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Stereochemistry; Homogeneous Catalysis | CC BY 4.0 | CHEMRXIV | 2022-04-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/624d62a37ffb638afef68527/original/enantioselective-synthesis-of-n-alkylindoles-enabled-by-nickel-catalyzed-modular-unified-c-c-coupling.pdf |
66acaf4401103d79c58ff428 | 10.26434/chemrxiv-2024-p3j5n | Manipulating Horizontal Zn Deposition with Indium Salt Additive for Anode-Free Zn Batteries | Anode-free Zn batteries are gaining significant interest due to their reduced weight and simplified production compared to traditional Zn metal batteries. However, challenges such as zinc dendrite formation and parasitic reactions continue to impact their efficiency and cycle life. In this study, we present an effective strategy to form a zincophilic interphase in situ via indium co-deposition during cycling, using InCl3 as an electrolyte additive. We investigated the zinc plating/stripping processes with and without InCl3 using operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D). Structural changes from zinc deposition and dissolution were quantified using hydrodynamic spectroscopy (HS) and validated by ex-situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Our findings demonstrate that the indium-containing electrolyte additive has triple functions: it induces oriented zinc deposition through pre-nucleation, suppresses hydrogen evolution reaction by forming an indium intermediate layer, and suppresses zinc hydroxide sulfate (ZHS) by consuming OH- with In2O3/InOOH formation. These advantages result in decreased overpotential and higher Coulombic efficiency, enhancing the design of highly reversible anode-free zinc batteries.
| Viktor Vanoppen; Leiting Zhang; Erik J. Berg; Xu Hou | Energy; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66acaf4401103d79c58ff428/original/manipulating-horizontal-zn-deposition-with-indium-salt-additive-for-anode-free-zn-batteries.pdf |
6798cac7fa469535b92b854e | 10.26434/chemrxiv-2025-g2q4q | Bending Diamondoids: Strained [3]Cyclo(4,9-diphenyldiamantylene) | A strained macrocycle containing both aromatic biphenylene and aliphatic diamantylene units is presented. [3]Cyclo(4,9-diphenyldiamantylene) 1, synthesized via gold-mediated macrocyclization, is a cycloparaphenylene (CPP)-type macrocycle featuring a rigid sp3 hybridized cage in its backbone. The single-crystal X-ray structure of 1 reveals a triangular shape that is nearly flattened along the stiff diamantane units. Nevertheless, the diamantylene subunit undergoes bending and exhibits compressed C–C bonds on the inner diameter compared to stretched C–C bonds in the outer diameter. As a consequence, the connecting biphenylene units show larger bending compared to CPPs of similar size to maintain the overall radial curvature. This is reflected in the UV/Vis absorption and fluorescence spectra of the macrocycle, with the absorption maximum being red-shifted by 0.83 eV compared to non-strained biphenyl. | Clara Douglas; Niklas Grabicki; Nils Trapp; Lukas Husarich; Josefine Sprachmann; Oliver Dumele | Organic Chemistry; Organometallic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Materials Chemistry; Crystallography – Organic | CC BY NC 4.0 | CHEMRXIV | 2025-01-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6798cac7fa469535b92b854e/original/bending-diamondoids-strained-3-cyclo-4-9-diphenyldiamantylene.pdf |
65da3c8466c138172972623e | 10.26434/chemrxiv-2024-l7zgc | Structure-based design of seed-competent proteomimetic macrocycles derived from 4R tauopathic folds | Tauopathies are a class of neurodegenerative disorders whose predominant feature is tau protein deposits in the brain. Misfolded tau has the capacity to seed the fibrillization of naïve tau, leading to the prion-like spread of aggregates. Tau protomers within filaments always exhibit cross-beta amyloid structure, but distinct conformations often correlate with specific diseases. An understanding of how these conformations impact seeding activity remains elusive. Identification of the minimal epitopes required for transcellular propagation represents a key step toward more relevant models of disease progression. Here, we implement a diversity-oriented peptide macrocyclization approach toward seed-competent miniature tau, or “mini-tau”, proteomimetics. Structural elucidation of a potent mini-tau macrocycle reveals several conformational features present in tau folds from patient-derived extracts. The potentiation of beta-arch form and function through peptide stapling has broad-ranging implications for the minimization and mimicry of other proteopathic amyloids. | Isaac Angera; Xueyong Xu; Benjamin Rajewski; Grace Hallinan; Bernardino Ghetti; Ruben Vidal; Wen Jiang; Juan Del Valle | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65da3c8466c138172972623e/original/structure-based-design-of-seed-competent-proteomimetic-macrocycles-derived-from-4r-tauopathic-folds.pdf |
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