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60c755c0567dfe41f4ec6342 | 10.26434/chemrxiv.14157038.v1 | Three-Dimensional Hydrazone-Functionalized Covalent Organic Frameworks as pH-Triggered Rotary Switches | <i>The property expansion of
three-dimensional (3D) functionalized covalent organic frameworks (COFs) is important
for developing their potential applications. Herein, we report the first case of 3D hydrazone-decorated
COFs as pH-triggered molecular switches,
and explore their application in the
stimuli-responsive drug delivery system. These functionalized
COFs with hydrazone groups on the channel walls were obtained via a
multi-component bottom-up synthesis strategy. They exhibit a reversible E/Z isomerization at various pH values,
confirmed by UV-vis absorption spectroscopy and proton conduction. Remarkably, after
loading cytarabine (Ara-C) as a model drug molecule, these pH-responsive <a></a><a>COFs
showed an </a>excellent and intelligent sustained-release effect with an almost <a></a><a>4-fold</a>
increase in the Ara-C release at pH = 4.8 than at pH = 7.4,</i>
<i>which will effectively improve drug-targeting
and reduce drug side effects. Thus, these results open a way toward designing
3D stimuli-responsive functionalized COF materials and
promote their potential application as drug carriers
in <a></a><a>the field of </a>disease treatment.</i> | Wenjuan Zhao; Chengyang Yu; Fengqian Chen; Xinyu Guan; Hui Li; Bin Tang; Valentin Valtchev; Yushan Yan; Shilun Qiu; Qianrong Fang | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755c0567dfe41f4ec6342/original/three-dimensional-hydrazone-functionalized-covalent-organic-frameworks-as-p-h-triggered-rotary-switches.pdf |
60c746c4469df4299df436fc | 10.26434/chemrxiv.9438611.v2 | The Aggregation of Striped Nanoparticles in Mixed Phospholipid Bilayers | <div>We have used molecular dynamics (MD) to study the interaction of ligand-functionalized nanoparticles (NPs) with striped configurations of hydrophobic and hydrophilic ligands with mixed bilayers. As such NPs have been considered a potential drug-delivery mechanism, it is important to consider the secondary effects the inclusion of such NPs may cause in the heterogeneous environment inside the lipid bilayer, which would give an insight into how to optimize the NP functionalization for the most efficient delivery. We show that NPs can aggregate by inducing raft-like formations around each NP, which allows the subsequent aggregation of the NPs which reduces the overall surface area of the line tension around each NP. <br /></div> | Sang Noh; Anthony Nash; Rebecca Notman | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746c4469df4299df436fc/original/the-aggregation-of-striped-nanoparticles-in-mixed-phospholipid-bilayers.pdf |
60c75422842e65feefdb40d0 | 10.26434/chemrxiv.13618922.v1 | Persistent Homology Metrics Reveal Quantum Fluctuations and Reactive Atoms in Path Integral Dynamics | Nuclear quantum effects (NQEs) are known to impact a number of features associated
with chemical reactivity and physicochemical properties, particularly for light atoms
and at low temperatures. In the imaginary time path integral formalism, each atom
is mapped onto a “ring polymer” whose spread is related to the quantum mechanical
uncertainty in the particle’s position i.e. its thermal wavelength. A number of metrics
have previously been used to investigate and characterize this spread and explain effects
arising from quantum delocalization, zero-point energy, and tunnelling. Many of these
shape metrics consider just the instantaneous structure of the ring polymers. However, given the significant interest in methods such as centroid molecular dynamics and ring
polymer molecular dynamics that link the molecular dynamics of these ring polymers to
real time properties, there exists significant opportunity to exploit metrics that also allow
for the study of the fluctuations of the atom delocalization in time. Here we consider the
ring polymer delocalization from the perspective of computational topology, specifically
persistent homology, which describes the 3-dimensional arrangement of point cloud
data (i.e. atomic positions). We employ the Betti sequence probability distribution to
define the ensemble of shapes adopted by the ring polymer. The Wasserstein distances
of Betti sequences adjacent in time are used to characterize fluctuations in shape, where
the Fourier transform and associated principal components provides added information
differentiating atoms with different NQEs based on their dynamic properties. We
demonstrate this methodology on two representative systems, a glassy system consisting
of two atom types with dramatically different de Broglie thermal wavelengths, and
ab initio molecular dynamics simulation of an aqueous 4 M HCl solution where the
H-atoms are differentiated based on their participation in proton transfer reactions.
Keywords: path integral molecular dynamics, persistent homology, quantum
delocalization, proton transfer, Wasserstein distances. <br /> | Yunfeng Hu; Phonemany Ounkham; Ondrej Marsalek; Thomas E. Markland; Bala Krishnamoorthy; Aurora Clark | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75422842e65feefdb40d0/original/persistent-homology-metrics-reveal-quantum-fluctuations-and-reactive-atoms-in-path-integral-dynamics.pdf |
60c75400bdbb8918f5a3a550 | 10.26434/chemrxiv.13603277.v1 | α-Glucosidic Hydroquinone Derivatives from Viburnum Erosum | <p>Six new compounds<b> </b>(<b>1−6</b>) were isolated from the leaves of <i>Viburnum erosum</i> along with four known compounds <b>7−10</b>. The structures were determined by NMR and MS spectroscopic analyses, and their absolute configurations were established by chemical and spectroscopic methods. Compounds <b>1–6</b> were <i>α</i>-glucosidic hydroquinone derivatives with different linear monoterpenoid structures. Compounds <b>1−10 </b>were also evaluated for their tyrosinase inhibitory activities, and <b>10</b> showed potent inhibition of tyrosinase enzyme with IC<sub>50</sub> of 37.9 <i>μ</i>M compared to 47.6 <i>μ</i>M of the positive control (<i>β</i>-arbutin).</p> | Jinyoung Park; Jiho Lee; Hyeon S. Jang; Birang Jeong; Seong Y. Choi; Juyeol Kim; Yong S. Kwon; Heejung Yang | Natural Products | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75400bdbb8918f5a3a550/original/glucosidic-hydroquinone-derivatives-from-viburnum-erosum.pdf |
6261552a1033880292f55e07 | 10.26434/chemrxiv-2022-xttst | Synthesis and hyperpolarization of 13C and 2H labeled vinyl pyruvate and pyruvate | The hyperpolarization of nuclear spins has enabled unique applications in chemistry, biophysics, and particularly in metabolic imaging. Parahydrogen-induced polarization (PHIP) offers a fast and cost-efficient way of hyperpolarization. Nevertheless, PHIP lags behind dynamic nuclear polarization (DNP), which is already being evaluated in clinical studies. This shortcoming is mainly due to problems in the synthesis of the corresponding PHIP precursor molecules. The most widely used DNP tracer in clinical studies, particularly for the detection of prostate cancer, is 1-13C-pyruvate. The ideal derivative for PHIP is the deuterated vinyl ester because the spin physics allows for 100% polarization. Unfortunately, there is no efficient synthesis for vinyl esters of -ketocarboxylic acids in general and pyruvate in particular. Here, we present an efficient new method for the preparation of vinyl esters, including 13C labeled, fully deuterated vinyl pyruvate using a palladium catalyzed procedure. Using 50 % enriched parahydrogen and mild reaction conditions, a 13C polarization of 12% was readily achieved; 36% are expected with 100% pH2. Higher polarization values can be potentially achieved with optimized reaction conditions. | Rainer Herges; Arne Brahms; Andrey Pravdivtsev; Tim Stamp; Frowin Ellermann; Frank Sönnichsen; Jan-Bernd Hövener | Organic Chemistry; Bioorganic Chemistry; Organic Synthesis and Reactions | CC BY NC 4.0 | CHEMRXIV | 2022-04-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6261552a1033880292f55e07/original/synthesis-and-hyperpolarization-of-13c-and-2h-labeled-vinyl-pyruvate-and-pyruvate.pdf |
674872d85a82cea2fa43991d | 10.26434/chemrxiv-2024-vxz10 | Insights into the Enhanced Ceftazidime Hydrolysis by Ent385 AmpC β-lactamase from Multiscale Simulations | The emergence of multidrug-resistant bacteria poses a significant threat to public health. Particularly, they are becoming increasingly resistant to β-lactam antibiotics, one of the most important drug classes for the treatment of bacterial infections. Ceftazidime-avibactam has shown promising activity against highly drug-resistant bacteria, including carbapenem-resistant Enterobacterales. However, an Ala294-Pro295 deletion in the Class C E. cloacae AmpC β-lactamase can confer reduced susceptibility to these agents. In this study, we investigated the molecular mechanisms underlying the enhanced hydrolysis of ceftazidime by E. cloacae Ent385 AmpC β-lactamase with the deletion using quantum mechanics/molecular mechanics (QM/MM) simulations. First, we used constant pH molecular dynamics simulations of the β-lactamase-ceftazidime acyl-enzyme complex to verify the likely protonation states, confirming Tyr150 primarily exists as a tyrosinate. We then used QM/MM (DFTB2/ff14SB) umbrella sampling to calculate reaction free energy barriers (Δ‡G) for the deacylation step of cephalosporin hydrolysis. This reveals that Tyr150 (rather than the substrate) acts as the base. Importantly, the difference in Δ‡G between the canonical E. cloacae AmpC (P99) and the Ent385 variant was in very good agreement with the difference deduced from experimental kinetic data. Detailed analysis of the transition state ensembles, alongside additional simulations, show that the Ala294-Pro295 deletion allows the entrance of an additional water molecule, that helps stabilize the tetrahedral intermediate. Overall, our QM/MM simulations provide valuable insights into the reaction mechanism and reasons for enhanced ceftazidime breakdown. This can contribute to understand other reported Class C beta-lactamase variants that confer reduced susceptibility to antibiotic treatment. | Anderson H. Lima; Marc W. van der Kamp | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2024-12-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674872d85a82cea2fa43991d/original/insights-into-the-enhanced-ceftazidime-hydrolysis-by-ent385-amp-c-lactamase-from-multiscale-simulations.pdf |
60c751ec337d6c2b1ee28629 | 10.26434/chemrxiv.12631103.v2 | Unlocking the Potential of Single Atoms Loaded Geobacter Hybrid Catalyst as Bifunctional Electrocatalyst for Water Splitting | Single-atom metal (SA-M) catalysts with high dispersion of active metal sites allow maximum atomic utilization. However, conventional synthesis of SA-M catalysts involves high-temperature treatments, leading to a low yield with random distribution of atoms. Herein, a facile method to synthesize SA-M catalysts (M = Fe, Ir, Pt, Ru, Cu, or Pd) in a single step at ambient temperature, using the extracellular electron transfer capability of Geobacter sulfurreducens (GS), is presented. Interestingly, the SA-M is coordinated to three nitrogen (N) atoms adopting an MN3 on the surface of GS. Dry samples of SA-Ir@GS without further heat treatments show exceptionally high activity for OER when compared to benchmark IrO2 catalyst and comparable HER activity to commercial 10 wt.% Pt/C. The SA-Ir@GS electrocatalyst exhibits the best water‐splitting performance compared to other SA-M@GS, showing a low applied potential of 1.65 V to achieve 10 mA cm−2 in 1.0 M KOH solution with cycling over 5 h. The density functional calculations reveal that the large adsorption energy of H2O and moderate adsorption energies of reactants and reaction intermediates for SA-Ir@GS favorably improve its activity. This nature-based facile synthesis method of SA-M at room temperature provides a versatile platform for the preparation of other transition metal SA-M catalysts for various energy-related applications by merely altering the metal precursors. <br /> | Srikanth Pedireddy; Mahesh Kumar Ravva; Chandrani Nayak; Dalaver Anjum; Shambhu Nath Jha; Krishna
P. Katuri; Pascal Elias Saikaly | Catalysts; Nanostructured Materials - Materials; Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Electrocatalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c751ec337d6c2b1ee28629/original/unlocking-the-potential-of-single-atoms-loaded-geobacter-hybrid-catalyst-as-bifunctional-electrocatalyst-for-water-splitting.pdf |
677f5560fa469535b9451121 | 10.26434/chemrxiv-2025-8bqws | A nature-inspired steroid-like electron acceptor to polarity-dependent probe for visualizing lipid evolution in Alzheimer’s disease | To date, most optical materials are derived from petrochemicals, facing problems like renewability, sustainability, and biocompatibility. Fluorescent materials derived from natural products with unique structures, stimuli-responsive photophysical properties, and superior compatibility are of extraordinary significance for biomedical applications. In this work, a nature-inspired electron acceptor with a steroid-like structure (DABT) has been constructed based on the tricyclic diterpene skeleton of natural rosin. Through substitution with variable electron donors, red-shifted and twisted intramolecular charge transfer can be realized. In particular, the dimethyl amino substituted compound, DABT-DMA, can be applied as a polarity-dependent bio-sensor with a dual responsiveness of distinct fluorescence wavelength and lifetime due to its outstanding solvent effect. In addition to the advantageous biocompatibility and steroid-like structure of DABT-DMA, successful lipid droplet-targeted imaging at dual channels can be achieved. Further investigations prove that dysfunction of lipid droplets induced by Aβ protein can result in the accumulation of cholesterol analogs, further exacerbating the pathological features of Alzheimer’s disease. This work not only proposes a novel natural electron acceptor with a steroid-like structure possessing both biocompatibility and targeting capability but also offers new insights into Alzheimer’s disease-related pathophysiological mechanisms, paving the way toward potential diagnostics. | Lulu Wu; Wen-Jin Wang; Yuting Lin; Weiren Zhong; Jifu Wang; Jianyu Zhang; Zheng Zhao; Fritz E. Kühn; Yun Xu; Qiang Yong; Ben Zhong Tang; Xu-Min Cai | Materials Science; Biocompatible Materials; Dyes and Chromophores; Optical Materials; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677f5560fa469535b9451121/original/a-nature-inspired-steroid-like-electron-acceptor-to-polarity-dependent-probe-for-visualizing-lipid-evolution-in-alzheimer-s-disease.pdf |
652645cebda59ceb9a535c13 | 10.26434/chemrxiv-2023-dcx32 | Photocatalytic chloride to chlorine conversion by ionic iron in aqueous aerosols: A combined experimental, quantum chemical and chemical equilibrium model study | Aerosol chamber experiments show that the ligand-to-metal charge transfer absorption in iron(III) chlorides can lead to the production of chlorine. Based on this mechanism, the photocatalytic oxidation of chloride in mineral dust-sea spray aerosols was recently shown to be the largest source of chlorine over the North Atlantic. However, there has not been a detailed analysis of the mechanism including the aqueous formation equilibria and the absorption spectra of the iron chlorides; neither has there been an analysis of which iron chloride is the main chromophore. Here we present the results of experiments of photolysis FeCl_3 · 6H_2O in specific wavelength bands, an analysis of the absorption spectra of the title compounds from n=1..4 made using density functional theory, and the results of an aqueous phase model that predicts the abundance of the iron chlorides with changes in pH and ion concentrations. Transition state analysis is used to determine the energy thresholds of the dissociations of the species. Based on a speciation model with conditions extending from dilute water droplet to acidic seawater droplet to brine to salty crust, and the absorption rates and dissociation thresholds, we find that FeCl_2^+ is the most important species for chlorine production for a wide range of conditions. The mechanism was found to be active in the range of 400 to 530 nm with a maximum around 440 nm. We conclude that iron chlorides will form in atmospheric aerosols from the combination of iron(III) cations with chloride and that they will be activated by sunlight, generating chlorine (Cl_2/Cl) from chloride (Cl-), in a process that is catalytic in both chlorine and iron. | Marie Kathrine Mikkelsen; Jesper Baldtzer Liisberg; Maarten M. J. W. van Herpen; Kurt V. Mikkelsen; Matthew S. Johnson | Theoretical and Computational Chemistry; Physical Chemistry; Earth, Space, and Environmental Chemistry; Photochemistry (Physical Chem.); Physical and Chemical Processes; Quantum Mechanics | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652645cebda59ceb9a535c13/original/photocatalytic-chloride-to-chlorine-conversion-by-ionic-iron-in-aqueous-aerosols-a-combined-experimental-quantum-chemical-and-chemical-equilibrium-model-study.pdf |
60c7455dbb8c1a29543da66f | 10.26434/chemrxiv.10007033.v1 | A Possible Mechanism behind the Discovery of Prussian Blue | In this work, we
synthesized Prussian Blue (PB) by pyrolysis of nitrogen-rich organic compounds
and ferric/ferrous salts in the presence of alkali metal salt in inert atmosphere
at high temperature, which was completely different form popular method based
on the reaction of ferric ions and ferrocyanide ions. By exploring the history
of Prussian Blue and some research results, we proposed a possible mechanism to
explain the formation of Prussian Blue. The mechanism is as follows: Firstly, carbon, nitrogen
and oxygen element in the mixture were transformed to cyanate by the catalysis
of alkali metal species. With the increasing of temperature, organic compounds
decomposed to release reducing gases such as H<sub>2</sub> and CO and
eventually formed carbon materials. The reducing gases reduced part of Fe<sup>3+</sup>
to Fe<sup>2+</sup> and the carbon reduced the cyanate to cyanide. So Prussian
Blue was formed by cyanide, Fe<sup>3+</sup> and Fe<sup>2+</sup>. The most import substance in the process is the alkali salts and a key intermediate product namely cyanate is proposed. Detailed experiments can be found in PDF file. | Youxin Duan; Junyan Zhang | Carbon-based Materials; Dyes and Chromophores; Ligands (Inorg.); Reaction (Inorg.); Transition Metal Complexes (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7455dbb8c1a29543da66f/original/a-possible-mechanism-behind-the-discovery-of-prussian-blue.pdf |
667d61585101a2ffa8a53d16 | 10.26434/chemrxiv-2024-qskp0 | Site-selective protein modification via peptide-directed proximity catalysis | Proximity catalysis exploits ligand-binding for localised, catalytic protein modification. In this work, we introduce catalyst-functionalised peptides as versatile ligands for this approach. Through the functionalisation of target-binding peptides with pyridinium oximes catalysts, we show that model proteins can be site-selectively modified with a variety of N-acyl-N-alkylsulfonamide reagents, to introduce common functionalities including fluorophores and affinity handles to the protein surface. Critically, we show that simple changes to the peptide-catalyst structure, moving the pyridinium oxime from N- to C-terminus, alter the site of modification. This opens up possibilities to develop peptide libraries for a particular target protein, and subsequently tuning the modification site for a given application. | Laetitia Raynal; Joe Nabarro; Lisa Miller; Adam Dowle; Sophie Moul; Steven Johnson; Martin Fascione; Christopher Spicer | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Bioorganic Chemistry; Chemical Biology; Organocatalysis | CC BY NC 4.0 | CHEMRXIV | 2024-07-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/667d61585101a2ffa8a53d16/original/site-selective-protein-modification-via-peptide-directed-proximity-catalysis.pdf |
67aa6101fa469535b9c6766f | 10.26434/chemrxiv-2025-gvr5b | Benchtop Proton NMR Study of Hyperpolarized Charged and Neutral Ir-IMes Hydride Intermediates in Acetonitrile | In this work, we utilize 1H benchtop nuclear magnetic resonance (NMR) spectrometer (proton frequency 44.7 MHz) for real-time monitoring of spin-transfer catalysis and hydrogen-assisted activation process starting from an iridium-based organometallic complex [Ir(IMes)(COD)Cl] (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, COD = cyclooctadiene). We identify two distinct activation pathways: first, via the formation of neutral intermediate complex [Ir(IMes)(COD)(H2)Cl], and second, via the formation of charged complexes [Ir{+}(IMes) (COD)(H2)R]Cl{-} with bound ligands R = acetonitrile, ammonia, and benzylamine. These ligands originate from substrate choice in the activation process. We conclude that the pathway direction is dominated by solvent polarity. On the basis of this, we develop a protocol for obtaining stable and long-lasting SABRE (Signal Amplification by Reversible Exchange) polarization of an acetonitrile solvent in the presence of a benzylamine coligand. These results are important for better understanding of the chemical dynamics in SABRE systems as well as for the fundamental physics experiments that require large and long-lasting polarization of highly-concentrated molecules (e.g., those from the solvent itself). | Raphael Kircher; Jingyan Xu; Erik Van Dyke; Rozana Mazlumian; Dmitry Budker; Danila Barskiy | Physical Chemistry; Catalysis; Analytical Chemistry; Spectroscopy (Anal. Chem.); Homogeneous Catalysis; Chemical Kinetics | CC BY 4.0 | CHEMRXIV | 2025-02-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67aa6101fa469535b9c6766f/original/benchtop-proton-nmr-study-of-hyperpolarized-charged-and-neutral-ir-i-mes-hydride-intermediates-in-acetonitrile.pdf |
677a827481d2151a02f4b4b4 | 10.26434/chemrxiv-2025-rzl3r | Visible-Light Photoredox Catalyzed, Facile Synthesis of 2-Amino-1,3,4-Thiadiazoles from Aldehydes and Thiosemicarbazides | A metal-free, visible light-mediated protocol has been developed towards the synthesis of 2-amino-1,3,4-thiadiazoles (ATZ) from commercially available aldehydes and thiosemicarbazides. This one-step conversion has been achieved by the condensa-tion of aldehydes with substituted thiosemicarbazides in the presence of 2,4,6-tri(p-tolyl) pyrylium tetrafluoroborate (TPP-TFB) as a photoredox catalyst. Different aldehydes/hetero aldehydes, as well as thiosemicarbazides, have reacted smoothly under the reaction conditions to afford the 2-amino-1,3,4-thiadiazoles in good to excellent yields. The practicality of the de-veloped method has been successfully extended for the convenient one-pot synthesis of commercial herbicide Tebuthiuron on a gram scale. A series of control experiments, cyclic voltammetry, and fluorescence studies have been carried out to investi-gate the reaction mechanism. | Sachin M. Thorat; Anindita Bhowmick ; Sunderraman Sambasivan; Dr. Ramakrishna G. Bhat | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677a827481d2151a02f4b4b4/original/visible-light-photoredox-catalyzed-facile-synthesis-of-2-amino-1-3-4-thiadiazoles-from-aldehydes-and-thiosemicarbazides.pdf |
6220e579daa4fb8a0a7e1eb5 | 10.26434/chemrxiv-2022-g2wdd | Sooting tendencies of terpenes and hydrogenated
terpenes as sustainable transportation biofuels | Terpenes are a diverse group of molecules that are synthesized by plants and microorganisms through combining units of isoprene (2 methyl 1,3 butadiene). They typically contain rings and methyl branches, which gives them high energy densities and low freezing points and makes them appealing candidates for sustainable transportation biofuels. Between the original biosynthesis and upgrading options such as hydrogenation, they have a large degree of freedom of structures, e.g., different carbon skeletons, positions of double bonds, and functional groups. Therefore, structure-property data is needed to downselect potential fuel candidates. Here, we measured the sooting tendencies of 17 C10 monoterpenes and 7 of their hydrogenated analogues. The hydrogenated compounds were custom synthesized, so the quantities were too small for conventional smoke point measurements. Thus, the sooting tendencies were quantified with yield sooting index (YSI), which is based on the soot yield in a fuel-doped non-premixed methane flame. Derived smoke points (DSPs) were estimated from a correlation between YSI and smoke point for other hydrocarbons. The YSI of terpenes and their derivatives varies widely from 85.6 to 248.5. The YSI follows the trend: terpenes > dihydroterpenes > tetrahydroterpenes. The DSPs of all the tetrahydroterpenes and some dihydroterpenes are higher than that of a Jet-A fuel sample, suggesting that they offer soot reduction benefits. The YSIs depend strongly on molecular structure; for example, α-pinene and β-pinene have identical carbon skeletons and differ only in the position of one carbon-carbon double bond, but the YSI of α-pinene is 34% higher than that of β-pinene. Detailed decomposition analysis via density functional theory (DFT) suggests that compared with β-pinene, α-pinene requires fewer steps to form the first aromatic ring and the process is more thermodynamically favorable. The YSI difference between the pinenes is mainly affected by the identity of the products from the dominant decomposition pathways. | Junqing Zhu; Juan V. Alegre-Requena; Patrick Cherry; Dominic Curtis; Benjamin G. Harvey; Mohamed A. Jabed; Seonah Kim; Charles S. McEnally; Lisa D. Pfefferle; Josanne-Dee Woodroffe | Theoretical and Computational Chemistry; Physical Chemistry; Energy; Computational Chemistry and Modeling; Fuels - Energy Science; Chemical Kinetics | CC BY 4.0 | CHEMRXIV | 2022-03-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6220e579daa4fb8a0a7e1eb5/original/sooting-tendencies-of-terpenes-and-hydrogenated-terpenes-as-sustainable-transportation-biofuels.pdf |
6379388f2079815aee2d6057 | 10.26434/chemrxiv-2022-b3k94 | Computational Characterization of the Inhibition Mechanism of Xanthine Oxidoreductase by Topiroxostat | Xanthine oxidase (XO) is a member of the molybdopterin-containing enzyme family. It interconverts xanthine to uric acid as the last step of purine catabolism in the human body. The high uric acid concentration in the blood directly leads to human diseases like gout and hyperuricemia. Therefore, drugs that inhibit the biosynthesis of uric acid by human XO have been clinically used for many years to decrease the concentration of uric acid in the blood. In this study, the inhibition mechanism of XO and a new promising drug, Topiroxostat (code: FYX-051), is investigated by employing molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) calculations. This drug has been reported to act as both a non-covalent and covalent inhibitor and undergoes a stepwise inhibition by all its hydroxylated metabolites, which include 2-hydroxy-FYX-051, dihydroxy-FYX-051, and trihydroxy-FYX-051. However, the detailed mechanism of inhibition of each metabolite remains elusive and can be useful for designing more effective drugs with similar inhibition functions. Hence, herein we present the computational investigation of the structural and dynamical effects of FYX-051 and the calculated reaction mechanism for all the oxidation steps catalyzed by the molybdopterin center in the active site. Calculated results for the proposed reaction mechanisms for each metabolite’s inhibition reaction in the enzyme’s active site, binding affinities, and the non-covalent interactions with surrounding amino acid residues are consistent with previously reported experimental findings. Analysis of the non-covalent interactions via EDA and NCI suggests residues L648, K771, E802, R839, L873, R880, R912, F914, F1009, L1014, and A1079 can be used as key interacting residues for further hybrid-type inhibitor development. | Yazdan Maghsoud; Chao Dong; G. Andrés Cisneros | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6379388f2079815aee2d6057/original/computational-characterization-of-the-inhibition-mechanism-of-xanthine-oxidoreductase-by-topiroxostat.pdf |
65b890af66c13817298d53c6 | 10.26434/chemrxiv-2023-2lwx8-v2 | Mechanistic rationale for ketene formation during vaping | Ketene is one of the most toxic vaping emissions identified to date. However, its high reactivity renders it relatively challenging to identify. In addition, theoretical studies show that realistic vaping temperature settings are too low to produce ketene. Each of these issues is addressed herein. First, an isotopically-labeled acetate precursor is used for the identification of ketene with enhanced rigor in vaped aerosols. Second, discrepancies between theoretical and experimental findings are explained by accounting for the effects of aerobic (experimental) versus anaerobic (simulated and theoretical) pyrolysis conditions. This finding is also relevant to explaining the relatively low temperature production of aerosol toxicants beyond ketene. Moreover, the study herein shows that ketene formation during vaping is not limited to molecules possessing a phenyl acetate substructure. This means that ketene emission during vaping, including from popular flavorants such as ethyl acetate, may be more prevalent than is currently known. | Kaelas Munger; Killian Anreise; Robert Jensen; David Peyton; Robert Strongin | Biological and Medicinal Chemistry; Organic Chemistry; Analytical Chemistry; Physical Organic Chemistry; Environmental Analysis; Chemical Biology | CC BY 4.0 | CHEMRXIV | 2024-01-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65b890af66c13817298d53c6/original/mechanistic-rationale-for-ketene-formation-during-vaping.pdf |
651d8b96bda59ceb9add494f | 10.26434/chemrxiv-2023-nlqqz-v3 | Two mechanisms for the spontaneous emergence, execution, and reprogramming of chemical logic circuits | A key question in origin-of-life research is how primitive life or life-like systems obtained reusable and reprogrammable machineries of processing information to respond to various environmental and internal stimuli. One strategy to approach this question is viewing living systems as universal chemical computers. This approach focuses upon uncovering how reusable and reprogrammable chemical NOT, AND, and OR logic gates could appear under prebiotically possible scenarios where simple chemicals and second- or lower-order reactions are more frequent than macromolecules and higher-order reactions. Here, we model two theoretical mechanisms of forming Boolean gates based on geochemically plausible reaction systems that could have preceded complex biopolymers. The mechanisms exploit simple bistable autocatalytic systems to encode binary variables and use heterogeneous dilution rates to differentially activate or deactivate autocatalysis in different reactors. We found that NOT, AND, and OR gates, as well as more complex logic circuits, can spontaneously arise from connected, well-mixed flow reactors based on (i) catalysis by a heterodimer between mutually inhibitory autocatalysts or (ii) selectively permeable tunnels connecting reactors. Our results suggest that the prebiotic emergence of chemical logic circuits provides new guides for experimentally actualizing chemical computation. | Zhen Peng; Zachary R. Adam | Physical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651d8b96bda59ceb9add494f/original/two-mechanisms-for-the-spontaneous-emergence-execution-and-reprogramming-of-chemical-logic-circuits.pdf |
63870b490058eb131f6aa340 | 10.26434/chemrxiv-2022-1g23h | Azatriseptanes - strained framework analogs of [7,7,7]circulenes | The syntheses and characterizations of heptagon-embedded polycyclic aromatic compounds are essential for understanding the effect of negative curvature on carbon allotropes such as fullerene and graphene that have applications in functional organic materials. However, owing to the synthetic difficulties in functionalizing and embedding 7-membered rings, these strain-challenged structures are relatively unexplored. We report here the synthesis and photophysical characterization of a triarylamine core bridged with ethane chains at the 2,2’-positions. In doing so, we provide access to the first heterocycle containing three fused heptagon rings with a nitrogen at its core (BATA-NHAc). DFT calculations and X-ray crystallography reveal a remarkably strained structure wherein two of the bridged aryl units approach coplanarity, whilst the third ring is twisted out of plane. The unique conformation of BATA-NHAc results in distinctive photophysical and electrochemical properties that open new avenues in understanding the structure-property relationships of curved π-aromatics and the construction of π-frameworks of increasing complexion. | Kai Zhang; Philip A. Hope; Mélissa El Bitar Nehme; Anthony Linden; Bernhard Spingler; Michel Rickhaus | Organic Chemistry; Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63870b490058eb131f6aa340/original/azatriseptanes-strained-framework-analogs-of-7-7-7-circulenes.pdf |
60c74a71f96a00a976287412 | 10.26434/chemrxiv.11312828.v2 | Metabolomics Analysis Reveals Both Plant Variety and Choice of Hormone Treatment Modulate Vinca Alkaloid Production in Catharanthus Roseus. | <p>The medicinal plant <i>Catharanthus roseus</i>produces numerous secondary metabolites of interest for the treatment of many diseases—most notably for the terpene indole alkaloid (TIA) vinblastine, which is used in the treatment of leukemia and Hodgkin’s lymphoma. Historically, methyl jasmonate (MeJA) has been used to induce TIA production, but in the past, this has only been investigated in either whole seedlings, cell culture, or hairy root culture. In this work, we investigate the induction capabilities of MeJA and ethylene, a different phytohormone, in both the shoots and roots of two varieties of <i>C. roseus. </i>Using LCMS and RT-qPCR, we demonstrate the importance of variety selection, as we observe markedly different induction patterns of important TIA precursor compounds. Additionally, both phytohormone choice and concentration have significant effects on TIA biosynthesis. Finally, our study suggests that several early-induction pathway steps as well as pathway-specific genes are likely to be transcriptionally regulated. Our findings highlight the need for a complete set of ’omics resources in commonly used <i>C. roseus </i>varieties.</p> | Valerie Fraser; Benjamin Philmus; Molly Megraw | Natural Products; Mass Spectrometry; Environmental biology; Plant Biology | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74a71f96a00a976287412/original/metabolomics-analysis-reveals-both-plant-variety-and-choice-of-hormone-treatment-modulate-vinca-alkaloid-production-in-catharanthus-roseus.pdf |
60c7464e0f50db6c77396404 | 10.26434/chemrxiv.7215269.v4 | The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces | <div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div> | Rubén Laplaza; Julia Contreras-García; Franck Fuster; François Volatron; Patrick Chaquin | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7464e0f50db6c77396404/original/the-inverted-bond-revisited-analysis-of-in-silico-models-and-of-1-1-1-propellane-using-orbital-forces.pdf |
65f46f5466c13817290f4f1f | 10.26434/chemrxiv-2024-kcqq1 | Localized nanopore fabrication in silicon nitride membranes by femtosecond laser exposure and subsequent controlled breakdown. | Controlled breakdown (CBD) has emerged as an effective method for fabricating solid-state nanopores in thin suspended dielectric membranes for various biomolecular sensing applications. On an unpatterned membrane, the site of nanopore formation by controlled breakdown is random. Nanopore formation on a specific site on the membrane has previously been realized using local thinning of the membrane by lithographic processes or laser-assisted photothermal etching under immersion in an aqueous salt solution. However, these approaches require elaborate and expensive cleanroom-based lithography processes or involve intricate procedures using custom-made equipment. Here, we present a rapid cleanroom-free approach using single pulse femtosecond laser exposures of 50 nm thick silicon nitride membranes in air to localize the site of nanopore formation by subsequent controlled breakdown to an area less than 500 nm in diameter on the membrane. The precise positioning of the nanopores on the membrane could be produced both using laser exposure powers which caused significant thinning of the silicon nitride membrane (up to 60 % of the original thickness locally), as well as at laser powers which caused no visible modification of the membrane at all. We show that nanopores made using our approach can work as single-molecule sensors by performing dsDNA translocation experiments. Due to the applicability of femtosecond laser processing to a wide range of membrane materials, we expect our approach to simplify the fabrication of localized nanopores by controlled breakdown in a variety of thin film material stacks, thereby enabling more sophisticated nanopore sensors. | Chrysovalantou V. Leva; Saumey Jain; Kevin Kistermann; Kasumi Sakurai; Göran Stemme; Anna Herland; Joachim Mayer; Frank Niklaus; Shyamprasad N. Raja | Nanoscience; Nanodevices; Nanofabrication | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f46f5466c13817290f4f1f/original/localized-nanopore-fabrication-in-silicon-nitride-membranes-by-femtosecond-laser-exposure-and-subsequent-controlled-breakdown.pdf |
60c7422c567dfe5dafec3f0b | 10.26434/chemrxiv.8234057.v1 | Unconventional Optical Response in Engineered Au-Ag Nanostructures | This
article describes the optical properties of nanostructures composed of silver
particles embedded into a gold matrix. In previous studies these materials were
shown to exhibit temperature dependent transitions to a highly conductive and
strongly diamagnetic state. Here we describe the anomalous optical properties
of these nanostructures. Most notably, these materials fail to obey Mie theory
and exhibit an unconventional resonance with a maximum at about 4 eV, while the
usual gold and silver localized surface plasmon resonances are suppressed. This
effect implies a significant deviation from the bulk dielectric functions of gold
and silver. We further resolved this resonance into its absorbance and
scattering sub-parts. It is observed that the resonance is largely comprised of
scattering, with negligible losses even at ultraviolet frequencies. | Dev Kumar Thapa; Subham Kumar Saha; Guru Pratheep Rajasekar; Biswajit Bhattacharyya; Rekha Mahadevu; Anshu Pandey | Nanostructured Materials - Materials; Optical Materials; Plasmonic and Photonic Structures and Devices; Optics | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7422c567dfe5dafec3f0b/original/unconventional-optical-response-in-engineered-au-ag-nanostructures.pdf |
64294b9ba029a26b4cc84666 | 10.26434/chemrxiv-2023-37qp8 | Extended Curtin-Hammett principle: Origin of pathway selection in reversible reaction networks under kinetic control | Curtin-Hammett principle works in a reaction sequence where slow irreversible reactions are connected to a fast reversible reaction and determines the product distribution depending only on the relative energy barriers of the two irreversible reactions, resulting in kinetic pathway selection. A basic question is whether Curtin-Hammett principle is applicable to reaction networks composed of reversible elementary reactions, though reversible reactions are generally governed by the laws of thermodynamics. Numerical simulations of model systems where reversible elementary reactions are connected linearly to an initial reversible reaction demonstrate that a metastable state far from equilibrium is transiently produced and that its lifetime is prolonged with increasing the number of connected reversible reactions. Pathway selection based on this extended concept of Curtin-Hammett principle was observed in molecular self-assembly of a Pd6L4 truncated tetrahedron, which supports the idea that the extended Curtin-Hammett principle is a key general concept underlining kinetic control in reversible reaction networks. | Satoshi Takahashi; Hirofumi Sato; Shuichi Hiraoka | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC 4.0 | CHEMRXIV | 2023-04-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64294b9ba029a26b4cc84666/original/extended-curtin-hammett-principle-origin-of-pathway-selection-in-reversible-reaction-networks-under-kinetic-control.pdf |
61fad034e0f529eb70a4fb3b | 10.26434/chemrxiv-2021-x4j63-v2 | A Statistical Representation of Stacking Disorder in Layered Covalent Organic Frameworks | Covalent organic frameworks (COFs) are among the fastest growing classes of materials with an almost unlimited number of achievable structures, topologies, and functionalities. The exact structure of layered COFs is, however, hard to determine due to often significant mismatch between experimental powder X-ray diffraction pattern (PXRD) and predicted geometries. We attribute these discrepancies to an inherent disorder in the stacking of layered COFs, invalidating standard theoretical 3D models. We have represented structure of COF-1, COF-5 and ZnPc-pz by stacking layers following the Maxwell-Boltzmann energy distribution of their stacking modes. Simulated PXRD patterns of the statistical COF models are close to the experiment, featuring an agreement in peak intensity, width and asymmetry never obtained before. The rarely considered ABC stacking mode proved to be important in layered COFs, as well as including solvent molecules. Our model also shows several general features in PXRD originating from the stacking disorder. | Yingying Zhang; Miroslav Položij; Thomas Heine | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2022-02-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61fad034e0f529eb70a4fb3b/original/a-statistical-representation-of-stacking-disorder-in-layered-covalent-organic-frameworks.pdf |
66a926acc9c6a5c07a86807e | 10.26434/chemrxiv-2024-dchgr | Barium Titanate BaTiO3 Raman Spectra and their deconvolution with q-BWF functions | Here we study the Raman spectra of Barium Titanate, BaTiO3, given in the RRUFF and ROD databases. Being the Raman bands strongly asymmetric, we are deconvoluting them by means of the q-BWF functions. These functions are generalizing the Breit-Wigner-Fano line shape in the framework of the q-exponential function of Tsallis statistics. Besides the deconvolution of Raman spectra, we consider the literature on BaTiO3 Raman spectroscopy, particularly the assignment of the bands. Being the wavenumbers of some A1 and E modes very close, the observed modes are mixed. Moreover, dips in the spectra have suggested as due to the presence of anharmonicity, interference and Fano resonance. | Amelia Carolina Sparavigna | Materials Science | CC BY 4.0 | CHEMRXIV | 2024-08-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66a926acc9c6a5c07a86807e/original/barium-titanate-ba-ti-o3-raman-spectra-and-their-deconvolution-with-q-bwf-functions.pdf |
6633edaf91aefa6ce1001e1b | 10.26434/chemrxiv-2024-7l33t | Computational Analysis of Fully Activated Orexin Receptor 2 Across Various Thermodynamic Ensembles with Surface Tension Monitoring | Molecular dynamics (MD) simulations play a crucial role in understanding dynamic biological processes at nanoscale, yet predicting non-equilibrium phenomena like receptor activation presents significant challenges. In such cases, the primary objective isn't merely achieving stable MD trajectories; rather, it's imperative to remove all artificial restraints in order to unveil suppressed mechanical modes within the simulated systems, and thus advancing computer-aided drug design. In this study, we investigated the stability of the fully activated conformation of the orexin receptor 2 (OX2R) embedded in a pure 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) bilayer using MD simulations. Various thermodynamic ensembles (i.e. NPT, NVT, NVE, NPAT, µVT and NPγT) were employed to explore the system's dynamics comprehensively. 11 physical quantities, including so called OX2R activation distance, essential protein dynamics, membrane thickness, hydrogen order parameters, and ligand-protein potential energies, across 104 MD trajectories covering 10.4 µs of chemical time were calculated and profoundly analyzed. Special attention was given to assessing surface tension within the simulation box, particularly under NPγT conditions, where 21 nominal surface tension constants were evaluated. Notably, our findings suggest that traditional thermodynamic ensembles like NPT may not adequately control physical properties of the POPC membrane, impacting the plausibility of the OX2R model. In general, the performed study underscores the importance of employing the NPγT ensemble for computational investigations of membrane-embedded receptors, as it effectively maintains zero surface tension in the simulated system. These results offer valuable insights for future research aimed at understanding receptor dynamics and designing targeted therapeutics. | Rafael Dolezal | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6633edaf91aefa6ce1001e1b/original/computational-analysis-of-fully-activated-orexin-receptor-2-across-various-thermodynamic-ensembles-with-surface-tension-monitoring.pdf |
61cf22f49efae746002cddba | 10.26434/chemrxiv-2022-drdn0 | Novel copolymers of vinyl acetate. 3 Ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates | Novel copolymers of vinyl acetate and ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2C2H5 (where R is 4-acetoxy, 4-acetamido, 2-cyano, 3-cyano, 4-cyano, 4-dimethylamino, 4-diethylamino, 2,4,6-trimethyl, 2,3-dimethyl-4-methoxy, 2,4-dimethoxy-3-methyl were prepared in solution with radical initiation at 70C. The propenoates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Thermal behavior of the copolymers was studied by DSC (Tg) and TGA. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 160-350ºC range with residue (1.5-15.1 wt%), which then decomposed in the 500-650ºC range. | Kamil M. Wojdyla; Benjamin Y. Killam; Carrie L. Grady; Faheem Jesani; Anne M. Johnson; Vickie Kalamaras; Jesse J. Kong; Kiersten L. Thompson; Charles A. Rallo; Anna L. Lampignano; Meenakshi Malhotra; Sarah Mikach; Gregory B Kharas | Organic Chemistry; Polymer Science; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Organic Polymers | CC BY 4.0 | CHEMRXIV | 2022-01-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61cf22f49efae746002cddba/original/novel-copolymers-of-vinyl-acetate-3-ring-substituted-ethyl-2-cyano-3-phenyl-2-propenoates.pdf |
60c73ffef96a008e252861e1 | 10.26434/chemrxiv.7072070.v4 | Recommendations for Reporting Ion Mobility Mass Spectrometry Measurements | Here we present a guide on ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties on mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N, (ii) ion mobility does not measure surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model, (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort towards establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. <br /><br /><br /> | Valerie Gabelica; Alexandre A. Shvartsburg; Carlos Afonso; Perdita E. Barran; Justin L. P. Benesch; Christian Bleiholder; Michael
T. Bowers; Aivett Bilbao; Matthew F. Bush; J. Larry Campbell; Iain D. G. Campuzano; Tim J. Causon; Brian H. Clowers; Colin Creaser; Edwin De Pauw; Johann Far; Francisco Fernandez-Lima; John C. Fjeldsted; Kevin Giles; Michael Groessl; Christopher J. Hogan, Jr.; Stephan Hann; Hugh I. Kim; Ruwan T. Kurulugama; Jody C. May; John A. McLean; Kevin Pagel; Keith Richardson; Mark. E. Ridgeway; Frédéric Rosu; Frank Sobott; Konstantinos Thalassinos; Stephen J. Valentine; Thomas Wyttenbach | Chemical Education - General; Analytical Chemistry - General; Analytical Apparatus; Biochemical Analysis; Chemoinformatics; Environmental Analysis; Mass Spectrometry; Separation Science; Bioinformatics and Computational Biology; Chemical Biology; Quality Control; Physical and Chemical Properties; Transport phenomena (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73ffef96a008e252861e1/original/recommendations-for-reporting-ion-mobility-mass-spectrometry-measurements.pdf |
6205444f0c0bf00710e4f0a8 | 10.26434/chemrxiv-2022-nq98h | Property-driven development of privileged macrocyclic scaffolds using heterocycles | Passive membrane permeability is a fundamental challenge in the development of bioactive macrocycles. To achieve this objective, chemists have resorted to various strategies, the most common of which is deployment of N-methylated amino acids and/or D-amino acids. Here we investigate the effect of heterocyclic grafts on the passive membrane permeability of macrocycles and report the structural consequences of iterative amino acid replacement by azole rings. Through stepwise sub-stitution of amino acid residues for heterocycles, we show that lipophilicity and PAMPA permeability of a macrocycle can be vastly improved. Overall, changes in permeability do not scale linearly as more heterocycles are incorporated, underscor-ing the subtleties of conformation-property relationships in this class of molecule. NMR analysis and molecular dynamics simulations provide insights into the structural consequences of the added heterocycles and foreshadow the emergence of privileged macrocyclic scaffolds for drug discovery. | George Saunders; Andrei Yudin | Organic Chemistry; Bioorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-02-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6205444f0c0bf00710e4f0a8/original/property-driven-development-of-privileged-macrocyclic-scaffolds-using-heterocycles.pdf |
641c09f262fecd2a834b96b0 | 10.26434/chemrxiv-2023-5h9df | Catalytic carbonylation of acrylic acid to succinic anhydride | Alternative sources for polymeric materials have been sought in the past few years to reduce our dependence on fossil feedstock. We report the catalytic carbonylation of acrylic acid, a platform chemical that can be bio-sourced, as a new pathway toward the formation of a useful monomer to polyesters, namely succinic anhydride. The novel system reported herein tackles the difficult carbonylation of unsaturated carboxylic acids through the utilization of an Earth-abundant metal catalyst, [Co2(CO)8], in presence of a bidentate ligand, 1,2-bis(dicyclohexylphosphino)ethane (dcpe), and H2. We investigated the influence of the reaction conditions through the variations of metal, ligand, temperature, pressure, and gas composition variations. The carbonylative ring-closure of acrylic acid was successfully obtained in high yield and selectivity toward the formation of succinic anhydride using mild conditions (90 °C and 16 bar of CO/H2 95:5). | Marie-Hélène Pietraru; Nicolas Lentz; Louise Ponsard; Emmanuel Nicolas; Thibault Cantat | Catalysis; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/641c09f262fecd2a834b96b0/original/catalytic-carbonylation-of-acrylic-acid-to-succinic-anhydride.pdf |
669f111001103d79c54f19b9 | 10.26434/chemrxiv-2024-zcggj | Applying Marcus Theory to Describe Photoluminescent Intermittency and Temperature Dependent Emission in CdTe Nanoplatelets | Photoluminescence (PL) intermittency (also known as blinking) is a critical aspect of the optical properties of molecules and nanomaterials. Considerable work has expounded on the mechanism of blinking in nanocrystals, with the canonical model arguing that intermittently trapped charges serve to quench emission via charge-exciton Auger recombination. The dynamics of the emission trace are analyzed by fitting a histogram of on- and off- times to power-law distributions. These histograms in turn, reveal non-exponential kinetics, arguing for a distribution of electron or hole traps. What is not revealed is the origin of these distributed states, whether they arise from various trap energetic depths, long-range electron or hole tunneling, or any other process which gives rise to distributions of rates. We explore a model which invokes both a distribution of trap energies, combined with the chemical intuition of charge transfer via Marcus theory. We find that a self-consistent Marcus theory model can explain different power-law slopes for on- and off- times, and the observed changes in intensity as a function of temperature in films of CdTe nanoplatelets (NPLs). We believe this provides a self-consistent model to describe blinking behavior that leads to unusually low PL quantum yield (QY) in CdTe, and argues that improved passivation will be critical to achieving higher QY. | Xuanheng Tan; Tasnim Ahmed; Linus Murphy; Belle Coffey; Justin Caram | Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Nanostructured Materials - Materials; Computational Chemistry and Modeling; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669f111001103d79c54f19b9/original/applying-marcus-theory-to-describe-photoluminescent-intermittency-and-temperature-dependent-emission-in-cd-te-nanoplatelets.pdf |
6691a8c65101a2ffa8390772 | 10.26434/chemrxiv-2024-000fk | Reductively Induced Aryl Transmetalation: An Alternative Catalytically Relevant Ni-Catalyzed Biaryl Coupling Mechanism | Ni-catalyzed cross-electrophile coupling reactions have gained increasing prominence for the construction of C–C bonds. Most prior studies of biaryl coupling invoke one of two possible mechanisms to form the key Ni(Ar)2 intermediate: (1) sequential Ni reduction/Ar–X oxidative addition with two Ar–X substrates, or (2) parallel formation of two NiII–Ar intermediates that undergo aryl transmetalation between two NiII centers. Herein, we provide evidence for a reductively induced transmetalation pathway leading to biaryl coupling from NiII–Ar species. Chemical or electrochemical reduction of (bpy)NiII(2-tolyl)Br (bpy = 2,2’-bipyridine) to a (bpy)NiI(2-tolyl) species initiates rapid transmetalation of the 2-tolyl ligand to a second equivalent of (bpy)NiII(2-tolyl)Br to afford (bpy)NiII(2-tolyl)2, which undergoes reductive elimination to afford 2,2’-bitolyl. Cyclic voltammetry studies, analysis of reactions under stoichiometric and catalytic conditions, and computational data provide valuable insights into this NiI-to-NiII transmetalation mechanism, which has important implications for Ni-catalyzed biaryl coupling reactions. | Antonio Romero-Arenas; Mihai Popescu; McKenna Goetz; Kyana Sanders; Ilia Guzei; Mohammad Rafiee; Daniel Weix; Robert Paton; Shannon Stahl | Organic Chemistry; Catalysis; Organometallic Chemistry; Electrocatalysis; Homogeneous Catalysis; Electrochemistry - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6691a8c65101a2ffa8390772/original/reductively-induced-aryl-transmetalation-an-alternative-catalytically-relevant-ni-catalyzed-biaryl-coupling-mechanism.pdf |
65ef38919138d23161390296 | 10.26434/chemrxiv-2024-gncw5 | Mapping Structure-Property Relationships in Fullerene Systems: A Computational Study from C20 to C60 | Fullerenes, as characteristic carbon nanomaterials, offer significant potential for diverse applications due to their structural diversity and tunable properties. Numerous isomers can exist for a specific fullerene size, yet a comprehensive understanding of their fundamental properties remains elusive. In this study, we construct an up-to-date computational database for C20-C60 fullerenes, consisting of 5770 structures, and calculate 12 fundamental properties using DFT, including stability (binding energy), electronic properties (HOMO-LUMO gap), and solubility (partition coefficient logP). Our findings reveal that the HOMO-LUMO gap weakly correlates with both binding energy and logP, indicating that electronic properties can be tailored for specific uses without affecting stability or solubility. In addition, we introduce a set of novel topological features and geometric measures to investigate structure-property relationships. For the first time, we apply atom, bond, and hexagon features to effectively predict the stability of C20-C60 fullerenes, surpassing the conventional qualitative isolated pentagon rule, and demonstrating their robust transferability to larger-size fullerenes beyond C60. Our work offers guidance for optimizing fullerenes as electron acceptors in organic solar cells and lays a foundational understanding of their functionalization and applications in energy conversion and nanomaterial sciences. | Bin Liu; Jirui Jin; Mingjie Liu | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2024-03-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65ef38919138d23161390296/original/mapping-structure-property-relationships-in-fullerene-systems-a-computational-study-from-c20-to-c60.pdf |
671790ec83f22e4214cb1be5 | 10.26434/chemrxiv-2024-65tgq | Assessing the feasibility of using a data-driven corrosion rate model for optimizing dosages of corrosion inhibitors | Optimizing dosages of corrosion inhibitors requires experimental data gathered from time-consuming methods. The current study examines the feasibility of optimizing inhibitor dosages using a model trained for predicting corrosion rates more easily measured using linear polarization resistance in a full-scale cooling water system. A comprehensive study on variable selection showed that linearly correlated variables are necessary to predict corrosion trends. The Sobol sensitivity of inhibitors is trivialized by variables linearly correlated to the corrosion rate. The study highlights the importance of achieving high model prediction accuracy and high Sobol sensitivity of inhibitors to the corrosion rate, for using the model for inhibitor dosage optimization. | Chamanthi Denisha Jayaweera; Ingmar Nopens; Arne Verliefde; Maxime Van Haeverbeke; David Fernandes del Pozo; Thomas Diekow; Ivaylo Hitsov | Materials Science; Chemical Engineering and Industrial Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671790ec83f22e4214cb1be5/original/assessing-the-feasibility-of-using-a-data-driven-corrosion-rate-model-for-optimizing-dosages-of-corrosion-inhibitors.pdf |
652ad5b68bab5d20555abe89 | 10.26434/chemrxiv-2023-85mkn-v3 | Unveiling the Power of Negative Ion Mode ESI-MS: Identifying Species with Remarkable Signal Intensity and Collisional Stability | Electrospray ionization mass spectrometry has long been the standard and most prevalent ionization method in mass spectrometry to detect and analyze molecules of low volatility that are relevant biologically, environmentally, and industrially. However, only a small number of analyses are conducted in negative ion mode, which has led to a dogmatic bias toward positive ion mode despite advantageous properties of the negative polarity, including lower background noise and divergent tandem mass spectrometry behavior. We hypothesized that this bias was rooted in the relatively poor ionization efficiency of anionic functional groups seen in biochemistry; to explore this notion herein we evaluated 25 ions based on three criteria: (1) signal intensity relative to a sodium dodecylsulfate internal standard; (2) resistance to collision induced dissociation based on survival of the precursor ion; and (3) diagnostic tandem mass spectrometry behavior. Among these species, highly fluorous ions exhibiting weakly coordinating and hydrophobic properties contributed to enhanced signal intensities. Trifluoromethanesulfonyl-containing ions proved to be unexpectedly labile, while tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were determined to be of optimal signal intensity with signal intensity ratios relative to sodium dodecylsulfate (12 + Na+) of 332.0% ± 25.0% and 939.0% ± 92.0%, respectively, as well as survival yields of 100.0% ± 0.0% and 72.6% ± 0.8% at –50 eV. To further emphasize their optimal signal intensity, ions tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were comparable in signal intensity across solvents of acetonitrile, methanol, isopropanol, water, and their respective 1:1 mixtures. Facile preparation of various salts of bis(nonafluoro-1-butane)sulfonimidate led to additional evaluation of cation effects where the signal intensity ratio ranged from 939.0% ± 92.0% to 3195.0% ± 145.0% across K+, NH4+, Na+, and H+ counter cations. The dogma of negative ion mode being less sensitive was then challenged by the analysis of the signal intensity of ion 25 to tetra-n-butylammonium, tetra-n-butylphosphonium, and (4-methylphenyl)diphenylsulfonium cations. These experiments showed that 25 was more sensitive by between 136.2% ± 5.5% and 180.7% ± 13.8%, thereby successfully challenging the positive polarity bias. | Benjamin Warnes; Jasmine Chihabi; Jeffrey Manthorpe | Analytical Chemistry; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652ad5b68bab5d20555abe89/original/unveiling-the-power-of-negative-ion-mode-esi-ms-identifying-species-with-remarkable-signal-intensity-and-collisional-stability.pdf |
60c74c67842e65d21cdb32e3 | 10.26434/chemrxiv.12470381.v1 | In-Silico Interaction of Hydroxychloroquine Drug with Various Proteins of Coronavirus (SARS-CoV-2): A Computational Approaches to Combat COVID-19 | <p><i>In silico</i> docking study
showed that hydroxychloroquine drug interactions with SARS-CoV2 show a higher
binding affinity with spike glycoprotein and PLPRO protein compared to protein
envelopes that could be ladder for potential targeting and synthesizing of
another aniviral drug. <i>In silico</i>
methods used in this study, the efficacy of a wide variety of repositioned
and/or novel drug candidates could also be tested prior to clinical evaluation.</p> | Rishee Kalaria; Hiren K. Patel | Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74c67842e65d21cdb32e3/original/in-silico-interaction-of-hydroxychloroquine-drug-with-various-proteins-of-coronavirus-sars-co-v-2-a-computational-approaches-to-combat-covid-19.pdf |
67a3b7a46dde43c908b75c93 | 10.26434/chemrxiv-2025-1h1kq | SONIC: A Speed of Sound Measurement for Nanobubble Characterization | Nanobubbles (NBs)—gas inclusions in water with diameters < 1 µm—are of growing interest because of their unique properties and their potential for transformative applications. For example, it has been reported that NBs exist in water over long periods (i.e. weeks to months) and can act as free gas reservoirs. However, NBs are a source of scientific debate, particularly regarding characterization methods. Conventional methods, such as dynamic light scattering, nanoparticle tracking analysis, and nanoflow cytometry, cannot distinguish between nanoparticles and NBs since they are insensitive to the differences of the physical properties of the materials. However, acoustic (speed of sound) measurements can be used to quantify NBs because they rely on the compressibility dependence of gases (𝜅𝑔𝑎𝑠) which is considerably larger than liquids (𝜅𝑤𝑎𝑡𝑒𝑟) and solids. In the present work, a speed of sound measurement for nanobubble characterization (SONIC) was designed and developed to probe the compressibility variations diagnostic to NBs in water. NBs in water act as acoustic scatters that reduce the speed of sound relative to the bubble-free water. This decrease in the speed of sound can only be attributed to the existence of gas bubbles due to the strong compressibility dependence that solid nanoparticles lack. The results obtained from the acoustic measurements are compared with the observations from nanoparticle tracking analysis to confirm the existence of NBs in water. SONIC was validated in water with different molalities of NaCl (aq), and in the presence of solid nanoparticles of similar size and concentration to the NBs. SONIC is the first technique that addresses an important bottleneck of NB characterization by providing an accurate and selective characterization on NBs in complex water mixtures that will help understand the behaviour of NBs and accelerate their application in many fields. | Jeas Grejoy Andrews; Sunaina Sunaina; Tatek Temesgen Terfasa; Peter Kusalik; Kelly Rees; Yihao Wang; W. Russ Algar; Susana Y. Kimura | Materials Science; Analytical Chemistry; Nanoscience; Analytical Chemistry - General; Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a3b7a46dde43c908b75c93/original/sonic-a-speed-of-sound-measurement-for-nanobubble-characterization.pdf |
6142e47bb817b4c2851e9ca1 | 10.26434/chemrxiv-2021-bkxzw | EnzymeML – a data exchange format for biocatalysis and enzymology | EnzymeML is an XML–based data exchange format that supports the comprehensive documentation of enzymatic data by describing reaction conditions, time courses of substrate and product concentrations, the kinetic model, and the estimated kinetic constants. EnzymeML is based on the Systems Biology Markup Language, which was extended by implementing the STRENDA Guidelines. An EnzymeML document serves as a container to transfer data between experimental platforms, modelling tools, and databases. EnzymeML supports the scientific community by introducing a standardised data exchange format to make enzymatic data findable, accessible, interoperable, and reusable according to the FAIR data principles. An Application Programming Interface in Python and Java supports the integration of applications. The feasibility of a seamless data flow using EnzymeML is demonstrated by creating an EnzymeML document from a structured spreadsheet or from a STRENDA DB database entry, by kinetic modelling using the modelling platform COPASI, and by uploading to the enzymatic reaction kinetics database SABIO-RK. | Jan Range; Colin Halupczok; Jens Lohmann; Neil Swainston; Carsten Kettner; Frank T. Bergmann; Andreas Weidemann; Ulrike Wittig; Santiago Schnell; Jürgen Pleiss | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Catalysis; Biochemistry; Chemoinformatics - Computational Chemistry; Biocatalysis | CC BY 4.0 | CHEMRXIV | 2021-09-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6142e47bb817b4c2851e9ca1/original/enzyme-ml-a-data-exchange-format-for-biocatalysis-and-enzymology.pdf |
655ced0f6e0ec7777f696962 | 10.26434/chemrxiv-2023-lwb83 | Corn Husk fused: Fe2O3 - A Symphony of Sustainable Solutions for Cationic Dyes | Dive into the colourful realm of textile wastewater, where α-Fe2O3 attached carbon material, born from the corn husk (Fe-AC@CH), emerges as an eco-hero in the battle against cationic dye pollution, starring Methylene Blue (MB) and Malachite Green (MG). Our journey ventures deep into the synthesis and structural mysteries of Fe-AC@CH, unravelling its secrets through a high-tech arsenal: Fourier-Transform Infra-Red (FT-IR), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), High-Resolution Transition Electron Microscopy (HRTEM), and Raman Spectroscopy. In the quest for optimal adsorption, we meticulously dissect the variables — adsorbent dose, contact time, solution pH, initial dye concentration, and temperature — orchestrating the perfect conditions for MB and MG removal. Isothermal revelations spotlight the Langmuir and D-R isotherm models as the guiding stars, while kinetic analyses unveil the captivating dance of the pseudo-first-order model, boasting stellar correlation coefficients (R2) and perfect harmony with experimental sorption capacities (Qe). Enter the realm of MG, where the intraparticle diffusion kinetic model adds another layer to our understanding, seamlessly aligning calculated Qe values with experimental results. The grand finale reveals physisorption as the masterstroke governing the enchanting adsorption narrative of both MB and MG onto the Fe-AC@CH composite. This ground-breaking study not only anoints Fe-AC@CH as the stalwart defender against cationic dyes in textile wastewater but also heralds corn husks as sustainable sorcery, conjuring eco-friendly adsorbents. The results, a treasure trove of insights, navigate the intricate interplay between composite structure, adsorption kinetics, and isothermal behavior, ushering in a green revolution in the removal of cationic dyes from our waterways. | Alibasha Akbar; Mihir Ghosh | Earth, Space, and Environmental Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655ced0f6e0ec7777f696962/original/corn-husk-fused-fe2o3-a-symphony-of-sustainable-solutions-for-cationic-dyes.pdf |
60c7548abdbb89676ba3a67b | 10.26434/chemrxiv.13663337.v1 | Theoretical Atomic Radii of Elements (H-Cm): A Non-Relativistic Study with Gaussian Basis Set Using HF, Post-HF and DFT Methods | <div><p>We
calculated the most probable radius of an atom for elements from H
to Cm. The
calculations were carried out by using non-relativistic, spin polarized, HF,
MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated
with the experimental first ionization energies. This non-relativistic
atomic radii were also compared with other theoretical atomic radii. With respect to the
Dirac-Slater data, our values were in good agreement with the elements up to
Sn. Relationship with van der
Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd
were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This
linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div> | Krishnamohan Prasanna; Sooraj Sunil; Ajith Kumar; Jamesh Joseph | Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7548abdbb89676ba3a67b/original/theoretical-atomic-radii-of-elements-h-cm-a-non-relativistic-study-with-gaussian-basis-set-using-hf-post-hf-and-dft-methods.pdf |
66996910c9c6a5c07aa12e5f | 10.26434/chemrxiv-2024-nm3cj | Photomediated Hexafluoroisopropoxylation of Unactivated Aryl Halides | The use of fluoroalkoxy groups, such as trifluoromethoxy and 2,2,2-trifluoroethoxy groups, in pharmaceutical and agrochemical development has increased dramatically in recent years. However, hexafluoroisopropoxy groups have remained significantly underrepresented, presumably due to limited synthetic methods for accessing this substituent in good yields. Herein, we report a mild, photochemical nucleophilic aromatic substitution (SNAr) approach for the synthesis of hexafluoroisopropyl aryl ethers from unactivated and abundant aryl halides. Notably, aryl chloride and bromide functionality are efficiently engaged by this methodology in addition to the traditional aryl fluoride nucleofuge. This method provide access to a diverse array of hexafluoroisopropyl aryl ethers, including multiple examples of late-stage functionalization of active pharmaceutical ingredients. A simple flow system was adapted for 10x scale-up, maintaining good yield for the reaction. Initial mechanistic studies indicate single electron oxidation of the arene as a key step in product formation. | Brooke Boyden; Sydney Tobin; Natalie Haen; Adia Metz; Cohen Wojnowiak; Trevor Taylor; Alex Cutty; Alex Litza; Isaac Stiles; Nathan Soehner; Alex Oberbroeckling; Nicole Oleary; Hannah Popp; Ian MacKenzie | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66996910c9c6a5c07aa12e5f/original/photomediated-hexafluoroisopropoxylation-of-unactivated-aryl-halides.pdf |
63e561ca9da0bc6b33a50b4b | 10.26434/chemrxiv-2023-0s98h | C3-Alkylation of Furfural Derivatives by Continuous Flow Homogeneous Catalysis | The C3-functionalization of furfural using homogeneous ruthenium catalysts requires the pre-installation of an ortho-directing imine group, as well as high temperatures, which did not allow scaling up, at least under batch conditions. In order to design a safer process, we set out to develop a continuous flow process specifically for the C3-alkylation of furfural (Murai reaction). The transposition of a batch process to a continuous flow process is often costly in terms of time and reagents. Therefore, we chose to proceed in two steps: the reaction conditions were first optimized using a laboratory-built pulsed-flow system to save reagents. The optimized conditions in this pulsed-flow mode were then successfully transferred to a continuous flow reactor. In addition, the versatility of this continuous flow device allowed both steps of the reaction to be carried out, namely the formation of the imine directing group and the C3-functionalization with some vinylsilanes and norbonene. | Gredy Kiala Kinkutu; Catherine Louis; Myriam Roy; Juliette Blanchard; Julie Oble | Organic Chemistry; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63e561ca9da0bc6b33a50b4b/original/c3-alkylation-of-furfural-derivatives-by-continuous-flow-homogeneous-catalysis.pdf |
6733131cf9980725cfedef3f | 10.26434/chemrxiv-2024-hhnzs | AI-driven simulation of stochastic electrochemiluminescence | Electrochemiluminescence (ECL) is a vital analytical technique widely used in immunosensing and emerging applica-tions in biological imaging. Traditional ECL simulations rely on finite element methods, which provide valuable insights into reaction dynamics and spatial distribution of species. However, such methods are limited in mesoscopic environ-ments where stochastic effects become significant. Here, I present a novel approach using ChatGPTo1 to generate a Py-thon-based stochastic simulation for ECL reactions in a nanofluidic channel, incorporating diffusion, electrochemical and chemical reactions, and photon emission. The simulation successfully replicates results from finite element models while offering additional insights into time-dependent behaviors and enabling noise analysis for simulated luminescence traces. The iterative development of this simulation using ChatGPT was rapid, requiring minimal coding expertise while leveraging the model’s "reasoning" capabilities to implement physical principles, verify calculations, and optimize per-formance. This work demonstrates that large language models (LLMs) can serve as effective co-intelligence tools, facili-tating the development of complex simulations in electrochemistry. AI-driven tools/LLMs have a promising role in ad-vancing electrochemistry research, though careful validation remains essential to ensure scientific accuracy. | Klaus Mathwig | Theoretical and Computational Chemistry; Physical Chemistry; Nanoscience; Computational Chemistry and Modeling; Artificial Intelligence; Electrochemistry - Mechanisms, Theory & Study | CC BY 4.0 | CHEMRXIV | 2024-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6733131cf9980725cfedef3f/original/ai-driven-simulation-of-stochastic-electrochemiluminescence.pdf |
60c74aa89abda2fde6f8ceb1 | 10.26434/chemrxiv.12234740.v1 | Catalytic Three-component C–C Bond Forming Dearomatization of Bromoarenes with Malonates and Diazo Compounds | A Pd-catalyzed dearomative three-component C–C bond formation of bromoarenes with diazo compounds and malonates was developed. Various bromoarenes ranging from benzenoids to azines and heteroles were transformed to the corresponding substituted alicyclic molecules. The key of this reaction is the generation of a benzyl-palladium intermediate, which reacts with malonates to form a Pd–<i>O</i>-enolate species. Strikingly, the present method enabled rapid access to multi-substituted alicycles through subsequent elaboration of dearomatized products. | Hiroki Kato; Itsuki Musha; Masaaki Komatsuda; Kei Muto; Junichiro Yamaguchi | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74aa89abda2fde6f8ceb1/original/catalytic-three-component-c-c-bond-forming-dearomatization-of-bromoarenes-with-malonates-and-diazo-compounds.pdf |
674741327be152b1d0144170 | 10.26434/chemrxiv-2024-csxt9 | Scaling Relations in Oxygen Reduction Reaction Electrocatalysis | Scaling relations represent a fundamental limitation in electrocatalysis, particularly for the oxygen reduction reaction (ORR), which underpins energy conversion technologies such as fuel cells and metal-air batteries. Improving the activity of ORR catalysts requires overcoming the scaling relations, i.e. correlations between adsorption energies of reaction intermediates. In this review, we summarise the existing literature by providing a critical meta-analysis, deriving new theoretical principles, and proposing a taxonomy of strategies for manipulating these relations. By addressing both historical foundations and future possibilities, this work redefines how to conceptualize and address ORR catalysis challenges. | Vladislav Ivaništšev; Ritums Cepitis; Jan Rossmeisl; Nadezda Kongi | Catalysis; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674741327be152b1d0144170/original/scaling-relations-in-oxygen-reduction-reaction-electrocatalysis.pdf |
6684a43ac9c6a5c07a1ab698 | 10.26434/chemrxiv-2024-fsl3k | High-Performance Polyimide Covalent Organic Frameworks for Lithium-Ion Batteries: Exceptional Stability and Capacity Retention at High Current Densities | Organic polymers are considered promising candidates for next-generation green electrode materials in lithium-ion batteries (LIBs). However, achieving long cycling stability and capacity retention at high current densities remains a significant challenge due to weak structural stability and low conductivity. In this study, we report the synthesis of two novel polyimide covalent organic frameworks (PI-COFs), COF-JLU85 and COF-JLU86, by combining truxenone-based triamine and linear acid anhydride through polymerization. These PI-COFs feature layers with pore channels embedded with 18 carbonyl groups, facilitating rapid lithium-ion diffusion and enhancing structural stability under high current densities. Compared to previously reported organic polymer materials, COF-JLU86 demonstrates the excellent performance at high current densities, with an impressive specific capacity of 1161.1 mA h g-1 at 0.1 A g-1, and outstanding cycling stability, retaining 1289.8 mA h g at 2 A g-1 after 1500 cycles and 401.1 mA h g-1 at 15 A g-1 after 10000 cycles. Additionally, in-situ infrared spectroscopy and density functional theory (DFT) calculations provide mechanistic insights, revealing that the high concentration of carbonyl redox-active sites and the optimized electronic structure contribute to the excellent electrochemical performance. These results highlight the potential of PI-COFs as high-performance organic electrode materials for LIBs, offering a promising solution to the challenges of long-term stability and capacity retention at high current densities. | Jiali Li; Jinkai Zhang; Yuxin Hou; Jinquan Suo; Jianchuan Liu; Hui Li; Shilun Qiu; Valentin Valtchev; Qianrong Fang; Xiaoming Liu | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6684a43ac9c6a5c07a1ab698/original/high-performance-polyimide-covalent-organic-frameworks-for-lithium-ion-batteries-exceptional-stability-and-capacity-retention-at-high-current-densities.pdf |
60c74dcd337d6c73a7e27e5c | 10.26434/chemrxiv.12662003.v1 | Unexpected Catalytic Activity of the Regulatory Protein QacR | Natural proteins often present binding or functional promiscuity. In biocatalysis, this promiscuity has been exploited for accessing new-to-nature reactions. Here, we report an unexpected catalytic reactivity for the regulatory protein QacR from the TetR family of multidrug resistance regulators. QacR is able to catalyze the enatioselective tandem Friedel-Crafts / enantioselective protonation reaction of indoles with alpha substituted conjugated enones with up to 40% yield and 83% ee. Mutagenesis and computational studies support the hypothesis that an acidic residue in the binding pocket of the protein is responsible for protonating the enolate intermediate. | Cora Gutiérrez de Souza; Lur Alonso-Cotchico; Manuela Bersellini; Gerard Roelfes | Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dcd337d6c73a7e27e5c/original/unexpected-catalytic-activity-of-the-regulatory-protein-qac-r.pdf |
674dd7acf9980725cfcbd9c7 | 10.26434/chemrxiv-2024-gvbl3-v2 | Detection and investigation of roméite group minerals in historical silicate glass using electron backscatter diffraction and microcathodoluminescence spectroscopy | Early 19th century silicate glass of opal beads made at Murano has been studied by means of X-ray fluorescence spectroscopy, scanning electron microscopy, energy dispersive X-ray spectral analysis and elemental mapping, electron backscatter diffraction, and cathodoluminescence spectroscopy and mapping. The studied glass has been found to contain micro crystals of some accessory minerals associated with the quartz raw material at the site of extraction; they got into the glass melt with quartz as an uncontrolled impurities during glass making. Most of these particles are minerals of the roméite group, mainly fluorcalcioroméite and “fluornatroroméite”; the glass studied also contains micro inclusions of baryte and cerussite. Micro cathodoluminescence spectra of opal glass and fluorcalcioroméite inclusions have been investigated; the spectra of fluorcalcioroméite consist of a broad high-energy band and a much narrower low-energy one at the temperature of both 300 and 80 K. A set of narrow lines with maximum close to the quantum energy of 1.7 eV are a feature of fluorcalcioroméite luminescence; these lines predominate at the temperature of 80 K in its low-energy CL band. Based on the mineral composition of the micro inclusions, possible places of mining of the quartz raw material used for the manufacture of opal beads in the 19th century have been discussed. Several locations in the territories of modern Italy, Switzerland and Austria have been considered. It is concluded that mineral particles in historical glass can be used for the provenance determination of the silica raw material used for the glass production. | Tatyana V. Yuryeva; Sergey A. Malyhin; Andrey A. Kudryavtsev; Ilya B. Afanasyev; Vladimir Y. Karpenko; Vladimir A. Yuryev | Materials Science; Analytical Chemistry; Geological Materials; Microscopy; Spectroscopy (Anal. Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674dd7acf9980725cfcbd9c7/original/detection-and-investigation-of-romeite-group-minerals-in-historical-silicate-glass-using-electron-backscatter-diffraction-and-microcathodoluminescence-spectroscopy.pdf |
60c74ff8f96a00f499287d1f | 10.26434/chemrxiv.12901766.v1 | Plausibly Deniable Chemical Encryption: Hiding a Molecule in a Haystack | We propose an outline of plausibly deniable chemical encryption algorithm, a technique aimed at increasing the cost of a small organic molecule identification in a sample by means of chemical analysis through mixing it with a rationally designed randomized mixture of analytical interferents, in a remote analogy to other domains of cryptography. The algorithm is then applied in a proof-of-concept demonstration example. | Wojciech Nogaś | Analytical Chemistry - General; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ff8f96a00f499287d1f/original/plausibly-deniable-chemical-encryption-hiding-a-molecule-in-a-haystack.pdf |
616694418b620d535b4dd4d4 | 10.26434/chemrxiv-2021-bk2t8 | Selective Manganese-Catalyzed Semihydrogenation of Alkynes with in-situ Generated H2 from KBH4 and Methanol | The selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)3(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as pre-catalyst is described. Hydrogen gas required for the hydrogenation is generated in situ upon alcoholysis of KBH4 with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl and terminal alkynes were readily hydrogenated to yield E-alkenes in good to excellent isolated yields. The reaction proceeds at 90°C with catalyst loadings of 0.5 -2 mol%. The implemented protocol tolerates a variety of electron donating and electron withdrawing functional groups including halides, phenols, nitriles, unprotected amines and heterocycles. The reaction can be upscaled to the gram scale. Mechanistic investigations including deuterium labelling studies and DFT calculations were undertaken to provide a reasonable reaction mechanism showing that initially formed Z-isomer undergoes fast isomerization to afford the thermodynamically more stable E-isomer. | Ronald Farrar-Tobar; Stefan Weber; Zita Csendes; Antonio Ammaturo; Sarah Fleissner; Helmuth Hoffmann; Luis Veiros; Karl Kirchner | Organic Chemistry; Catalysis; Organometallic Chemistry; Transition Metal Complexes (Organomet.) | CC BY 4.0 | CHEMRXIV | 2021-10-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/616694418b620d535b4dd4d4/original/selective-manganese-catalyzed-semihydrogenation-of-alkynes-with-in-situ-generated-h2-from-kbh4-and-methanol.pdf |
622243f7c3e9dafc0a80159d | 10.26434/chemrxiv-2021-s5fkj-v3 | The potential scarcity, or not, of polymeric overall water splitting photocatalysts | We perform a high-throughput computational screening of a set of 3240 conjugated alternating binary co-polymers and homo-polymers, in which we predict their ability to drive sacrificial hydrogen evolution and overall water splitting when illuminated with visible light. We use the outcome of this screening to analyse how common the ability to drive either reaction is for conjugated polymers loaded with suitable co-catalysts, and to suggest promising (co-)monomers for polymeric overall water splitting catalysts. | Benedict Saunders; Liam Wilbraham; Andrew Prentice; Reiner Sebastian Sprick; Martinus Antonius Zwijnenburg | Theoretical and Computational Chemistry; Catalysis; Polymer Science; Organic Polymers; Computational Chemistry and Modeling; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/622243f7c3e9dafc0a80159d/original/the-potential-scarcity-or-not-of-polymeric-overall-water-splitting-photocatalysts.pdf |
6384e78cebc1c7616ed5e30f | 10.26434/chemrxiv-2022-fkldz | Metastability and Photoelectrochemical Properties of Cu2SnO3 and Cu2-xLixTiO3: Two New Cu(I)-Based Oxides with Delafossite Structures | Metastable, p-type Cu(I)-based semiconductors were synthesized using cation exchange reactions between delafossite-type layered precursors and CuCl flux, yielding Cu2SnO3 (I) and Cu2-xLixTiO3 (II, xmin ~ 0.4). These represent the first reported crystalline semiconductors found in the Cu-Sn-O or Cu-Ti-O chemical systems (and not currently predicted within any materials databases), with their kinetic stabilization requiring a relatively low reaction temperature of ~475°C. Both phases crystallize in the monoclinic crystal system in space group C2/c, exhibiting edge-shared hexagonal ‘MO3’ (M = Sn or Ti) layers that also contain octahedrally-coordinated Li(I)/Cu(I) cations. These layers are bridged by linearly-coordinated Cu(I) cations. Magnetic susceptibility measurements confirm the +1 oxidation state of the copper cations. The optical band gaps were found to be indirect and to significantly redshift with Cu(I) content, down to ~2.31 eV for I and ~1.46 eV for II. Electronic structure calculations show the decreased band gaps can be attributed to a higher-energy valence band derived from the filled 3d10 orbitals of the Cu(I) cations, which most notably arise from the octahedrally-coordinated Cu(I) cations within the layers. Total energy calculations reveal an increasing metastability with respect to decomposition to Cu2O and SnO2 or TiO2 as a result of occupation of the intralayer sites by Cu(I) cations. In both phases, their edge-shared hexagonal layers lead to highly-dispersive conduction bands and small electron effective masses of ~0.51 me for I and ~0.41 me for II. Polycrystalline films of both were deposited onto fluorine-doped tin oxide slides and exhibited p-type photocurrents under 100 mW cm-2 irradiation in the range of ~50 to 250 μA cm-2. This study thus reveals new fundamental relationships between the origin of metastability in Cu(I)-oxide semiconductors, i.e., octahedral coordination, and enhanced optical and photoelectrochemical properties. | Shaun O'Donnell; Reinhard Kremer; Paul Maggard | Theoretical and Computational Chemistry; Inorganic Chemistry; Reaction (Inorg.); Solid State Chemistry; Theory - Inorganic; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6384e78cebc1c7616ed5e30f/original/metastability-and-photoelectrochemical-properties-of-cu2sn-o3-and-cu2-x-lix-ti-o3-two-new-cu-i-based-oxides-with-delafossite-structures.pdf |
6797b5e16dde43c908998471 | 10.26434/chemrxiv-2025-wf19q | Deconjugative Photoisomerization of Cyclic Enones | The deconjugative isomerization of α,β-unsaturated carbonyl compounds enables regioisomeric products to be forged with simultaneous Umpolung of alkene reactivity. Although highly enabling, the endergonic nature of the net process coupled with governing regioselectivity outcomes, renders it challenging. Innovations in the positional isomerization of linear species, often by light-triggered activation, have re-energized this area. However, the deconjugative isomerization of cyclic enones is underdeveloped and often associated with impractical reaction conditions, limited substrate scopes, and a lack of mechanis-tic clarity. Herein, we report an operationally simple photochemical isomerization of cyclic enones using near-UV (372 nm) irradiation with catalytic amounts of Brønsted acid (HCl). This platform enables exocyclic deconjugative isomerization of a diverse array of enones including α-isophorone (a key intermediate in a variety of industrial processes), terpenoids and ster-oids. Mechanistic studies reveal the pivotal role of the solvent as a key mediator in the isomerization, where sequential hy-drogen atom transfer (HAT) and reverse-HAT (RHAT) are proposed to be operational. | Lukas Blank; Jungwon Kim; Constantin Daniliuc; Alissa Götzinger; Marc-André Müller; Jan Schütz; Bettina Wüstenberg; Ryan Gilmour | Organic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6797b5e16dde43c908998471/original/deconjugative-photoisomerization-of-cyclic-enones.pdf |
66b049ce5101a2ffa81d4bc8 | 10.26434/chemrxiv-2024-d3mhz | Leveraging GPT-4 to transform chemistry from paper to practice | Large Language Models (LLMs) have revolutionized numerous industries as well as accelerated scientific research. However, their application in planning and conducting experimental science, has been limited. In this study, we introduce an adaptable prompt-set with GPT-4, converting literature experimental procedures into actionable experimental steps for a Mettler Toledo EasyMax automated laboratory reactor. Through prompt engineering, we developed a 2-step sequential prompt: the first prompt converts literature synthesis procedures into step-by-step instructions for reaction planning; the second prompt generates an XML script to communicate these instructions to the EasyMax reactor, automating experimental design and execution. We successfully automated the reproduction of three distinct literature-based synthetic procedures and validated the reactions by monitoring and characterizing the products. This approach bridges the gap between text-to-procedure transcription and automated execution and streamline the literature procedure reproduction | Wenyu Zhang; Mason Guy; Jerrica Yang; Lucy Hao; Junliang Liu; Joel Hawkins; Jason Mustakis; Sebastian Monfette; Jason Hein | Physical Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Process Chemistry; Robotics; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-08-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b049ce5101a2ffa81d4bc8/original/leveraging-gpt-4-to-transform-chemistry-from-paper-to-practice.pdf |
647f57abe64f843f416bab92 | 10.26434/chemrxiv-2023-vmwqw | Contributions of CO2, O2 and H2O to the Oxidative Stability of Solid Amine Direct Air Capture Sorbents at Intermediate Temperature | Aminopolymer-based sorbents are preferred materials for extraction of CO2 from ambient air (direct air capture of CO2, or DAC) owing to their high CO2 adsorption capacity and selectivity at ultra dilute conditions. While those adsorptive properties are important, the stability of a sorbent is a key element in developing high-performing, cost-effective, and long-lasting sorbents that can be deployed at scale. Along with process upsets, environmental components such as CO2, O2, and H2O may contribute to long-term sorbent instability. As such, unraveling the complex effects of such atmospheric components on sorbent lifetime as they appear in the environment is a critical step to understanding sorbent deactivation mechanisms and designing more effective sorbents and processes. Here, PEI/Al2O3 sorbent is assessed over continuous and cyclic dry and humid conditions to determine the effect of the co-presence of CO2 and O2 on stability at an intermediate temperature of 70 °C. Thermogravimetric and elemental analysis in combination with in situ HATR-IR spectroscopy are performed to measure the extent of deactivation, elemental content, and molecular level changes in the sorbent due to deactivation. The thermal/thermogravimetric analysis results reveal that incorporating CO2 with O2 accelerates sorbent deactivation using these sorbents in dry and humid conditions compared to CO2-free air in similar conditions. In situ HATR-IR spectroscopy results of PEI deactivation under a CO2-air environment show the formation of primary amine species in higher quantity (compared to conditions without O2 or CO2), which arise due to C-N bond cleavage at the primary and secondary amine due to oxidative degradation. We hypothesize the formation of bound CO2 species such as carbamic acids catalyze C-N cleavage reactions in the oxidative degradation pathway by shuttling protons, resulting in a lower activation energy barrier for degradation, as probed by metadynamics simulations. In the cyclic experiment after 30 cycles, results show a gradual loss in stability (dry: 29%, humid: 52%) under CO¬2 containing air (0.04% CO2/21% O2 balance N2). However, the loss in capacity during cyclic studies is significantly less than continuous deactivation as expected. | Yoseph A. Guta; Juliana Carneiro; Sichi Li; Giada Innocenti; Simon H. Pang; Miles A. Sakwa-Novak; Carsten Sievers; Christopher W. Jones | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/647f57abe64f843f416bab92/original/contributions-of-co2-o2-and-h2o-to-the-oxidative-stability-of-solid-amine-direct-air-capture-sorbents-at-intermediate-temperature.pdf |
60c74fdc842e651d99db38fc | 10.26434/chemrxiv.11902980.v2 | The Anomalous Effect of Quantum Interference in Organic Spin Filters | The molecular topology in the single-molecular nano-junctions through which the de Broglie wave propagates plays a crucial role in controlling the molecular conductance. The enhancement and reduction of the conductance due to constructive and destructive Quantum Interference (QI) in para and meta connected molecules respectively has already been well established. Herein, we investigated the influence of QI on spin transport in the molecular junctions containing organic radicals as magnetic centres. The role of the localized spins on the QI as well as on spin filtering capability is investigated employing density functional theory in combination with non-equilibrium Green's function (NEGF-DFT) techniques. Various organic radicals including nitroxide (NO), phenoxy (PO) and methyl (CH2) radicals attached to the central benzene ring of pentacene with different terminal connections (para and meta) to gold electrodes are examined. Due to more obvious QI effects, para connected pentacene is found to be more conductive than meta one. Surprisingly, on incorporating a radical centre, along with spin filtering, a significant quenching of QI effects is observed which manifests itself in such a way that the conductance of meta coupled radicals is found to be more than para by two orders of magnitude. The decoherence induced by radical centre is analysed and discussed in terms of spin-spin coupling of radical's unpaired electron with the tunneling electrons.<br /> | Ashima Bajaj; Prabhleen Kaur; Aakanksha Sud; Marco Berritta; Md. Ehesan Ali | Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74fdc842e651d99db38fc/original/the-anomalous-effect-of-quantum-interference-in-organic-spin-filters.pdf |
6501c89cb338ec988a69c6e3 | 10.26434/chemrxiv-2023-fd6l9 | STEM SerialED: achieving high-resolution data for ab initio structure determination of beam-sensitive nanocrystalline materials | Serial electron diffraction (SerialED), which applies a snapshot data acquisition strategy on each crystal, was introduced to tackle the problem of radiation damage in the structure determination of beam-sensitive materials by three-dimensional electron diffraction (3D ED). The snapshot data acquisition in SerialED can be realized both in transmission and scanning transmission electron microscopes (TEM/STEM). However, the current SerialED workflow based on STEM setups requires special external devices and software, which brings challenges for its broader adoption. Here, we present a simplified experimental implementation of STEM-based SerialED on Thermo Fisher Scientific STEMs using common proprietary software interfaced through Python scripts to automate data collection. Specifically, we utilize TEM Imaging and Analysis (TIA) scripting and TEM scripting to access the STEM functionalities of the microscope, and DigitalMicrograph (DM) scripting to control the camera for snapshot data acquisition. Data analysis adapts the existing workflow using the software CrystFEL developed for serial X-ray crystallography. Our workflow for SerialED can be used on any Gatan or Thermo Fisher Scientific camera. We apply this workflow to collect high-resolution STEM SerialED data from two aluminosilicate zeolites, Zeolite Y and ZSM-25, and demonstrate, for the first time, ab initio structure determination through direct methods using the STEM SerialED data. Zeolite Y is relatively stable under the electron beam, and SerialED data extend to 0.60 Å. We show that the structural model obtained using SerialED data merged from 358 crystals is nearly identical to that using continuous rotation electron diffraction (cRED) data from one crystal. This demonstrates that accurate structures can be obtained from SerialED. Zeolite ZSM-25 is very beam-sensitive and has a complex structure. We show that SerialED greatly improves data resolution of ZSM-25, compared to serial rotation electron diffraction (SerialRED), from 1.50 Å to 0.90 Å. This allows for the first time the use of standard phasing methods such as direct methods for ab initio structure determination of ZSM-25. | Pascal Hogan-Lamarre; Yi Luo; Robert Bücker; R. J. Dwayne Miller; Xiaodong Zou | Materials Science; Inorganic Chemistry; Nanoscience; Solid State Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6501c89cb338ec988a69c6e3/original/stem-serial-ed-achieving-high-resolution-data-for-ab-initio-structure-determination-of-beam-sensitive-nanocrystalline-materials.pdf |
66a9da0ec9c6a5c07a924ece | 10.26434/chemrxiv-2024-j2tk2 | A Machine Learning-Guided Approach to Navigate the Substrate Activity Scope of Galactose Oxidase: Application in the Conversion of Pharmaceutically Relevant Bulky Secondary Alcohols | Biocatalysis is increasingly being adopted in industry for producing important chemicals in a selective, efficient, and sustainable way. Engineering an enzyme can often confer it with an altered chemical scope, making it accessible to new and desirable chemistry. Identifying enzymes with the desired substrate specificity and activity, however, remains time-consuming and costly. Galactose oxidase (GOase) is a copper-dependent enzyme that coverts alcohols to their corresponding carbonyls, an important transformation in industrial synthesis. Here, we present a machine learning aided protocol to develop a catalytic activity prediction model (R2~0.7-0.9) for GOase based on a focused dataset of engineered GOase variants with activity toward bulky benzylic secondary alcohols. The trained GOase activity prediction models (with no additional training) also retained their predictive power when applied to another member of the oxidase family, an aryl-alcohol oxidase. Inspired by the fragment-based optimization methods used in drug discovery, we developed an active-site structure-aware substrate library for GOase. Experimental validation of a subset of the constructed substrate library indicates that the trained models provide good prediction (R2=0.61) of GOase activity, enabling the identification of the best GOase variant for each new substrate. This ability to identify optimal GOase variants for the synthesis of industrially important chemicals was demonstrated for Dyclonine, an FDA-approved drug. Our machine learning-guided approach enables rapid navigation of the substrate-activity scope of GOase, thereby reducing the burden of extensive experimental screening, and streamlining the deployment of biocatalysis in industrial synthesis. | Shreyas Supekar; Dillon W. P. Tay; Wan Lin Yeo; Kwok Wai Eric Tam; Ying Sin Koo; Jie Yang See; Jhoann M.T. Miyajima; Sebastian Maurer-Stroh; Ee Lui Ang; Yee Hwee Lim; Hao Fan | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Artificial Intelligence; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66a9da0ec9c6a5c07a924ece/original/a-machine-learning-guided-approach-to-navigate-the-substrate-activity-scope-of-galactose-oxidase-application-in-the-conversion-of-pharmaceutically-relevant-bulky-secondary-alcohols.pdf |
6618e080418a5379b0adf385 | 10.26434/chemrxiv-2024-0l74f | Tuning and Matching Error Compensated, Quantitative Solid-state NMR | Abstract NMR spectroscopy has long been recognized as a powerful quantitative analytical tool. Quantification is commonly done against internal and external standards. A third approach is to quantify against an electronic reference which combines the advantages of the two methods. The implementation of this approach in solid-state NMR is more challenging due to the single-coil design of double resonance probes. In this study, a novel approach for implementing the electronic referencing method in solid-state NMR by injecting the reference signal using a broadband antenna installed near the NMR receiver coil is presented. This method demonstrates excellent accuracy and precision, as it remains robust to changes in the electronic conditions of the probe, including tuning and matching errors. | Hector Javier Cortes Sanchez; Lukas Paul Rüthing; Jörn Schmedt auf der Günne | Analytical Chemistry; Spectroscopy (Anal. Chem.) | CC BY NC 4.0 | CHEMRXIV | 2024-04-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6618e080418a5379b0adf385/original/tuning-and-matching-error-compensated-quantitative-solid-state-nmr.pdf |
615db85caa918dc78921c968 | 10.26434/chemrxiv-2021-dm5jq-v2 | Medium and Large N-Heterocycle Formation via Allene Hydroamination with a Bimetallic Rh(I) Catalyst | We report the synthesis of a bimetallic Rh(I) complex containing a bridging CO ligand that facilitates Rh–Rh bond formation. This bimetallic complex enables intramolecular allene hydroamination to form seven to ten-member rings in high yield. Monometallic Rh complexes, in contrast, fail to achieve any product formation. We demonstrate a broad substrate scope for formation of a variety of N-heterocycles in good to excellent yields. Macrocyclization reactions that form eleven to fifteen-membered heterocycles are also demonstrated. Mechanistic studies show that the reaction likely proceeds via catalyst protonation by trifluoroacetic acid, followed by reversible allene insertion and C–N bond-forming reductive elimination. The difference in product selectivity observed with our bimetallic catalyst vs monometallic Rh complexes may result from cooperativity between the two metals. | Kelton Forson; Benjamin Bohman; Coriantumr Wayment; Rachel Owens; Caitlyn McKnight; Rhen Davis; Lillian Stillwell; Stacey Smith; David Michaelis | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis; Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/615db85caa918dc78921c968/original/medium-and-large-n-heterocycle-formation-via-allene-hydroamination-with-a-bimetallic-rh-i-catalyst.pdf |
67bdc2596dde43c9086a6da4 | 10.26434/chemrxiv-2025-99d55 | Exploring Multi-functionality in Spin Crossover Complexes: A Special Emphasis on Synergistic Luminescence and Dielectric Properties | Molecules exhibiting multifunctional properties, such as magnetic bistability, luminescence, and dielectric properties have excellent potential for application in magnetic optoelectronic devices. Research into luminescent magnets and switching materials is continuously expanding because, in these cases, spin-state change can be expressed by the fluorescence signal, and this can provide materials with practical application prospects. This review presents the recent progress in multi-functional spin crossover (SCO) systems, particularly emphasizing the need for synergistic luminescence or dielectric response of SCO systems. The present work highlights syntheses, design strategies, crystal structures, magnetic, luminescence, and dielectric response to obtain materials with potential applications in switches, sensors, and other practical domains. | Bijoy Dey; Debopam Sarkar; Sounak Ghosh; Sakshi Mehta; Krishna Kaushik; Subrata Ghosh; Abhishake Mondal | Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism; Materials Chemistry; Crystallography – Inorganic | CC BY 4.0 | CHEMRXIV | 2025-02-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bdc2596dde43c9086a6da4/original/exploring-multi-functionality-in-spin-crossover-complexes-a-special-emphasis-on-synergistic-luminescence-and-dielectric-properties.pdf |
6293510fff2dabe50c3b37e4 | 10.26434/chemrxiv-2022-d1qfc | Solvent-dependent dual emission processes in charge-transfer excited states of phenothiazine-triphenyltriazine conformers | We have investigated the solvent effects on charge-transfer excited states in a donor-acceptor type luminescent material, phenothiazine-triphenyltriazine (PTZ-TRZ), which has characteristic two conformers: quasi-axial and quasi-equatorial conformers. Solvent permittivity dependence of steady-state photoluminescence spectra using mixture solvents of toluene and tetrahydrofuran (THF) indicated that the two conformers have almost the same excited-state dipole moments. Time-resolved photoluminescence and transient absorption spectra in toluene and THF showed a different solvent dependence between the two conformers. From the detailed analysis of these time-resolved spectra, we revealed the solvent-dependent emission processes in the two conformers. | Ryu Tomohiro; Kiyoshi Miyata; Masaki Saigo; Yuushi Shimoda; Youichi Tsuchiya; Hajime Nakanotani; Chihaya Adachi; Ken Onda | Physical Chemistry; Photochemistry (Physical Chem.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-05-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6293510fff2dabe50c3b37e4/original/solvent-dependent-dual-emission-processes-in-charge-transfer-excited-states-of-phenothiazine-triphenyltriazine-conformers.pdf |
60c743abee301cd245c7901f | 10.26434/chemrxiv.9391925.v1 | Interactions of Different Janus Particles with Passive Tracers | In this manuscript we want to expand the strategies on tuneable phoretic interactions. Previously, we had kept the swimmer body fixed and varied fuel and light source. In this report we fix the fuel to hydrogen peroxide and change the species that favours its degradation, i.e. the 'catalytic' half on the Janus particles. Many materials are known to degrade hydrogen peroxide and our selection includes copper and silver, which present interesting effects besides the well known platinum. | Purnesh Chattopadhyay; Juliane Simmchen | Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743abee301cd245c7901f/original/interactions-of-different-janus-particles-with-passive-tracers.pdf |
652f53668bab5d2055932972 | 10.26434/chemrxiv-2023-pxgxl | Long-term performance of epoxy-based coatings: Hydrothermal exposure | We examined the effects of prolonged exposure to high temperature and water on epoxy-based powder barrier coatings applied to steel panels, which are commonly used in many industrial applications including oil & gas pipelines. The coatings’ performance was evaluated over 85 weeks at 65°C using deionized water. We also compared the mass transport properties of free-standing coating films with the barrier performance of the coated steel panels. This research lays the groundwork for predicting cumulative damage and time-dependent barrier performance of defect-free coating systems. Despite the fact that these coating systems are intended for decades of in-service use, we found that degradation effects caused by permeant sorption within the coatings can be detected as early as 8 weeks in the ageing process. The first 200 days of exposure emerged as critical for underlying corrosion reactions, marking the completion of epoxy network degradation and the onset of a steady state in mass transport mechanisms. Despite the protective barrier coatings, we observed readily occurring under-coating oxidation of the steel substrate after 182 days, as confirmed by cross-sectional and focused ion beam milling analysis. We also analyzed the adhesion strength of the coated panels over time. The epoxy-based coating’s pull-off strength declines rapidly due to water-induced plasticization, but the adhesion properties of the epoxy network show a slight recovery due to secondary cross-linking by Type II bound water. This study underscores the complexity associated with predicting the time-to-failure for epoxy coating systems. However, the data and analyses provided herein offer valuable insights into the implications of extreme exposure conditions, aiding in the construction of lifetime predictions using a stochastic process. In real-world scenarios, pipelines undergo various fluctuations in parameters like temperature and humidity, potentially leading to failure. A deterministic physical/chemical model under simplified conditions can serve as input for the probability distribution function of future failure events. | Hossein Zargarnezhad; Dennis Wong; C.N. Catherine Lam; Edouard Asselin | Materials Science; Polymer Science; Coating Materials | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652f53668bab5d2055932972/original/long-term-performance-of-epoxy-based-coatings-hydrothermal-exposure.pdf |
674f34a55a82cea2fadaa0a4 | 10.26434/chemrxiv-2024-mk39b | Polyetherureas as aqueous binders for Li ion
Batteries | We report here the application of polyetherureas as a new class of aqueous binder for the LiFePO4 positive electrode material in lithium-ion batteries. Polyetherureas have been synthesized using a greener route (avoiding conventionally used toxic diisocyanate feedstock) by ruthenium-catalysed dehydrogenative coupling of polyethylene glycol diamine and methanol. The best binder performance was obtained when polyetherurea was used in combination with SBR (Styrene-Butadiene Rubber) exhibiting an initial coulombic efficiency of ~97% and a cell polarization of 30 mV. Remarkably, the combination of polyetherurea/SBR as a binder outperforms CMC (Carboxymethyl cellulose) which is a commonly used aqueous binder for lithium-ion batteries. Evidence of the involvement of polyetherureas on binder performance have been provided using IR spectroscopy, and scanning electron microscopy. Physical, electrochemical, and mechanical properties of the polyetherurea have been studied using TGA, DSC, powder XRD, cyclic voltammetry, nanoindentation, tensile testing and 180o peel test that shed light on why this polymer acts as a good binder. | Mei Tan; Garima Saini; Maximillian Stanzione; Ketan Pancholi; Harini Sampathkumar; Matthew Walker; Charlie Patterson; Massimo Vassalli; Aaron Naden; Oxana Magdysyuk; Robert Armstrong; Amit Kumar | Polymer Science; Energy; Organic Polymers; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674f34a55a82cea2fadaa0a4/original/polyetherureas-as-aqueous-binders-for-li-ion-batteries.pdf |
61dc829190fc8adb1ff285c1 | 10.26434/chemrxiv-2022-5lcrq | Order beyond a monolayer: the story of two 4,4’-bipyridine layers on the Sb(111) | ionic liquid interface | The interface between semi-metallic Sb(111) electrode and ionic liquid with 4,4’-bipyridine addition has been studied. Using in situ scanning tunnelling microscopy and electrochemical impedance spectroscopy, the desorption of 4,4’-bipyridine was demonstrated and a dense underlying structure, formed below a sparse self-assembled monolayer, was visualized. The first SAM layer in contact with the electrode consisted of tightly packed ordered rows, which fine structure has been identified with density functional theory calculations supported by machine learning. The second SAM layer, on top of the first, is characterised by low surface concentration and its unit cell was obtained experimentally. The detection of two separate adsorbed layers indicates that the ordering of organic molecules could extend well beyond the monolayer on the electrode’s surface. These insights are of fundamental and practical importance in the development of nanoelectronic devices. | Heigo Ers; Liis Siinor; Carolin Siimenson; Enn Lust; Piret Pikma | Physical Chemistry; Materials Science; Nanoscience; Nanostructured Materials - Materials; Electrochemistry - Mechanisms, Theory & Study; Self-Assembly | CC BY NC 4.0 | CHEMRXIV | 2022-01-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61dc829190fc8adb1ff285c1/original/order-beyond-a-monolayer-the-story-of-two-4-4-bipyridine-layers-on-the-sb-111-ionic-liquid-interface.pdf |
644f6d940d87b493e39511bd | 10.26434/chemrxiv-2023-lwrsl | A Brief Review on Recent Lab-on-Chip and Nanotechnology driven advances in Salivary Biomarkers Biosensing for oral disease diagnosis | Salivary diagnostics offers a promising method for early diagnosis, prognosis, and post-therapy monitoring. Saliva contains various hormones, proteins, enzymes, antibodies, antimicrobial constituents, and cytokines that can provide diagnostic information. Saliva is easy to collect, non- invasive, cost-effective, and can be easily stored and transported, making it a valuable tool for diagnosis and monitoring of various diseases. Salivary biomarkers can be used for early detection, diagnosis, and monitoring of disease progression, as well as predicting treatment response. Saliva has been identified as a promising diagnostic fluid for detecting various oral diseases such as dental caries, periodontal disease, and oral cancer. This review explores the latest advancements in identifying biomarkers for prevalent oral diseases and the biosensing technologies that can detect these biomarkers with enhanced sensitivity, selectivity, accuracy, and practicality. | Rahul Sharma; Amit Patel | Analytical Chemistry; Analytical Apparatus; Biochemical Analysis; Electrochemical Analysis | CC BY 4.0 | CHEMRXIV | 2023-05-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/644f6d940d87b493e39511bd/original/a-brief-review-on-recent-lab-on-chip-and-nanotechnology-driven-advances-in-salivary-biomarkers-biosensing-for-oral-disease-diagnosis.pdf |
62f64561e78f70d22b38d456 | 10.26434/chemrxiv-2022-48s6j | Design localized high concentration electrolytes via donor number and solubility | The salt-concentrated electrolytes offer superior properties beyond conventional dilute electrolytes yet suffer from high cost and viscosity that hinder their practical applications. A key strategy to address this challenge is to introduce a secondary solvent as a diluent that reduces the salt content while maintaining the local structure of salt-concentrated electrolytes, giving rise to localized high concentration electrolytes (LHCEs). Through a thorough investigation involving ~700 samples, we find that, the dielectric constant of solvent, a widely used parameter for electrolyte design, does not serve as a useful screening criterion for diluents; instead, donor number (DN) is an effective design parameter to achieve LHCE structure, i.e., the primary solvent must have DN > 10 and the diluent must have DN < 10. Correlating DN with solvent solubility leads to a simpler screening rule: Li-salt-insoluble solvents are diluents while Li-salt-soluble solvents become co-solvents. Both DN- and solubility-based design principles can be understood in an atomistic model of LHCE and are applicable to other electrolyte systems. | Juner Chen; Han Zhang; Changming Ke; Shi Liu; Jianhui Wang | Physical Chemistry; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Solution Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62f64561e78f70d22b38d456/original/design-localized-high-concentration-electrolytes-via-donor-number-and-solubility.pdf |
617253b864e2af3fd30e31d1 | 10.26434/chemrxiv-2021-7jxpq-v2 | Liquid water simulation using hydrogen bond corrected SCAN and neural network potentials. | Accurately reproducing the structure of liquid water with ab initio molecular dynamics (AIMD) simulation is a crucial first step on the path towards accurately predicting the properties of liquid solutions without relying on experiment. Density functional theory (DFT) is normally used to approximate the forces in these simulations. However, no DFT functional has been shown to give an entirely satisfactory description of the structure of liquid water. Here, I propose a simple correction to the strongly constrained and appropriately normalised (SCAN) DFT functional, that corrects the strength of the hydrogen bonding interaction with a simple exponential potential fitted to dimer energy calculations. The resulting SCAN-CH functional provides an excellent description of the structure of liquid water. Long time scale NPT simulations are enabled by the use of neural network potentials, which demonstrate that the simulations are well converged and that the density of water is also more accurately reproduced with this method. | Timothy Duignan | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Theory - Computational; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/617253b864e2af3fd30e31d1/original/liquid-water-simulation-using-hydrogen-bond-corrected-scan-and-neural-network-potentials.pdf |
6422b43962fecd2a8392553b | 10.26434/chemrxiv-2023-7m018 | Pathway-dependent quantitative self-assembly of a metastable Pd6L4 square-based pyramid promoted by template and assist anions | Precise control of molecular self-assembly process is one of ultimate goals in molecular self-assembly because this enables us to make a rational design of self-assembly pathway to selectively obtain even metastable assemblies, which is impossible under thermodynamic control. Toward this goal, modulation of the energy landscape of molecular self-assembly is demanded. Here, we report that a metastable Pd6L4 square-based pyramid (SP) was almost quantitatively assembled by a pathway-dependent process with the aid of template and assist anions, which properly modulate the energy landscape, while usual heating a mixture of building blocks without modulation of the energy landscape gave a mixture of Pd6L4 SP and uncharacterized species in equilibrium. These results indicate that synergy of template and assist effects is powerful approach for pathway selection in metal-organic assembly resulting in a metastable product selectively. | Tsukasa Abe; Shinnosuke Horiuchi; Shuichi Hiraoka | Inorganic Chemistry; Supramolecular Chemistry (Inorg.) | CC BY NC 4.0 | CHEMRXIV | 2023-03-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6422b43962fecd2a8392553b/original/pathway-dependent-quantitative-self-assembly-of-a-metastable-pd6l4-square-based-pyramid-promoted-by-template-and-assist-anions.pdf |
63d2b0f7fa87ebeb2b55c275 | 10.26434/chemrxiv-2023-h9fj1 | Generation and Wagner-Meerwein Rearrangement of α-Carbonyl Cations from Brønsted Acid-Catalyzed Alkyne Oxidations with Pyridine N-Oxides | α-Carbonyl cations are the umpolung forms of the synthetically fundamental α-carbonyl carbanions. They are highly reactive yet rarely studied and utilized species and their precursors were rather limited. Herein, we report the generation of α-carbonyl cations from HNTf2-catalyzed alkyne oxidations with pyridine N-oxides and the interception of them via Wagner-Meerwein rearrangement. Broad spectrum of alkynes including aryl alkyne, ynamide, and alkynyl sulfide could be utilized and the migrating priorities of different groups in the Wagner-Meerwein rearrangement step was elucidated. DFT calculations further supported the generation of α-carbonyl cations via the N-O bond cleavage. Another key feature of this methodology was the fragmentation of synthetically inert tert-butyl groups into readily transformable olefin functionalities. The synthetic potential was highlighted by the scale-up reaction and the downstream diversifications including the formal synthesis of nicotlactone B and galbacin. | Weilin Wang; Junrui Zhou; Fenfang Zuo; Shupeng Liu; Pathan Mosim Amin; Kangbao Zhong; Ruopeng Bai; Youliang Wang | Organic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63d2b0f7fa87ebeb2b55c275/original/generation-and-wagner-meerwein-rearrangement-of-carbonyl-cations-from-br-nsted-acid-catalyzed-alkyne-oxidations-with-pyridine-n-oxides.pdf |
653b998ca8b423585a5afc78 | 10.26434/chemrxiv-2023-cbm9z | A Multi-metal Approach for the Reticulation of Iridium into Metal-Organic Framework Building Units | Noble metals (Ag, Au, Pt, Rh, Ir, Pd, Ru and Os) are ubiquitous in our everyday life, from medical applications to electronic devices and synthetic chemistry. Iridium is one of the least abundant elements, and despite its scarcity, it remains essential for efficient and active catalytic processes. Consequently, the development of heterogeneous catalysts with presence of active iridium sites is of enormous interest as it leads to the improvement of their recyclability and reusability. Here, we demonstrate a strategy to incorporate iridium atoms into metal-organic frameworks (MOFs), as part of their secondary building units (SBUs), resulting in robust and reusable materials with heterogeneous photocatalytic activity. | Raluca Loredana Vasile; Mari Carmen Borrallo-Aniceto; Fátima Esteban-Betegón; Enrique Gutiérrez-Puebla; M Angeles Monge; Marta Iglesias; Felipe Gándara | Materials Science; Catalysts; Hybrid Organic-Inorganic Materials; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/653b998ca8b423585a5afc78/original/a-multi-metal-approach-for-the-reticulation-of-iridium-into-metal-organic-framework-building-units.pdf |
60c73e16702a9b2483189cd6 | 10.26434/chemrxiv.6502652.v1 | Evaluation of a New Vocus Reagent-Ion Source and Focusing Ion-Molecule Reactor for use in Proton-Transfer-Reaction Mass Spectrometry | <div>We evaluate the performance of a new chemical ionization source called Vocus, consisting of a discharge reagent-ion source and focusing ion-molecule reactor (FIMR) for use in protontransfer-reaction time-of-flight mass spectrometry (PTR-TOF) measurements of volatile organic compounds (VOCs) in air. The reagent ion source uses a low-pressure discharge. The FIMR consists of a glass tube with a resistive coating, mounted inside a radio-frequency (RF) quadrupole. The axial electric field is used to enhance ion collision energies and limit cluster ion formation. The RF field focuses ions to the central axis of the reactor and improves the detection efficiency of product ions. Ion trajectory calculations demonstrate the mass-dependent focusing of ions and enhancement of the ion collision energy by the RF field, in particular for the lighter ions. Product ion signals are increased by a factor of 10 when the RF field is applied (5,000-18,000 cps ppbv<sup>-1</sup>), improving measurement precision and detection limits while operating at very similar reaction conditions as traditional PTR instruments. Due to the high water mixing ratio in the FIMR, we observe no dependence of the sensitivity on ambient sample humidity. In this work, the Vocus is interfaced to a TOF mass analyzer with a mass resolving power up to 14,000, which allows clear separation of isobaric ions, observed at nearly every nominal mass when measuring ambient air. Measurement response times are determined for a range of ketones with saturation vapor concentrations down to 5×10<sup>4</sup> μg m<sup>-3</sup> and compare favorably with previously published results for a PTR-MS instrument.</div> | Jordan Krechmer; Felipe
D. Lopez-Hilfiker; Abigail R. Koss; Manuel A. Hutterli; Carsten Stoermer; Benjamin L. Deming; Joel R. Kimmel; Carsten Warneke; Rupert Holzinger; John T. Jayne; Douglas
R. Worsnop; Katrin Fuhrer; Marc Gonin; Joost de Gouw | Atmospheric Chemistry; Analytical Chemistry - General; Analytical Apparatus; Environmental Analysis; Mass Spectrometry; Spectroscopy (Anal. Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2018-06-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e16702a9b2483189cd6/original/evaluation-of-a-new-vocus-reagent-ion-source-and-focusing-ion-molecule-reactor-for-use-in-proton-transfer-reaction-mass-spectrometry.pdf |
640a28a76642bf8c8f413f32 | 10.26434/chemrxiv-2023-sm0lj | History-Agnostic Battery Degradation Inference | Lithium-ion batteries (LIBs) have attracted widespread attention as an efficient energy storage device on electric vehicles (EV) to achieve emission-free mobility. However, the performance of LIBs deteriorates with time and usage, and the state of health of used batteries are difficult to quantify and to date are poorly understood. Having accurate estimations of a battery's remaining life across different life stages would benefit maintenance, safety, and serve as a means of qualifying used batteries for second-life applications. Since the full history of a battery may not always be available in downstream applications, in this study, we demonstrate a deep learning framework that enables dynamic degradation trajectory prediction, while requiring only the most recent battery usage information. Specifically, our model takes a rolling window of current and voltage time-series inputs, and predicts the near-term and long-term capacity fade via a recurrent neural network. We exhaustively benchmark our model against a naive extrapolating model by evaluating the error on reconstructing the discharge capacity profile under different settings. We show that our model's performance in accurately inferring the battery's degradation profile is "agnostic" with respect to cell cycling history and its current state of health. | Mehrad Ansari; Steven B. Torrisi; Amalie Trewartha; Shijing Sun | Energy; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/640a28a76642bf8c8f413f32/original/history-agnostic-battery-degradation-inference.pdf |
619400b658bc4b931a95b35c | 10.26434/chemrxiv-2021-7tclk | Synthesis and styrene copolymerization of novel alkyl ring-substituted t-butyl phenylcyanoacrylates | Novel alkyl ring-substituted t-butyl phenylcyanoacrylates, RPhCH=C(CN)CO2C(CH3)3 (where R is H, 2-methyl, 3-methyl, 4-methyl, 2-ethyl, 4-ethyl, 4-propyl, 4-i-propyl, 4-butyl, 4-i-butyl) were prepared and copolymerized with styrene. The acrylates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and t-butyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C NMR. All the ethylenes were copolymerized with styrene in solution with radical initiation (ABCN) at 70C. The compositions of the copolymers were calculated from nitrogen analysis. | Daniah H. Ibrahim; Tarick Abu-Alrob; Maria Agoytia; John K. Butterfield; Maura K. Devine; Jennifer Y. Dinh; Angelo R. Donis; Kristen A. Folkes; Firyal M. Khan; Caroline J. Shishem; Sara Rocus; William Schjerven; Gregory Kharas | Organic Chemistry; Polymer Science; Organic Synthesis and Reactions; Organic Polymers; Polymerization (Polymers) | CC BY 4.0 | CHEMRXIV | 2021-12-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/619400b658bc4b931a95b35c/original/synthesis-and-styrene-copolymerization-of-novel-alkyl-ring-substituted-t-butyl-phenylcyanoacrylates.pdf |
60c74606bb8c1a710b3da7e6 | 10.26434/chemrxiv.10325984.v1 | Integrating Disciplines in a Plant Chemistry Laboratory Module to Enhance Interdisciplinary and Scientific Thinking in Undergraduate Students | Here, we describe a hands-on medicinal plant chemistry laboratory module (Phytochemical Laboratory Activities for iNtegrative Thinking and Enhanced Competencies; PLANTEC) for undergraduates that targets the development of core competencies in (i) critical thinking and analysis of text and data, (ii) interdisciplinary and systems thinking, (iii) oral and written communication of science, and (iv) teamwork and collaboration.<br /> | Lucas Busta; Sabrina E. Russo | Chemical Education - General | CC BY NC ND 4.0 | CHEMRXIV | 2019-11-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74606bb8c1a710b3da7e6/original/integrating-disciplines-in-a-plant-chemistry-laboratory-module-to-enhance-interdisciplinary-and-scientific-thinking-in-undergraduate-students.pdf |
62c79916cd7a990e6abd6ce3 | 10.26434/chemrxiv-2022-j78bc | Dynamic Structural Evolution of [Rh(NO)2]+ Complex/Rh Metal Cluster in Zeolite during deNOx via In Situ Formed NH3 under Lean/Rich Periodic Conditions | The dynamic structural evolution of Rh species in mordenite (MOR) zeolite was investigated using in situ spectroscopic techniques and DFT calculations. In situ X-ray absorption spectroscopy and operando infrared (IR) revealed that metallic Rh species were oxidized to afford isolated [Rh(NO)2]+ species under NO flow at 200°C, whereas small Rh metal clusters is formed under the subsequent H2 flow. Ab initio thermodynamics analysis shows that the plausible structures under NO and H2 at 200°C are [Rh(NO)2]+ and Rh clusters in MOR, which is consistent with the experimental observations. A comparative study of Rh-loaded Al2O3 suggests that Al sites in MOR increase the thermodynamic stability of isolated Rh+ species and thus prevent their overoxidation to Rh2O3 under NO. NO capture in the form of [Rh(NO)2]+ and its selective reduction toward NH3 under H2 flow were observed by in situ IR measurements. The RhMOR catalyst exhibited ~60% of NOx conversion above 200°C under periodic lean/rich conditions. Transition state calculations showed that the activation barrier for NO reduction to NH3 on [Rh(NO)2]+ (178 kJ/mol) is higher than that for Rh13 (156 kJ/mol), suggesting that Rh metal clusters are preferable NH3 formation sites, where the Rh13-catalyzed NO reduction into N2 and N2O was less preferable than NH3 formation, which is consistent with the experimental results. Combined with operando IR experiments under lean (NO + O2) and rich (NO + H2) conditions, we show that the reversible dynamic structural evolution of Rh species ([Rh(NO)2]+ Rh metal clusters under lean and rich conditions) is a key mechanistic feature for unsteady-state de-NOx via the capture of NO, its selective reduction to NH3, and the selective reduction of NO with NH3 formed in situ. | Shunsaku Yasumura; Taisetsu Kato; Yucheng Qian; Takashi Toyao; Zen Maeno; Ken-ichi Shimizu | Catalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c79916cd7a990e6abd6ce3/original/dynamic-structural-evolution-of-rh-no-2-complex-rh-metal-cluster-in-zeolite-during-de-n-ox-via-in-situ-formed-nh3-under-lean-rich-periodic-conditions.pdf |
675b506b7be152b1d0c716db | 10.26434/chemrxiv-2024-wzr9s-v2 | Deep-Learning-Enhanced Modeling of Electrosprayed Particle Assembly on Non-spherical Droplet Surfaces | Monolayer assembly of charged colloidal particles at liquid interfaces opens a new avenue for advancing the additive manufacturing of thin film materials and devices with tailored properties. In this study, we investigated the dynamics of electrosprayed colloidal particles at curved droplet interfaces through a combination of physics-based computational simulations and machine learning. We employed a novel mesh-constrained Brownian dynamics (BD) algorithm coupled with Ansys® electric field simulations to model the transport and assembly of charged particles on a non-spherical droplet surface. We demonstrated that the electrostatic repulsion between particles, electrophoretic forces induced by substrate surface charge, and Brownian motion are the key factors influencing the compactness and ordering of the assembly structure. We further trained a deep neural network surrogate model using the data generated from the BD simulations to predict radial distribution functions (RDF) of particle assembly. By coupling the surrogate model with Bayesian optimization, we identified the optimal particle and substrate charge densities that yield the best match between the simulation and experimental assembly. Using the optimal charge densities, the RDF profile of the simulated assembly accurately matches the experiment with a similarity of 96.4%, and the corresponding average bond order parameter differs by less than 5% from the experimental one. This deep-learning-based approach significantly reduces computational time while maintaining high accuracy in predicting the important features of the assembly structures. The charge densities inferred from the modeling provide critical insights into the surface charge accumulation in the electrospray process. | Nasir Amiri; Joseph Prisaznuk; Peter Huang; Paul Chiarot; Xin Yong | Theoretical and Computational Chemistry; Physical Chemistry; Machine Learning; Interfaces; Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675b506b7be152b1d0c716db/original/deep-learning-enhanced-modeling-of-electrosprayed-particle-assembly-on-non-spherical-droplet-surfaces.pdf |
64a629029ea64cc167854da6 | 10.26434/chemrxiv-2023-x76xj | Visible-Light-Mediated aza Paternò-Büchi Reaction of Acyclic Oximes and Alkenes for the Synthesis of Monocyclic Azetidines | The aza Paternò-Büchi reaction is a [2+2]-cycloaddition reaction between imines and alkenes that is arguably the most atom-economical method to access 4-membered nitrogen-containing heterocycles. Although the azetidine products obtained are highly desirable for pharmaceutical applications, these transformations remain limited due to challenges associated with the decreased photoreactivity of acyclic imine precursors. Currently, successful examples rely primarily on either intramolecular variants or cyclic imines. To fully realize the synthetic potential of aza Paternò-Büchi reactions, previously elusive acyclic imines must engage productively with alkenes to provide currently inaccessible azetidines. Here we report that matching of the frontier molecular orbital energies of alkenes with those of acyclic oximes can overcome these challenges and lead to the successful development of visible-light-mediated aza Paternò-Büchi reactions via triplet energy transfer catalysis. Insights obtained into this transformation are expected to inform and advance future developments in [2+2]-cycloadditions. | Corinna Schindler; Heather Kulik; Emily Wearing; Yu-Cheng Yeh; Gianmarco Terrones; Seren Parikh; Ilia Kevlishvili | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64a629029ea64cc167854da6/original/visible-light-mediated-aza-paterno-buchi-reaction-of-acyclic-oximes-and-alkenes-for-the-synthesis-of-monocyclic-azetidines.pdf |
65279b09bda59ceb9a66ce7f | 10.26434/chemrxiv-2023-4bft7 | Neuroengineering: ferromagnetic nano (micro) implants. Magnetic-hypnotic effect control of animal behavior by an external magnetic field | A method of injecting barium hexaferrite-based ferromagnetic implants into the brain of animals is proposed. Behavioral responses of mice to external magnetic influence after the introduction of non-toxic nanomagnetic particles of barium hexaferrite were studied. A decrease in the BOLD-signal value at nitric oxide "outflow" within the framework of the proposed kinetic model was shown. | Sergey Varfolomeev; Valeriy Kalinichenko; Yuriy Kuznetsov; Valeriy Bykov; Irina Gachok; Svetlana Tsybenova | Physical Chemistry; Biological and Medicinal Chemistry; Bioengineering and Biotechnology; Biophysical Chemistry; Chemical Kinetics | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65279b09bda59ceb9a66ce7f/original/neuroengineering-ferromagnetic-nano-micro-implants-magnetic-hypnotic-effect-control-of-animal-behavior-by-an-external-magnetic-field.pdf |
6166e9028b620d79824e0bba | 10.26434/chemrxiv-2021-nz4gt | Modulated Self-Assembly of an Interpenetrated MIL-53 Sc Metal-Organic Framework with Excellent Volumetric H2 Storage and Working Capacity | To achieve optimal performance in gas storage and delivery applications, metal-organic frameworks (MOFs) must combine high gravimetric and volumetric capacities. One potential route to balancing high pore volume with suitable crystal density is interpenetration, where identical nets sit within the void space of one another. Herein, we report an interpenetrated MIL-53 topology MOF, named GUF-1, where one-dimensional Sc(µ2-OH) chains are connected by 4,4’-(ethyne-1,2-diyl)dibenzoate linkers into a material that is an unusual example of an interpenetrated MOF with a rod-like secondary building unit. A combination of modulated self-assembly and grand canonical Monte Carlo simulations are used to optimise the porosity of GUF-1; H2 adsorption isotherms reveal a very high Qst for H2 of 7.6 kJ mol-1 and a working capacity of 41 g L-1 in a temperature-pressure swing system, which is comparable to benchmark MOFs. These results show that interpenetration is a viable route to high performance gas storage materials comprised of relatively simple building blocks. | Alexander Thom; David Madden; Rocio Bueno-Perez; Ali Al Shakhs; Ciaran Lennon; Ross Marshall; Claire Wilson; Claire Murray; Stephen Thompson; Gemma Turner; Dominic Bara; Stephen Moggach; David Fairen-Jimenez; Ross Forgan | Materials Science; Inorganic Chemistry; Hybrid Organic-Inorganic Materials; Hydrogen Storage Materials; Supramolecular Chemistry (Inorg.); Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2021-10-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6166e9028b620d79824e0bba/original/modulated-self-assembly-of-an-interpenetrated-mil-53-sc-metal-organic-framework-with-excellent-volumetric-h2-storage-and-working-capacity.pdf |
676b6a5efa469535b9b23e1e | 10.26434/chemrxiv-2024-wr63b | Electrocatalysis of Bacterial Membrane Vesicles | The establishment of bioelectrochemical systems is an appealing strategy to further the development of eco-friendly and efficient bioengineering technologies. However, the major biocomponents used as catalysts have been limited to purified enzymes and live microorganisms. Here, we examined the electrocatalytic activity of membrane vesicles (MVs) produced by Shewanella oneidensis MR-1. We demonstrate that the MR-1 MVs exhibit electrocatalysis coupled with formate oxidation over 16 days and a more stable catalytic current compared with live cells. A colorimetric assay and electrochemical analysis revealed that different MV biogenesis routes critically affect the electrocatalytic activity of MVs. Electrochemical analysis of MVs from gene-deletion mutants revealed electron transfer mechanisms between MVs and electrodes in pathways both dependent and independent of c-type cytochromes in MVs. This research highlights MVs as promising platforms for the design of robust and controllable bioelectrocatalysts, paving the way for future research in biosensing, energy conversion, and biochemical production. | Thomas Kouyou Savage; Seiya Tsujimura; Nobuhiko Nomura; Masanori Toyofuku; Yoshihide Tokunou | Biological and Medicinal Chemistry; Catalysis; Microbiology; Biocatalysis; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/676b6a5efa469535b9b23e1e/original/electrocatalysis-of-bacterial-membrane-vesicles.pdf |
6361830d3110727ad3f8daa5 | 10.26434/chemrxiv-2022-fz69r | Electrolytes for Aluminum Ion Batteries: A Molecular Dynamics Study | A vital component in the fight against climate change is the development of highly efficient energy storage for renewable resources. The aluminum ion battery (AIB) is a promising technology, but there is a lack of understanding of the desired nature of the batteries’ electrolytes. These properties cannot simply be extrapolated from other metal ion batteries, as the ionic charge carriers in these batteries are not simply Al3+ ions but the anionic AlCl4− and Al2Cl7−, which form in the electrolyte. This study aims to illustrate the effect of mole ratios and organic solvents to improve the AIB electrolytes with the aid of computational techniques. To this end, molecular dynamics simulations were carried out on varying ratios forming acidic, neutral and basic mixtures of the AlCl3 salt with 1-ethyl-3-methylimidazolium chloride (EMImCl) ionic liquid (IL) and an organic solvent electrolyte (dichloromethane (DCM) or toluene). The data obtained from both viscosity and diffusion calculations indicate that the solvents could improve the transport properties. Both DCM and toluene lead to lower viscosities, higher diffusion coefficients, and higher conductivity. Detailed calculations demonstrated solvents can effectively improve the formation of AlCl3···Cl (AlCl4−) and AlCl4− …AlCl4− (Al2Cl7−) especially in acidic mixtures. Densities which were averaged around 1.25 g/cm3 for pure electrolyte mixture of AlCl3-EMImCl were of comparable values to the experimental reports. These results are all in agreement with experimental findings, and strongly suggest that DCM in acidic media with AlCl3 and EMImCl might provide a promising basis for battery development. | Maryam Kosar; S. Maryamdokht Taimoory; Owen Diesenhaus; John Trant | Theoretical and Computational Chemistry; Physical Chemistry; Energy; Computational Chemistry and Modeling; Energy Storage; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6361830d3110727ad3f8daa5/original/electrolytes-for-aluminum-ion-batteries-a-molecular-dynamics-study.pdf |
631fe7943940c245b9fd1709 | 10.26434/chemrxiv-2022-bpjbg | X-ray Absorption Spectroscopy Illustrates the Participation of Oxygen in the Electrochemical Cycling of Li4Mn2O5 | A combination of oxygen redox and Mn-based oxides would be the best option for high-energy density Li-ion batteries crucial for a sustainable society. The disordered rock-salt Li4Mn2O5 was recently reported to display very large capacity of 460 mAh/g with relative reversibility. Previous studies proposed the involvement of lattice oxygen redox in such intriguing electrochemical performance, whereas no direct evidence was presented. To clarify the charge compensation mechanism, we systematically investigated the evolution of the electronic structure of both Mn and O upon cycling via Mn/O K-edge XAS spectroscopy. Mn K-edge XAS unequivocally demonstrates the participation of Mn redox upon the initial stages of charging, yet changes are arrested at the high potentials, while O continues to evolve according to O K-edge XAS. Upon discharging, both Mn and O partially recover to their pristine states. The results highlight the significance of a disordered structure in maintaining the reversible redox chemistry of both transition metals and oxygen to design cathode materials with high energy density. | Haifeng Li; Indrani Roy; Mateusz Starczewski; John Freeland ; Jordi Cabana | Materials Science; Energy; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631fe7943940c245b9fd1709/original/x-ray-absorption-spectroscopy-illustrates-the-participation-of-oxygen-in-the-electrochemical-cycling-of-li4mn2o5.pdf |
630fae58f07ee167bcf90b0b | 10.26434/chemrxiv-2022-q92j8 | Electrophoresis-assisted multilayer assembly of nanoparticles for sensitive lateral flow immunoassay | Lateral flow immunoassay (LFIA) is a rapid, simple, and inexpensive method for point-of-need analysis. A major limitation of LFIA is a high limit of detection (LOD), which impacts its diagnostic sensitivity. To overcome this limitation, we introduce a signal-enhancement procedure that is performed after completing LFIA and involves controllably moving biotin- and streptavidin-functionalized gold nanoparticles along the test strip by electrophoresis. The nanoparticles link to immunocomplexes and each other forming multilayer aggregates on the test strip, thus, enhancing the signal. Here, we demonstrate lowering the LOD of hepatitis B surface antigen from approximately 8 to 0.12 ng/mL, making it clinically acceptable. Testing 76 clinical samples of serum and plasma for hepatitis B revealed that signal enhancement increased diagnostic sensitivity of LFIA from 72% to 98% while not affecting its 90% specificity. Electrophoresis-driven detection enhancement of LFIA is universal (antigen-independent), takes two minutes, and can be performed by an untrained person using an inexpensive accessory. | Vasily Panferov; Nikita Ivanov; Tony Mazzulli; Davor Brinc; Vathany Kulasingam; Sergey Krylov | Analytical Chemistry; Analytical Chemistry - General; Biochemical Analysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/630fae58f07ee167bcf90b0b/original/electrophoresis-assisted-multilayer-assembly-of-nanoparticles-for-sensitive-lateral-flow-immunoassay.pdf |
65c4d20766c138172936fdb9 | 10.26434/chemrxiv-2024-g7fqk-v2 | Exploring Optimized Organic Fluorophore Search Through Simple Experimental Data-Driven VAE | Designing organic fluorescent molecules with tailored optical properties is challenging in decades, while the new avenue was opened by the statistical models. Inverse design has garnered considerable interest in organic materials science but concentrates on arbitrary design or theoretical properties. Here, we introduce a strategy that enables direct optimization of specific experimental properties in the inverse design process, utilizing a variational autoencoder (VAE) with a latent vector-based prediction model. Omitting the Kullback-Leibler divergence and separate training strategy successfully improved the generator's robustness and molecular diversity. We confirm the latent vectors obtained from VAE are powerful inputs for downstream prediction models of experimental properties, fluorescence energy and quantum yield. Our approach for the optimized search of organic fluorescent materials, substantiated by gradient space derived from latent vector and validated by newly synthesized and uncharacterized molecules, shows potential for broader applications in diverse organic material design. | Chengwei Ju; Yuzhi Xu; Yongrui Luo; Bo Li; Weikang Jiang; Jingyu Zhang; Hanzhi Bai; Zhiqiang Wang; Jiankai Ge; Ruiming Lin; Zehan Mi; Haozhe Zhang; Yifeng Tang; Michael Jones; Xiaotian Li; John Zhang | Theoretical and Computational Chemistry; Physical Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c4d20766c138172936fdb9/original/exploring-optimized-organic-fluorophore-search-through-simple-experimental-data-driven-vae.pdf |
623dd513202c069887e0e12c | 10.26434/chemrxiv-2021-7qb90-v3 | Three-Dimensional Fully pi-Conjugated Macrocycles: When 3D-Aromatic and when 2D-Aromatic-in-3D?
| Several fully pi-conjugated macrocycles with puckered or cage-type structures were recently found to exhibit aromatic character according to both experiments and computations. We examine their electronic structures and put them in relation to 3D-aromatic molecules (e.g., closo-boranes) and to 2D-aromatic polycyclic aromatic hydrocarbons. Using qualitative theory combined with quantum chemical calculations, we find that the macrocycles explored thus far should be described as 2D-aromatic with three-dimensional molecular structures (abbr. 2D-aromatic-in-3D) and not as truly 3D-aromatic. 3D-aromatic molecules have highly symmetric structures (or nearly so), leading to (at least) triply degenerate molecular orbitals, and for molecules with tetrahedral or octahedral structures an aromatic closed-shell electronic structure results with 6n + 2 electrons. On the other hand, 2D-aromatic-in-3D structures exhibit aromaticity that results from the fulfillment of Hückel’s 4n + 2 rule for each individual macrocyclic path, yet, their pi-electron counts are coincidentally 6n + 2 numbers for macrocycles with three tethers of equal lengths. The 3D-macrocyclic molecules, suggested to be 3D-aromatic, are instead similar to naphthalene. It is notable that 2D-aromatic-in-3D macrocyclic cages can be aromatic with tethers of different lengths, i.e., when their pi-electron counts differ from 6n + 2. Finally, we identify tetrahedral and cubic pi-conjugated molecules that fulfill the 6n + 2 rule and exhibit significant electron delocalization. Yet, their properties resemble those of analogous compounds with electron counts that differ from 6n + 2. Thus, despite that these tetrahedral and cubic molecules show substantial pi-electron delocalization they cannot be classified as true 3D-aromatics. | Ouissam El Bakouri; Dariusz Szczepanik; Kjell Jorner; Rabia Ayub; Patrick Bultinck; Miquel Solà; Henrik Ottosson | Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry | CC BY 4.0 | CHEMRXIV | 2022-03-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/623dd513202c069887e0e12c/original/three-dimensional-fully-pi-conjugated-macrocycles-when-3d-aromatic-and-when-2d-aromatic-in-3d.pdf |
675015e8f9980725cf00893e | 10.26434/chemrxiv-2024-5pcps | Effect of multiple cationic substitutions on structure and magnetism of honeycomb-layered hexagonal tellurates Na2M2TeO6 (M = Co, Ni, Cu, Zn) | Hexagonal layered Na2T2TeO6 (T = Co1/3Ni1/3Cu1/3) and Na2Z2TeO6 (Z = Co1/4Ni1/4Cu1/4Zn1/4) have been prepared by solid-state reactions. According to the X-ray Rietveld refinement, Na2Z2TeO6 is isostructural with its honeycomb-ordered constituents Na2M2TeO6 (M = Co, Zn), space group P6322. For Na2T2TeO6, however, only subcell (ignoring T/Te ordering) could be successfully refined despite presence of weak superstructure reflection. This is attributed to intergrowth of two packing modes with similar lattice parameters: P63/mcm (characteristic of Na2Ni2TeO6) and P6322. According to magnetic susceptibility and heat capacity measurements, both materials undergo antiferromagnetic ordering at low temperatures with negative Weiss temperatures of −38 and −26 K for the T- and Z-compositions, respectively. The Néel point of Na2T2TeO6, 16.9 K, is considerably lower than those of its Ni and Co constituents (both being about 27 K), in contrast to the sister system, monoclinic Na3T2SbO6, where TN is intermediate between those of Ni and Co constituents. Further lowering of the Néel point in Na2Z2TeO6, 8.6 K, is attributed to the diamagnetic dilution with Zn2+. | Vladimir Nalbandyan; Igor Shukaev; Maria Evstigneeva; Alexander Vasiliev; Tatyana Vasilchikova | Inorganic Chemistry; Magnetism; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/675015e8f9980725cf00893e/original/effect-of-multiple-cationic-substitutions-on-structure-and-magnetism-of-honeycomb-layered-hexagonal-tellurates-na2m2te-o6-m-co-ni-cu-zn.pdf |
62c7d74a332f022c09e05e6a | 10.26434/chemrxiv-2021-vxkpq-v3 | Photocatalytic activity and electron storage capability of TiO2 aerogels with adjustable surface area | Mesoporous TiO2 aerogels with surface area larger than 600 m2 g-1 have been prepared via acid-catalyzed sol-gel synthesis and supercritical drying. Varying temperature treatment in air results in changes in the morphology of the aerogels and their specific surface area. Interestingly, the ability to store photogenerated electrons in the surface states of the aerogels upon illumination of dispersions in water-methanol mixtures increases with lower calcination temperature. Additionally, the extent of electron storage capability also depends on hole scavenger concentration. Increasing the calcination temperature to 500 °C results in decreased surface area and electron storage capability, however in increased hydrogen evolution rates. Finally, nitrogen reduction to ammonia in the dark is performed with photogenerated stored electrons in TiO2 aerogels, separating the charge carrier photogeneration from the dark reduction reaction. | Alexandra Rose; Anja Hofmann; Pascal Voepel; Barbara Milow; Roland Marschall | Materials Science; Catalysis; Energy; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c7d74a332f022c09e05e6a/original/photocatalytic-activity-and-electron-storage-capability-of-ti-o2-aerogels-with-adjustable-surface-area.pdf |
6269e6ebebac3a19d8e58233 | 10.26434/chemrxiv-2022-1r7rm | DNA Sequence and Length Dictate the Assembly of Nucleic Acid Block Copolymers | The self-assembly of block copolymers is often rationalized by structure and microphase separation; pathways that diverge from this parameter space may provide new mechanisms of polymer self-assembly. Here, we show that the sequence and length of single-stranded DNA directly influence the self-assembly of sequence-defined DNA block copolymers. While increasing the length of DNA led to predictable changes in self-assembly, changing only the sequence of DNA produced three distinct structures: spherical micelles (spherical nucleic acids, SNAs) from flexible poly(thymine) DNA, fibers from semi-rigid mixed-sequence DNA, and networked superstructures from rigid poly(adenine) DNA. The secondary structure of poly(adenine) DNA strands drives a temperature-dependent polymerization and assembly mechanism: copolymers stored in an SNA reservoir form fibers after thermal activation, which then aggregate upon cooling to form interwoven networks. DNA is often used as a programming code that aids in nanostructure addressability and function; Here, we show that the inherent physical and chemical properties of single-stranded DNA sequences also make them an ideal material to direct self-assembled morphologies and select for new methods of supramolecular polymerization. | Felix Rizzuto; Michael Dore; Muhammad Ghufran Rafique; Xin Luo; Hanadi Sleiman | Polymer Science; Nanoscience; Biopolymers; Polymerization (Polymers); Polymer morphology; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6269e6ebebac3a19d8e58233/original/dna-sequence-and-length-dictate-the-assembly-of-nucleic-acid-block-copolymers.pdf |
6557606adbd7c8b54b73f22a | 10.26434/chemrxiv-2023-bv1fp | Isonitriles as Alkyl Radical Precursors in Visible-Light Mediated Hydro– and Deuterodeamination Reactions | Herein, we report the use of isonitriles as alkyl radical precursors in light-mediated hydro- and deuterodeamination reactions. The reaction is scalable, shows broad functional group compatibility and potential to be used in late-stage functionalization. Importantly, the method is general for Cα-1º, Cα-2º and Cα-3º alkyl isonitriles. For most examples, high yields were obtained through direct visible-light irradiation of the isonitrile in the presence of a silyl radical precursor. Interestingly, in the presence of an organic photocatalyst (4CzIPN) a dramatic acceleration was observed. In depth mechanistic studies using UV-vis absorption, steady-state and time-resolved photoluminescence, and transient absorption spectroscopy suggest that the excited state of 4CzIPN is able to sensitize the isonitrile through a single electron transfer. | Irene Quiros; Maria Martin; Miguel Gomez-Mendoza; Maria Jesus Cabrera-Afonso; Marta Liras; Israel Fernandez; Luis Novoa; Mariola Tortosa | Organic Chemistry; Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6557606adbd7c8b54b73f22a/original/isonitriles-as-alkyl-radical-precursors-in-visible-light-mediated-hydro-and-deuterodeamination-reactions.pdf |
6416f0bfaad2a62ca1017b3f | 10.26434/chemrxiv-2023-l8n67 | Evaluation of Data Dependent MS/MS Acquisition
Parameters for Non-targeted Metabolomics and Molecular
Networking of Environmental Samples - Focus on the Q
Exactive Platform | Non-targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) is a widely used
tool for the detection and annotation of small molecules in complex environmental samples.
Data Dependent Acquisition (DDA) of product ion spectra is thereby currently one of the most
frequently applied data acquisition strategies. The optimization of DDA parameters is central
to ensuring high spectral quality, coverage and number of compound annotations. Here, we
evaluated the influence of 10 central DDA settings of the Q Exactive mass spectrometer on
natural organic matter samples from ocean, river, and soil environments. After data analysis
with Classical and Feature-based Molecular Networking using MZmine and GNPS, we
compared the total number of network nodes, multivariate clustering, and spectrum quality
related metrics such as annotation and singleton rates, MS/MS placement and coverage. Our
results show that Automatic Gain Control, Microscans, Mass Resolution, and Dynamic
Exclusion are the most critical parameters, whereas Collision Energy, TopN, and Isolation
Width had moderate and Apex Trigger, Monoisotopic Selection, and Isotopic Exclusion minor
effects. The insights into the data acquisition ergonomics of the Orbitrap platform presented
here can guide new users and provide them with initial method parameters, some of which
may also be transferable to other sample types and MS platforms. | Paolo Stincone; Abzer K. Pakkir Shah; Robin Schmid; Lana Graves; Stilianos P. Lambidis; Ralph Torres; Shu-Ning Xia; Vidit Minda; Allegra Aron; Mingxun Wang; Chambers C. Hughes; Daniel Petras | Analytical Chemistry; Chemical Education; Environmental Analysis; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6416f0bfaad2a62ca1017b3f/original/evaluation-of-data-dependent-ms-ms-acquisition-parameters-for-non-targeted-metabolomics-and-molecular-networking-of-environmental-samples-focus-on-the-q-exactive-platform.pdf |
60c745404c89190f72ad296f | 10.26434/chemrxiv.10000751.v1 | Rational Design of Quasi Zero-Strain NCM Cathode Materials for Minimizing Volume Change Effects in All-Solid-State Batteries | Measures to improve the cycling performance and stability of bulk-type all-solid-state batteries (SSBs) are currently being developed with the goal of substituting conventional Li-ion battery (LIB) technology. As known from liquid electrolyte based LIBs, layered oxide cathode materials undergo volume changes upon (de)lithiation, causing mechanical degradation due to particle fracture, among others. Unlike solid electrolytes, liquid electrolytes are somewhat capable of accommodating morphological changes. In SSBs, the rigidity of the materials used typically leads to adverse contact loss at the interfaces of cathode material and solid electrolyte during cycling. Hence, designing zero- or low-strain electrode materials for application in next-generation SSBs is desirable. In the present work, we report on novel Co-rich NCMs, NCM361 (60% Co) and NCM271 (70% Co), showing minor volume changes up to 4.5 V vs Li<sup>+</sup>/Li, as determined by <i>operando</i> X-ray diffraction and pressure measurements of LIB pouch and pelletized SSB cells, respectively. Both cathode materials exhibit good cycling performance when incorporated into SSB cells using argyrodite Li<sub>6</sub>PS<sub>5</sub>Cl solid electrolyte, albeit their morphology and secondary particle size have not yet been optimized. | Florian Strauss; Lea de Biasi; A-Young Kim; Jonas Hertle; Simon Schweidler; Juergen Janek; Pascal Hartmann; Torsten Brezesinski | Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c745404c89190f72ad296f/original/rational-design-of-quasi-zero-strain-ncm-cathode-materials-for-minimizing-volume-change-effects-in-all-solid-state-batteries.pdf |
60c74711337d6cdeaee272a6 | 10.26434/chemrxiv.9778670.v2 | Identifying Domains of Applicability of Machine Learning Models for Materials Science | We present an extension to the usual machine learning process that allows for the identification of the domain of applicability of a fitted model, i.e., the region in its domain where it performs most accurately. This approach is applied to several vastly different but commonly used materials representations (namely the n-gram approach, SOAP, and the many body tenor representation), which are practically indistinguishable based on performance using a single error statistic. Moreover, these models appear unsatisfactory for screening applications as they fail to reliably identify the ground state polymorphs. When applying our newly developed analysis for each of the models, we can identify the domain of applicability for each model according to a simple set of interpretable conditions. We show that identification of the domain of applicability in the prediction of the formation energy enables a more accurate ground-state search - a crucial step for the discovery of novel materials. | Christopher Sutton; Mario Boley; Luca M. Ghiringhelli; Matthias Rupp; Jilles Vreeken; Matthias Scheffler | Computational Chemistry and Modeling; Theory - Computational; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74711337d6cdeaee272a6/original/identifying-domains-of-applicability-of-machine-learning-models-for-materials-science.pdf |
6504bf8c99918fe5370380eb | 10.26434/chemrxiv-2023-p6hgf | Electrochemically Modulated Separation of Olefin-Paraffin Gas Mixtures in Membrane Electrode Assemblies | Olefin-Paraffin separations are large-volume energy-intensive processes used in preparing purified monomers such as ethylene and propylene. Currently, these separations are performed using distillations which account for 90-95 % of the energy utilization in the chemical and petroleum refining industries. In this work, we demonstrate an alternative olefin-paraffin separation method based on an electrochemically modulated swing absorption system. Nickel maleonitriledithiolate, an electrochemically-active organometallic complex, is dispersed in the ionogel binder of a membrane electrode assembly (MEA). When exposed to propylene-propane gas mixtures, propylene is selectively captured during the oxidation of the complex and is then released when the complex is reduced. Our results suggest that transport limitations of olefins to electrochemical active sites play an important role in determining separation efficacy. Experiments conducted under varying oxidative (from 1 to 3 V) and a reductive potential of -2 V demonstrated operational robustness of the MEA over multiple capture-and-release cycles. This proof-of-concept demonstration represents a new non-thermal route for the production of some of the largest organic chemical commodities in industry. | Toshihiro Akashige; Adlai Katzenberg; Daniel Frey; Debdyuti Mukherjee; Cesar Urbina-Blanco; Brian Chen; Yoshiyuki Okamoto; Miguel Modestino | Chemical Engineering and Industrial Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6504bf8c99918fe5370380eb/original/electrochemically-modulated-separation-of-olefin-paraffin-gas-mixtures-in-membrane-electrode-assemblies.pdf |
60c74f0e4c89197ebead3b34 | 10.26434/chemrxiv.12844655.v1 | Doping by Design: Finding New n-type Dopable ABX4 Zintl Phases for Thermoelectrics | Doping remains a bottleneck in discovering novel functional materials for applications such as thermoelectrics (TE) and photovoltaics. The current computational approach to materials discovery is to identify candidates by predicting the functional properties of a pool of known materials, and hope that the candidates can be appropriately doped. What if we could "design" new materials that have the desired functionalities and doping properties? In this work, we use an approach, wherein we perform chemical replacements in a prototype structure, to realize doping by design. We hypothesize that the doping characteristics and functional performance of the prototype structure are translated to the new compounds created by chemical replacements. Discovery of new <i>n</i>-type Zintl phases is desirable for TE; however, <i>n</i>-type Zintl phases are a rarity. We demonstrate our doping design strategy by discovering 7 new, previously-unreported ABX<sub>4</sub> Zintl phases that adopt the prototypical KGaSb<sub>4</sub> structure. Among the new phases, we computationally confirm that NaAlSb<sub>4</sub>, NaGaSb<sub>4</sub> and CsInSb<sub>4</sub> are <i>n</i>-type dopable and potentially exhibit high <i>n</i>-type TE performance, even exceeding that of KGaSb<sub>4</sub>. Our structure prototyping approach offers a promising route to discover new materials with designed doping and functional properties. | Jiaxing Qu; Vladan Stevanovic; Elif Ertekin; Prashun Gorai | Solid State Chemistry; Theory - Inorganic; Computational Chemistry and Modeling; Theory - Computational; Piezoelectricity and Thermoelectricity | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f0e4c89197ebead3b34/original/doping-by-design-finding-new-n-type-dopable-abx4-zintl-phases-for-thermoelectrics.pdf |
60c742e7702a9b1d4218a4f1 | 10.26434/chemrxiv.8796950.v1 | A Physics-Infused Deep Learning Model for the Prediction of Refractive Indices and Its Use for the Large-Scale Screening of Organic Compound Space | <div><div><div><p>We present a multitask, physics-infused deep learning model to accurately and efficiently predict refractive indices (RIs) of organic molecules, and we apply it to a library of 1.5 million compounds. We show that it outperforms earlier machine learning models by a significant margin, and that incorporating known physics into data-derived models provides valuable guardrails. Using a transfer learning approach, we augment the model to reproduce results consistent with higher-level computational chemistry training data, but with a considerably reduced number of corresponding calculations. Prediction errors of machine learning models are typically smallest for commonly observed target property values, consistent with the distribution of the training data. However, since our goal is to identify candidates with unusually large RI values, we propose a strategy to boost the performance of our model in the remoter areas of the RI distribution: We bias the model with respect to the under-represented classes of molecules that have values in the high-RI regime. By adopting a metric popular in web search engines, we evaluate our effectiveness in ranking top candidates. We confirm that the models developed in this study can reliably predict the RIs of the top 1,000 compounds, and are thus able to capture their ranking. We believe that this is the first study to develop a data-derived model that ensures the reliability of RI predictions by model augmentation in the extrapolation region on such a large scale. These results underscore the tremendous potential of machine learning in facilitating molecular (hyper)screening approaches on a massive scale and in accelerating the discovery of new compounds and materials, such as organic molecules with high-RI for applications in opto-electronics.</p></div></div></div> | Mojtaba Haghighatlari; Gaurav Vishwakarma; Mohammad Atif Faiz Afzal; Johannes Hachmann | Computational Chemistry and Modeling; Machine Learning; Artificial Intelligence; Quantum Computing; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-07-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c742e7702a9b1d4218a4f1/original/a-physics-infused-deep-learning-model-for-the-prediction-of-refractive-indices-and-its-use-for-the-large-scale-screening-of-organic-compound-space.pdf |
62a20caf8f92d94f674b2469 | 10.26434/chemrxiv-2022-xzkvs | Enabling the Circular Economy through Chemical Recycling and Upcycling of End-of-Use Plastics | Widespread plastic pollution has led to an environmental crisis, motivating new and effective methods for recycling and upcycling “end-of-use” plastics. In this review, we highlight recent advances in chemical recycling and upcycling pathways, namely, hydroconversion, pyrolysis, and solvent treatment for the deconstruction and valorization of post-consumer plastics. We highlight the advances in the design of supported metal catalysts (Pt, Ru, Zr), for the hydroconversion of plastics, especially polyolefins (PO) and polyesters. We deduce mechanistic insights by comparing and contrasting small alkane and PO hydroconversion reactions. We also review the two types of solvent treatments: chemical solvent treatment (solvolysis) for condensation polymers and solvent extraction for composite polymers. Further, we discuss advances in pyrolysis and cross alkane metathesis to deconstruct POs into liquid hydrocarbons, and finally, the functionalization of POs into vitrimers and adhesives. We highlight the challenges and envision the path forward in optimal catalyst and process design that will enable the development of chemical upcycling technologies for building a circular plastic economy. | Siddhesh Borkar; Ryan Helmer; Fatima Mahnaz; Wafaa Majzoub; Waad Mahmoud; Ma'moun Al-Rawashdeh; Manish Shetty | Catalysis; Energy; Chemical Engineering and Industrial Chemistry; Reaction Engineering; Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62a20caf8f92d94f674b2469/original/enabling-the-circular-economy-through-chemical-recycling-and-upcycling-of-end-of-use-plastics.pdf |
60c73d51337d6cfe7ae2613a | 10.26434/chemrxiv.5764671.v1 | Photothermal Circular Dichroism Induced by Plasmon Resonances in Chiral Metamaterial Absorbers and Bolometers | Chiral photochemistry remains a challenge
because of the very small asymmetry in the chiro-optical absorption of
molecular species. However, we think that the rapidly developing fields of
plasmonic chirality and plasmon-induced circular dichroism demonstrate very
strong chiro-optical effects and have the potential to facilitate the
development of chiral photochemistry and other related applications such as
chiral separation and sensing. In this study, we propose a new type of chiral
spectroscopy – photothermal circular dichroism. It is already known that the
planar plasmonic superabsorbers can be designed to exhibit giant circular
dichroism signals in the reflection. Therefore, upon illumination with chiral
light, such planar metastructures should be able to generate a strong asymmetry
in their local temperatures. Indeed, we demonstrate this chiral photothermal effect
using a chiral plasmonic absorber. Calculated temperature maps show very strong
photothermal circular dichroism. One of the structures computed in this paper could
serve as a chiral bolometer sensitive to circularly polarized light. Overall, this
chiro-optical effect in plasmonic metamaterials is much greater than the
equivalent effect in any chiral molecular system or plasmonic bio-assembly. Potential
applications of this effect are in polarization-sensitive surface photochemistry and chiral bolometers. | Xiang-Tian Kong; Larousse Khosravi Khorashad; Zhiming Wang; Alexander O. Govorov | Metamaterials; Optical Materials; Thermal Conductors and Insulators; Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2018-01-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d51337d6cfe7ae2613a/original/photothermal-circular-dichroism-induced-by-plasmon-resonances-in-chiral-metamaterial-absorbers-and-bolometers.pdf |
6707130451558a15efa4ba6d | 10.26434/chemrxiv-2024-h59x8 | Launching Graphene into 3D-Space: Symmetry, Topology, and Strategies for Bottom-Up Synthesis of Schwarzites | Schwarzites are hypothetical carbon allotropes in the form of a continuous negatively curved surface with a three-dimensional periodicity. These materials of the future attract interest because of the expectation for their large surface area per volume, high porosity, tunable electric conductivity, and excellent mechanical strength combined with light weight. Three-decades long history attempting synthesize Schwarzites from the gas phase carbon atoms went without success. Design of Schwarzites is both digital art and science of placing tiles of sp2-carbon polygons on mathematically defined triply periodic minimal surfaces. The knowledge of how to connect polygons in sequence using the rules of symmetry unlocks paths for the bottom-up synthesis of Schwarzites by organic chemistry methods. Schwarzite tiling by heptagons is systematically analyzed and classified by symmetry and topology. For the first time, complete plans for a bottom-up synthesis of many Schwarzites are demonstrated. A trimer of heptagons is suggested as the key building block for most synthetic schemes. | Alexey Ignatchenko | Organic Chemistry; Supramolecular Chemistry (Org.) | CC BY NC 4.0 | CHEMRXIV | 2024-10-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6707130451558a15efa4ba6d/original/launching-graphene-into-3d-space-symmetry-topology-and-strategies-for-bottom-up-synthesis-of-schwarzites.pdf |
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