jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Samuel A. Johnson | Amrita Makhijani | Miu Tsuji | Tomoyasu Mani
Source: The Journal of Physical Chemistry B (article, 2022-10-25)
Field: Chemistry — Physical and Theoretical Chemistry

Acceleration of Nonradiative Charge Recombination Reactions at Larger Distances in Kinked Donor–Bridge–Acceptor Molecules Photoinduced electron transfer in donor-bridge-acceptor (D-B-A) molecular systems can occur via tunneling over long distances (<i>r</i><sub>DA</sub>) of well over 10 Å. We commonly observe decreasing rates of electron transfer with increasing distances, a result of a decrease in the electronic coupling of the donor and acceptor moiety. In the study of D-B-A molecules with Ru(bpy)<sub>3</sub><sup>2+</sup> as a bridge/core, Kuss-Petermann and Wenger observed the opposite trend (<i>J. Am. Chem. Soc.</i><b>2016</b>, <i>138</i>, 1349); a maximum rate constant of electron transfer was observed at an intermediate electron transfer distance. Within the high-temperature limit of the classical Marcus equation, their observation was qualitatively explained by a sharp distance dependence of outer sphere (or solvent) reorganization energy, as predicted by Sutin and co-workers (<i>J. Am. Chem. Soc.</i><b>1984</b>, <i>106</i>, 6858), and almost distance-independent electronic couplings. Here, we report another example of such an underexplored behavior with three kinked D-B-A systems of <i>r</i><sub>DA</sub> ∼ 10-19 Å, showing increasing rates of nonradiative charge recombination with increasing <i>r</i><sub>DA</sub>. The three D-B-A systems are based on boron dipyrromethene and triphenylamine as electron acceptor and donor groups, respectively, with aryl bridges where the donor and acceptor moieties are connected at <i>meso</i>-positions. These D-B-A molecules exhibit radiative electron transfer reactions (or charge-transfer emission), which enables us to experimentally determine the solvent reorganization energy and the electronic couplings. The analysis of charge-transfer emission that explicitly considers electron-vibration coupling, in conjunction with the temperature-dependent analysis and computational method, revealed that the solvent reorganization energy indeed increases with distance, and at the same time, the electronic coupling decreases with distance expectedly. Therefore, under the right conditions for solvent reorganization energy and electronic coupling values, our results show that we can observe the acceleration of electron transfer reactions with increasing distance, even when we have the expected distance dependence of electronic coupling. This work indicates that the acceleration of electron transfer with increasing distance may be achieved with a fine-tuning of molecular design. Chemistry ; Acceptor ; Electron transfer ; Molecule ; Atomic physics ; Electron ; Photochemistry ; Physics Photochemistry and Electron Transfer Studies ; Molecular Junctions and Nanostructures ; CO2 Reduction Techniques and Catalysts
Authors: Rui Jiao | Jiaqi Han | Wenbing Huang | Yu Rong | Yang Liu
Source: arXiv (Cornell University) (preprint, 2022-07-18)
Field: Materials Science — Materials Chemistry

Energy-Motivated Equivariant Pretraining for 3D Molecular Graphs Pretraining molecular representation models without labels is fundamental to various applications. Conventional methods mainly process 2D molecular graphs and focus solely on 2D tasks, making their pretrained models incapable of characterizing 3D geometry and thus defective for downstream 3D tasks. In this work, we tackle 3D molecular pretraining in a complete and novel sense. In particular, we first propose to adopt an equivariant energy-based model as the backbone for pretraining, which enjoys the merits of fulfilling the symmetry of 3D space. Then we develop a node-level pretraining loss for force prediction, where we further exploit the Riemann-Gaussian distribution to ensure the loss to be E(3)-invariant, enabling more robustness. Moreover, a graph-level noise scale prediction task is also leveraged to further promote the eventual performance. We evaluate our model pretrained from a large-scale 3D dataset GEOM-QM9 on two challenging 3D benchmarks: MD17 and QM9. Experimental results demonstrate the efficacy of our method against current state-of-the-art pretraining approaches, and verify the validity of our design for each proposed component. Equivariant map ; Robustness (evolution) ; Computer science ; Exploit ; Gaussian ; Graph ; Theoretical computer science ; Artificial intelligence ; Machine learning ; Mathematics ; Pure mathematics Machine Learning in Materials Science ; Fuel Cells and Related Materials ; Computational Drug Discovery Methods
Authors: Xingjie Wang | Zoha H. Syed | Zhihengyu Chen | David Bazak | Xinyi Gong | Megan C. Wasson | Nancy Washton | Karena W. Chapman | Justin M. Notestein | Omar K. Farha
Source: ACS Applied Materials & Interfaces (article, 2022-11-17)
Field: Materials Science — Materials Chemistry

Enhanced Catalytic Performance of a Ce/V Oxo Cluster through Confinement in Mesoporous SBA-15 To increase catalytic efficiency, mesoporous supports have been widely applied to immobilize well-defined metal oxide clusters due to their ability to stabilize highly dispersed clusters. Herein, a redox-active heterometallic Ce<sub>12</sub>V<sub>6</sub>-oxo cluster (CeV) was first presynthesized and then incorporated into mesoporous silica, SBA-15, via a straightforward impregnation method. Scanning transmission electron microscopy (STEM) and Fourier transform infrared spectroscopy (FTIR), in concert with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), verified the successful introduction of the CeV cluster inside the pore of SBA-15. The <sup>51</sup>V magic angle spinning solid-state nuclear magnetic resonance (<sup>51</sup>V MAS NMR) spectroscopy and differential pair distribution function (dPDF) analysis confirmed the structural integrity of the CeV cluster inside the SBA-15. The composite was then benchmarked for liquid-phase oxidation of 2-chloroethyl ethyl sulfide (CEES) under mild conditions and gas-phase oxidative dehydrogenation (ODH) of propane under high temperatures (up to 550 °C). The catalytic reactivity results demonstrated 8- and 14-fold increase in turnover frequency (TOF) values of the composite (CeV@10SBA-2) than the bulk CeV cluster under the same conditions for CEES oxidation and ODH, respectively. These results highlight the improved reactivity of the catalytically active CeV cluster as attributed to the higher dispersion of the discrete cluster upon immobilization within the SBA-15 support. Materials science ; Mesoporous material ; Fourier transform infrared spectroscopy ; Magic angle spinning ; Catalysis ; Scanning transmission electron microscopy ; Reactivity (psychology) ; Scanning electron microscope ; Mesoporous silica ; Spectroscopy ; Chemical engineering ; Nuclear magnetic resonance spectroscopy ; Chemistry ; Organic chemistry ; Composite material Polyoxometalates: Synthesis and Applications ; Catalytic Processes in Materials Science ; Catalysis and Oxidation Reactions
Authors: Zexin Wang | Renfu Li | Li Chen | Xin Zhai | Wei Liu | Xiang Lin | Liwei Chen | Nannan Chen | Shitao Sun | Zhenli Li | Jinle Hao | Xueyuan Chen | Bin Lin | Lijun Xie
Source: Frontiers in Chemistry (article, 2022-01-20)
Field: Materials Science — Materials Chemistry

Precise Molecular Design of a Pair of New Regioisomerized Fluorophores With Opposite Fluorescent Properties Aggregation-induced emission (AIE) has attracted much attention in the past 2 decades. To develop novel AIE-active materials, ACQ-to-AIE transformation <i>via</i> regioisomerization is one of the most straightforward method. However, most of the reported ACQ-to-AIE transformations are achieved by migrating bulky units. In this work, a facile conversion was realized by migrating a small pyrrolidinyl group from <i>para</i>- to <i>ortho</i>-position on the rofecoxib scaffold. As a result, a pair of new isomers named <b>MOX2</b> and <b>MOX4</b> exhibited AIE behavior and ACQ activity, respectively. Moreover, <b>MOX2</b> also showed solvatochromic, mechanochromic, and acidochromic properties with reversible multi-stimulus behavior. Single crystal X-ray analysis of <b>MOX2</b> revealed that the molecular conformation and its packing mode were responsible for the AIE emission behavior. Further investigation indicated that <b>MOX2</b> showed high lipid droplets staining selectivity. Taken together, the current work not only provides a new design philosophy for achieving ACQ-to-AIE conversion by migrating a small pyrrolidinyl group but also presents a promising candidate <b>MOX2</b> for potential applications such as in security ink, optical recording and biological applications. Fluorescence ; Chemistry ; Nanotechnology ; Biophysics ; Materials science ; Photochemistry ; Biology ; Physics ; Optics Luminescence and Fluorescent Materials ; Molecular Sensors and Ion Detection ; Porphyrin and Phthalocyanine Chemistry
Authors: Moein Zarei | Beata Michalkiewicz | Mirosława El Fray
Source: ChemRxiv (preprint, 2022-12-23)
Field: Materials Science — Biomaterials

The effect of segmental composition of bio-based PBS-DLS-PEG copolymers on their physico-chemical properties and processability by 3D printing and electrospinning In this study, the synthesis and physico-chemical properties of poly(butylene succinate-dilinoleic succinate-ethylene glycol succinate) (PBS-DLS-PEG) copolymers differing in segmental composition are discussed in order to determine their structure-properties relationship and translate it to their electrospinability and 3-D printability. The copolymers, containing sustainable monomers such as succinic acid and dilinoleic diol, were successfully synthesized by two-step transesterification and polycondensation, and collected directly from the reactor as crystallized filaments suitable for 3D printing. Chemical characterization indicated the formation of expected functional ester groups. Crystallized copolymers revealed spherulitic morphology and phase transitions typical for thermoplastic elastomers. Interestingly, incorporation of 5 wt% PEG into copolymers containing higher hard segments content (70 wt%) disturbed the banded spherulitic morphology of copolymers, contributed to the increase of elasticity up to 830%, and reduced the water contact angle indicating improvement of copolymers hydrophilicity. The mechanical properties and printability of the copolymers depended on their segmental composition, with higher hard segment content facilitating good printability. In solution processing, the copolymers turned into nanofibers via electrospinning with average fiber diameters between 400 and 600 nm. The obtained results showed excellent melt and solution processability, rubber-like elasticity and tailored physical characteristics dependent from segmental composition of the new sustainable PBS-DLS-PEG copolymers. Copolymer ; Materials science ; Chemical engineering ; Electrospinning ; Polymer chemistry ; Ethylene glycol ; Polybutylene succinate ; Polyester ; Thermoplastic elastomer ; PEG ratio ; Dynamic mechanical analysis ; Polymer ; Composite material biodegradable polymer synthesis and properties ; Electrospun Nanofibers in Biomedical Applications ; Additive Manufacturing and 3D Printing Technologies
Authors: Yue Yin | Hongbin Chen | Pengcheng Lin | Weitai Yu | Xiaobao Cao | Xinxin Sheng | Josep Puigmartí‐Luis
Source: Science China Materials (article, 2022-12-30)
Field: Materials Science — Materials Chemistry

Flexible fluorescent metal-organic frameworks towards highly stable optical fibers and biocompatible cell platforms Microfiber ; Materials science ; Nanotechnology ; Microfluidics ; Fluorescence ; Biocompatibility ; Ultimate tensile strength ; Spinning ; Polymer ; Optical fiber ; Metal-organic framework ; Coaxial ; Composite material ; Optics ; Organic chemistry Luminescence and Fluorescent Materials ; Metal-Organic Frameworks: Synthesis and Applications ; Advanced Sensor and Energy Harvesting Materials
Authors: Elizabeth J. Fear | Aneurin J. Kennerley | Peter J. Rayner | Philip Norcott | Soumya S. Roy | Simon B. Duckett
Source: Magnetic Resonance in Medicine (article, 2022-03-07)
Field: Chemistry — Spectroscopy

SABRE hyperpolarized anticancer agents for use in <sup>1</sup>H MRI Here, we demonstrate the power of SABRE to deliver a fast and cost-effective route to hyperpolarization of important chemical motifs of anticancer agents. The SABRE approach outlined here lays the foundations for realizing continuous flow, hyperpolarized tracking of drug delivery/pathways. Hyperpolarization (physics) ; Spin isomers of hydrogen ; Chemistry ; Nuclear magnetic resonance spectroscopy ; Nuclear magnetic resonance ; Polarization (electrochemistry) ; Hydrogen ; Physics ; Stereochemistry ; Physical chemistry Advanced NMR Techniques and Applications ; Atomic and Subatomic Physics Research ; Solid-state spectroscopy and crystallography
Authors: Maria Simonova | А. С. Симагин | Д. М. Каморин | С. В. Орехов | А. П. Филиппов | О. А. Казанцев
Source: Polymers (article, 2022-12-19)
Field: Materials Science — Surfaces, Coatings and Films

The Solution Properties of Polymethacrylate Molecular Brushes with Oligo(ethylene glycol) and Oligo(propylene glycol) Side Chains The properties of polymer brushes based on three macromonomers were investigated in aqueous and organic solutions. Methacrylic monomers with different compositions of the oligo(oxyalkylene) substituents and arrangements of the oligo(ethylene glycol) and oligo(propylene glycol) blocks were used for the synthesis of polymers. There were methoxy [oligo(ethylene glycol)<sub>10.3</sub>-block-oligo(propylene glycol)<sub>4.7</sub>] methacrylate, methoxy [oligo(propylene glycol)<sub>8.3</sub>-block-oligo(ethylene glycol)<sub>6.6</sub>] methacrylate, and methoxy oligo(propylene glycol)<sub>4.2</sub> methacrylate. Molecular brushes were investigated by the methods of molecular hydrodynamics and optics in dilute solutions in acetonitrile, chloroform, and water. The peculiarities of behavior of poly[oligo(oxyalkylene) methacrylates] in aqueous solutions and water-toluene systems have been found; in particular, the solubility of the polymers in water and organic solvents, the polymers equilibrium distribution between the phases, and the surface activity in the water-toluene system have been established. The thermo-responsibility in aqueous solutions and values of a critical concentration of micelle formation were shown. Depending on the arrangement of blocks in the side chains of molecular brushes, they are characterized by different intramolecular density. Ethylene glycol ; Methacrylate ; Polymer chemistry ; Polyvinyl alcohol ; Polymer ; Aqueous solution ; Side chain ; Monomer ; Materials science ; Chemistry ; Organic chemistry Polymer Surface Interaction Studies ; Surfactants and Colloidal Systems ; Advanced Polymer Synthesis and Characterization
Authors: Imogen A. Z. Squire | Christopher A. Goult | Benedict C. Thompson | Elias Alexopoulos | Adrian C. Whitwood | Theo F. N. Tanner | Luke A. Wilkinson
Source: Inorganic Chemistry (article, 2022-11-18)
Field: Chemistry — Organic Chemistry

Enhancing the Air Stability of Dimolybdenum Paddlewheel Complexes: Redox Tuning through Fluorine Substituents The optical and electrochemical properties of quadruply bonded dimolybdenum paddlewheel complexes (Mo<sub>2</sub>PWCs) make them ideal candidates for incorporation into functional materials or devices, but one of the greatest bottlenecks for this is their poor stability toward atmospheric oxygen. By tuning the potential at which the Mo<sub>2</sub> core is oxidized, it was possible to increase the tolerance of Mo<sub>2</sub>PWCs to air. A series of homoleptic Mo<sub>2</sub>PWCs bearing fluorinated formamidinate ligands have been synthesized and their electrochemical properties studied. The oxidation potential of the complexes was tuned in a predictable fashion by controlling the positions of the fluorine substituents on the ligands, as guided by a Hammett relationship. Studies into the air stability of the resulting complexes by multinuclear NMR spectroscopy show an increased tolerance to atmospheric oxygen with increasingly electron-withdrawing ligands. The heteroleptic complex Mo<sub>2</sub>(D<sup>F</sup>ArF)<sub>3</sub>(OAc) [where D<sup>F</sup>ArF = 3,5-(difluorophenyl)formamidinate] shows remarkable tolerance to oxygen in the solid state and in chloroform solutions. Through the employment of easily accessible ligands, the stability of the Mo<sub>2</sub> core toward oxygen has been enhanced, thereby making Mo<sub>2</sub>PWCs with electron-withdrawing ligands more attractive candidates for the development of functional materials. Chemistry ; Homoleptic ; Electrochemistry ; Atmospheric oxygen ; Oxygen ; Redox ; Chloroform ; Fluorine ; Combinatorial chemistry ; Ligand (biochemistry) ; Photochemistry ; Inorganic chemistry ; Organic chemistry ; Physical chemistry ; Metal ; Electrode Organometallic Complex Synthesis and Catalysis ; N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Synthetic Organic Chemistry Methods
Authors: Nicola Melchioni | Filippo Fabbri | Alessandro Tredicucci | Federica Bianco
Source: Micromachines (article, 2022-10-03)
Field: Materials Science — Materials Chemistry

Periodic Structural Defects in Graphene Sheets Engineered via Electron Irradiation Artificially-induced defects in the lattice of graphene are a powerful tool for engineering the properties of the crystal, especially if organized in highly-ordered structures such as periodic arrays. A method to deterministically induce defects in graphene is to irradiate the crystal with low-energy (<20 keV) electrons delivered by a scanning electron microscope. However, the nanometric precision granted by the focused beam can be hindered by the pattern irradiation itself due to the small lateral separation among the elements, which can prevent the generation of sharp features. An accurate analysis of the achievable resolution is thus essential for practical applications. To this end, we investigated patterns generated by low-energy electron irradiation combining atomic force microscopy and micro-Raman spectroscopy measurements. We proved that it is possible to create well-defined periodic patterns with precision of a few tens of nanometers. We found that the defected lines are influenced by electrons back-scattered by the substrate, which limit the achievable resolution. We provided a model that takes into account such substrate effects. The findings of our study allow the design and easily accessible fabrication of graphene devices featuring complex defect engineering, with a remarkable impact on technologies exploiting the increased surface reactivity. Graphene ; Materials science ; Irradiation ; Nanotechnology ; Electron beam processing ; Composite material ; Optoelectronics ; Physics Graphene research and applications ; Electron and X-Ray Spectroscopy Techniques ; Ion-surface interactions and analysis
Authors: Elisabeth Weber | E. Richter | Rudolf Holze
Source: Journal of Solid State Electrochemistry (article, 2022-03-03)
Field: Materials Science — Polymers and Plastics

o-Toluidine in electrochemistry – an overview Abstract The substituted aromatic amine o -toluidine (2-methylaniline, 1-amino-2-methylbenzene) is frequently encountered in electrochemical research as a soluble corrosion inhibitor dissolved in aqueous media used e.g., in cooling systems, as a homomonomer for formation of intrinsically conducting poly- o -toluidine and as a comonomer in formation of respective copolymers and their composites. The obtained polymers are suggested as corrosion protection coatings, as active materials in devices for electrochemical energy storage, but more frequently, they are examined as active components in electrochemical sensors. The significant and pronounced carcinogenicity of o -toluidine has hardly been addressed; presumably, most researchers are not even aware of this property. After a brief summary of the health risks and effects, the following overview presents typical examples of said studies and applications. If possible, substitutes with lower health risks are proposed, at least further studies enabling such replacement are suggested. Comonomer ; Electrochemistry ; Amine gas treating ; Toluidine ; Corrosion ; Materials science ; Aqueous solution ; Polymer ; Copolymer ; Chemistry ; Organic chemistry ; Metallurgy ; Composite material ; Physical chemistry ; Electrode Conducting polymers and applications ; Analytical Chemistry and Sensors ; Electrochemical Analysis and Applications
Authors: Hui Li | Jérôme Ollivier | Sophie M. Guillaume | Jean‐François Carpentier
Source: Angewandte Chemie (article, 2022-03-14)
Field: Materials Science — Biomaterials

Tacticity Control of Cyclic Poly(3‐Thiobutyrate) Prepared by Ring‐Opening Polymerization of Racemic β‐Thiobutyrolactone Abstract We report here on the ring‐opening polymerization (ROP) of racemic β‐thiobutyrolactone ( rac ‐TBL), as the first chemical synthesis of poly(3‐thiobutyrolactone) (P3TB), the thioester analogue of the ubiquitous poly(3‐hydroxybutyrate) (P3HB). The ROP reactions proceed very fast (TOF &gt;12 000 h −1 at r.t.) in the presence of various metal‐based catalysts. Remarkably, catalyst systems based on non‐chiral yttrium complexes stabilized by tetradentate amino alkoxy‐ or diamino‐bis(phenolate) ligands {ONXO R1,R2 } 2− (X=O, N) provide access to cyclic P3TB with either high isoselectivity ( P m up to 0.90) or high syndiotactic bias ( P r up to 0.70). The stereoselectivity can be controlled by manipulation of the substituents on the ligand platform and adequate choice of the reaction solvent and temperature as well. The cyclic polymer topology is evidenced by MALDI‐ToF MS, NMR and TGA. Highly isotactic cyclic P3TB is a semi‐crystalline material as revealed by DSC. Tacticity ; Alkoxy group ; Polymer chemistry ; Polymerization ; Ring-opening polymerization ; Catalysis ; Ligand (biochemistry) ; Lactide ; Chemistry ; Stereoselectivity ; Ring (chemistry) ; Materials science ; Polymer ; Organic chemistry biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis ; Polyoxometalates: Synthesis and Applications
Authors: Jasimuddin Ahmed | Graham C. Haug | Viet D. Nguyen | Arka Porey | Ramon Trevino | Oleg V. Larionov
Source: Synthesis (article, 2022-08-15)
Field: Chemistry — Organic Chemistry

Catalytic Dienylation: An Emergent Strategy for the Stereoselective Construction of Conjugated Dienes and Polyenes Stereoselective construction of conjugated dienes and polyenes has remained an enduring synthetic problem, due to the central roles they play in natural product synthesis, methodology, and medicine. This review focuses on the recent developments in dienylation as an emerging strategy for the direct installation of unsaturated four carbon atom units of conjugated π-systems, outlining the regio- and stereoselectivity, as well as the synthetic scope of reactions with various dienylating reagents and the mechanistic implications of the catalytic cross-coupling processes that are used to enable dienylation. Chemistry ; Stereoselectivity ; Conjugated system ; Reagent ; Catalysis ; Combinatorial chemistry ; Natural product ; Ring (chemistry) ; Organic chemistry Asymmetric Synthesis and Catalysis ; Catalytic C–H Functionalization Methods ; Catalytic Cross-Coupling Reactions