jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Akhil S. Nair | Biswarup Pathak
Source: Wiley Interdisciplinary Reviews Computational Molecular Science (article, 2020-12-10)
Field: Materials Science — Materials Chemistry

Computational strategies to address the catalytic activity of nanoclusters Abstract Metal nanoclusters have been emerged as imperative elements of heterogenous catalysis. Remarkably different properties from the bulk at the atomic level asserts construction of unique principles for understanding nanocluster catalysis. Computational studies abided by delicate theoretical framework are versatile tools for unveiling the structural, energetic, and mechanistic aspects of nanocluster‐based catalysis. Unlike other systems, nanoclusters feature properties derived from the unique surface structure, size dependence, and dynamics insisting fine‐tuning of computational approaches for accurate prediction of catalytic properties. Finding a balance between realistic simulation and computational affordability is of pressing priority. We highlight the urgency of computational models and practices to be updated by learning from the recent developments in this field. Focus is given to less explored factors governing the catalytic potential of nanoclusters. This article is categorized under: Structure and Mechanism &gt; Computational Materials Science Electronic Structure Theory &gt; Density Functional Theory Structure and Mechanism &gt; Reaction Mechanisms and Catalysis Nanoclusters ; Mechanism (biology) ; Catalysis ; Field (mathematics) ; Nanotechnology ; Computer science ; Density functional theory ; Computational model ; Biochemical engineering ; Feature (linguistics) ; Materials science ; Computational chemistry ; Chemistry ; Physics ; Artificial intelligence ; Engineering ; Mathematics ; Quantum mechanics Nanocluster Synthesis and Applications ; Catalytic Processes in Materials Science ; Machine Learning in Materials Science
Authors: Shubhadeep Chandra | Fritz Weißer | Sinja Klenk | Julia Beerhues | David Schweinfurth | Biprajit Sarkar
Source: Dalton Transactions (article, 2020-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Dinuclear Ru<sup>II</sup>complexes with quinonoid bridges: tuning the electrochemical and spectroscopic properties of redox-switchable NIR dyes through judicious bridge design Bridging quinonoid ligands are important platforms for generating metal-based switchable optoelectronic and magnetic materials. A possible sound way of influencing the properties of the aforementioned materials is to modify the direct metal-ligand interface. We present herein a series of dinuclear RuII complexes where the set of donor atoms at the bridging quinonoid ligands range from [O,O,O,O], [O,O,O,N], [O,N,O,N] and [O,N,O,N']. Additionally, the substituents on the N-donors were varied as well (a total of eight different quinonoid bridges are compared). We also present a mononuclear RuII complex for comparison purposes. The dinuclear complexes act as switchable NIR dyes, absorbing in the NIR region in their mixed-valent RuII/RuIII form but not in the neighboring RuII/RuII and RuIII/RuIII states. The switching potentials (the potentials at which NIR absorptions appear) and the λmax of the NIR band can be fine-tuned by varying the donor atoms as well as the electron-donating ability of the substituents on the nitrogen atoms (tuning E by ca. 0.4 V and λmax by ca. 450 nm). Introducing more electron-rich substituents at the nitrogen atoms of the bridge results in higher band energies and more cathodic redox potentials. Unsymmetrical bridging ligands increase the thermodynamic stability of the mixed-valent state. Whereas almost all of the mixed-valent species presented here belong to the delocalised type III of the Robin-Day classification, the most unsymmetrical complex 2O,N(Mes) shows characteristic signs of a borderline Class-II-III compounds. This comprehensive study thus establishes the lesser used unsymmetrically substituted quinones as excellent bridges for generating and tuning a series of properties in their corresponding metal complexes. Chemistry ; Electrochemistry ; Bridging ligand ; Metal ; Redox ; Ligand (biochemistry) ; Crystallography ; Bridging (networking) ; Ruthenium ; Photochemistry ; Inorganic chemistry ; Physical chemistry ; Catalysis ; Electrode ; Organic chemistry Magnetism in coordination complexes ; Metal-Organic Frameworks: Synthesis and Applications ; Metal complexes synthesis and properties
Authors: Olga Mazur | Jan Awrejcewicz
Source: Symmetry (article, 2020-04-02)
Field: Materials Science — Materials Chemistry

Ritz Method in Vibration Analysis for Embedded Single-Layered Graphene Sheets Subjected to In-Plane Magnetic Field Vibrations of single-layered graphene sheets subjected to a longitudinal magnetic field are considered. The Winkler-type and Pasternak-type foundation models are employed to reproduce the surrounding elastic medium. The governing equation is based on the modified couple stress theory and Kirchhoff–Love hypotheses. The effect of the magnetic field is taken into account due to the Lorentz force deriving from Maxwell’s equations. The developed approach is based on applying the Ritz method. The proposed method is tested by a comparison with results from the existing literature. The numerical calculations are performed for different boundary conditions, including the mixed ones. The influence of the material length scale parameter, the elastic foundation parameters, the magnetic parameter and the boundary conditions on vibration frequencies is studied. It is observed that an increase of the magnetic parameter, as well as the elastic foundation parameters, brings results closer to the classical plate theory results. Furthermore, the current study can be applied to the design of microplates and nanoplates and their optimal usage. Lorentz force ; Boundary value problem ; Magnetic field ; Vibration ; Ritz method ; Graphene ; Foundation (evidence) ; Mechanics ; Physics ; Classical mechanics ; Mathematical analysis ; Materials science ; Mathematics ; Acoustics Nonlocal and gradient elasticity in micro/nano structures ; Composite Structure Analysis and Optimization ; Numerical methods in engineering
Authors: Boon Siong Wee | Eric Kwabena Droepenu | Suk Fun Chin | Kok, K. Y. | Ebenezer Aquisman Asare
Source: Biointerface Research in Applied Chemistry (article, 2020-03-29)
Field: Materials Science — Materials Chemistry

Synthesis and characterization of single phase ZnO nanostructures via solvothermal method: influence of alkaline source Single phase ZnO nanostructures were synthesized by simple and low temperature solvothermal process from two different alkaline sources; Potassium hydroxide (KOH) and Sodium hydroxide (NaOH) with zinc acetate dihydrate (Zn(CH3COO)2∙2H2O) as precursor. This facile and rapid synthesis technique achieve high purity of Zinc oxide (ZnO) nanostructures on large scale negating the use of complex and high temperature routes. The synthesized particles were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared (FT-IR) Spectroscopy, Ultraviolet Visible (UV-Vis) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. ZnO synthesized using KOH and NaOH exhibit wurtzite hexagonal and flake-like nanostructures with average crystallite size of 11.0 nm and 14.9 nm respectively. Surface area of 59.50 m2/g and 31.43 m2/g were determined for KOH and NaOH sources respectively. The optical absorption spectra of the two samples showed absorption bands of 367.70 and 365.30 nm. The results showed the effect of alkaline sources on the surface morphology, structural and optical properties of ZnO. Materials science ; Wurtzite crystal structure ; Crystallite ; Fourier transform infrared spectroscopy ; Potassium hydroxide ; Zinc ; Transmission electron microscopy ; Sodium hydroxide ; Scanning electron microscope ; Spectroscopy ; Absorption spectroscopy ; Analytical Chemistry (journal) ; Solvothermal synthesis ; Band gap ; Nuclear chemistry ; Chemical engineering ; Inorganic chemistry ; Nanotechnology ; Chemistry ; Organic chemistry ZnO doping and properties ; Copper-based nanomaterials and applications ; Gas Sensing Nanomaterials and Sensors
Authors: Q. Zhang | W. You | N. Bauer | M.A. Kelly
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2020-08-20)
Field: Materials Science — Materials Chemistry

The Curious Case of Fluorination of Conjugated Polymers for Solar Cells ConspectusOrganic solar cells (OSCs) have been a rising star in the field of renewable energy since the introduction of the bulk heterojunction (BHJ) in 1992. Recent advances have pushed the efficiencies of OSCs to over 13%, an impressive accomplishment via collaborative efforts in rational materials design and synthesis, careful device engineering, and fundamental understanding of device physics. Throughout these endeavors, several design principles for the conjugated donor polymers used in such solar cells have emerged, including optimizing the conjugated backbone with judicious selection of building blocks, side-chain engineering, and substituents. Among all of the substituents, fluorine is probably the most popular one; improved device characteristics with fluorination have frequently been reported for a wide range of conjugated polymers, in particular, donor-acceptor (D-A)-type polymers. Herein we examine the effect of fluorination on the device performance of solar cells as a function of the position of fluorination (on the acceptor unit or on the donor unit), aiming to outline a clear understanding of the benefits of this curious substituent.As fluorination of the acceptor unit is the most adopted strategy for D-A polymers, we first discuss the effect of fluorination of the acceptor units, highlighting the five most widely utilized acceptor units. While improved device efficiency has been widely observed with fluorinated acceptor units, the underlying reasons vary from case to case and highly depend on the chemical structure of the polymer. Second, the effect of fluorination of the donor unit is addressed. Here we focus on four donor units that have been most studied with fluorination. While device-performance-enhancing effects by fluorination of the donor units have also been observed, it is less clear that fluorine will always benefit the efficiency of the OSC, as there are several cases where the efficiency drops, in particular with "over-fluorination", i.e., when too many fluorine substituents are incorporated.Finally, while this Account focuses on studies in which the polymer is paired with fullerene derivatives as the electron accepting materials, non-fullerene acceptors (NFAs) are quickly becoming key players in the field of OSCs. The effect of fluorination of the polymers on the device performance may be different when NFAs are used as the electron-accepting materials, which remains to be investigated. However, the design of fluorinated polymers may provide guidelines for the design of more efficient NFAs. Indeed, the current highest-performing OSC (∼13%) features fluorination on both the donor polymer and the non-fullerene acceptor. Conjugated system ; Polymer ; Materials science ; Astrobiology ; Polymer science ; Chemistry ; Physics ; Organic chemistry Silicone and Siloxane Chemistry ; Fiber-reinforced polymer composites
Authors: Jing Yuan Ching | Brian J. Huang | Yu‐Ting Hsu | Yit Lung Khung
Source: Scientific Reports (article, 2020-05-29)
Field: Materials Science — Surfaces, Coatings and Films

Anti-Adhesion Behavior from Ring-Strain Amine Cyclic Monolayers Grafted on Silicon (111) Surfaces In this manuscript, a series of amine tagged short cyclic molecules (cyclopropylamine, cyclobutylamine, cyclopentylamine and cyclohexylamine) were thermally grafted onto p-type silicon (111) hydride surfaces via nucleophilic addition. The chemistries of these grafting were verified via XPS, AFM and sessile droplet measurements. Confocal microscopy and cell viability assay was performed on these surfaces incubated for 24 hours with triple negative breast cancer cells (MDA-MB 231), gastric adenocarcinoma cells (AGS) endometrial adenocarcinoma (Hec1A). All cell types had shown a significant reduction when incubated on these ring-strain cyclic monolayer surfaces than compared to standard controls. The expression level of focal adhesion proteins (vinculin, paxilin, talin and zyxin) were subsequently quantified for all three cell types via qPCR analysis. Cells incubate on these surface grafting were observed to have reduced levels of adhesion protein expression than compared to positive controls (collagen coating and APTES). A potential application of these anti-adhesive surfaces is the maintenance of the chondrocyte phenotype during in-vitro cell expansion. Articular chondrocytes cultured for 6 days on ring strained cyclopropane-modified surfaces was able to proliferate but had maintained a spheroid/aggregated phenotype with higher COL2A1 and ACAN gene expression. Herein, these findings had help promote grafting of cyclic monolayers as an viable alternative for producing antifouling surfaces. Chemistry ; Adhesion ; Monolayer ; Biophysics ; Cell adhesion ; Spheroid ; Focal adhesion ; Vinculin ; Biochemistry ; Cell ; In vitro ; Biology ; Organic chemistry Polymer Surface Interaction Studies ; Molecular Junctions and Nanostructures ; Nanofabrication and Lithography Techniques
Authors: S. Boyce | Jules Moutet | Lukas Niederegger | Thomas Simler | Grégory Nocton | Corinna R. Hess
Source: Inorganic Chemistry (article, 2020-12-15)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Influence of a Lanthanide Ion on the Ni Site of a Heterobimetallic 3d–4f Mabiq Complex This work presents the synthesis and characterization of a 3d-4f bimetallic complex based on the redox-active macrocyclic biquinazoline ligand, Mabiq. The mixed Yb-Ni complex, [(Cp*)<sub>2</sub>Yb(Mabiq)Ni]BArF (<b>3</b>), was synthesized upon reaction of [Ni<sup>II</sup>(Mabiq)]BArF (<b>2</b>) with (Cp*)<sub>2</sub>Yb<sup>II</sup>(OEt<sub>2</sub>). The molecular structures of <b>3</b> and its sister complex, [(Cp*)<sub>2</sub>Yb(Mabiq)Ni][(Cp*)<sub>2</sub>Yb(OTf)<sub>2</sub>] (<b>1</b>), confirmed the presence of a Yb(III) center and a reduced Ni-Mabiq unit. Spectroscopy (absorption and NMR), cyclic voltammetry, and magnetic susceptibility studies were employed to analyze the electronic structure of <b>3</b>, which is best described by the [(Cp*)<sub>2</sub>Yb<sup>III</sup>(Mabiq<sup>•</sup>)Ni<sup>II</sup>]<sup>+</sup> formulation. Notably, the ligand-centered radical is delocalized over both the diketiminate and bipyrimidine units of the Mabiq ligand. The magnetic susceptibility and variable temperature NMR studies for <b>3</b> denote coupling between the Ni-Mabiq site and the peripheral Yb center-previously unobserved in 3d-3d Mabiq complexes. The complex nature of the exchange interactions is highlighted by the multiconfigurational ground state for <b>3</b>, comprising nearly degenerate singlet and triplet states. Chemistry ; Delocalized electron ; Magnetic susceptibility ; Ligand (biochemistry) ; Bimetallic strip ; Lanthanide ; Crystallography ; Singlet state ; Macrocyclic ligand ; Cyclic voltammetry ; Paramagnetism ; Ion ; Stereochemistry ; Crystal structure ; Metal ; Physical chemistry ; Atomic physics ; Organic chemistry ; Electrochemistry Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Viktoria Steck | Daniela Maria Carminati | Nathan Johnson | Rudi Fasan
Source: ChemRxiv (preprint, 2020-07-13)
Field: Chemistry — Organic Chemistry

Enantioselective Synthesis of Chiral Amines via Biocatalytic Carbene N—H Insertion Optically active amines represent highly valuable building blocks for the synthesis of advanced pharmaceutical intermediates, drug molecules, and biologically active natural products. Hemoproteins have recently emerged as promising biocatalysts for the formation of C—N bonds via carbene transfer, but asymmetric N—H carbene insertion reactions using these or other enzymes have so far been elusive. Here, we report the successful development of a biocatalytic strategy for the asymmetric N—H carbene insertion of aromatic amines with 2-diazopropanoate esters using engineered variants of myoglobin. High activity and stereoinduction in this reaction could be achieved by tuning the chiral environment around the heme cofactor in the metalloprotein in combination with catalyst-matching and tailoring of the diazo reagent. Using this approach, an efficient biocatalytic protocol for the synthesis of a broad range of substituted aryl amines with up to 82% ee was obtained. In addition, a stereocomplementary catalyst useful to access the mirrorimage form of the N—H insertion products was identified. This work paves the way to asymmetric amine synthesis via biocatalytic carbene transfer, and the present strategy based on the synergistic combination of protein and diazo reagent engineering is expected to prove useful in the context of these as well as other challenging asymmetric carbene transfer reactions. Carbene ; Enantioselective synthesis ; Chemistry ; Diazo ; Combinatorial chemistry ; Catalysis ; Biocatalysis ; Reagent ; Context (archaeology) ; Organic chemistry ; Reaction mechanism Cyclopropane Reaction Mechanisms
Authors: Mattia Zangoli | Francesca Di Maria | Giovanna Barbarella
Source: ChemistryOpen (review, 2020-04-01)
Field: Materials Science — Biomaterials

Supramolecular Assembly of Thiophene‐Based Oligomers into Nanostructured Fluorescent Conductive and Chiral Microfibers The implementation of nano/microelectronic devices requires efficient strategies for the realization of supramolecular structures with desired function and supported on appropriate substrates. This article illustrates a strategy based on the synthesis of thiophene oligomers having the same "sulfur-overrich" quaterthiophene inner core (non bonding interactional algorithm) and different terminal groups. Nano/microfibers are formed on surfaces having a morphology independent of the nature of the deposition substrate and displaying a wide tuning of properties that make the fibers optoelectronically suitable for application in devices. Thiophene ; Microfiber ; Microelectronics ; Supramolecular chemistry ; Materials science ; Nanotechnology ; Substrate (aquarium) ; Fluorescence ; Electrical conductor ; Realization (probability) ; Self-assembly ; Molecule ; Chemistry ; Organic chemistry ; Composite material Supramolecular Self-Assembly in Materials ; Photochromic and Fluorescence Chemistry ; Molecular Junctions and Nanostructures
Authors: Denis Danilov | Elaheh Sedghamiz | Heike Fliegl | Hendrik Frisch | Christopher Barner‐Kowollik | Wolfgang Wenzel
Source: Polymer Chemistry (article, 2020-01-01)
Field: Chemistry — Organic Chemistry

Tacticity dependence of single chain polymer folding Precision polymerization techniques offer the exciting opportunity to manufacture single-chain nanoparticles (SCNPs) with intramolecular crosslinks placed in specific positions along the polymer chain. Single chain ; Tacticity ; Intramolecular force ; Polymer ; Folding (DSP implementation) ; Polymerization ; Chain (unit) ; Polymer chemistry ; Nanoparticle ; Polymer science ; Chemistry ; Materials science ; Chemical engineering ; Nanotechnology ; Organic chemistry ; Physics Advanced Polymer Synthesis and Characterization ; Polymer Surface Interaction Studies ; Dendrimers and Hyperbranched Polymers
Authors: Sergey O. Ilyin | V. Ya. Ignatenko | Tatyana Anokhina | D. S. Bakhtin | Anna V. Kostyuk | Evgenia Dmitrieva | С. В. Антонов | А. В. Волков
Source: Membranes (article, 2020-01-03)
Field: Materials Science — Polymers and Plastics

Formation of Microfiltration Membranes from PMP/PIB Blends: Effect of PIB Molecular Weight on Membrane Properties A series of microfiltration membranes were fabricated by the extraction of polyisobutylene (PIB) from its immiscible blends with polymethylpentene (PMP). Three PIB with different molecular weight of 7.5 × 10<sup>4</sup> (Oppanol B15), 34 × 10<sup>4</sup> (Oppanol B50) and 110 × 10<sup>4</sup> (Oppanol B100) g/mol, respectively, were used to evaluate the effect of molecular weight on the porous structure and transport properties of resulting PMP-based membranes. To mimic the conditions of 3D printing, the flat-sheet membranes were fabricated by means of melting of mixtures of various PMP and PIB concentrations through the hot rolls at 240 ∘ C followed by a quick cooling. The rheology study of individual components and blends at 240 ∘ C revealed that PIB B50 possessed the most close flow curve to the pure PMP, and their blends demonstrated the lowest viscosity comparing to the compositions made of PIB with other molecular weights (B15 or B100). SEM images of the cross-section PMP membranes after PIB extraction (PMP/PIB = 55/45) showed that the use of PIB B50 allowed obtaining the sponge-like porous structure, whereas the slit-shaped pores were found in the case of PIB B15 and PIB B100. Additionally, PMP/B50 blends demonstrated the optimum combinations of mechanical properties (<sub>str</sub> = 9.1 MPa, <i>E</i> = 0.20 GPa), adhesion to steel (<sub>adh</sub> = 0.8 kPa) and retention performance (<i>R</i><sub>240 nm</sub> = 99%, <i>R</i><sub>38 nm</sub> = 39%). The resulting membranes were non- or low-permeable for water if the concentration of PIB B50 in the initial blends was 40 wt.% or lower. The optimal filtration performance was observed in the case of PMP/B50 blends with a ratio of 55/45 (<i>P</i><sub>water</sub> = 1.9 kg/m<sup>2</sup>hbar<i>, R</i><sub>240 nm</sub> = 99%, <i>R</i><sub>38 nm</sub> = 39%) and 50/50 (<i>P</i><sub>water</sub> = 1100 kg/m<sup>2</sup>hbar<i>, R</i><sub>240 nm</sub> = 91%, <i>R</i><sub>38 nm</sub> = 36%). Membrane ; Microfiltration ; Materials science ; Chemical engineering ; Porosity ; Extraction (chemistry) ; Rheology ; Chemistry ; Polymer chemistry ; Chromatography ; Composite material ; Biochemistry Polymer crystallization and properties ; Membrane Separation Technologies ; Electrospun Nanofibers in Biomedical Applications
Authors: Taoli Deng | Xianbang Jiang | Qiuyun Zhang
Source: Frontiers in Chemistry (article, 2020-09-29)
Field: Materials Science — Materials Chemistry

Sustainably Adjusting the Up-Conversion White-Emitting Luminescence Properties of GdAlO3: Er3+/Yb3+/Tm3+ Phosphors Doping heteroatom in phosphor can effectively improve luminescent properties, which has attracted great attention recently. GdAlO3 phosphors (GAP) doped with Er<sup>3+</sup>/Yb<sup>3+</sup>/Tm<sup>3+</sup> were prepared via the co-precipitation method. Upon 980 nm excitation, strong blue, green, and red up-conversion (UC) emissions centered at 476, 524, 546, and 659 nm were observed, which could be successfully combined to form pure white light. It was found that changing the doping concentration of Er<sup>3+</sup> and Yb<sup>3+</sup> ions, the calcination temperature of the precursor, the laser power of the excitation light source, and doping Li+ could systematically adjust red/green/blue colors of GdAlO3:Er3+/Yb3+/Tm3+ phosphors to optimize the white emitting luminescence. When the Er3+ doping concentration of the phosphors increased, each color distribution successfully moved, making the maximum shift of the CIE coordinate. Finally, the influence of each factor on adjusting the UC white light performance and its mechanism were explored. Phosphor ; Doping ; Luminescence ; Materials science ; Ion ; Excitation ; Calcination ; Green-light ; White light ; Heteroatom ; Analytical Chemistry (journal) ; Optoelectronics ; Chemistry ; Blue light ; Catalysis ; Chromatography ; Organic chemistry Luminescence Properties of Advanced Materials ; Luminescence and Fluorescent Materials