jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Rudy Rubini | Il’ya Yu. Ivanov | Clemens Mayer
Source: Chemistry - A European Journal (article, 2019-10-24)
Field: Chemistry — Organic Chemistry

A Screening Platform to Identify and Tailor Biocompatible Small‐Molecule Catalysts Interfacing biocompatible, small-molecule catalysis with cellular metabolism promises a straightforward introduction of new function into organisms without the need for genetic manipulation. However, identifying and optimizing synthetic catalysts that perform new-to-nature transformations under conditions that support life is a cumbersome task. To enable the rapid discovery and fine-tuning of biocompatible catalysts, we describe a 96-well screening platform that couples the activity of synthetic catalysts to yield non-canonical amino acids from appropriate precursors with the subsequent incorporation of these nonstandard building blocks into GFP (quantifiable readout). Critically, this strategy does not only provide a common readout (fluorescence) for different reaction/catalyst combinations, but also informs on the organism's fitness, as stop codon suppression relies on all steps of the central dogma of molecular biology. To showcase our approach, we have applied it to the evaluation and optimization of transition-metal-catalyzed deprotection reactions. Biocompatible material ; Interfacing ; Catalysis ; Nanotechnology ; Combinatorial chemistry ; Small molecule ; Yield (engineering) ; Chemistry ; Computer science ; Biochemical engineering ; Materials science ; Biochemistry ; Engineering ; Biomedical engineering Click Chemistry and Applications ; Chemical Synthesis and Analysis ; Synthesis and Catalytic Reactions
Authors: Kanchana Samarakoon | Christopher S. Satterfield | Mechelle C. McCoy | Daniel A. Pivaral-Urbina | Timur İslamoğlu | Victor W. Day | Tendai Gadzikwa
Source: Inorganic Chemistry (article, 2019-07-03)
Field: Chemistry — Inorganic Chemistry

Uniform, Binary Functionalization of a Metal–Organic Framework Material General routes to confined spaces of well-defined chemical composition and complex three-dimensional structure have long been sought by materials chemists. Here, we introduce metal-organic framework (MOF) materials as an ideal scaffold upon which such organized complexity can be built. Employing an orthogonal coordination strategy, we constructed a large-pore MOF material with two different modifiable linkers in well-defined positions relative to each other. The <i>independent</i> and <i>quantitative</i> covalent grafting of two distinct chemical groups onto these differently reactive linkers yielded a uniformly bifunctionalized MOF material. Not only does this methodology offer an efficient route via which the properties of well-defined microporous materials can be fine-tuned, but it also creates a solid-state platform for synthetically accessing constructs that better emulate the well-ordered intricacy of biological structures. Chemistry ; Microporous material ; Metal-organic framework ; Covalent bond ; Nanotechnology ; Surface modification ; Well-defined ; Metal ; Grafting ; Organic chemistry ; Polymer ; Materials science ; Adsorption Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Dendrimers and Hyperbranched Polymers
Authors: Yafei Guo | Kai Zhang | Yijie Tao | Zhang Chaoyang | Haifeng Cheng
Source: Solar Energy Materials and Solar Cells (article, 2019-03-14)
Field: Materials Science — Polymers and Plastics

Synthesis and electrochromic properties of soluble 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-embedded conjugated polymers and their applications on preparing green-to-transmissive electrochromics via solution co-processing Hypsochromic shift ; Electrochromism ; Polymer ; Materials science ; Conjugated system ; Band gap ; Absorption (acoustics) ; Photochemistry ; Anthracene ; Absorption band ; Electrochromic devices ; Steric effects ; Chemical engineering ; Optoelectronics ; Organic chemistry ; Chemistry ; Optics ; Fluorescence ; Physical chemistry ; Electrode ; Composite material Conducting polymers and applications ; Transition Metal Oxide Nanomaterials ; Organic Electronics and Photovoltaics
Authors: Dikhi Firmansyah | Seong‐Jin Hong | Ranjan Dutta | Qing He | Jinhee Bae | Hongil Jo | Hakwon Kim | Kang Min Ok | Vincent M. Lynch | Hye Ryung Byon | Jonathan L. Sessler | Chang‐Hee Lee
Source: Chemistry - A European Journal (article, 2019-01-26)
Field: Materials Science — Materials Chemistry

Trapping of Stable [4<i>n</i>+1] π‐Electron Species from Peripherally Substituted, Conformationally Rigid, Antiaromatic Hexaphyrins Peripherally substituted antiaromatic naphthorosarins have been synthesized for the first time. The synthesis was accomplished by acid-catalyzed condensation of naphthobipyrrole building blocks with aromatic aldehydes. The naphthobipyrrole building blocks were synthesized by simple oxidative coupling of the corresponding pyrrole substituted aromatics. Solid-state structural analyses of the synthesized naphthorosarins revealed that the presence of meso-2,6-dichlorophenyl- and 5,6-difluoro-substitution substantially alter the geometry and properties of the naphthorosarins. The substituents affect the redox potentials as well and, in turn, the proton-coupled electron-transfer processes leading to the formation of one- and two-electron reduced forms of the corresponding naphthorosarins. One particular naphthorosarin that bears both peripheral fluorine and meso-2,6-dichlorophenyl substituents forms a stable 25 π-electron species upon treating with TFA that was characterized by single-crystal X-ray diffraction analysis. The current study underscores how structural modifications can be used to fine-tune the electronic features of naphthorosarins, including stabilization of odd electron species. Antiaromaticity ; Chemistry ; Electron transfer ; Electron ; Redox ; Pyrrole ; Crystallography ; Crystal structure ; Condensation ; Fluorine ; Coupling (piping) ; Computational chemistry ; Photochemistry ; Materials science ; Organic chemistry ; Molecule ; Aromaticity Porphyrin and Phthalocyanine Chemistry ; Photochemistry and Electron Transfer Studies ; Photochromic and Fluorescence Chemistry
Authors: Ulises A. Zitare | Jonathan Szuster | María C. Santalla | María‐Eugenia Llases | Marcos N. Morgada | Alejandro J. Vila | Daniel H. Murgida
Source: Inorganic Chemistry (article, 2019-01-15)
Field: Chemistry — Electrochemistry

Fine Tuning of Functional Features of the Cu<sub>A</sub> Site by Loop-Directed Mutagenesis Here we report the spectroscopic and electrochemical characterization of three novel chimeric Cu<sub>A</sub> proteins in which either one or the three loops surrounding the metal ions in the Thermus thermophilus protein have been replaced by homologous human and plant sequences while preserving the set of coordinating amino acids. These conservative modifications mimic basic differences between Cu<sub>A</sub> sites from different organisms and allow for fine tuning the energy gap between alternative electronic ground states of Cu<sub>A.</sub>. This results in a systematic modulation of thermodynamic and kinetic electron transfer (ET) parameters and in the selection of one of two possible redox-active molecular orbitals, which differ in the ET reorganization energy by a factor of 2. Moreover, the ET mechanism is found to be frictionally controlled, and the modifications introduced into the different chimeras do not affect the frictional activation parameter. Chemistry ; Thermus thermophilus ; Electron transfer ; Mutagenesis ; Copper protein ; Amino acid ; Ion ; Site-directed mutagenesis ; Characterization (materials science) ; Biophysics ; Nanotechnology ; Biochemistry ; Mutation ; Gene ; Copper ; Physical chemistry Electrochemical Analysis and Applications ; Electrocatalysts for Energy Conversion ; Photosynthetic Processes and Mechanisms
Authors: Wenjie Tang | Yue Wu | Anhou Xu | Tingting Gao | Yingqing Wei | Guowei Zhou
Source: Journal of Porous Materials (article, 2019-03-28)
Field: Materials Science — Materials Chemistry

Hybrid porous hypercrosslinking polyanilines: facile Friedel–Crafts preparation, CO2 capture and Cr(VI) removal properties Polyaniline ; Adsorption ; Friedel–Crafts reaction ; Porosity ; Catalysis ; Alkylation ; Materials science ; Sorption ; Chemical engineering ; Specific surface area ; Polymer ; Polymer chemistry ; Chemistry ; Organic chemistry ; Composite material ; Polymerization Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Membrane Separation and Gas Transport
Authors: Sandra Kauffmann‐Weiss | K. Iida | C. Tarantini | Torben Boll | Reinhard Schneider | Taito Ohmura | Takuya Matsumoto | Takafumi Hatano | Marco Langer | Sven Meyer | J. Jaroszyński | Dagmar Gerthsen | Hiroshi Ikuta | B. Holzäpfel | Jens Hänisch
Source: Nanoscale Advances (article, 2019-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Microscopic origin of highly enhanced current carrying capabilities of thin NdFeAs(O,F) films Fe-based superconductors present a large variety of compounds whose physical properties strongly depend on the crystal structure and chemical composition. Among them, the so-called 1111 compounds show the highest critical temperature <i>T</i> <sub>c</sub> in the bulk form. Here we demonstrate the realization of excellent superconducting properties in NdFeAs(O<sub>1-<i>x</i></sub> F <sub><i>x</i></sub> ). We systematically investigated the correlation between the microstructure at the nanoscale and superconductivity in an epitaxial 22 nm NdFeAs(O<sub>1-<i>x</i></sub> F <sub><i>x</i></sub> ) thin film on a MgO single crystalline substrate (<i>T</i> <sub>c</sub> = 44.7 K). Atomic resolution analysis of the microstructure by transmission electron microscopy and atom probe tomography identified several defects and other inhomogeneities at the nanoscale that can act as extrinsic pinning centers. X-Ray diffraction and transmission electron microscopy displayed a broad variation of the <i>a</i>-axis lattice parameter either due to a partially strained layer at the interface to the substrate, high local strain at dislocation arrays, mosaicity, or due to composition variation within the film. The electrical transport properties are substantially affected by intrinsic pinning and a matching field corresponding to the film thickness and associated with the Bean-Livingston surface barrier of the surfaces. The thin film showed a self-field critical current density <i>J</i> <sub>c</sub>(4.2 K) of ∼7.6 MA cm<sup>-2</sup> and a record pinning force density of <i>F</i> <sub>p</sub> ≈ 1 TN m<sup>-3</sup> near 35 T for <i>H</i>‖<i>ab</i> at 4.2 K. These investigations highlight the role of the microstructure in fine-tuning and possibly functionalizing the superconductivity of Fe-based superconductors. Microstructure ; Materials science ; Transmission electron microscopy ; Superconductivity ; Mosaicity ; Condensed matter physics ; Thin film ; Dislocation ; High-resolution transmission electron microscopy ; Atom probe ; Diffraction ; Crystallography ; Epitaxy ; Nanotechnology ; Layer (electronics) ; Composite material ; Optics ; Chemistry ; Physics Iron-based superconductors research ; Physics of Superconductivity and Magnetism ; Superconductivity in MgB2 and Alloys
Authors: Marina Santana Vega | Andrés Guerrero‐Martínez | Fabio Cucinotta
Source: Nanomaterials (article, 2019-03-03)
Field: Materials Science — Materials Chemistry

Facile Strategy for the Synthesis of Gold@Silica Hybrid Nanoparticles with Controlled Porosity and Janus Morphology Hybrid materials prepared by encapsulation of plasmonic nanoparticles in porous silica systems are of increasing interest due to their high chemical stability and applications in optics, catalysis and biological sensing. Particularly promising is the possibility of obtaining gold@silica nanoparticles (Au@SiO₂ NPs) with Janus morphology, as the induced anisotropy can be further exploited to achieve selectivity and directionality in physical interactions and chemical reactivity. However, current methods to realise such systems rely on the use of complex procedures based on binary solvent mixtures and varying concentrations of precursors and reaction conditions, with reproducibility limited to specific Au@SiO₂ NP types. Here, we report a simple one-pot protocol leading to controlled crystallinity, pore order, monodispersity, and position of gold nanoparticles (AuNPs) within mesoporous silica by the simple addition of a small amount of sodium silicate. Using a fully water-based strategy and constant content of synthetic precursors, cetyl trimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS), we prepared a series of four silica systems: (A) without added silicate, (B) with added silicate, (C) with AuNPs and without added silicate, and (D) with AuNPs and with added silicate. The obtained samples were characterised by transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and UV-visible spectroscopy, and kinetic studies were carried out by monitoring the growth of the silica samples at different stages of the reaction: 1, 10, 15, 30 and 120 min. The analysis shows that the addition of sodium silicate in system B induces slower MCM-41 nanoparticle (MCM-41 NP) growth, with consequent higher crystallinity and better-defined hexagonal columnar porosity than those in system A. When the synthesis was carried out in the presence of CTAB-capped AuNPs, two different outcomes were obtained: without added silicate, isotropic mesoporous silica with AuNPs located at the centre and radial pore order (C), whereas the addition of silicate produced Janus-type Au@SiO₂ NPs (D) in the form of MCM-41 and AuNPs positioned at the silica⁻water interface. Our method was nicely reproducible with gold nanospheres of different sizes (10, 30, and 68 nm diameter) and gold nanorods (55 × 19 nm), proving to be the simplest and most versatile method to date for the realisation of Janus-type systems based on MCM-41-coated plasmonic nanoparticles. Tetraethyl orthosilicate ; Materials science ; Sodium silicate ; Chemical engineering ; Colloidal gold ; Nanoparticle ; Silicate ; Mesoporous silica ; Halloysite ; Mesoporous material ; Nanotechnology ; Catalysis ; Organic chemistry ; Chemistry Catalytic Processes in Materials Science ; Pickering emulsions and particle stabilization ; Mesoporous Materials and Catalysis
Authors: Maria Barbara Banella | Greta Giacobazzi | Micaela Vannini | Paola Marchese | Martino Colonna | Annamaria Celli | Alessandro Gandini | Claudio Gioia
Source: Macromolecular Chemistry and Physics (article, 2019-07-09)
Field: Chemistry — Organic Chemistry

A Novel Approach for the Synthesis of Thermo‐Responsive Co‐Polyesters Incorporating Reversible Diels–Alder Adducts Abstract The proof of concept for a new copolymerization approach taking advantage of the thermally reversible aptitude of the furan/maleimide Diels–Alder (DA) adducts is reported here. A new monomer bearing two carboxylic acids as end‐groups and a Diels–Alder adduct within its structure is synthesized using benign and mild reaction conditions. Two polyesters are then fabricated from the DA‐diacid and 1,6‐hexanediol and 1,4‐benzenedimethanol, respectively, and characterized by 1 H‐NMR, GPC, DSC, and TGA. Kinetic studies of these polyesters, performed by 1 H‐NMR spectroscopy at variable temperatures, establish the appropriate conditions for their controlled depolymerization, through the retro Diels–Alder reaction (rDA), and their re‐construction through the DA reaction, showing moreover the reproducibility of this rDA/DA cycle. Finally, by exploiting this peculiar feature, a copolyester is successfully synthesized from the concomitant treatment of the two homopolymers, demonstrating the effectiveness of the method. The present approach provides a new method for the fabrication of multicomponent copolymers based on the DA/rDA strategy that is extendable to a variety of other polycondensation materials, such as polyesters, polyamides, polyurethanes, and epoxies, allowing the establishment of a library of novel architectures through this one‐pot approach. Polyester ; Maleimide ; Copolyester ; Copolymer ; Adduct ; Condensation polymer ; Polymer chemistry ; Depolymerization ; Phthalic anhydride ; Diels–Alder reaction ; Chemistry ; Materials science ; Monomer ; Organic chemistry ; Polymer ; Catalysis Synthetic Organic Chemistry Methods ; Synthesis and properties of polymers ; Polymer composites and self-healing
Authors: Julien Daubignard | Remko J. Detz | Bas de Bruin | Joost N. H. Reek
Source: Organometallics (article, 2019-08-28)
Field: Chemistry — Inorganic Chemistry

Phosphine Oxide Based Supramolecular Ligands in the Rhodium-Catalyzed Asymmetric Hydrogenation A series of bisphosphine monoxides and a phosphoramidite have been used for the preparation of supramolecular ligands. A structural analysis of the complexes using NMR spectroscopy and DFT calculations revealed the formation of strong hydrogen bonding between the two ligands. The complexes have been evaluated in the hydrogenation of several functionalized alkenes, leading to very high enantioselectivity for the substrates bearing a hydroxyl group. Also, kinetic studies showed that enhanced reaction rates of hydrogenation are observed in comparison with the supramolecular catalytic systems based on urea groups. In-depth NMR spectroscopy experiments and computational studies have highlighted the crucial role of the hydrogen bond between the phosphine oxide ligands and the substrate during the hydrogenation reaction. Chemistry ; Supramolecular chemistry ; Rhodium ; Catalysis ; Phosphine ; Asymmetric hydrogenation ; Phosphine oxide ; Hydrogen bond ; Nuclear magnetic resonance spectroscopy ; Organometallic chemistry ; Substrate (aquarium) ; Oxide ; Polymer chemistry ; Combinatorial chemistry ; Photochemistry ; Organic chemistry ; Molecule ; Enantioselective synthesis Asymmetric Hydrogenation and Catalysis ; Surface Chemistry and Catalysis ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Tao Sun | Xiaomin Shuai | Kaixin Ren | Xingxing Jiang | Yujie Chen | Xinyu Zhao | Qianqian Song | Shaoqiang Hu | Zhiqiang Cai
Source: Molecules (article, 2019-08-30)
Field: Chemistry — Spectroscopy

Amphiphilic Block Copolymer PCL-PEG-PCL as Stationary Phase for Capillary Gas Chromatographic Separations This work presents the first example of utilization of amphiphilic block copolymer PCL-PEG-PCL as a stationary phase for capillary gas chromatographic (GC) separations. The PCL-PEG-PCL capillary column fabricated by static coating provides a high column efficiency of 3951 plates/m for <i>n</i>-dodecane at 120 °C. McReynolds constants and Abraham system constants were also determined in order to evaluate the polarity and possible molecular interactions of the PCL-PEG-PCL stationary phase. Its selectivity and resolving capability were investigated by using a complex mixture covering analytes of diverse types and positional, structural, and cis-/trans-isomers. Impressively, it exhibits high resolution performance for aliphatic and aromatic isomers with diverse polarity, including those critical isomers such as butanol, dichlorobenzene, dimethylnaphthalene, xylenol, dichlorobenzaldehyde, and toluidine. Moreover, it was applied for the determination of isomer impurities in real samples, suggesting its potential for practical use. The superior separation performance demonstrates the potential of PCL-PEG-PCL and related block copolymers as stationary phases in GC and other separation technologies. Copolymer ; Dodecane ; Structural isomer ; PEG ratio ; Selectivity ; Phase (matter) ; Chemistry ; Amphiphile ; Gas chromatography ; Polycaprolactone ; Chemical engineering ; Materials science ; Chromatography ; Organic chemistry ; Polymer Analytical Chemistry and Chromatography ; Microfluidic and Capillary Electrophoresis Applications ; Mass Spectrometry Techniques and Applications
Authors: Dmitry I. Konovalov | Anton A. Ivanov | Yuri A. Vorotnikov | Anton I. Smolentsev | Ilia V. Eltsov | Olga A. Efremova | Noboru Kitamura | Yuri V. Mironov | Michael A. Shestopalov
Source: Polyhedron (article, 2019-03-16)
Field: Chemistry — Inorganic Chemistry

Octahedral chalcogenide rhenium cluster complexes with imidazole Chemistry ; Rhenium ; Imidazole ; Chalcogenide ; Cationic polymerization ; Cluster (spacecraft) ; Crystallography ; Octahedron ; Luminescence ; Single crystal ; Crystal structure ; Inorganic chemistry ; Stereochemistry ; Polymer chemistry ; Organic chemistry ; Optics Inorganic Chemistry and Materials ; Organometallic Complex Synthesis and Catalysis ; Nanocluster Synthesis and Applications
Authors: Mohamad Azani Jalani | Leny Yuliati | Siew Ling Lee | Hendrik O. Lintang
Source: Beilstein Journal of Nanotechnology (article, 2019-07-05)
Field: Chemistry — Organic Chemistry

Highly ordered mesoporous silica film nanocomposites containing gold nanoparticles for the catalytic reduction of 4-nitrophenol We report that transparent mesostructured silica/gold nanocomposite materials with an interpore distance of 4.1 nm, as-synthesized from a templated sol-gel synthesis method using discotic trinuclear gold(I) pyrazolate complex, were successfully utilized for the fabrication of thin film mesoporous silica nanocomposites containing gold nanoparticles. The material exhibited a highly ordered hexagonal structure when subjected to a thermal hydrogen reduction treatment at 210 °C. In contrast, when the material was subjected to calcination as a heat treatment from 190 to 450 °C, the thin film nanocomposites showed an intense <i>d</i> <sub>100</sub> X-ray diffraction peak. Moreover, gold nanoparticles inside the thin film nanocomposites were confirmed by the presence of the <i>d</i> <sub>111</sub> diffraction peak at 2θ = 38.2°, a surface plasmon resonance peak between 500-580 nm, and the spherical shape observed in the transmission electron microscope images, as well as the visual change in color from pink to purple. Interestingly, by simply dipping the material into a reaction solution of 4-nitrophenol at room temperature, the highly ordered structure of the as-fabricated silica/gold nanoparticle thin film composite after thermal hydrogen reduction at 210 °C resulted in an improved catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol compared to the material calcined at 250 °C. Such catalytic activity is due to the presence of gold nanoparticles of smaller size in the silicate channels of the highly ordered mesoporous film nanocomposites. Materials science ; Nanocomposite ; Calcination ; Colloidal gold ; Chemical engineering ; Nanoparticle ; Mesoporous material ; Mesoporous silica ; Surface plasmon resonance ; Nanotechnology ; Thin film ; Transmission electron microscopy ; Catalysis ; Organic chemistry ; Chemistry Nanomaterials for catalytic reactions ; Catalytic Processes in Materials Science ; Nanocluster Synthesis and Applications