jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Malibongwe P. Shandu | Jairus L. Lamola | Cedric W. Holzapfel | Munaka Christopher Maumela | Paseka T. Moshapo
Source: ChemistrySelect (article, 2022-11-03)
Field: Chemistry — Organic Chemistry

Application of <i>P</i> ‐Bridged Biaryl Phosphines in Pd‐Catalyzed <i>α</i> ‐Arylation Reactions Abstract The use of catalysts derived from Pd 2 (dba) 3 and phosphatrioxa‐adamantane framework (Cg) has been demonstrated to facilitate the effective alpha( α) ‐arylation of ketones using a diverse array of aryl halides under mild reaction conditions (40 °C–80 °C). The evaluation of phosphines with dissimilar stereoelectronic properties revealed the pivotal role of fine‐tuning the ligand's steric bulk. In particular, catalysts based on the Cg‐biphenyl ligand ( 1 ) proved efficient for facile α ‐arylation of electronically and sterically diverse aryl bromides and chlorides. Steric effects ; Aryl ; Catalysis ; Ligand (biochemistry) ; Halide ; Chemistry ; Biphenyl ; Combinatorial chemistry ; Adamantane ; Medicinal chemistry ; Stereochemistry ; Organic chemistry ; Alkyl ; Receptor Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis
Authors: Somayeh Asgharpour | L. América | Marc Spehr | Paolo Carloni | Mercedes Alfonso‐Prieto
Source: Handbook of experimental pharmacology (article, 2022-01-01)
Field: Chemistry — Spectroscopy

Fluoride Transport and Inhibition Across CLC Transporters Fluoride ; Chloride ; Chemistry ; Transporter ; Chloride channel ; Ion transporter ; Proton transport ; Proton ; Membrane transport protein ; Mutagenesis ; Biochemistry ; Inorganic chemistry ; Membrane ; Organic chemistry ; Mutation ; Gene Molecular Sensors and Ion Detection ; Chemical Analysis and Environmental Impact ; Mass Spectrometry Techniques and Applications
Authors: Jian Hou | Franklin O. Egemole | Faith M. Eyimegwu | Jaehan Yun | Wongi Jang | Hongsik Byun | Jun‐Hyun Kim
Source: ChemistrySelect (article, 2022-08-10)
Field: Materials Science — Materials Chemistry

Experimental Selection of Bases for Colloidal Gold‐Polymer Composite Catalyst in Homocoupling Reactions Abstract This work describes the empirical screening of base types and amounts on the catalytic property of gold‐polymer composite particles in the aerobic homocoupling of arylboronic acid. As these particles notably improve the yields of biaryl in the presence of bases, various bases and their amounts are systematically tested to experimentally identify an ideal base that can provide high reactivity and recyclability of the composite particles in mild and green conditions. Interestingly, the following conditions ‐ soluble strong bases at sub‐stoichiometric quantities (0.5 eq.) and insoluble weak bases at excess amounts (3.0 eq.) in EtOH ‐ significantly enhance the catalytic activities of the composite particles. Upon screening two ideal bases, overall catalytic properties of the composite particles including reaction rate at three different temperatures, activation energy (51–52 kJ/mole), and recyclability (7 cycles) were compared. Understanding the effect of bases and fine‐tuning reaction conditions can potentially improve overall reactivity and recyclability of the composite particles as a green quasi‐homogenous catalyst. Catalysis ; Composite number ; Reactivity (psychology) ; Base (topology) ; Stoichiometry ; Polymer ; Chemistry ; Chemical engineering ; Materials science ; Activation energy ; Organic chemistry ; Composite material ; Mathematics Nanocluster Synthesis and Applications ; Nanomaterials for catalytic reactions ; Asymmetric Hydrogenation and Catalysis
Authors: Mohammad Kazem Bagheri | Mehdi Hosseini | Mahdi Bahadoran
Source: Physica Scripta (article, 2022-11-15)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Tunable broad-band absorber consisted of crossed-oval shape of graphene Abstract A three-dimensional broadband absorber structure was proposed based on the crossed-oval shape of graphene (COSG) on a wafer layout. This structure consisted of silicon/gold/silica wafer and a superstrate layer of graphene patterns in the form of crossed-oval placed on top of the wafer. The effect of geometrical parameters on the absorption was studied. Results show that this structure can absorb over 99% of the incoming light over a broad range of THz frequencies. The absorption peaks were fine-tuned by changing the geometrical and physical parameters. This property is vital and desirable in optical detectors, chemical sensors, and other optical devices. Wafer ; Graphene ; Materials science ; Terahertz radiation ; Broadband ; Absorption (acoustics) ; Optoelectronics ; Optics ; Broad band ; Silicon ; Layer (electronics) ; Range (aeronautics) ; Nanotechnology ; Composite material ; Physics Metamaterials and Metasurfaces Applications ; Advanced Antenna and Metasurface Technologies ; Plasmonic and Surface Plasmon Research
Authors: María Victoria Biezma Moraleda | O. Gómez de la Rasilla | Roland Haubner | P. Linhardt
Source: Practical Metallography (article, 2022-05-01)
Field: Materials Science — Materials Chemistry

Etching of Manganese Aluminum Bronze by Ultrasound in Seawater Abstract Manganese Aluminum Bronze (MAB), UNS designation C95700, is an alloy widely used for large marine propellers and other components in hydropower units. MAB has a complex microstructure due to precipitation of intermetallic phases as consequence of the cast process or thermal treatments. When investigating the marine corrosion behavior of MAB alloys, it was found that a metallographic etching attack occurred under the effect of ultrasound, similar to that observed with chemical reagents used for high-alloy bronzes. The main aim of this work is to compare the effects of etching on polished metallographic samples by ultrasound in seawater with that obtained with conventional chemical agents. It can be concluded that the effect of ultrasound is able to reveal, with great precision, the microstructure of MAB alloys, without the use of aggressive chemical agents, while the time under the influence of ultrasonic energy allows for fine-tuning the etching effect. Materials science ; Microstructure ; Metallurgy ; Bronze ; Manganese ; Alloy ; Etching (microfabrication) ; Isotropic etching ; Intermetallic ; Aluminium ; Seawater ; Corrosion ; Ultrasonic sensor ; Composite material ; Geology Metallurgy and Material Science ; Extraction and Separation Processes ; Recycling and Waste Management Techniques
Authors: Kausani Ghatak | Han Vinh Huynh
Source: Applied Organometallic Chemistry (article, 2022-05-04)
Field: Chemistry — Organic Chemistry

Palladium hetero‐di(N‐heterocyclic carbene) complexes and their catalytic activities in direct C–H arylation of heteroarenes A library of neutral and cationic palladium complexes of cis ‐chelating hetero‐dicarbene ligands have been prepared. These ligands contain two different NHC donors allowing for a wider degree of variation, and the impact of the distinct NHC units has been compared using various spectroscopic means. In addition, the catalytic activities of these complexes in the direct C‐H arylation of thiophenes with aryl halides were studied leading to the finding that the neutral dibromido complexes of the type [PdBr 2 (diNHC)] generally outperformed their cationic [Pd (NCMe) 2 (diNHC)](OTf) 2 counterparts. More importantly, complexes containing more distinct NHC units give rise to superior catalysts due to an amplified “stereoelectronic asymmetry” within the complex. A preliminary photophysical study of some selected thiophene reaction products has been conducted as well. The ability to individually change each NHC donor in such dicarbene ligands allows for a better fine‐tuning of complex properties in search for superior catalysts. Chemistry ; Cationic polymerization ; Carbene ; Catalysis ; Palladium ; Aryl ; Halide ; Thiophene ; Chelation ; Medicinal chemistry ; Stereochemistry ; Combinatorial chemistry ; Polymer chemistry ; Organic chemistry ; Alkyl N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods
Authors: Wennie Yun Lee | Dana V. Chapman | Fei Yu | William R. T. Tait | R. Paxton Thedford | Guillaume Freychet | Mikhail Zhernenkov | Lara A. Estroff | Ulrich Wiesner
Source: Macromolecules (article, 2022-10-17)
Field: Materials Science — Materials Chemistry

Triblock Terpolymer Thin Film Nanocomposites Enabling Two-Color Optical Super-Resolution Microscopy Self-assembled block copolymer (BCP) thin films and their nanocomposites provide nanostructures useful in myriad applications. While conventional characterization techniques provide an understanding of film surface and internal structures, optical super-resolution microscopy (OSRM) has recently emerged as an alternative way to characterize nanoscopic polymer morphology. This work describes self-assembled poly(isoprene)-block-poly(styrene)-block-poly(N,N-dimethylaminoethyl methacrylate) (PI-b-PS-b-PDMAEMA or ISA) triblock terpolymer thin films with all three blocks exposed at the top surface. Structural characterization of neat films with standard techniques, including grazing-incidence small-angle X-ray scattering (GISAXS), atomic force microscopy (AFM), and electron microscopy (EM), reveals a co-continuous network in the substructure of the films and hexagonally ordered top surface structures. Nanocomposite thin films incorporating two chemically and optically orthogonal core–shell optical nanoparticle probes by simple physical mixing and evaporation-induced self-assembly (EISA) retain this morphology while enabling two-color OSRM imaging of different BCP nanodomains. This approach suggests that fine-tuned organic ligand shells enable labeling of different blocks based on shell polarity, demonstrating a straightforward pathway to multicolor OSRM characterization of chemically distinct nanodomains. Grazing-incidence small-angle scattering ; Materials science ; Copolymer ; Thin film ; Nanocomposite ; Characterization (materials science) ; Nanostructure ; Methacrylate ; Nanotechnology ; Polymer ; Microscopy ; Chemical engineering ; Scattering ; Optics ; Composite material ; Small-angle neutron scattering Block Copolymer Self-Assembly ; Advanced Polymer Synthesis and Characterization ; Polymer Surface Interaction Studies
Authors: A. S. Morozova | S. A. Ziganshina | Марат А. Зиганшин | А. А. Бухараев
Source: Russian Journal of General Chemistry (article, 2022-07-01)
Field: Materials Science — Biomaterials

Self-Organization of Di- and Triglycine Oligopeptides in Thin Films on the Hydrophilic and Hydrophobic Silicon Surface under Exposure to Organic Compounds Vapors The influence of the substrate hydrophobicity degree and of the number of amino acid residues in the oligopeptide molecule on the self-assembly of glycyl-glycine and glycyl-glycyl-glycine under exposure to vapors of organic compounds was studied. The effect of strong and weak proton donor and proton acceptor vapors on the morphology of the thin films of the glycine-based oligopeptides was examined by atomic force microscopy. The possibility of controlling the self-assembly of oligopeptides by fine-tuning the substrate type and vapor of the organic compounds used for thin film saturation was demonstrated. A technique for surface state monitoring of the oligopeptide thin film by using atomic force spectroscopy was proposed. Oligopeptide ; Chemistry ; Substrate (aquarium) ; Thin film ; Silicon ; Glycine ; Chemical engineering ; Organic chemistry ; Amino acid ; Polymer chemistry ; Nanotechnology ; Peptide ; Materials science ; Biochemistry Supramolecular Self-Assembly in Materials ; Diatoms and Algae Research ; Polydiacetylene-based materials and applications
Authors: Joseph M. Parr | Clarissa Olivar | Thomas Saal | Ralf Haiges | Michael S. Inkpen
Source: Dalton Transactions (article, 2022-01-01)
Field: Chemistry — Organic Chemistry

Pushing steric limits in osmium( <scp>iv</scp> ) tetraaryl complexes Investigations into the reactivity, properties, and applications of osmium(IV) tetraaryl complexes have been hampered by their low yielding syntheses from volatile and toxic OsO<sub>4</sub> (typically ≤34%). Here we show that known air-stable M(aryl)<sub>4</sub> compounds (M = Os, Ru; aryl = 2-tolyl, 2,5-xylyl) can be prepared in ≤73% yields using new, less hazardous (Oct<sub>4</sub>N)<sub>2</sub>[MX<sub>6</sub>] precursors (M = Os, Ru; X = Cl, Br). This approach also facilitates the preparation of Os(mesityl)<sub>4</sub> (Os3) for the first time, a complex comprising bulky 2,6-dimethyl substituted aryl ligands, albeit in low yield (5%). To better understand these yield extremes, we track, by synthesizing two additional new complexes with different 2-substituted σ-aryl ligands, a clear relationship between the yields of Os(aryl)<sub>4</sub> and ligand steric bulk. Single-crystal X-ray structures of these compounds indicate that the observed yield trend reflects the ease of accommodating aryl substituents into an open pocket that lies directly opposite each M-aryl coordination site. We perform variable-temperature <sup>1</sup>H NMR studies of Os3, utilize a "tetrahedricity" metric to assess geometric distortion in Ru(aryl)<sub>4</sub> and Os(aryl)<sub>4</sub> materials, and calculate cone angle and percentage buried volume metrics to further illustrate and help quantify σ-aryl ligand steric properties. Solution cyclic voltammograms of Os(aryl)<sub>4</sub> show that the potentials of their reversible 1-/0 and 0/1+ redox features can be fine-tuned by varying aryl substituents, and that Os3 exhibits an additional 1+/2+ redox event not previously observed in this class of compounds. Taken together, this work helps to advance the potential application of these relatively underexplored organometallic complexes in established and emerging areas of molecular materials science, such as extended molecular frameworks and self-assembled monolayers, where analogous tetraphenylmethane and silane species (M = C, Si) have been frequently targeted. Aryl ; Steric effects ; Osmium ; Chemistry ; Ligand (biochemistry) ; Yield (engineering) ; Reactivity (psychology) ; Redox ; Medicinal chemistry ; Crystallography ; Stereochemistry ; Ruthenium ; Organic chemistry ; Materials science ; Catalysis Organometallic Complex Synthesis and Catalysis ; Catalytic Cross-Coupling Reactions ; N-Heterocyclic Carbenes in Organic and Inorganic Chemistry
Authors: Jin-Ze Fan | Zhan-Bo Fang | Chaojie Luo | Hui Zhang
Source: Acta Physica Sinica (article, 2022-01-01)
Field: Materials Science — Materials Chemistry

Charge density waves in low-dimensional material Charge density waves (CDWs) have triggered off extensive research in low-dimensional systems. The discovery of CDW offers a new crucial clue to understanding the intrinsic mechanisms of low-dimensional electron-phonon coupling and electron correlation. In addition, the physical properties of low-dimensional material such as magnetism and superconductivity can be fine-tuned with accurately and effectively controlled CDW phase. At the beginning,we briefly introduce the basic properties of CDW in one-dimensional and quasi one-dimensional materials, revealing the physical proprieties of the CDW, for instance, the excited state and the manipulation technologies. Then, focusing on the CDW in a two-dimensional system, we mainly introduce the recent research progress and the generation mechanism of CDW of two-dimensional materials. The interaction between CDW and Mott insulator and between superconductivity and other orders such as spin density wave and pair density wave provide a new perspective to research the multi-electron collective excitation and electron interaction. The manipulation of multi-electron collective excitation and electron-phonon interaction in CDW through doping, high pressure and laser pulse is also introduced and shares similarity with the one-dimensional system. Finally, in this article we propose a potential research application of two dimensional CDW. Charge density wave ; Condensed matter physics ; Superconductivity ; Mott insulator ; Physics ; Electron ; Excited state ; Excitation ; Quantum mechanics Electronic and Structural Properties of Oxides ; Quantum and electron transport phenomena ; Physics of Superconductivity and Magnetism
Authors: Grace Buckey | Olivia E. Owens | Ainslee W. Gabriel | Claudia M. Downing | Margaret C. Calhoun | David E. Cliffel
Source: Molecules (article, 2022-09-16)
Field: Chemistry — Electrochemistry

Adsorption and Electropolymerization of p-Aminophenol Reduces Reproducibility of Electrochemical Immunoassays This paper investigates the electrochemical behavior of <i>p</i>-aminophenol (PAP) on commercially available carbon screen-printed electrodes (CSPEs) and gold screen-printed electrodes (GSPEs) at neutral and basic pHs for the development of inexpensive immunoassays. The electrochemical oxidative signal from PAP results from its adsorption to the electrode. The formation of self-assembled monolayers on gold electrodes prevented PAP adsorption but also reduced its oxidative current, confirming that adsorption increases signal production. On bare electrodes, PAP adsorption results in oxidative current variability depending on the electroactive surface area of the screen-printed electrode. This variability could not be remedied by cleaning and reusing the same GSPE. Decreasing the PAP concentration to 3.8 μM greatly improved the consistency of the measurements, suggesting that the adsorption of PAP is concentration-dependent. Multiple PAP oxidations on the same electrode caused polymerization, limiting PAP in continuous monitoring applications. Infrared and Raman spectroscopy allow the distinction between adsorbed PAP and electropolymerized PAP on the surface of a gold wafer. The results from this study suggest that the use of PAP production in immunoassays with SPEs must be fine-tuned, and electrodes must be cleaned or disposed of between measurements. Adsorption ; Electrode ; Electrochemistry ; Raman spectroscopy ; Chemistry ; Polymerization ; Analytical Chemistry (journal) ; Materials science ; Chromatography ; Organic chemistry ; Polymer Electrochemical Analysis and Applications ; Conducting polymers and applications ; Electrochemical sensors and biosensors
Authors: Alvaro Muñoz‐Castro
Source: Physical Chemistry Chemical Physics (article, 2022-01-01)
Field: Materials Science — Materials Chemistry

Ligand–core interaction in ligand-protected Ag<sub>25</sub>(XR)<sub>18</sub> (X = S, Se, Te) superatoms and evaluation of the anchor atom role <i>via</i> relativistic DFT calculations The isostructural and isoelectronic silver [Ag<sub>25</sub>(SR)<sub>18</sub>]<sup>-</sup> (R = ligand) cluster, similar to [Au<sub>25</sub>(SR)<sub>18</sub>]<sup>-</sup> gold clusters, allows for further understanding of the fundamental similarities between Au and Ag at the ultrasmall nanoscale (<2 nm), featuring an eight cluster electron (8-ce) M<sub>13</sub> core. Our results indicate a less favorable protecting-layer to core interaction, leading to a more symmetrical Ag<sub>13</sub> core owing to a less tight ligand shell. The stabilizing embrace of Ag<sub>13</sub> is of an electrostatic character, with bonding contributions occupying the formally unoccupied superatomic shells, given by 1D, 2S, and 2F, indicating their role as acceptor core orbitals to provide further core-ligand bonding upon the formation of the cluster. The optical properties exhibit a red-shift for the first 1P → 1D peak along the [Ag<sub>25</sub>(XMe)<sub>18</sub>]<sup>-</sup> series, which is in contrast with the blue-shift observed for the gold counterpart, by replacing the S-anchor atom with Se and Te. Moreover, the S<sub>1</sub> → S<sub>0</sub> emission exhibits a red-shift. Thus, the role of the anchor atom is to modify the bonding and optical features of the [Ag<sub>25</sub>(XMe)<sub>18</sub>]<sup>-</sup> species, affording fine-tuning of the molecular behavior. Isostructural ; Ligand (biochemistry) ; Cluster (spacecraft) ; Chemistry ; Atom (system on chip) ; Core (optical fiber) ; Crystallography ; Gold cluster ; Electronic structure ; Computational chemistry ; Materials science ; Crystal structure Nanocluster Synthesis and Applications ; Advanced Nanomaterials in Catalysis ; Gold and Silver Nanoparticles Synthesis and Applications
Authors: M. Bardají | Mercè Font-Bardı́a | Albert Gallén | Beltzane Garcia‐Cirera | Montserrat Ferrer | Manuel Martı́nez
Source: Dalton Transactions (article, 2022-12-21)
Field: Materials Science — Materials Chemistry

Iron complexes of bridging azo ligands in aqueous solution: changes in the thermal switching mechanism on coordination and oxidation state of metal centres Three azobenzenes CN(C<sub>6</sub>H<sub>4</sub>)-NN-(C<sub>5</sub>H<sub>4</sub>N) (py-iso), CN(C<sub>6</sub>H<sub>4</sub>)-NN-(C<sub>6</sub>H<sub>4</sub>)CN (cyano-iso) and CN(C<sub>6</sub>H<sub>4</sub>)-NN-(C<sub>6</sub>H<sub>4</sub>)NC (iso-iso) with good coordinating groups (pyridine, phenylcyano or phenylisocyano) at the ends of the diazenyl unit have been synthesized and fully characterised. These compounds have been used as ligands in the synthesis of water-soluble metallic species by coordination to {Fe<sup>II</sup>(CN)<sub>5</sub><sup>3-</sup>} units, either in one or two of the anchoring groups of the derivatives. Both the azo derivatives and their complexes are photochemically active with respect to their <i>trans</i>-to-<i>cis</i> isomerisation process. Their <i>cis</i>-to-<i>trans</i> reverse thermal reaction has been thoroughly studied as a function of the donor groups, solvent, temperature and pressure, in order to gain insight into the rotation or inversion mechanisms involved in the process. A comparison of the isomerisation mechanism between the iron complexes and the corresponding free ligands revealed an interesting fine tuning of the process on coordination of the {Fe<sup>II</sup>(CN)<sub>5</sub><sup>3-</sup>} moieties, which may even produce, in some cases, non-photoswitchable species containing typically photoactive units. Bridging (networking) ; Aqueous solution ; Mechanism (biology) ; Oxidation state ; Metal ; Chemistry ; Thermal ; Coordination complex ; Photochemistry ; Organic chemistry ; Computer science ; Thermodynamics Photochromic and Fluorescence Chemistry ; Free Radicals and Antioxidants ; Porphyrin and Phthalocyanine Chemistry