jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Enrique R. Batista
Source: OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (article, 2024-02-01)
Field: Materials Science — Materials Chemistry

Self-consistent QM/MM methodologies for structural refinement of photosystem II and other macromolecules of biological interest The combination of quantum mechanics and molecular mechanics (QM/MM) is one of the most promising approaches to study the structure, function, and properties of proteins and nucleic acids. However, there some instances in which the limitations of either the MM (lack of a proper electronic description) or QM (limited to a few number of atoms) methods prevent a proper description of the system. To address this issue, we review here our approach to fine-tune the structure of biological systems using post-QM/MM refinements. These protocols are based on spectroscopy data, and/or partitioning of the system to extend the QM description to a larger region of a protein. We illustrate these methodologies through applications to several biomolecules, which were pre-optimized at the QM/MM level and then further refined using postQM/MM refinement methodologies: mod(QM/MM), which refines the atomic charges of the residues included in the MM region accounting for polarization effects; mod(QM/MM)-opt that partition the MM region in smaller parts and optimizes each part in an iterative. self-consistent way, and the Polarized-Extended X-Ray Absorption Fine Structure (P-EXAFS) fitting procedure, which fine-tune the atomic coordinates to reproduce experimental polarized EXAFS spectra. The first two techniques were applied to the guanine quadruplex. while the P-EXAFS refinement was applied to the oxygen evolving complex of photosystem II. Photosystem II ; Macromolecule ; Chemistry ; Chemical physics ; Nanotechnology ; Biological system ; Materials science ; Biology ; Biochemistry ; Photosynthesis Enzyme Structure and Function
Authors: Penghui Ni | Jing Tan | Wujiu Jiang | Yuxing Tan | Guo‐Jun Deng
Source:  (preprint, 2024-06-22)
Field: Chemistry — Organic Chemistry

Copper(I)-Catalyzed Tunable Synthesis of Polythioindoles by Insertion of Sulfur Copper(I)-catalyzed temperature- and oxidant-induced selective synthesis of pentathiepinoindoles and diindole tetrasulfides is demonstrated. Among them, unsymmetric tetrathiadiindole compounds were synthesized for the first time. In this strategy, the key intermediate biindolyls were in situ generated through Cu-catalyzed direct C–H transformations of indoles. The biindolyls could be selectively converted into the corresponding products by fine-tuning reaction conditions. More than 50 polythioindole products were synthesized with excellent regioselectivity and broad functional group tolerance. Regioselectivity ; Catalysis ; Copper ; Sulfur ; Functional group ; Combinatorial chemistry ; Chemistry ; In situ ; Reaction conditions ; Organic chemistry Catalytic C–H Functionalization Methods ; Sulfur-Based Synthesis Techniques ; Synthesis and Catalytic Reactions
Authors: Mohamed A. Abdelaziz | Neil D. Danielson
Source: Separations (article, 2024-01-05)
Field: Chemistry — Analytical Chemistry

A Cyanoalkyl Silicone GC Stationary-Phase Polymer as an Extractant for Dispersive Liquid–Liquid Microextraction In this work, three cyanoalkyl silicone GC stationary-phase polymers, namely OV-105, OV-225, and OV-275, were investigated as potential extractants for dispersive liquid–liquid microextraction (DLLME). The OV-225 polymer (cyanopropylmethyl-phenylmethylsilicone) exhibited the cleanest chromatographic background and was extensively studied. The proposed polymer was tested through the DLLME of four non-steroidal anti-inflammatory drugs from aqueous samples, followed by HPLC separation with UV detection at 230 nm. To achieve the maximum enrichment, the experimental conditions that influence the DLLME process were optimized using one-factor-at-a-time and design-of-experiment (DoE) approaches. The extraction variables (polymer mass, dispersive solvent volume, buffer pH, and mixing time) were screened by implementing a two-level full factorial design (FFD). Significant variables were fine-tuned using response surface methodology based on a face-centered central composite design (CCD). The optimum conditions were 10 mg of polymer (extraction medium); 50 µL of tetrahydrofuran (dispersive solvent); 100 µL of phosphate buffer pH 2.75 ([PO43−] = 100 mM); and 3 min of vortex mixing. The addition of salt had a minimal effect on the enrichment factors. In the optimum conditions, enrichment factors up to 46 were achieved using 1.5 mL samples. Calibration curves exhibited correlation coefficients &gt; 0.999 using 4-pentylbenzoic acid as an internal standard. The limits of quantitation were 5 ng/mL for naproxen, 10 ng/mL for diflunisal, 25 ng/mL for indomethacin, and 75 ng/mL for ibuprofen. The analysis of spiked tap water samples showed adequate relative recoveries and precision. In conclusion, the proposed polymer (OV-225) is a potential greener alternative to traditional organic extractants used in DLLME. Chromatography ; Chemistry ; Central composite design ; Extraction (chemistry) ; Response surface methodology ; Factorial experiment ; Polymer ; High-performance liquid chromatography ; Solvent ; Calibration curve ; Enrichment factor ; Detection limit ; Analytical Chemistry (journal) Analytical chemistry methods development ; Analytical Chemistry and Chromatography ; Pharmaceutical and Antibiotic Environmental Impacts
Authors: Bastian Achenbach | Christian Näther | Norbert Stock
Source: ChemRxiv (preprint, 2024-11-10)
Field: Materials Science — Materials Chemistry

New Isostructural Family of Mixed-Metal Na-M(III)-MOFs Based on Glycolic Acid A series of new isostructural metal–organic frameworks based on trivalent metal ions (Al, Fe, Ga), Na+ ions and glycolate ions as the linker molecules, denoted as M-CAU-64, with the framework composition [M(III)Na(H2O)2(C2H2O3)2] · x H2O were obtained using high-throughput methods. The crystal structures of the title compounds were determined from single crystal or powder X-ray diffraction data. Thermogravimetric analyses indicate a thermal stability up to 340 °C for Ga-CAU-64, while variable temperature powder X-ray diffraction (VT-PXRD) revealed various structural changes including phase transformations and a rearrangement of the inorganic building unit of CAU-64, associated with the loss of adsorbed water molecules upon thermal treatment. Water sorption measurements confirmed the porosity of the CAU-64 compounds and sorption capacities up to 360 mg/g were found. Furthermore, the synthesis of multivariate MOFs (Alx-Fe1-x-CAU-64) enabled the fine-tuning of both thermal stability and sorption characteristics. Isostructural ; Glycolic acid ; Metal ; Chemistry ; Materials science ; Crystallography ; Crystal structure ; Organic chemistry ; Biology ; Lactic acid Thermal and Kinetic Analysis ; Metal-Organic Frameworks: Synthesis and Applications ; Solid-state spectroscopy and crystallography
Authors: Tersilla Virgili | Lucia Ganzer | Benedetta Maria Squeo | Arrigo Calzolari | Mariacecilia Pasini
Source: Molecules (article, 2024-06-03)
Field: Materials Science — Materials Chemistry

Interplay between Theory and Photophysical Characterization in Symmetric α-Substituted Thienyl BODIPY Molecule 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based molecules have emerged as interesting materials for optoelectronic applications due to the possibility to easily fine-tune their photophysical and optical properties, dominated by two main absorption bands in the visible range. However, no studies have been reported on the nature of these spectral features. By means of ultrafast spectroscopy, we detect intramolecular energy transfer in a spin-coated film of di-thieno-phenyl BODIPY (DTPBDP) dispersed in a polystyrene matrix after pumping the high-energy absorption band. The same effect is not present upon pumping the lowest-energy band, which instead allows the achievement of efficient amplified spontaneous emission. Density functional calculations indicate the different nature of the two main absorption bands, explaining their different photophysical behavior. BODIPY ; Intramolecular force ; Absorption (acoustics) ; Photochemistry ; Materials science ; Density functional theory ; Molecule ; Characterization (materials science) ; Absorption spectroscopy ; Spectroscopy ; Fluorescence ; Chemical physics ; Optoelectronics ; Molecular physics ; Chemistry ; Computational chemistry ; Nanotechnology ; Optics ; Physics ; Organic chemistry Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Organic Electronics and Photovoltaics
Authors: Guillem Seychal | Bernard Miranda Campos | Gabriel Perli | Vincent Placet | Bruno Grignard | Fanny Bonnet | Christophe Detrembleur | Haritz Sardón | Nora Aranburu | Jean‐Marie Raquez
Source: ChemRxiv (preprint, 2024-12-18)
Field: Materials Science — Polymers and Plastics

Implementing recyclable bio- and CO2-sourced synergetic dynamic matrices via precise control of curing and properties for natural fiber composites within industrially relevant resin transfer molding Natural Fiber Composites (NFCs) offer significant environmental benefits. However, the use of thermoset matrices presents major challenges since they are oil-based, non-recyclable, and require energy-intensive curing processes, which diminishes their sustainability. Various proposed alternatives, particularly sustainable, dynamic matrices, have limited industrial applicability as they often lack the appropriate curing kinetics and viscosity needed for conventional composite processing techniques, such as Resin Transfer Molding (RTM). CO2-derived polyhydroxyurethanes (PHUs) show promise as NFC matrices but are hampered by poor processability and complex workup procedures, confining them mainly to laboratory settings. This study explores a synergetic copolymerization strategy that combines epoxy and PHU to allow fine-tuned polymerization kinetics and, thus, suitability for the RTM process. We demonstrate a synergetic catalytic effect that accelerates curing compared to each neat component. The formulation maintains a low viscosity (<5 Pa.s) at room temperature while curing within 30 minutes at 80°C—unattainable conditions with pure PHUs. The RTM-made composite achieves a fiber volume fraction of 58-60% and a porosity below 1%, making it ideal for high-quality NFCs. Moreover, the catalyst-free dynamic matrix allows the reshaping after curing, and flax fibers can be easily separated without toxic reagents from the polymer under mild conditions (60°C for 2 hours) and reused, retaining properties similar to those of virgin yarns. This strategy could broaden the application of PHU chemistry in sustainable NFC manufacturing while preserving both natural and fossil feedstock. Curing (chemistry) ; Composite material ; Transfer molding ; Materials science ; Molding (decorative) ; Mold Natural Fiber Reinforced Composites ; biodegradable polymer synthesis and properties ; Polymer composites and self-healing
Authors: Andreas Schmidt | Julia Rienmüller | Florian Weigend | Stefanie Dehnen
Source: Angewandte Chemie (article, 2024-10-08)
Field: Chemistry — Inorganic Chemistry

Affecting Charges and Structures of {Bi<sub>6</sub>} Architectures by 12‐Electron Transition Metal Fragments Abstract Molecules based on polyatomic bismuth substructures are currently attracting a lot of attention owing to this heavy and essentially non‐toxic element's uncommon chemical and physical properties, which include unprecedented bonding properties. Hexaatomic {Bi 6 } substructures that underly more complex cluster structures were recently reported to adopt different structures or exhibit different structural details as a consequence of the charge of the {Bi 6 } unit. This leads to either crown‐shaped cycles for a nominal Bi 6 6− or differently distorted trigonal prisms for compositions close to Bi 6 2− . It was predicted by quantum chemistry that Bi 6 4− should adopt a distinctly distorted boat‐like shape, yet a corresponding compound has remained elusive. Here, we report a proof of this assumption by the synthesis of [K(crypt‐222)] 2 [Bi 6 {Zn(hmds)} 2 ] ⋅ 1.5THF ( 1 ), comprising a bimetallic [Bi 6 {Zn(hmds)} 2 ] 2− cluster that fulfills the prediction for the geometric and electronic structure of the missing link (crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo‐[8.8.8]hexa‐cosane, hmds=hexamethyldisilazanid). A detailed quantum chemical study shows how the nature of Lewis‐acidic transition metal complexes—in particular, 12‐electron fragments—control and fine‐tune the resulting {Bi 6 } architectures in accordance with the degree of electron‐withdrawal from the polybismuthide core. Chemistry ; Bismuth ; Electron counting ; Transition metal ; Bimetallic strip ; Crystallography ; Molecule ; Cluster (spacecraft) ; Chemical physics ; Electron ; Nanotechnology ; Metal ; Computational chemistry ; Materials science ; Organic chemistry ; Physics Synthesis and characterization of novel inorganic/organometallic compounds ; Inorganic Chemistry and Materials ; Inorganic Fluorides and Related Compounds
Authors: Siddharth Pratap Singh | Amar Bahadur Verma | Ankur Srivastava | Kamlesh K. Chaurasiya | Anil Kumar | Prashant Kumar Singh | Sindhu Singh
Source: THE SCIENTIFIC TEMPER (article, 2024-06-15)
Field: Materials Science — Materials Chemistry

Design, structural, and electrical conduction behavior of Zr-modified BaTiO3-BiFeO3 perovskite ceramics This study employs the solid-state reaction method to synthesize [(Ba0.7 Bi0.3) (Ti0.7-y Zry) Fe0.3] O3 (y = 0.0, 0.2, 0.3, 0.4, 0.6) for investigating their structural and DC conduction behavior. XRD analysis suggests a perovskite phase for all the compositions having a cubic crystal structure. Initially, average crystallite size increases for y ≥ 0.3 and then decreases for y = 0.4. The temperature-dependent DC electrical conductivity demonstrated the semiconducting nature for all the compositions. The introduction of Zr modifies the material’s structure and electrical properties evident in the observed variations in crystallite size and conductivity behavior. These findings contribute to the understanding of Zr-modified [(Ba0.7 Bi0.3) (Ti0.7-y Zry) Fe0.3] O3 ceramics, shedding light on their potential applications in semiconductor devices and solid-state electronics. The investigation underscores the importance of tailoring composition parameters for fine-tuning material characteristics, opening avenues for optimized utilization in electronic and energy-related technologies Perovskite (structure) ; Materials science ; Ceramic ; Thermal conduction ; Electrical conduction ; Composite material ; Mineralogy ; Crystallography ; Chemistry Ferroelectric and Piezoelectric Materials ; Multiferroics and related materials ; Dielectric materials and actuators
Authors: G. N. Dar | Arfat Firdous | S. Irfan | A. H. Pandith | Irfan Nazir | Khurshed A. Shah | Nisar Ali | Shazia Showket | Muzaffar Qadir Lone
Source: MatSci express. (article, 2024-07-28)
Field: Materials Science — Materials Chemistry

Synthesis and Characterization of CdS and Sr-Doped CdS Quantum Dots: Impedance Analysis for Nano-Tuned Electronic Applications This study reports the synthesis and comprehensive characterization of cadmium sulfide (CdS) and strontium-doped CdS quantum dots (QDs) using a straightforward chemical precipitation method. N, N-Dimethylformamide served as the stabilizing agent, while specific metal precursors facilitated the formation of the nanostructures. The incorporation of strontium into the CdS matrix aimed to enhance the electronic properties of the quantum dots. Energy Dispersive X-ray Analysis (EDAX) confirmed the successful doping of Sr into the CdS QDs. X-ray Diffraction (XRD) analysis verified the high-crystallinity of the synthesized quantum dots, with the mean crystal sizes determined to be 3.18 nm for pure CdS and 3.99 nm for Sr-doped CdS (2mM and 4mM concentrations). Impedance spectroscopy was utilized to study the frequency-dependent electrical properties of the QDs at room temperature, revealing significant variations in impedance with frequency. The results demonstrated that both pure and Sr-doped CdS QDs exhibit capacitive admittance, which is indicative of their potential application in nano-tuned electronic devices. The ability to fine-tune the resonant frequency by controlling the size and doping level of the quantum dots presents a significant advantage for their use in advanced electronic applications. The study highlights the promising application of CdS and Sr-doped CdS quantum dots in the development of high-performance, frequency-tunable nanoscale electronic devices. Quantum dot ; Doping ; Characterization (materials science) ; Nano- ; Materials science ; Optoelectronics ; Electrical impedance ; Nanotechnology ; Physics ; Composite material ; Quantum mechanics Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films
Authors: Abhishek Pareek | Muhammad Yasir Mehboob | Maciej Cieplak | Maciej Majdecki | Hubert Szabat | Krzysztof Noworyta | Piotr Połczyński | Maja Morawiak | Piyush Sindhu Sharma | Cina Foroutan‐Nejad | Przemysław Gaweł
Source: ChemRxiv (preprint, 2024-11-17)
Field: Chemistry — Organic Chemistry

Indoloindolizines: A New Class of Polycyclic Aromatic Materials from Design to Organic Field-Effect Transistor Applications The development of stable and tunable polycyclic aromatic compounds (PACs) is crucial for advancing organic optoelectronics. Conventional polycyclic aromatic hydrocarbons (PAHs), such as acenes, often suffer from poor stability due to photooxidation and oligomerization, which are linked to their frontier molecular orbital energy levels. To address these limitations, we have designed and synthesized a new class of π-expanded indoloindolizines by merging indole and indolizine moieties into a single polycyclic framework. Guided by the Glidewell-Lloyd rule—which predicts that in fused polycyclic systems, larger rings lose aromaticity in favor of smaller ones—we achieved precise modulation of the electronic structure by controlling the aromaticity of specific rings. Benzannulation at targeted positions allowed fine-tuning of the HOMO-LUMO gap, leading to distinct shifts in optoelectronic properties. We developed a scalable synthetic protocol to produce a wide range of π-expanded derivatives. The structural, electronic, and optical properties of these compounds were extensively characterized. Single-crystal X-ray diffraction confirmed their molecular structure, while theoretical calculations provided insights into the observed experimental trends. These indoloindolizines exhibit vivid colors and fluorescence across the visible spectrum, and enhanced stability against photooxidation. Reactivity studies demonstrated high regioselectivity in electrophilic substitutions, highlighting the indole-like behavior of these compounds and opening avenues for further functionalization. To showcase the practical utility of these materials, we fabricated organic field-effect transistors (OFETs) using the newly developed indoloindolizines, which revealed competitive performance with ambipolar charge transport properties. Overall, our work establishes indoloindolizines as a promising platform for the development of stable, tunable organic materials for optoelectronic applications. By leveraging rational molecular design guided by the Glidewell-Lloyd rule, we offer a new pathway for molecular innovation in organic electronics. Class (philosophy) ; Field (mathematics) ; Transistor ; Field-effect transistor ; Organic field-effect transistor ; Materials science ; Computer science ; Engineering ; Electrical engineering ; Mathematics ; Artificial intelligence ; Pure mathematics Synthesis and Reactivity of Heterocycles ; Synthesis and pharmacology of benzodiazepine derivatives ; Synthesis and Properties of Aromatic Compounds
Authors: Amit Kolhe | Vijaylaxmi Biradar
Source: International Journal of Scientific Research in Science and Technology (article, 2024-06-18)
Field: Chemistry — Spectroscopy

Versatile Chip-Scale Lasers : Bridging Near-Ultraviolet to Near-Infrared Spectra Narrow-linewidth lasers that are widely tunable in the visible spectrum are crucial for various applications such as quantum optics, optical clocks, and atomic and molecular physics. However, current laser systems are typically bulky and confined to laboratory settings, limiting their practical use beyond research environments. In this study, we introduce a chip-scale visible laser platform capable of producing tunable and narrow-linewidth lasers spanning from near-ultraviolet to near-infrared wavelengths. By leveraging micrometer-scale silicon nitride resonators and off-the-shelf Fabry–Pérot laser diodes, we achieve significant coarse tuning capabilities of up to 12.5 nm, coupled with mode-hop-free fine tuning up to 33.9 GHz. Remarkably, our lasers exhibit intrinsic linewidths as low as a few kilohertz. Additionally, our platform demonstrates impressive fine-tuning speeds of up to 267 GHz per microsecond, alongside fiber-coupled powers reaching up to 10 mW and typical side-mode suppression ratios surpassing 35 dB. These remarkable specifications of our chip-scale lasers rival those previously attainable only with large, state-of-the-art benchtop laser systems. This breakthrough positions our lasers as powerful tools poised to drive the next generation of visible-light technologies, enabling practical applications in various fields beyond the confines of traditional laboratory setups. Ultraviolet ; Bridging (networking) ; Laser ; Chip ; Optoelectronics ; Infrared ; Spectral line ; Materials science ; Scale (ratio) ; Near-infrared spectroscopy ; Optics ; Physics ; Computer science ; Telecommunications Spectroscopy and Laser Applications ; Solid State Laser Technologies ; Semiconductor Lasers and Optical Devices
Authors: Shinichi Nishihaya | Malcolm J. A. Jardine | Hadass S. Inbar | Aranya Goswami | Jason T. Dong | Aaron N. Engel | Yu-Hao Chang | Connor P. Dempsey | Makoto Hashimoto | Dong-Hui Lu | Noa Marom | C. J. Palmstrøm
Source: arXiv (Cornell University) (preprint, 2024-12-16)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Near-half-metallic state in the half Heusler PtMnSb film on a III-V substrate The interplay between half-metallic ferromagnetism and spin-orbit coupling within the inversion symmetry-broken structure of half Heuslers provides an ideal platform for various spintronics functionalities. Taking advantage of good lattice matching, it is highly desired to epitaxially integrate promising Heuslers into III-V semiconductor-based devices. PtMnSb is one of the first half Heuslers predicted to be an above-room-temperature half-metal with large spin orbit coupling, however, its half-metallicity and potential as a spintronics material has remained elusive due to lack of high quality samples. Here we demonstrate epitaxial growth of single crystal PtMnSb(001) film on GaSb(001) substrates using molecular beam epitaxy. Direct observation of the band structure via angle-resolved photoemission spectroscopy and many-body perturbation theory within the quasiparticle self-consistent GW approximation (QPGW) reveal that PtMnSb hosts rather a near-halfmetallic state with both spin bands crossing the Fermi level and with high spin polarization over 90%. Temperature dependence of magnetization also shows an anomalous enhancement below 60 K, which can be associated with the development of such a near-half-metallic state at low temperatures. Epitaxial growth of high crystalline PtMnSb on a III-V paves the way for systematic clarification of its spin transport properties with fine-tuning of strain in heterostructure devices. Substrate (aquarium) ; Materials science ; State (computer science) ; Condensed matter physics ; Metal ; Metallurgy ; Physics ; Geology ; Computer science Heusler alloys: electronic and magnetic properties ; 2D Materials and Applications ; Topological Materials and Phenomena