jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Dmitry Tsymbarenko | Dimitry Grebenyuk | М. А. Бурлакова | A. S. Shurkina
Source: Russian Journal of Coordination Chemistry (article, 2022-03-01)
Field: Materials Science — Materials Chemistry

Tetranuclear Hydroxo Complexes of Rare-Earth Elements with the Cubane Core as Products of Self-Controlled Hydrolysis Abstract Tetranuclear hydroxo complexes [La 4 (Deta) 4 (OH) 4 (Tfa) 3 (DetadcH) 2 ](HTfa)(H 2 O) 7 (Tfa) 3 ( I ) and [Nd 4 (Deta) 4 (OH) 4 (Tfa) 3 (DetadcH) 2 ](H 2 O) n (Tfa) 3 ( II ) with diethylene- N , N ′-dicarbamate anions (DetadcH – ) are synthesized for the first time by the reactions of lanthanum trifluoroacetate and neodymium trifluoroacetate with a solution of diethylenetriamine (Deta) in air under the self-controlled hydrolysis conditions and are characterized by X-ray diffraction, powder X-ray diffraction, IR spectroscopy, and elemental analysis. Compounds I and II contain the same-type complex cationic fragment with the cubane metal–oxygen core stabilized due to four chelate Deta ligands and two bridging DetadcH – ligands. The DFT calculations of the geometry and vibrational spectrum of the [La 4 (Deta) 4 (OH) 4 (Tfa) 3 (DetadcH) 2 ] 3+ complex cation are performed. Chemistry ; Cubane ; Diethylenetriamine ; Hydrolysis ; Cationic polymerization ; Powder diffraction ; Elemental analysis ; Lanthanum ; Inorganic chemistry ; Infrared spectroscopy ; Crystallography ; Medicinal chemistry ; Polymer chemistry ; Organic chemistry ; Crystal structure Lanthanide and Transition Metal Complexes ; Magnetism in coordination complexes ; Radioactive element chemistry and processing
Authors: Chloe M. Taylor | Nathan L. Kilah
Source: Journal of Inclusion Phenomena and Macrocyclic Chemistry (article, 2022-03-31)
Field: Chemistry — Physical and Theoretical Chemistry

Synthesis of [2+2] Schiff base macrocycles by a solvent templating strategy and halogen bonding directed assembly Abstract Schiff base imine condensations are a useful tool for macrocycle synthesis and applications within supramolecular chemistry. Here we address the mixtures of products that can arise from template free synthesis using dicarbonylheterocycles and diamines, and look to develop metal-free template methods for selective macrocycle formation. A range of alkyl α,ω-diamines were combined with phenanthroline and pyridine heterocyclic dicarbaldehydes under standard literature conditions. The reaction conditions were modified to demonstrate a relationship between choice of solvent and product equilibria. It was observed that benzene and toluene could shift a mixture of products and unreacted starting materials to form predominantly one imine product for a number of systems. Once the macrocyclic products had been characterized in selected solvents, iodinated halogen bonding guest molecules were added to direct macrocycle assemblies using non-covalent interactions. Studies to investigate host – guest suitability and halogen bond interactions were conducted, and it was found that tetraiodoethylene had an influence on the formation of a phenanthroline based macrocycle. Proof of concept experiments were performed to show the influence of the guest molecule, tetraiodoethylene, on the macrocyclic products formed under competitive dynamic combinatorial chemistry conditions. Chemistry ; Imine ; Supramolecular chemistry ; Pyridine ; Halogen bond ; Alkyl ; Combinatorial chemistry ; Molecule ; Schiff base ; Solvent ; Halogen ; Polymer chemistry ; Covalent bond ; Organic chemistry ; Catalysis Crystallography and molecular interactions ; Supramolecular Chemistry and Complexes ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Meinan Wan | Mo Xiong | Shouqin Tian | Xingzhu Chen | Zhong‐Yuan Lu | Xuesong Lu | Xiujian Zhao
Source: Materials (article, 2022-12-26)
Field: Materials Science — Polymers and Plastics

Modulation of Structure and Optical Property of Nitrogen-Incorporated VO2 (M1) Thin Films by Polyvinyl Pyrrolidone VO<sub>2</sub>, as a promising material for smart windows, has attracted much attention, and researchers have been continuously striving to optimize the performance of VO<sub>2</sub>-based materials. Herein, nitrogen-incorporated VO<sub>2</sub> (M1) thin films, using a polyvinylpyrrolidone (PVP)-assisted sol-gel method followed by heat treatment in NH<sub>3</sub> atmosphere, were synthesized, which exhibited a good solar modulation efficiency (<i>ΔT<sub>sol</sub></i>) of 4.99% and modulation efficiency of 37.6% at 2000 nm (<i>ΔT<sub>2000 nm</sub></i>), while their visible integrated transmittance (<i>T<sub>lum</sub></i>) ranged from 52.19% to 56.79% after the phase transition. The crystallization, microstructure, and thickness of the film could be regulated by varying PVP concentrations. XPS results showed that, in addition to the NH<sub>3</sub> atmosphere-N doped into VO<sub>2</sub> lattice, the pyrrolidone-N introduced N-containing groups with N-N, N-O, or N-H bonds into the vicinity of the surface or void of the film in the form of molecular adsorption or atom (N, O, and H) filling. According to the Tauc plot, the estimated bandgap of N-incorporated VO<sub>2</sub> thin films related to metal-to-insulator transition (<i>E<sub>g</sub></i><sub>1</sub>) was 0.16-0.26 eV, while that associated with the visible transparency (<i>E<sub>g</sub></i><sub>2</sub>) was 1.31-1.45 eV. The calculated <i>E<sub>g</sub></i><sub>1</sub> and <i>E<sub>g</sub></i><sub>2</sub> from the first-principles theory were 0.1-0.5 eV and 1.4-1.6 eV, respectively. The Tauc plot estimation and theoretical calculations suggested that the combined effect of N-doping and N-adsorption with the extra atom (H, N, and O) decreased the critical temperature (<i>τ<sub>c</sub></i>) due to the reduction in <i>E<sub>g</sub></i><sub>1</sub>. Materials science ; Nitrogen ; Thin film ; Polyvinyl acetate ; Modulation (music) ; Chemical engineering ; Polymer chemistry ; Composite material ; Chemistry ; Nanotechnology ; Polymer ; Organic chemistry Transition Metal Oxide Nanomaterials ; Gas Sensing Nanomaterials and Sensors ; Conducting polymers and applications
Authors: С. В. Кузнецов | S.A. Burikov | A.A. Fedyanina | E.A. Filippova | V. Yu. Proydakova | V.V. Voronov | N.Yu. Tabachkova | P.P. Fedorov | Tatiana A. Dolenko
Source: Nanosystems Physics Chemistry Mathematics (article, 2022-06-30)
Field: Materials Science — Materials Chemistry

Impact of sensitizer Yb and activator Tm on luminescence intensity of beta-NaYF4:Yb/Tm nanoluminophores In this study, the impact of sensitizer and activator ions concentration on the intensity of upconversion luminescence of nanoluminophores -NaYF 4 :Yb 3+ /Tm 3+ in dimethyl sulfoxide (DMSO) was investigated. Analysis of all luminescence spectral bands allows one to establish that the ratio of concentrations of ytterbium and thulium ions strongly effects on the luminescent properties of nanoluminophores. Increase of sensitizer concentration at constant activator concentration leads to an increase of the luminescence integral intensity. Optimal concentration of activators at fixed sensitizer concentration was determined: 2 mol.% for thulium and 18 mol.% for ytterbium. The sensitivity of each luminescence spectrum band to changes in the concentration of activators and sensitizers was explained by cross-relaxation processes in activator ions. KEYWORDS up-conversion luminescence, Activator (genetics) ; Ytterbium ; Luminescence ; BETA (programming language) ; Intensity (physics) ; Materials science ; Optics ; Chemistry ; Physics ; Doping ; Optoelectronics ; Computer science Luminescence Properties of Advanced Materials ; Inorganic Fluorides and Related Compounds ; Solid State Laser Technologies
Authors: Radostina Kalinova | Ivaylo Dimitrov
Source: Nanomaterials (article, 2022-01-27)
Field: Materials Science — Biomaterials

Triblock Copolymer Micelles with Tunable Surface Charge as Drug Nanocarriers: Synthesis and Physico-Chemical Characterization Polymeric micelles have gained increasing interest as efficient drug delivery systems for cancer treatment and diagnosis. The aim of the present study was to construct and to evaluate novel polymeric nanosized drug carriers with tunable surface charges. Initially, amphiphilic triblock copolymers with predetermined molar mass characteristics were synthesized by applying controlled polymerization techniques. The copolymers self-assembled in aqueous media into core-shell spherical micelles, comprising a biodegradable hydrophobic poly(D,L-lactide) core, positively charged middle layer of poly((2-dimethylamino)ethyl methacrylate), and an outer shell of neutral hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate), with various densities of the short polyether side chains. The block copolymer micelles with average diameters of about 70 nm and surface charges varying from strongly positive to neutral were characterized and loaded with the model, natural, hydrophobic drug curcumin. Characteristics such as drug loading efficiency, in-vitro drug release profiles, and stability under physiological conditions were evaluated and discussed in terms of nanocarriers' composition. As a result, the most promising candidates for potential application in nanomedicine were identified. Nanocarriers ; Copolymer ; Micelle ; Ethylene glycol ; Materials science ; Amphiphile ; Methacrylate ; Drug delivery ; Chemical engineering ; Polymer chemistry ; Polymerization ; Nanomedicine ; Aqueous solution ; Chemistry ; Nanotechnology ; Organic chemistry ; Nanoparticle ; Polymer ; Composite material Nanoparticle-Based Drug Delivery ; Advanced Polymer Synthesis and Characterization ; biodegradable polymer synthesis and properties
Authors: Justin Dubbert | Marco Valtolina | Alexander Huber | Tim D. Scherz | Christoph Wölper | Constantin G. Daniliuc | Ofer Filiba | Saumik Sen | Igor Schapiro | Fabio Rizzo | Jens Voskuhl
Source: ChemPhotoChem (article, 2022-08-25)
Field: Materials Science — Materials Chemistry

Tuning the Emission Behaviour of Halogenated Bridged Ethers in Solution, as Solids and as Aggregates by Chalcogen Substitution Abstract In this contribution, we describe a set of three chlorinated bridged ethers with varying numbers of sulfur and oxygen atoms. The substitution leads to highly emissive compounds with tunable photophysical properties in relationship to their state of aggregation, i. e. in solution, as aggregates and in the solid state. Additionally, an in‐depth X‐ray diffractometric analysis supported by a Hirshfeld study of non‐covalent interactions and quantum chemical simulations was carried out. As the outcome, it was found that the content of sulfur in the compounds regulates the tuning of emission in solution as well as in the aggregated states as a consequence of their variation of planarity. Chalcogen ; Planarity testing ; Sulfur ; Chemistry ; Substitution (logic) ; Aggregation-induced emission ; Covalent bond ; Solid-state ; Photochemistry ; Computational chemistry ; Crystallography ; Organic chemistry ; Physical chemistry Luminescence and Fluorescent Materials ; Molecular Sensors and Ion Detection ; Covalent Organic Framework Applications
Authors: Sriram Sundaresan | Marcel Diehl | Luca M. Carrella | Eva Rentschler
Source: Magnetochemistry (article, 2022-09-18)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Triggering of Valence Tautomeric Transitions in Dioxolene-Based Cobalt Complexes Influenced by Ligand Substituents, Co-ligands, and Anions We report the multistep synthesis of the 1,1′-(piperazine-1,4-diyl)bis(N,N-bis(pyridin-2-ylmethyl)methanamine)(Ltpbap) octadentate ligand, which, in combination with the known 3,5-di-tert-butylcatechol (3,5-dbcat), allowed the preparation of two di-nuclear cobalt complexes [Co2(Ltpbap)(3,5-dbcat)2](SO4)·5.5MeOH·2H2O (3a) and [Co2(Ltpbap)(3,5-dbcat)2 ](ClO4)2·1.5H2O (3b). We also report the synthesis of two mono-nuclear cobalt complexes [Co(3,5-dbsq)(3,5-dbcat)(4-Mepip)2] (1) with 4-Mepip being 4-methylpiperidine and (Hpip)[Co(tbcat)2(pip)2]·CH3CN (2) where Hpip denotes a piperidinium cation and tbcat is the tetra-bromocatechol ligand. The obtained complexes were characterized by single-crystal X-ray crystallography, SQUID magnetometry, and IR spectroscopy. The structure of the crystalline material in all the cases was determined at 173 K. The magnetic properties of all complexes were measured between 2 and 380 K. The magnetic data clearly show that mono-nuclear complex 1 and di-nuclear complex 3a exhibit valence tautomerism with onset around 300 K and 370 K, respectively, whereas the other two complexes 2 and 3b remain unchanged over the measured temperature range. Tautomer ; Piperazine ; Chemistry ; Cobalt ; Valence (chemistry) ; Ligand (biochemistry) ; Crystallography ; Magnetic susceptibility ; Crystal structure ; Stereochemistry ; Inorganic chemistry ; Organic chemistry Magnetism in coordination complexes ; Porphyrin and Phthalocyanine Chemistry ; Metal-Catalyzed Oxygenation Mechanisms
Authors: Alexis Hocken | Frederick L. Beyer | Jae Sang Lee | Bradley J. Grim | Husain Mithaiwala | Matthew Green
Source: Soft Matter (article, 2022-01-01)
Field: Materials Science — Polymers and Plastics

Covalently integrated silica nanoparticles in poly(ethylene glycol)-based acrylate resins: thermomechanical, swelling, and morphological behavior Nanocomposites integrate functional nanofillers into viscoelastic matrices for electronics, lightweight structural materials, and tissue engineering. Herein, the effect of methacrylate-functionalized (MA-SiO<sub>2</sub>) and vinyl-functionalized (V-SiO<sub>2</sub>) silica nanoparticles on the thermal, mechanical, physical, and morphological characteristics of poly(ethylene glycol) (PEG) nanocomposites was investigated. The gel fraction of V-SiO<sub>2</sub> composites decreases upon addition of 3.8 wt% but increases with further addition (>7.4 wt%) until it reaches a plateau at 10.7 wt%. The MA-SiO<sub>2</sub> induced no significant changes in gel fraction and both V-SiO<sub>2</sub> and MA-SiO<sub>2</sub> nanoparticles had a negligible impact on the nanocomposite glass transition temperature and water absorption. The Young's modulus and ultimate compressive stress increased with increasing nanoparticle concentration for both nanoparticles. Due to the higher crosslink density, MA-SiO<sub>2</sub> composites reached a maximum mechanical stress at a concentration of 7.4 wt%, while V-SiO<sub>2</sub> composites reached a maximum at a concentration of 10.7 wt%. Scanning electron microscopy, transmission electron microscopy, and small-angle X-ray scattering revealed a bimodal size distribution for V-SiO<sub>2</sub> and a monomodal size distribution for MA-SiO<sub>2</sub>. Although aggregates were observed for both nanoparticle surface treatments, V-SiO<sub>2</sub> dispersion was poor while MA-SiO<sub>2</sub> were generally well-dispersed. These findings lay the framework for silica nanofillers in PEG-based nanocomposites for advanced manufacturing applications. Materials science ; Nanocomposite ; Glass transition ; Nanoparticle ; Ethylene glycol ; Dynamic mechanical analysis ; Composite material ; Methacrylate ; Chemical engineering ; Acrylate ; Polymer ; Copolymer ; Nanotechnology Polymer Nanocomposites and Properties ; Polymer composites and self-healing ; biodegradable polymer synthesis and properties
Authors: Lansong Yue | Xiuyi Shi | Guofu Zhou | Laurens T. de Haan
Source: International Journal of Molecular Sciences (article, 2022-03-18)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Controlling the Phase Behavior and Reflection of Main-Chain Cholesteric Oligomers Using a Smectic Monomer Cholesteric liquid crystals (CLCs) are a significant class of temperature-responsive photonic materials that have the ability to selectively reflect light of a specific wavelength. However, the fabrication of main-chain CLC oligomers with dramatic reflection band variation upon varying the temperatures remains a challenge. Here, a feasible method for improving and controlling the responsiveness of main-chain cholesteric liquid crystal oligomers by the incorporation of a smectic monomer is reported. The smectic monomer strengthens the smectic character of the oligomers and enhances the magnitude of the change of the pitch as a function of temperature upon approaching the cholesteric-smectic phase transition temperature. The central wavelength of the reflection band can be easily modified by mixing in an additional chiral dopant. This promising method will open the door to the preparation of temperature-responsive photonic devices with excellent responsiveness. Cholesteric liquid crystal ; Monomer ; Materials science ; Reflection (computer programming) ; Dopant ; Liquid crystal ; Phase (matter) ; Wavelength ; Side chain ; Fabrication ; Doping ; Polymer ; Optoelectronics ; Chemistry ; Organic chemistry ; Composite material Liquid Crystal Research Advancements ; Photochromic and Fluorescence Chemistry ; Advanced Materials and Mechanics
Authors: Irene Alexandra Spiridon | Irina-Draga Căruntu | Iuliana Spiridon | Radu Brăescu
Source: Pharmaceutics (review, 2022-11-04)
Field: Materials Science — Biomaterials

Insight into Potential Biomedical Application of Mesoporous Materials The physicochemical properties of many drugs have a decisive impact on their bioavailability, as well as the pharmacokinetic efficiency in various disease therapeutics. That is why mesoporous materials have attracted a special interest in the drug delivery field, facilitating the loading of drugs into their pores due to their high surface area and porosity. The interfacial interactions established with drug molecules represent the driving force for efficient drug loading and controlled release kinetics. Moreover, these materials offer an optimal design for implantable local-delivery devices or for improving the accuracy of imaging techniques in clinical diagnosis. Their use is validated by improvements in therapeutic outcome and prevention of side effects. This review discusses the role of mesoporous materials in different biomedical applications. Drug delivery ; Mesoporous material ; Nanotechnology ; Bioavailability ; Controlled release ; Drug ; Materials science ; Medicine ; Chemistry ; Pharmacology Nanoparticle-Based Drug Delivery ; Mesoporous Materials and Catalysis ; Bone Tissue Engineering Materials
Authors: Lucie Petrásková | Kristýna Káňová | Katerina Brodsky | Anastasiia Hetman | Barbora Petránková | Helena Pelantová | Vladimı́r Křen | Kateřina Valentová
Source: International Journal of Molecular Sciences (article, 2022-05-20)
Field: Chemistry — Spectroscopy

Sulfated Phenolic Substances: Preparation and Optimized HPLC Analysis Sulfation is an important reaction in nature, and sulfated phenolic compounds are of interest as standards of mammalian phase II metabolites or pro-drugs. Such standards can be prepared using chemoenzymatic methods with aryl sulfotransferases. The aim of the present work was to obtain a large library of sulfated phenols, phenolic acids, flavonoids, and flavonolignans and optimize their HPLC (high performance liquid chromatography) analysis. Four new sulfates of 2,3,4-trihydroxybenzoic acid, catechol, 4-methylcatechol, and phloroglucinol were prepared and fully characterized using MS (mass spectrometry), <sup>1</sup>H, and <sup>13</sup>C NMR. The separation was investigated using HPLC with PDA (photodiode-array) detection and a total of 38 standards of phenolics and their sulfates. Different stationary (monolithic C18, C18 Polar, pentafluorophenyl, ZICpHILIC) and mobile phases with or without ammonium acetate buffer were compared. The separation results were strongly dependent on the pH and buffer capacity of the mobile phase. The developed robust HPLC method is suitable for the separation of enzymatic sulfation reaction mixtures of flavonoids, flavonolignans, 2,3-dehydroflavonolignans, phenolic acids, and phenols with PDA detection. Moreover, the method is directly applicable in conjunction with mass detection due to the low flow rate and the absence of phosphate buffer and/or ion-pairing reagents in the mobile phase. Sulfation ; Chemistry ; Chromatography ; High-performance liquid chromatography ; Phenols ; Phloroglucinol ; Ammonium acetate ; Mass spectrometry ; Caffeic acid ; Organic chemistry ; Biochemistry Analytical Chemistry and Chromatography ; Genomics, phytochemicals, and oxidative stress ; Phytochemicals and Antioxidant Activities
Authors: Kun Zhou | Li‐Ya Wang | Ruijie Wang | Chengyuan Wang | Chun Tang
Source: Materials (article, 2022-11-18)
Field: Materials Science — Materials Chemistry

One Dimensional Twisted Van der Waals Structures Constructed by Self-Assembling Graphene Nanoribbons on Carbon Nanotubes Twisted van der Waals heterostructures were recently found to possess unique physical properties, such as superconductivity in magic angle bilayer graphene. Owing to the nonhomogeneous stacking, the energy of twisted van der Waals heterostructures are often higher than their AA or AB stacking counterpart, therefore, fabricating such structures remains a great challenge in experiments. On the other hand, one dimensional (1D) coaxial van der Waals structures has less freedom to undergo phase transition, thus offer opportunity for fabricating the 1D cousin of twisted bilayer graphene. In this work, we show by molecular dynamic simulations that graphene nanoribbons can self-assemble onto the surface of carbon nanotubes driven by van der Waals interactions. By modifying the size of the carbon nanotubes or graphene nanoribbons, the resultant configurations can be controlled. Of particular interest is the formation of twisted double walled carbon nanotubes whose chiral angle difference can be tuned, including the 1.1° magic angle. Upon the longitudinal unzipping of such structures, twisted bilayer graphene nanoribbons can be obtained. As the longitudinal unzipping of carbon nanotubes is a mature technique, we expect the strategy proposed in this study to stimulate experimental efforts and promote the fast growing research in twistronics. van der Waals force ; Graphene ; Carbon nanotube ; Bilayer graphene ; Materials science ; Stacking ; Nanotechnology ; Chemical physics ; Bilayer ; Graphene nanoribbons ; Condensed matter physics ; Chemistry ; Physics ; Molecule ; Membrane Graphene research and applications ; Carbon Nanotubes in Composites ; Fullerene Chemistry and Applications