jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Emine Gül Cansu Ergun
Source: Süleyman Demirel Üniversitesi Fen Edebiyat Fakültesi Fen Dergisi (article, 2019-05-22)
Field: Materials Science — Polymers and Plastics

Synthesis and Characterization of an Electrochromic Copolymer Film Bearing Two Different Donor-Acceptor-Donor Type Electrochromes Two donor-acceptor-donor type monomers (EC and TB) were selected to grow a copolymer via electrochemical techniques. EC monomer contains 3,4-ethylenedioxythiophene as the donor and carbazole as the acceptor units, while TB monomer includes thiophene and benzothiadiazole as the donor and the acceptor, respectively. The resulting copolymer film was investigated in terms of its electrochemical and optical properties and compared with the homopolymers of EC and TB. The copolymer film exhibited different electrochromic properties from their corresponding homopolymers. The neutral state faded-orange color of the polymer of EC and magenta color of the polymer of TB possesed a brownish color of the copolymer in the neutral state, with having a broader absorption band in the visible region by covering the characteristic absorption bands coming from both homopolymers. The physico-chemical properties, energy gaps, optical contrasts and coloring efficiencies for the homopolymers and for copolymer were systematically studied. Copolymer ; Electrochromism ; Monomer ; Materials science ; Acceptor ; Carbazole ; Thiophene ; Polymer chemistry ; Polymer ; Photochemistry ; Electrochemistry ; Chemistry ; Organic chemistry ; Physical chemistry ; Electrode Conducting polymers and applications ; Transition Metal Oxide Nanomaterials ; Organic Electronics and Photovoltaics
Authors: Glynis L. Coyne
Source: eScholarship (California Digital Library) (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

Efforts Towards the Synthesis of Ceylonamide A via a Stereocontrolled Polyene Cyclization This thesis describes efforts made towards the synthesis of ceylonamide A via a stereocontrolled cationic polyene cyclization. Chapter 1 provides background on the ceylonamide family of natural products and reviews the use of cationic polyene cyclizations as a general synthetic approach. This chapter reviews a particular cyclization methodology recently reported by the Vanderwal group which allows for a new mode of access to specific polycyclic structural motifs. A novel application of this technology is proposed towards the synthesis of the bioactive diterpene ceylonamide A.Chapter 2 discusses the efforts made towards the synthesis of ceylonamide A. The preparation of a key intermediate and attempts to carry out the desired cyclization are described. In addition, control studies to investigate the confounding factors of this cyclization are detailed, along with the synthesis of the substrates utilized in each experiment. Polyene ; Diterpene ; Cationic polymerization ; Chemistry ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry Synthetic Organic Chemistry Methods ; Synthesis and Biological Activity
Authors: プルネンス プシュパナンダン
Source: Kyushu University Institutional Repository (QIR) (Kyushu University) (article, 2019-09-25)
Field: Materials Science — Materials Chemistry

Studies on Synthesis, Structure, and Properties of Metal Coordinated N-Confused Calixphyrin Analogues. Metal ; Chemistry ; Materials science ; Metallurgy Porphyrin and Phthalocyanine Chemistry ; Supramolecular Chemistry and Complexes
Authors: Jing Zuo
Source: UvA-DARE (University of Amsterdam) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Structure design and applications of upconversion nanoparticles Lanthanide (Ln3+) doped upconversion nanoparticles (UCNPs) have displayed attractive potentiality in numerous fields such as solar cells, biology, display, anti-counterfeiting due to their unique luminescence property of converting near-infrared (NIR) photons to ultraviolet (UV) or visible (VIS) photons. To further promote the practical applications of UCNPs, enhancing the UC efficiency is therefore regarded as one of the most important goals in the UCNPs-related fields. In this aspect a thorough comprehension of the UC process is of great necessity. With traditional analysis methods based on the rate equations it is difficult to obtain a distinct microscopic picture on the role of excitation migration in UC process since they primarily focus on the interactions just between sensitizer and activator. This thesis describes the exploration of UC dynamic processes by quantitatively considering the influence of energy migration from sensitizer to sensitizer. By integrating Monte Carlo simulations with spectroscopic studies and nanostructure designs, we have unraveled the significant role of the excitation migration process in UC. On the basis of this improved picture, we have designed “dopant ions spatial separation” (DISS) structures to precisely tune the rise and decay behaviors of the UC emission over a broad time range. We also designed novel structures, i.e., NaErF4@NaYF4 and its derivatives to realize a relatively efficient UC with advanced properties. The intensive UC luminescence of Er3+-rich nanosystem breaks the concentration quenching limit and provides a new possibility for realizing highly efficient UC as well as more promising applications. Photon upconversion ; Luminescence ; Dopant ; Lanthanide ; Nanotechnology ; Photon ; Nanoparticle ; Materials science ; Nanostructure ; Excitation ; Fluorescence ; Ion ; Chemistry ; Computer science ; Doping ; Optoelectronics ; Physics ; Optics Luminescence Properties of Advanced Materials ; Radiation Detection and Scintillator Technologies ; Advanced Semiconductor Detectors and Materials
Authors: Marcelo A. Muñoz | María-Paz Orellana | Daniela Poblete
Source: Journal of the Chilean Chemical Society (article, 2019-06-01)
Field: Chemistry — Spectroscopy

A SINGLE COLUMN CHIROPTICAL HPLC BATCH ANALYSIS OF TEN AROMATIC ALCOHOLS The HPLC chiral resolution of ten chiral aromatic alcohols were screened using six different polysaccharides-based chiral stationary phases (CSP) and under four normal phase conditions, using UV absorbance as detection. The screening showed that all compounds can be baseline resolved in at least one of the tested conditions, being the cellulose-methylbenzoate CSP the one with the best performance by resolving the full set. Furthermore, the use of two chiroptical detectors, based in optical rotation and electronic circular dichroism, permitted the ascertain of the elution order for each of the baseline separations. Finally, several options for a single-column batch analysis, in which samples of all compounds are tested for enantiomeric excess and absolute configuration, are proposed to analyze samples from the asymmetric reduction of the corresponding ketones. These options vary in the number of injections, analysis time and reliability, and their choice will mostly depend on the hardware and standards availability. Optical rotation ; Enantiomer ; Chemistry ; Circular dichroism ; Chromatography ; Absorbance ; Specific rotation ; Elution ; Chiral column chromatography ; High-performance liquid chromatography ; Resolution (logic) ; Cellulose ; Chiral stationary phase ; Enantiomeric excess ; Absolute configuration ; Analytical Chemistry (journal) ; Organic chemistry ; Stereochemistry ; Enantioselective synthesis ; Computer science Analytical Chemistry and Chromatography ; Molecular spectroscopy and chirality ; Chromatography in Natural Products
Authors: Christopher John | Greg M. Swain | Robert P. Hausinger | Denis A. Proshlyakov
Source: ChemRxiv (preprint, 2019-08-12)
Field: Chemistry — Inorganic Chemistry

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD 2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an &lt;i&gt;in situ&lt;/i&gt; structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations. Redox ; Dioxygenase ; Chemistry ; Heme ; Ferric ; Active site ; Carboxylate ; Shewanella oneidensis ; Ferrous ; Moiety ; Photochemistry ; Catalytic cycle ; Stereochemistry ; Catalysis ; Inorganic chemistry ; Enzyme ; Organic chemistry Metal-Catalyzed Oxygenation Mechanisms ; Microbial metabolism and enzyme function ; Hemoglobin structure and function
Authors: Erik Nykwest
Source: OpenCommons at University of Connecticut (University of Connecticut) (article, 2019-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Coercing Magnetism into Diamagnetic Ceramics: A Case Study in Alumina Ceramics are very diverse class of materials whose properties can vary greatly. It is this diversity that make ceramics so useful in advanced technology. The relatively open crystal structure of ceramics makes it possible to impart functionalities via judicious doping. This work focuses on developing a generalized method for introducing magnetism into normally non-magnetic (diamagnetic) ceramics, using the example case of alumina (Al2O3). Here, substitutional doping of Al atoms with 3d transition metal in α- and θ-alumina was studied. Density functional theory was used to predict the structural, electronic, and magnetic properties of doped alumina, as well as its stability. The results show that adding small concentrations of transition metals to alumina may increase magnetic activity by generating unpaired electrons whose net magnetic moments may couple with external magnetic fields. The dopant species and dopant coordination environment are the most important factors in determining the spin density distribution (localized or delocalized from the dopant atom) and net magnetic moment, which strongly direct the ability of the doped alumina to couple with an external field. Our findings show conclusively that significant spin delocalization can only occur in α- alumina when there are unpaired electrons in the transition metal eg states. Similar coordination environments in different phases produce similar spin densities and magnetic moments, indicating that the results presented in this work may be generalizable to the other five or more metastable phases of alumina not studied here. The results of our slab studies indicate that if originally introduced into the bulk all of the dopant except for Fe and Co will remain there, or diffuse further into the bulk. This work serves as a template for determining promising dopants that may induce magnetism in other diamagnetic ceramics. Such doping may aid in the creation of an advanced, high strength, chemically resistant, dilute magnetic semiconductor oxides for use in advanced systems for spintronics or magnetic qubit systems, and decrease the difficulty of magnetoforming the gain structure of such diamagnetic ceramics. Diamagnetism ; Magnetism ; Ceramic ; Materials science ; Condensed matter physics ; Metallurgy ; Physics ; Magnetic field ; Quantum mechanics Magnetic Properties of Alloys ; Magnetic Bearings and Levitation Dynamics ; Material Selection and Properties
Authors: Shashini M. Premathilaka
Source: ScholarWorks@BGSU (Bowling Green State University) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Synthesis and Optical Properties of Colloidal PbS Nanosheets Colloidal semiconductor nanocrystals are emerging materials for next-generation optoelectronic devices including solar cells and light-emitting diodes (LEDs). Colloidal quantum dots have been developed in the past decades to make solar cells and LEDs with decent efficiencies. However, their performances are limited by low conductivity. To address this problem, two-dimensional nanosheets (also known as nanoplatelets, quantum-belts or nanoribbons) have been developed recently. They have a much higher conductivity than quantum-dot films and tunable optical properties. The new method is developed for the synthesis of colloidal PbS nanosheets with a 100% success rate. We confirmed that residual acetate in the reaction mixture influence for the formation of colloidal nanosheets. Therefore, we have introduced an acetate-free method. The energy gap of the nanosheet is mainly determined by its thickness while the lateral size of the nanosheet has a significant effect on its conductivity, electronic coupling with other materials and the rate of light emission. Therefore, tuning the lateral size of the nanosheet is critical for its application in functional devices. Our work has addressed the challenge of tuning the lateral size of colloidal PbS nanosheets by changing reaction parameters, reducing the Pb to S molar ratio, using long-chain chloroalkane and changing the concentration of chloroalkane. Nanosheets with a small lateral size called nanoplatelets to show a narrow light-emission linewidth around 70 mev and an exciton peak. The platelets have a square shape with a typical width and length 20 nm. The exciton binding energy derived from the absorption spectrum is about 25 meV. Efficient electron transfer from photoexcited electrons from colloidal PbS nanosheets to TiO2 nanoparticles is demonstrated. This transfer occurred faster than compared to quantum dots. This will be more useful for fabricating future solar cell devices. Colloid ; Materials science ; Nanotechnology ; Chemical engineering ; Engineering Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films
Authors: Bertrand Heidinger
Source: theses.fr (ABES) (article, 2019-11-27)
Field: Materials Science — Materials Chemistry

Reactive grinding synthesis of (La,Sr,Ce)(Mn,Fe,Co)O3 perovskites : Caracterisation and catalytic properties for the toluene total oxidation reaction Des matériaux de type pérovskite ABO3 (A : La ; B : Mn, Fe, Co) ont été synthétisés par une méthode originale de broyage réactif, qui possède l’avantage d’être très simple à mettre en œuvre, peu coûteuse et n’implique que peu ou pas de solvant. La synthèse a été réalisée en trois étapes successives : (i) une calcination à haute température permettant l’obtention de la structure pérovskite à partir des oxydes simples respectifs ; (ii) un broyage haute énergie permettant une réduction de la taille de domaine cristallin (Dc), de l’ordre micrométrique à nanométrique, par fractionnement ; (iii) un broyage à basse énergie permettant l’augmentation de surface spécifique par désagglomération des particules. Les matériaux obtenus après ces trois étapes ont montré des tailles de cristallites réduites (Dc ~10-20 nm), une surface spécifique raisonnable (respectivement 10, 19 et 20 m2·g−1 pour LaMnO3,15, LaFeO3 et LaCoO3) ainsi qu’une réductibilité du site B accrue. L’amélioration des propriétés texturales et redox des matériaux conduit à une amélioration significative des performances catalytiques vis-à-vis de la réaction d’oxydation totale du toluène. La composition LaCoO3 a présenté les meilleurs résultats et cette formulation a ensuite été utilisée comme base pour évaluer l’impact de la substitution du site A par le strontium ou le cérium : La1-xSrxCoO3 (x = 0,05–0,40) et La1-xCexCoO3 (x = 0,01–0,20). Les matériaux substitués ont montré des propriétés texturales similaires et des propriétés catalytiques supérieures à la référence non substituée (LaCoO3), avec un optimum observé pour La0.8Sr0.2CoO3 et La0.99Ce0.01CoO3. Pour La1-xCexCoO3, seule une faible quantité de cérium peut être insérée dans la structure, une phase secondaire CeO2 se formant au-delà et empoisonnant le catalyseur. Dans le cas de La1-xSrxCoO3, l’incorporation du strontium est complète, induisant : (i) un désordre structural localisé permettant une meilleure mobilité de l’oxygène, ainsi que (ii) une modification importante de la réductibilité du cobalt, allant jusqu’à sa réduction totale à basse température pour les plus fortes teneurs en strontium. Catalysis ; Calcination ; Redox ; Heterogeneous catalysis Catalytic Processes in Materials Science ; Advancements in Solid Oxide Fuel Cells ; Iron and Steelmaking Processes
Authors: Sabine Alsaoub
Source: Dokumentenrepositorium der RUB (Ruhr University Bochum) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Synthesis of stable Os-complex modified polymers for the applications in biosensors, biofuel cells and biosupercapacitors Die vorliegende Arbeit beschreibt die Synthese von Os-Komplex modifizierte Redoxpolymeren, die spektroskopisch und elektrochemisch charakterisiert wurden. Die Polymere konnten in Biobrennstoffzellen, Biosuperkondensatoren und amperometrische Biosensoren eingesetzt werden. Das Redoxpotential der Polymere konnte durch Modifizierung der Ligandensphäre der Os-Komplex gezielt eingestellt werden. Zudem konnten die Eigenschaften der Polymere durch Wahl geeigneter Monomere hinsichtlich Hydrophilie, Quellverhalten und Löslichkeit beeinflusst werden. Die Polymere konnten für die Darstellung eines Nernst-Biosuperkondensators sowie für den ersten intrinsischen Biosuperkondensator, der rein auf Redoxpolymer/Enzym Elektroden basiert, verwendet werden. Die Modifizierung von Benzoxazin basierten Monomeren mit Os-Komplexen ermöglichte die elektrochemisch induzierte Ko-Abscheidung zusammen mit Glucose Oxidase. Diese Elektroden konnten für die amperometrische Detektion von Glukose eingesetzt werden. Chemistry ; Polymer chemistry ; Glucose oxidase ; Biosensor ; Biochemistry Polyoxometalates: Synthesis and Applications ; Chemical Synthesis and Reactions ; biodegradable polymer synthesis and properties
Authors: Yanqiong Yang
Source: Institutional Repositories DataBase (IRDB) (article, 2019-09-25)
Field: Chemistry — Organic Chemistry

Synthesis and Functions of New Block Copolymers Possessing Dense Triazole Blocks Moieties 1 1-2.Huisgen Reaction to Copolymer ; Block (permutation group theory) ; Computer science ; Materials science ; Mathematics ; Polymer ; Combinatorics ; Composite material Synthesis of Tetrazole Derivatives
Authors: Mary Allison Kelly
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-12)
Field: Materials Science — Materials Chemistry

Fundamental Studies of Ternary Blends for Bulk heterojunction Solar Cells Organic photovoltaics have risen to prominence in the last twenty-five years, with efficiencies broaching 12 %, but the inherent limitation of a narrow absorption window has restricted the performance of these solar cells. Ternary blends offer an attractive solution to this conundrum: combining the extended complementary absorption of a tandem solar cell with the ease of single-junction fabrication. Parallel-like bulk heterojunctions (PBHJ) not only exhibit improved current, but a tunable voltage, which is a promising development. However, the development of such ternary blends is still largely an empirical process. In this dissertation, we investigate the guidelines for material selection for ternary blend solar cells. We begin by ascertaining the importance of backbone structure for compatibility in PBHJ OPVs. It immediately becomes clear that to obtain a working PBHJ, a common donor moiety is required in the polymer backbone. We build on this by comparing the performance and behavior of a physically fluorinated vs. chemically fluorinated system. In this case, the characteristics of both blends are nearly identical, indicating that compatible, miscible polymers will behave similarly to their random copolymer. Additionally, this study highlighted that the addition of a high mobility polymer into a PBHJ can improve the hole mobility and fill factor. Finally, we used these guidelines to selected high performance polymers for use in PBHJs and tested their behavior. Interestingly, with these polymers, the behavior of the physical blend differed significantly from that of the copolymer, demonstrating the complexity of ternary blends. What is true of one materials system may not hold for another. Ternary operation ; Materials science ; Engineering physics ; Physics ; Computer science Chemical and Physical Properties of Materials ; Organic Electronics and Photovoltaics ; solar cell performance optimization
Authors: Meenakshi | Ajeet Kumar Kushwaha | Avadhesh Pratap Singh | Raj Kumar Dubey
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2019-11-01)
Field: Chemistry — Organic Chemistry

Aluminium(III) derivatives of N and O chelating ligands: Preparation, spectral [IR (1H, 13C and 27Al) NMR] and mass studies Synthetic Inorganic and Metallo-organic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttrar Pradesh, India Department of Chemistry, Kamala Nehru Institute of Physical and Social Sciences, Sultanpur-228 118, Uttar Pradesh, India <em>E-mail</em>: avadheshchem@ymail.com <em>Manuscript received online 11 April 2018, revised and accepted 20 September 2019</em> Reaction of Al(OPr<sup>i</sup> )<sub>3</sub> with 2-(o-hydroxy phenyl)-benzimidazole (pbmzH) and 2-(o-hydroxy phenyl)-benzothiazole (pbtzH) in different molar ratio in benzene solution afforded complex of the types [(µ-OPr<sup>i</sup> )Al2 (pbmz)<sub>2</sub> (OPr<sup>i</sup> )<sub>2</sub> ] 1, [Al(OPr<sup>i</sup> )(pbmz)<sub>2</sub> ] 2, [Al(pbmz)<sub>3</sub> ] 3, [(µ-OPr<sup>i</sup> )Al<sub>2</sub> (pbtz)<sub>2</sub> (OPr<sup>i</sup> )<sub>2</sub> ] 4, [Al(OPr<sup>i</sup> )(pbtz)<sub>2</sub> ] 5 and [Al(pbtz)<sub>3</sub> ] 6. All these white to creamy white solid complexes are soluble in common organic solvents (such as C<sub>6</sub> H<sub>6</sub> , CCl<sub>4</sub> , n-hexane, DMSO, DMF etc.) and were characterized by elemental (C, H, N and Al) analysis as well as spectral [IR (<sup>1</sup>H, <sup>13</sup>C and <sup>27</sup>Al) NMR] and mass studies. On the basis of these spectroscopic data a plausible structure tentatively has been proposed for these complexes. Chelation ; Carbon-13 NMR ; Aluminium ; Chemistry ; Proton NMR ; Stereochemistry ; Organic chemistry Inorganic and Organometallic Chemistry ; X-ray Diffraction in Crystallography ; Metal complexes synthesis and properties
Authors: 壮一郎 赤木
Source: Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) (article, 2019-03-25)
Field: Materials Science — Materials Chemistry

A Study on the Excited Triplet States of Octahedral Hexamolybdenum(II) Clusters Excited state ; Octahedron ; Physics ; Crystallography ; Chemistry ; Atomic physics ; Crystal structure Nanocluster Synthesis and Applications ; Metalloenzymes and iron-sulfur proteins ; Magnetism in coordination complexes
Authors: César Moreno
Source: DIGITAL.CSIC (Spanish National Research Council (CSIC)) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Atomically-precise graphene architectonics: 0D dots, 1D ribbons and 2D porous grapehne Resumen del trabajo presentado al 5th Muju International Winter School Series (MIWS2), celebrado en la República de Korea del 20 al 24 de enero de 2019. Graphene ; Materials science ; Condensed matter physics ; Nanotechnology ; Physics Graphene research and applications ; Graphene and Nanomaterials Applications ; Supercapacitor Materials and Fabrication