Search results for "Bromide"
showing 10 items of 591 documents
Synthesis of Quinoline-Based Anion Receptors and Preliminary Anion Binding Studies with Selected Derivatives
2014
Six quinoline-based anion receptors were designed, prepared, and characterized, among which the crystal structure of an indole derivative was obtained. Selected receptors were tested for the recognition of halide anions in solution and showed some selectivity of chloride over bromide and iodide.
Mixed Iodide-Bromide Methylammonium Lead Perovskite-based Diodes for Light Emission and Photovoltaics.
2015
Vacuum deposition techniques are used to prepare mixed iodide–bromide methylammonium lead perovskite diodes via an intermediate double layer of the pure iodide and bromide perovskites. The diodes lead to bright electroluminescence, whose emission spectra maxima shift from the infrared toward the visible with increasing bromide content. When illuminated with AM1.5 simulated sunlight the devices function as efficient solar cells with power conversion efficiencies as high as 12.9%.
Oxidative halogenation of substituted pyrroles with Cu(II). PartIII. Bromination and chlorination of 2-benzoylpyrrole
1992
The bromination of 2-benzoylpyrrole with copper(II) bromide in the homogeneous and the heterogeneous phase is described, giving 4- and 5-monobromo derivatives whose ratio decreases as the temperature is increased. The same reaction with copper(II) chloride in acetonitrile at 60° produces 5-chloro-2-benzoylpyrrole as the major product. 4,5-Dihalopyrroles in good yields are obtained with an excess of halogenating agent.
Reversible Solvent‐Exchange‐Driven Transformations in Multifunctional Coordination Polymers Based on Copper‐Containing Organosulfur Ligands
2014
The preparation by simple direct synthesis of a series of coordination polymers based on copper with chloride or bromide and dipyrimidinedisulfide is reported. The structural characterisations of these compounds reveal a rich structural variety as a result of the number of coordination modes available to the organosulfur ligand, in combination with the bridging capabilities of the halides. Interestingly, some of the polymers displayed fully reversible solvent exchange/removal crystal-to-crystal 2D to 0D and 2D to 2D transformations. These materials show multifunctional electronic properties. Thus, some of them are semiconductors and present weak antiferromagnetic interactions, and the CuI/C…
Efficient Diffusion-Controlled Ligand Exchange Crystal Growth of Isostructural Inorganic–Organic Halogenidorhodates(III): The Missing Hexaiodidorhoda…
2015
The monohydrates of piperazine-1,4-diium hexabromidorhodate(III) bromide and hexaiodidorhodate(III) iodide were obtained by a diffusion-controlled ligand exchange crystal growth method using a hydrochloric acid solution of rhodium(III) chloride trihydrate and piperazine, dissolved in hydrobromic and hydroiodic acid, respectively, separated by a layer of hydrohalic acid. Both inorganic–organic hybrids are defined by the general formula (C4H12N2)2[RhX6]X·H2O (X = Br, 1 or I, 2). They both crystallize in the orthorhombic Pnma space group, and they are isostructural with an isostructurality index above 95%. The cationic building blocks—piperazine-1,4-diium ions and the inorganic components—slig…
The glass transition behaviour of salted nylon 6
1981
Glass transition measurements of nylon-6/lithium halides mixtures have been carried out in wide range of frequency with the aid of different experimental techniques. The results show an increase of the glass transition temperature when the salt is present and prove the larger effectiveness of lithium chloride with respect of lithium bromide. This effect, in line with the large reduction of the specific volume caused by the salt, is due to the formation of a pseudo-cross-linking between lithium ions and the carbonyl-oxygen groups of the polyamide.
Combining oxyanionic polymerization and click-chemistry: a general strategy for the synthesis of polyether polyol macromonomers
2014
We describe a synthetic pathway to tailor-made amphiphilic macromonomers by a combination of anionic ring-opening polymerization and copper-catalyzed azide–alkyne cycloaddition (CuAAC). Linear polyglycerol and poly(glyceryl glycerol) were synthesized in a controlled manner by anionic ring-opening polymerization of ethoxyethyl glycidyl ether or isopropylidene glyceryl glycidyl ether, respectively, with narrow and monomodal molecular weight distributions (Mw/Mn < 1.20) and molecular weights ranging from 850 g mol−1 to 2500 g mol−1. After end-capping with propargyl bromide and removal of the protecting groups, the hydrophilic precursors were quantitatively clicked to a series of hydrophobic az…
Catalytic triad of microsomal epoxide hydrolase: replacement of Glu404 with Asp leads to a strongly increased turnover rate
1998
Microsomal epoxide hydrolase (mEH) belongs to the superfamily of α/β-hydrolase fold enzymes. A catalytic triad in the active centre of the enzyme hydrolyses the substrate molecules in a two-step reaction via the intermediate formation of an enzyme-substrate ester. Here we show that the mEH catalytic triad is composed of Asp226, Glu404 and His431. Replacing either of these residues with non-functional amino acids results in a complete loss of activity of the enzyme recombinantly expressed in Saccharomyces cerevisiae. For Glu404 and His431 mutants, their structural integrity was demonstrated by their retained ability to form the substrate ester intermediate, indicating that the lack of enzymi…
Glycosidsynthese mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyrancsylbromid
1982
Die Glycosylierung von Benzylalkohol und Cholesterin gelingt mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosylbromid (2) in Gegenwart von Silbersalzen in hoher Ausbeute. Die bei Koenigs-Knorr-Synthesen mit 2,3,4,6-Tetra-O-acetyl-α-D-glucopyranosylbromid (5) storende Orthoesterbildung wird beim Einsatz von 2 weitgehend unterdruckt. Die Lenkung der Reaktion zugunsten der Glycosidbildung wird dadurch erklart, das der tert-Butyl-Substituent im zwischenzeitlich gebildeten Acyloxoniumion A den nucleophilen Angriff am Acyloxoniumkohlenstoff sterisch behindert. Glycoside Synthesis Using 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosyl Bromide In the presence of silver salts the glycosylation of benzyl alc…
Inhibitoren der Korrosion 10 (1). Nachweis der Sekundärinhibition durch Allyl-triphenyl-phosphonium- bzw. arsoniumbromid und N-Allyl-chinaldiniumbrom…
1971
Triphenyl-allyl-phosphonium- (1) und -arsoniumsalze (2) sowie Allyl-chinaldinium-bromid (4) sind Korrosionsinhibitoren mittlerer Wirksamkeit. Sie werden von Carbonyleisenpulver im sauren Medium zu Triphenylphosphin bzw. Triphenylarsin bzw. Chinaldin reduziert. Triphenylphosphin und Triphenylarsin, die sich als Schicht auf dem Carbonyleisenpulver befinden, konnen nach Extraktion dunnschichtchromatographisch identifiziert werden. Die Allylgruppe wird aus den Verbindungen 1, 2 und 4 durch Eisen als Propen, Propan und wahrscheinlich als Cyclopropan abgelost. Die gaschromatographisch bestimmten Mengen an Kohlenwasserstoffen stehen in guter Ubereinstim-mung mit den gravimetrisch ermittelten Werte…