Search results for "copper"
showing 10 items of 3029 documents
Experimental and Theoretical Study of Dynamic Structural Transformations between Sensing Copper(II)-Uracil Antiferromagnetic and Metamagnetic Coordin…
2020
This paper describes the synthesis and characterization of several Copper(II)-uracil-1-propionic acid (UPrOH) coordination compounds, including the theoretical and experimental study of their cryst...
A distorted honeycomb motif in divalent transition metal compounds based on 4-phosphonbenzoic acid and exchange coupled Co(II) and Cu(II): synthesis,…
2013
The first example of a two-dimensional inorganic hybrid material with cobalt as an open-shell transition metal ion and 4-phosphonbenzoic acid as a linker is presented together with its copper analogue. For both metal ions the inorganic part consists of edge-sharing metal–oxygen octahedra leading to a metal honeycomb motif. The magnetic properties of the cobalt compound are reported together with those of the corresponding copper compound based on the remarkably six-coordinated copper(II) ions.
Copper-O2 reactivity of tyrosinase models towards external monophenolic substrates: molecular mechanism and comparison with the enzyme.
2011
The critical review describes the known dicopper systems mediating the aromatic hydroxylation of monophenolic substrates. Such systems are of interest as structural and functional models of the type 3 copper enzyme tyrosinase, which catalyzes the ortho-hydroxylation of tyrosine to DOPA and the subsequent two-electron oxidation to dopaquinone. Small-molecule systems involving μ-η²:η² peroxo, bis-μ-oxo and trans-μ-1,2 peroxo dicopper cores are considered separately. These tyrosinase models are contrasted to copper–dioxygen systems inducing radical reactions, and the different mechanistic pathways are discussed. In addition to considering the stoichiometric conversion of phenolic substrates, t…
Physicochemical Properties of Copper(II) Bis(2-ethylhexyl) Sulfosuccinate Reversed Micelles
1998
Abstract Measurements of some physicochemical properties (density, viscosity, conductance, UV–vis spectra, IR spectra) of the water/copper(II) bis(2-ethylhexyl) sulfosuccinate (Cu(DEHSS) 2 )/CCl 4 microemulsions, at a fixed surfactant molal concentration ([Cu (DEHSS) 2 ] = 0.05003 mol kg −1 ), as function of the molar ratio R ( R = [water]/[DEHSS − ]) have been performed at 25°C. Information on some structural and dynamical properties of the water-containing Cu(DEHSS) 2 reversed micelles and of their evolution with R are derived from the experimental results. The comparison with the same properties of water-containing sodium bis(2-ethylhexyl) sulfosuccinate reversed micelles allows to evide…
Viscosity-molecular weight relationship for cellulose solutions in either NMMO monohydrate or cuen
2010
The intrinsic viscosities, [η], of nine cellulose samples, with molar masses from 50 × 103 to 1 390 × 103 were determined in the solvents NMMO*H2O (N-methyl morpholin N-oxide hydrate) at 80°C and in cuen (copper II-ethlenediamine) at 25°C. The evaluation of these results with respect to the Kuhn–Mark–Houwink relations shows that the data for NMMO*H2O fall on the usual straight line in the double logarithmic plots only for M ≤ 158 103; the corresponding [η]/M relation reads log ([η]/mL g−1) = –1.465 + 0.735 log M. Beyond that molar mass [η] remains almost constant up to M ≈ 106 and increases again thereafter. In contrast to NMMO*H2O the cellulose solutions in cuen behave normal and the Kuhn–…
Influence of the position of two dehydro-amino acids residues in the oligopeptide sequence on the binding ability towards Cu(II) ions
2005
Abstract Studies on the binding ability of bis-dehydro-hexa- and pentapeptides have shown that the hexapeptides bind Cu+2 with similar efficacy as pentapeptides. The increase of distance between two dehydro-amino acid residues in the peptide backbone has no impact on the efficacy in metal ion binding. The type of isomeration [(Z) or (E)] has an influence on the coordination of the metal ion only to the first amide nitrogen.
Synthesis, crystallographic and spectroscopic characterization and magnetic properties of dimer and monomer ternary copper(II) complexes with sulfona…
2010
Abstract Three dinuclear and one mononuclear copper(II)-1,10-phenanthroline ternary complexes, [Cu(L1)(phen)(OH)]2 (1), [Cu(L2)(phen)(OH)]2·3H2O (2), [Cu(L3)(phen)(OH)]2 (3) and [Cu(L4)2(phen)(H2O)] (4), with thiadiazole sulfonamide derivative ligands: HL1 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)naphthalene-1-sulfonamide), HL2 (N-(5-ethylthio)-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide), HL3 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide) and HL4 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide) have been synthesized and characterized. In the four complexes each copper atom is five-coordinated. The structure of complexes 1, 2 and 3 consists of a dimeric unit with a C2 sy…
Propargyl-functional aliphatic polycarbonate obtained from carbon dioxide and glycidyl propargyl ether.
2013
The synthesis of propargyl-functional poly(carbonate)s with different content of glycidyl propargyl ether (GPE) units is achieved via the copolymerization of propargyl glycidyl ether and carbon dioxide. A new type of functional poly(carbonate) synthesized directly from CO(2) and the glycidyl ether is obtained. The resulting polymers show moderate polydispersities in the range of 1.6-2.5 and molecular weights in the range of 7000-10 500 g mol(-1). The synthesized copolymers with varying number of alkyne functionalities and benzyl azide are used for the copper-catalyzed Huisgen-1,3-dipolar addition. Moreover, the presence of vicinal alkyne groups opens a general pathway to produce functional …
Hyperbranched polyethylenimine-supported copper(II) ions as a macroliganted homogenous catalyst for strict click reactions of azides and alkynes in w…
2019
Abstract Loading hyperbranched polyethylenimine (PEI) with copper(II) ions leads to the formation of a new water-soluble metallodendritic polymer Cu(II)-PEI that has been found to effectively catalyze the clickable azide-alkyne [3 + 2] cycloaddition reactions in water under ambient conditions, in the lack of any external reducing agent. A positive dendritic effect on the catalyst activity was observed in the click of 1,2,3-triazole by lowering the reduction potential of copper(II) into the in-situ generation of the catalytically active species copper(I). The reaction proceeds straightforwardly to afford the corresponding 1,4-disubstituted-1,2,3-triazole derivatives in a regioselective manne…
Coordination of copper(II) ions by α,β-dehydro-dipeptides. Potentiometric and spectroscopic study
1991
Abstract Potentiometric and spectroscopic data have shown that the double bond within dehydro-peptides considerably affects their behaviour as ligands relative to their saturated parents, with proton and copper(II) ions.