Search results for "copper"

Low-Temperature Optical Spectroscopy of Native and Azide-Reacted Bovine Cu,Zn Superoxide Dismutase. A Structural Dynamics Study

1994

The optical absorption spectra of native and N(3-)-reacted Cu,Zn superoxide dismutase (SOD) has been studied in the temperature range 300-10 K. The broad d-d bands observed in the room temperature spectrum, centered at 14,700 cm-1 (native enzyme) and at 15,550 cm-1 (N(3-)-reacted enzyme), are clearly split at low temperature into two bands each, centered at 12,835 and 14,844 cm-1 and at 14,418 and 16,300 cm-1, respectively. The thermal behavior of the 23,720 cm-1 band present in the spectrum of the native enzyme indicates that this band belongs to the His61-->Cu(II) ligand to metal charge transfer transition. Analysis of the zeroth, first, and second moments of the various bands as a functi…

Studies on metal-drug complexes. Crystal structure and characterization of μ-sulfato bromazepam copper(II) complex

1987

Abstract The compound Cu(Bromazepam) SO 4 having been synthesized, its crystal structure shows distorted octahedral environment for the Copper(II) ion. Because of the long Cu-O(4) length (2.90 A), we can consider that there is a semicoordinative interaction with the sulfate group acting as tridentate bridging ligand. The structure is a polymeric chain where dimeric units are linked by the oxygen (C-O(5)) atom of the Bromazepam carbonyl group. The drug consequently acts as a tridentate ligand in this compound. The magnetic results show a very weak antiferromagnetic interaction.

Effect of ethylenediamine on the anodic stripping voltammetric determination of heavy metals in the presence of humic acid

1994

Ligand competition coupled with differential pulse anodic stripping voltammetry has been investigated for the determination of copper, lead and cadmium. Ethylenediamine displaces humic acid in its metal complexes forming kinetically labile compounds. It also eliminates interferences associated with the oxidation of copper. This enhances the sensitivity of the determination of the metals over a wide range of humic acid concentration (up to 30 mg/l). The procedure has been applied to the determination of heavy metals in a real water sample.

Alkyl- and aryl-substituted corroles. 5. Synthesis, physicochemical properties, and X-ray structural characterization of copper biscorroles and porph…

2004

The synthesis and characterization of cofacial copper biscorroles and porphyrin-corroles linked by a biphenylenyl or anthracenyl spacer are described. The investigated compounds are represented as (BCA)Cu(2) and (BCB)Cu(2) in the case of the biscorrole (BC) derivatives and (PCA)Cu(2) and (PCB)Cu(2) in the case of porphyrin (P)-corrole (C) dyads, where A and B represent the anthracenyl and biphenylenyl bridges, respectively. A related monomeric corrole (Me(4)Ph(5)Cor)Cu and monomeric porphyrin (Me(2)Et(6)PhP)Cu that comprise the two halves of the porphyrin-corrole dyads were also studied. Electron spin resonance (ESR), (1)H NMR, and magnetic measurements data demonstrate that the copper corr…

Syntheses, crystal structures and magnetic properties of tricyanomethanide-containing bis(2-pyrimidylcarbonyl)amidate copper(II) complexes

2008

Abstract Three new copper(II) complexes of formulae [Cu(bpcam)(tcm)(H2O)] · 2H2O (1), [Cu(bpcam)(tcm)(H2O)] (2) and [Cu(bpcam)(tcm)]n (3) [bpcam = bis(2-pyrimidylcarbonyl)amidate and tcm = tricyanomethanide] have been prepared and their structures determined by single crystal X-ray diffraction. Complexes 1 and 2 are mononuclear species where each copper atom is five-coordinated in a somewhat distorted square pyramidal environment with a tridentate bpcam ligand and a terminally bound tcm group building the basal plane and a water molecule in the apical position. Compound 3 is a uniform copper(II) chain where the [Cu(bpcam)]+ units are connected through single μ-1,5-tcm bridges which link one…

Helicate Extension as a Route to Molecular Wires

2008

We describe the preparation of a helicate containing four closely spaced, linearly arrayed copper(I) ions. This product may be prepared either directly by mixing copper(I) with a set of precursor amine and aldehyde subcomponents, or indirectly through the dimerization of a dicopper(I) helicate upon addition of 1,2-phenylenediamine. A notable feature of this helicate is that its length is not limited by the lengths of its precursor subcomponents: each of the two ligands wrapped around the four copper(I) centers contains one diamine, two dialdehyde, and two monoamine residues. This work thus paves the way for the preparation of longer oligo- and polymeric structures. DFT calculations and elec…

Copper(I)‐chitin biopolymer based: An efficient and recyclable catalyst for click azide–alkyne cycloaddition reactions in water

2021

2,2’Bipyrimidine: A Useful Tool in Designing Polynuclear Complexes of Controlled Nuclearity

1996

The versatility of a simple ligand such as 2,2’-bipyrimidine (bpym) which can adopt chelating and bis(chelating) coordination modes facilitates the preparation of both mononuclear and polynuclear complexes whose nuclearity can be controlled by playing with the metal to bpym molar ratio, the nature of the counterion and the presence of additional ligands. In this work, we summarize our results dealing with the preparation and the structural and magnetic characterization of complexes between first-row transition metal ions and bpym. Examples of orbital reversal and tunable exchange in bpym-containing copper(II) complexes are presented and discussed. The influence of the number of unpaired ele…

Cobalt(II), nickel(II) and copper(II) complexes withN-cyano-N?-methyl-N?(2-[(5-methyl-1H-imidazol-4-yl)methylthio]ethyl)guanidine

1985

N-Cyano-N′-methyl-N″(2-[(5-methyl-1H-imidazol-4-yl)-methylthio] ethyl) guanidine cimetidine (CM), complexes with CoII, NiII and CuII are described. The compounds are of stoichiometry [M(CM)2]SO4 · nH2O [M = CoII, NiII or CuII; n = 3,3 or 4, respectively], [M(CM)2](ClO4)2 [M = CoII or NiII], [M(CM)2]Cl2 · nH2O [M=CoII, NiII or CuII; n = 1, 2, or 2, respectively] and [Cu(CM)SO4] · 2H2O. The electronic spectra of the compounds in solid state, magnetic susceptibilities and i.r. and e.p.r. spectra were studied. Octahedral environments are proposed for the complexes: [M(CM)2]SO4·nH2O, [M(CM)2](ClO4)2, [Ni(CM)2]Cl2 · 2H2O, [Cu(CM)2]Cl2 · 2H2O and [Cu(CM)SO4] · 2H2O and a tetrahedral structure for …

Spin control in oxamato-based manganese(II)-copper(II) coordination polymers with brick-wall layer architectures.

2011

Two new heterobimetallic manganese(II)-copper(II) coordination polymers of formulas [Mn(2)Cu(2)(Me(3)mpba)(2)(H(2)O)(6)]·8H(2)O (1) and [Mn(2)Cu(2)(Me(4)ppba)(2)(H(2)O)(6)]·8H(2)O (2) [Me(3)mpba = 2,4,6-trimethyl-N,N'-1,3-phenylenebis(oxamate) and Me(4)ppba = 2,3,5,6-tetramethyl-N,N'-1,4-phenylenebis(oxamate)] have been synthesized following a molecular-programmed self-assembly method from the corresponding dicopper(II) complexes acting as metalloligands toward Mn(II) ions. 1 and 2 consist of neutral Mn(II)(2)Cu(II)(2) layers with a brick-wall structure made up of oxamato-bridged Mn(II)Cu(II) chains connected through double meta- (1) and para-substituted (2) permethylated phenylene spacers.…