Search results for "COPP"
showing 10 items of 3147 documents
Hydrogen-bond tuning of ferromagnetic interactions: synthesis, structure and magnetic properties of polynuclear copper(ii) complexes incorporating p-…
2006
The reaction of copper(II) hydroxide with 2,2'-bipyridine (bipy) (1 : 1) in alkaline aqueous solution (pH 14) at room temperature affords the alternating carbonate/hydroxo-bridged copper(II) polymeric chain compound {[Cu3(bipy)3(mu-OH)2(mu-CO3)2].11H2O}n, 1, as determined by single-crystal X-ray diffraction. The structure of 1 is built up from two similar centro-symmetric dinuclear [(bipy)Cu(mu-OH)]2 cores which link together via bridging carbonate groups to mononuclear [(bipy)Cu] fragments to form the chain. Interdigitation of adjacent chains through pi-pi interactions, which involve each bipy ligand, forms sheets that are separated by the water molecules of crystallisation. Variable-tempe…
Study of the interaction between [Cu(bipy)]2+ and oxalate in dimethyl sulfoxide. Crystal structure of [Cu2(bipy)2(H2O)2ox]SO4·[Cu(bipy)ox]
1991
Abstract A study of complex formation between [Cu(bipy)]2+ and ox2− (bipy and ox2− being 2,2′-bipyridyl and the dianion of oxalic acid), has been carried out by potentiometry in dimethyl sulfoxide solution. The constants of the equilibria and are log β110 = 11.165(1) and log β210 = 13.185(5) at 25 °C and 0.1 mol dm−3 tetra-n- butylammonium perchlorate. The high values of these constants are consistent with the symmetrical bidentate and bis-bidentate modes of oxalate in [Cu(bipy)ox] and [Cu2(bipy)2ox]2+ units, respectively, as shown by X-ray diffraction studies. Well-formed single crystals of [Cu2(bipy)2(H2O)2ox]SO4· [Cu(bipy)ox] were grown from aqueous solutions and characterized by X-ray d…
Copper(II)-assisted hydrolysis of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt): syntheses, crystal structures and magnetic properties of [Cu(bpcam)…
2005
Abstract The reaction of the 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt) ligand with copper(II) perchlorate or sulfate in aqueous solution affords complexes [Cu(bpcam)(H2O)2]ClO4 · 3H2O (1), [Cu(bpcam)(H2O)2][Cu(bpcam)(H2O)(SO4)] · 2H2O (2) and [Cu2(bpcam)2(H2O)2(SO4)] · H2O (3) [bpcam = bis(2-pyrimidylcarbonyl)amidate], whose structures have been determined by single-crystal X-ray diffraction studies. Copper(II) promotes the hydrolysis of tpymt in mild conditions yielding the bpcam group which is present in the structures of 1–3 as a tridentate ligand. The structure of 1 consists of mononuclear [Cu(bpcam)(H2O)2]+ cations, uncoordinated perchlorate anions and water of crystallization. Th…
Stabilities and Coordination Modes of α-Alaninephosphonic Acid in Copper(II) Heteroligand Complexes with Ethylenediamine, Diethylenetriamine or N,N,N…
2011
Solution equilibrium studies on Cu2+–L1–L2 ternary systems have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods (L1 corresponds to polyamines such as ethylenediamine (en), diethylenetriamine (dien), or N,N,N′,N′,N″-pentamethyldiethylenetriamine (Me5dien) and L2 represents 1-aminoethylphosphonic acid (α-alaninephosphonic acid)). The obtained results suggest the formation of heteroligand complexes with [Cu(L1)(α-Ala(P))] stoichiometry in all studied systems. Additionally, in the system with en the [Cu(en)(α-Ala(P))H−1]− species is formed in basic solution. Our spectroscopic results indicate tetragonal geometry for the [Cu(en)(α-Ala(P))] species, geometry slightly …
Ferromagnetic coupling through a carbonate bridge in the copper (II) chain [Cu(CO3)(4-apy)2] · H2O (4-apy = 4-aminopyridine)
1999
Abstract Atmospheric CO2 fixation by aqueous solutions containing copper(II) bromide and 4-aminopyridine (4-apy) yields the first carbonatobridged copper(II) chain of formula [Cu(CO3)(4-apy)2] · H2O that exhibits an intrachain ferromagnetic coupling.
Electrochemically assisted anion insertion in Au(I)–Cu(I) heterotrimetallic clusters bearing ferrocenyl groups: Application to the fluoride/chloride …
2010
The heterotrimetallic Au(I)–Cu(I) aggregate [{Au3Cu2(C2C6H4Fc)6}Au3(PPh2C6H4PPh2)3](PF6)2 exhibits a well-defined solid state electrochemistry in contact with aqueous media, based on ferrocenyl-centred oxidation processes involving anion insertion. Upon attachment of microparticulate deposits of the cluster to graphite electrodes, distinctive electrochemical responses can be obtained for fluoride and chloride ions in aqueous media. Keywords: Heterometallic clusters, Gold, Copper, Fluoride/chloride discrimination, Electrochemical anion insertion
Oxamidato complexes. Part 4. Electrochemical study of the copper(III)/copper(II) couple in monomeric N,N?-bis(substituent)oxamidatocopper(II) complex…
1993
The electrochemical behaviour of a series of monomeric N,N′-bis(substituent)oxamidato copper(II) complexes of formula Na2[Cu(3,5,3′,5′-X4obbz)]·4H2O [X = Cl (1), Br (2), I (3) and obbz = oxamidobis(benzoato)], Na2-[Cu(obbz)]·4H2O (4), Na2[Cu(5,5′-Me2obbz)]·4H2O (5), Na2[Cu(4,5,4,5′-(MeO)4obbz)]·4H2O(6),Na2[Cu(obp)]· 3.5H2O (7) (obp = oxamidobis(propionato)) and Na2[Cu(pba)]·6H2O (8), [pba = propylenebis(oxamate)] has been investigated by cyclic voltammetry, rotating disk electrode and coulometry in water and dimethylsulphoxide (dmso) solutions. NaNO3 (0.1 M) and n-Bu4NPF6 (0.1 M) were used as supporting electrolytes in H2O and dmso respectively, all solutions being thermostatted at 25 °C. I…
Electrochemistry of copper complexes with macrocyclic polyamines containing pyrazole units.
2006
The voltammetric behaviour of bi- and mono-nuclear complexes formed in solution by Cu(2+) with three polyazacyclophanes containing pyrazole units in aqueous solution is described. Cyclic and square wave voltammetric responses at glassy carbon electrodes indicate that the reduction of copper-macrocycle complexes in solution takes place in two successive one-electron per Cu transfer processes coupled with preorganization and protonation reactions that mimic the behaviour of superoxide dismutase. The electrochemistry of ternary Cu(2+)-receptor-dopamine complexes exhibits significant differences with respect to the protection of the neurotransmitter from post-electron transfer cyclization react…
Polyfunctional Tetraaza-Macrocyclic Ligands: Zn(II), Cu(II) Binding and Formation of Hybrid Materials with Multiwalled Carbon Nanotubes
2017
The binding properties of HL1, HL2, and HL3 ligands toward Cu(II) and Zn(II) ions, constituted by tetraaza-macrocyclic rings decorated with pyrimidine pendants, were investigated by means of potentiometric and UV spectrophotometric measurements in aqueous solution, with the objective of using the related HL-M(II) (HL = HL1–HL3; M = Cu, Zn) complexes for the preparation of hybrid MWCNT-HL-M(II) materials based on multiwalled carbon nanotubes (MWCNTs), through an environmentally friendly noncovalent procedure. As shown by the crystal structure of [Cu(HL1)](ClO4)2, metal coordination takes place in the macrocyclic ring, whereas the pyrimidine residue remains available for attachment onto the s…
Complex formation equilibria between the acetazolamide ((5-acetamido-1,3,4-thiadiazole)-2-sulphonamide), a potent inhibitor of carbonicanhydrase, and…
1990
Abstract The stability constants for the equilibrium of complexation between acetazolamide and the divalent metal ions copper(II), nickel(II), zinc(II), and cobalt(II) have been determined by potentiometry both in water and in water-ethanol 50 vol. % solutions in 0.15 mol dm −3 NaNO 3 at 25°C. This mixed solvent has been used in order to obtain higher concentrations of acetazolamide in solution. For copper(II) and nickel(II), the binuclear species [Cu 2 (Acm) 2 ] and [Ni 2 (Acm) 3 ] 2− are detected in both solvents together with hydroxo species. The values of the stability constants are always higher in the mixed solvent than in water. For cobalt(II) and zinc(II), while in aqueous solution …