Abstract
Ternary copper(II) complexes with the molecular formulae of [Cu-II LL']X or [Cu-II LL'X]; L = L-Valinate; L' = alpha, (sic)-bipyridyl or 1,10 - phenanthroline and X is Cl, Br, NO3, AcO, 1/2SO(4)(2-) - or ClO4 were synthesized. Elemental and thermal analysis in addition to electrochemical (molar conductance and cyclic voltammetry), magnetic moment measurements as well spectral (FT-IR, UV-Vis and ESR) techniques were used to characterize the complexes. The spectroscopic results suggested square pyramidal and square planar geometries for the five- and four-coordinate complexes respectively. Powder X-ray diffraction spectral data along with the structure solution program Expo 2014 has been used for structural elucidation of the sulfato complexes 1 and 5. Stopped follow technique was employed to study the substitution of the nonelectrolytic coordinately counter anion ligand by using thiourea (TU) as a function of nucleophile and a biphasic process is proposed. An initial fast reaction is followed by a slower one and the initial one was found to be counter ion dependent. Bio-mimicking the multicopper oxidase enzyme such as catechol oxidase and phenoxazinone synthase is a further goal of the present study. Catalytic examinations displayed that the present complexes are promising candidates as functional mimic of the examined enzymes and the probable mechanistic catalytic sequences are discussed. (C) 2019 Published by Elsevier B.V.