Synthesis and Characterization of Ternary Copper(II) Complexescontaining L-Valine. Catechol Oxidase and Phenoxazinone Synthase Biomimetic Catalytic Activity. - .

. A new series of ternary copper(II) complexes having molecular formulae [CuLL?X] and [CuLL?]X has been synthesized. For this ligand system LL?, L is the amino acid L-Valine and L? is 2-aminomethyl pyridine while X¯ is Cl¯, Br¯, NO3¯, ½SO42- or ClO4¯. The structure characterization of these newly synthesized copper(II) complexes was achieved by various physicochemical techniques, viz. elemental analysis, Thermal analysis (TGA and DTG), magnetic susceptibility measurements, IR, electronic, and EPR spectral studies. The spectral and magnetic measurements in addition to the electrolytic conductance results indicate that complex2is five -coordinate square pyramidal while the other complex species are found to have four-coordinate square-pyramidal geometry. It has been shown that the stereochemistry of complexes is dependent on the type of counter anions incorporated in the complex molecule. The kinetics and mechanism of substitution by thiourea (TU) were studied in detail as a function of nucleophile concentration in methanol as solvent. The kinetics showed that the substitution reaction of all complexes is a biphasic process. Mimicking copper-oxidase enzymes namely catechol oxidase and phenoxazinone synthase was investigated and the results obtained demonstrated that, the reported copper(II) complexes are suitable as catalysts for the catalytic aerobic oxidation of 3,5-di-tert-butylcatechol(3,5-DTBCH2) to 3,5-di-tert-butyl-benzoquinone (3,5-DTBQ) (catechol oxidase activity), and o-aminophenol (OAPH) to 2-aminophenoxazine-3-one (APX) (phenoxazinone synthase activity) with dioxygen at ambient condition in good yields. - See more at: