Molecular structure and catechol oxidase activity of a new copper(I) complex with sterically crowded monodentate N-donor ligand.

The attempted alkylation of 1,3-bis(2'-pyridylimino)isoindoline (indH) by the use of n-BuLi and subsequent alkyl halides led to quaternization of the pyridine nitrogens and the zwitterionic monodentate N-ligand (Me(2)ind)I was formed. By the use of the ligand the copper(I) complex [Cu(I)(Me(2)ind)I(2)] was prepared and its structure determined. It was found to be good catalyst for the oxidation of 3,5-di-tert-butylcatechol (DTBCH(2)) to 3,5-di-tert-butyl-1,2-benzoquinone (DTBQ) and H(2)O(2) by dioxygen. Detailed kinetic studies revealed first-order dependence on the catalyst and dioxygen concentration and saturation type behavior with respect to the substrate.

Syntheses, structural properties and catecholase activity of copper(II) complexes with reduced Schiff base N-(2-hydroxybenzyl)-amino acids.

A number of dicopper(II) complexes of reduced Schiff base ligands, N-(2-hydroxybenzyl)-amino acids [Cu2L2(H2O)x].yH2O (L = Sgly (1), D-Sala (2), L-Sala (3), DL-Sala (4), Sab2 (5), Sbal (6), Sab4 (7), Sval (8), Shis (9), Styr (10) and Stryp (11), x= 0-2 & y= 0-2) have been synthesized, and the solid-state structures of, and have been determined. The compounds and are binuclear in which the Cu(II) centres have square-pyramidal geometry with apical sites occupied by aqua ligands. In and one axial site is occupied by water and the other by an oxygen atom of the carboxylate group from the adjacent dimer through oxygen atoms to form 1D helical polymer. Variable temperature magnetic measurements of the dimer and helical polymer showed that they are typical for moderately strong antiferromagnetic coupling. All the complexes show significant catalytic activity on the oxidation of 3,5-di-tert-butylcatechol. The activity measured in terms of Kcat in the range 199-3800 h(-1) has been found to follow the order: 7>6>8>3>5 approximately 2 approximately 1>4 >10 >9 >11. The catalytic activity is found to increase with increasing the length of the methylene side chain of the amino acid in the reduced Schiff base ligands.