| Abstract |
A new symmetrical polyaza macrocyclic binucleating ligand L(1) and its permethylated derivative ligand L(2) have been synthesized by using the precursor compound 2-[2-(2,6-diformyl-4-methylphenoxy)propoxyl]-5-methylisophthalaldehyde and bis(aminoethyl) amine. The molecular structure of the precursor compound and the ligand L(2) were determined by the single crystal XRD method. The ligands L(1) and L2 were treated with two equivalents of Cu(ClO(4))(2) center dot 6H(2)O to afford the new binuclear complexes [Cu(2)L(1)(mu-OH)(ClO(4))(2)](ClO(4)) (1) and [Cu(2)L(2)(mu-OH)(ClO(4))(2)](ClO(4)) (2), respectively. Both the complexes were characterized by elemental and spectral methods. A cyclic voltammetric investigation of these Cu(II) complexes show a quasireversible followed by an irreversible one electron reduction processes around E(pc)(1) = -0.59 V, -0.55 V and E(pc)(2) = -1.07 V, -1.02 V. ESR spectra of the copper(II) complexes 1 and 2 show a broad signal at g = 2.08 and 2.10, and mu(eff) values of 1.43 and 1.46 BM, respectively, which convey a spin-spin interaction between the two copper(II) ions. The initial rate (V(in)) for the oxidation of 3,5-di-tert-butylcatechol to o-quinone by the binuclear Cu(II) complexes 1 and 2 are 1.15 X 10(-4) and 1.66 x 10(-4) Ms(-1) respectively. Both the complexes remarkably promote the hydrolytic cleavage of super-coiled plasmid DNA under physiological conditions in the presence of H(2)O(2) at pH 7.2 and 37 degrees C. The reaction profile for the complex 1 mediated reaction displayed approximately pseudo-first-order kinetic behavior, with k(obs) similar to 0.07 min(-1) and R(2) = 0.984. (C) 2008 Elsevier Ltd. All rights reserved. |
