New Dihydro OO'Bis(Salicylidene) 2,2' AminobenzothiazolylBorate Complexes: Kinetic and Voltammetric Studies of Dimethyltin Copper Complex with Guanine, Adenine, and Calf Thymus DNA

摘要

The newly synthesized ligand, dihydro OO'bis(salicylidene) 2,2'aminobenzothiazolyl borate (2), was derived from the reaction ofSchiff base of 2-aminobenzothiazole and salicylaldehyde withKBH4.CuII(3) andZnII(4) complexes of (2) were synthesized and further metallated with dimethyltindichloride toyield heterobimetallic complexes (5) and (6). All complexes havebeen thoroughly characterized by elemental analysis, and IR, NMR,EPR, and UV-Vis spectroscopy and conductance measurements. Thespectroscopic data support square planar environment around theCuIIatom, while theSnIVatom acquires pentacoordinate geometry. The interaction of complex (5) with guanine, adenine,and calf thymus DNA was studied by spectrophotometric,electrochemical, and kinetic methods. The absorption spectra ofcomplex (5) exhibit a remarkable ?hyperchromic effect?in the presence of guanine and calf thymus DNA. Indicative ofstrong binding of the complex to calf thymus DNA preferentiallybinds throughN7position of guanine base, while the adenineshows binding to a lesser extent. The kinetic data were obtainedfrom the rate constants,kobs, values under pseudo-first-order conditions. Cyclic voltammetry was employed tostudy the interaction of complex (5) with guanine, adenine, andcalf thymus DNA. The CV of complex (5) in the absence and in thepresence of guanine and calf thymus DNA altered drastically, witha positive shift in formal peak potentialEpaandEpcvalues and a significant increase in peak current. The positiveshift in formal potentials with increase in peak current favoursstrong interaction of complex (5) with calf thymus DNA. The netshift inE1/2has been used to estimate the ratio of equilibrium constants for the binding of Cu(II) and Cu(I) complexes to calf thymus DNA.