Abstract
Complex formation of the tetradentate ligand bis(2-picolyl) glycine, BPG, with both Zn(II) and Cu(II) ions in aqueous solution was investigated spectroscopically by using H-1 NMR and UV-visible titrations as well as electrochemically by using cyclic voltammetry. Analysis of the titration data indicated that the aqua complexes [BPG-Zn(OH2)(2)](+) 1 and [BPG-Cu(OH2)(2)](+) 2 deprotonate at pH = 10.6 and 9.7. The catalytic hydrolysis of the activated phosphate ester tris(p-nitrophenyl) phosphate (TNPP) by using these model complexes was examined and the released phenolate anions were determined by using electroanalytical technique. The kinetic results indicate that copper(II) complex 2 is more active hydrolytic catalyst than zinc(II) complex 1, presumably a reflection of the effective electron-withdrawing as well as the greatest electrophilicity of copper(II) ion.