Hydrolysis of p-nitrophenyl picolinate catalyzed by copper(II) and zinc(II) binuclear complexes coordinating tripeptide in micellar solution

The kinetic model of binuclear metal complex catalysis involving a ternary complex in CTAB micellar solution is proposed in this paper. The catalyzed hydrolysis of p-nitrophenyl picolinate catalyzed by Cu(II) and Zn(II) coord inating tripeptide was studied kinetically by observing the rates of the re lease of p-nitrophenol in the buffered micellar solution at 25 degreesC and different pH values. The proposed kinetic model is confirmed by experiment al results which indicate that the 1:2 complexes of the ligand to metal ion are the active species in the reaction and the complexes catalyze efficien tly the hydrolysis of PNPP especially Cu(II) complex. The pK(a) of hydroxyl group of the ternary complex was determined to be 8.24, and the maximum ra te constant which shows that the nucleophilic reactivity of complexes was d etermined to be 0.0262 s(-1) for Cu(II) complex. The catalytic mechanism of reaction is discussed in bifunctional mechanism.