Metallomicellar catalysis: Hydrolysis of phosphodiester with Cu(II) and Zn(II) complexes in micellar solution

The effects of two metal complexes of 2,2'-dipyridylamine (bpya) ligand, [(bpya)Cu]Cl-2 and [(bpya)Zn]Cl-2, in promoting the hydrolysis of bis(4-nitrophenyl) phosphate (BNPP) have been kinetically investigated in Brij35 micellar solution and at 298 K, pH ranging from 6.41 to 8.6. In neutral micellar solution at 298 K, pH 7.02, the rate constants for the catalytic hydrolysis of BNPP by [(bpya)Cu]Cl-2 and [(bpya)Zn]Cl-2 are 1.2 x 10(6) times and 1.5 x 10(5) times higher than those for the spontaneous hydrolysis, respectively. Kinetic studies show that the active species in the catalytic hydrolysis of BNPP is the aquo-hydroxy form, and the relative kinetic and thermodynamic parameters indicate that the mechanism of the reaction involves intramolecular nucleophilic attack on the metal center-bound diester.