Catalytic hydrolysis of p-nitrophenyl picolinate by dioxocyclam zinc(II) complexes in micellar solution

The effects of dioxocyclam Zn2+ ion complexes in micellar solution on the hydrolysis of PNPP have been investigated in this paper. Second order rate constants of the hydrolysis of PNPP catalyzed by dioxocyclam Zn2+ ion complexes at various pH and the deprotonation constants of H2O coordinated to the dioxocyclam Zn2+ ion complexes pK(a) were determined kinetically, and the catalytic mechanism was discussed. The results unexpectedly showed that the activation was much larger for lipophilic ligand under micellar condition than for hydrophilic ligands under non-micellar conditions, indicating the dioxocyclam Zn2+ ion complex to be an excellent model of carbonic anhydrase.