Abstract A series of ligands derived from the bis-2-pyridinylmethylamine structure, which bear either additional hydroxyl or aromatic amino groups, were prepared and their Zn II complexes were studied as catalysts for the cleavage of bis-p-nitrophenyl phosphate (BNP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) diesters. A comparative kinetic study indicated that the insertion of organic groups, capable of acting as nucleophiles or as ...