The dihydroxo complexes [Zn2L(OH)(2)](2+) (L = di-nucleating ligands containing two polyamine units separated by polyoxa chains) promote both p-nitrophenyl acetate and bis(p-nitrophenyl) phosphate hydrolysis. In NA cleavage, the hydrolytic properties depend mainly on the nucleophilicity of the Zn(II)-OH functions, while in BNP hydrolysis, the activity is modulated by the interaction of the phosphate ester with the two metal centers.