Two new copper(II) chloride complexes of N-(2-hydroxyethyl)bis(pyridylmethyl)amine (CuL(2)) and N-(3-hydroxypropyl)bis(pyridylmethyl)amine (CuL(3)) have been synthesized and characterized. The reactivities of CuL(2) and CuL(3) for cleaving bis(2,4-dinitrophenyl) phosphate (BDNPP) have been compared to that of copper(II) chloride complex of bis(pyridylmethyl)amine (CuL(1)). The copper complex with the hydroxypropyl group (CuL(3)) cleaves the phosphate diester by transesterification while the complex with the hydroxyethyl group (CuL(2)) or the complex without any pendant alcohol groups (CuL(1)) cleaves it by hydrolysis. Furthermore, CuL(3) (k = 7.2 x 10(-1) M(-1) s(-1) at 25 degrees C, pH 8.8) is about two orders of magnitude more reactive than CuL(2) (k = 9.5 x 10(-3) M(-1) s(-1)) and CuL(1) (k = 2.0 x 10(-2) M(-1) s(-1)) for cleaving the diester. The differences in the mechanisms and the reactivities are explained in terms of the differences in the structures of the three copper complexes. Crystal structures of [(L(1)’)-Cu(OP(O)(OCH3)(2))(HOCH3)]Cl and [(L(2)’)Cu(Cl)]Cl have been determined as structural models of CuL(1) and CuL(2), respectively (L(1)’ = bis(2-benzimidazolylmethyl)amine; L(2)’ = N-(2-hydroxyethyl)bis(2-benzimidazolylmethyl)amine).