Hydrolysis of phosphate diester catalyzed by new mononuclear copper(II) complexes containing selenium ligands

Three new copper(II) mononuclear complexes containing different organoselenium groups (1–3) were synthesized and characterized by the following techniques: elemental analysis, IR and UV-Vis spectroscopies, electrochemical and conductimetric analysis, and mass spectrometry. Three new complexes, with substituents made in the para position of the aromatic portion of the N,N-bis(2-(phenylselanyl)ethyl)amine ligand: p-OCH₃ (1), p-CH₃ (2), and p-Cl (3), were synthetized to compare with the already published complex (4), with no substituents. The ligand coordinates to the copper(II) center in a tridentate way with Se, N, Se as donor atoms. The hydrolytic activity in phosphate diester cleavage of the complexes was investigated using 2,4-BDNPP as substrate. The modifications in the ligand are reflected in the difference between the catalytic and activation parameters, where the k_cat values follow the order: 4 > 2 > 3 > 1.