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.