Synthesis, characterization and phosphotriesterase mimetic activity of some Zn(II) and Cu(II) complexes

Abstract

We report here the synthesis and characterization of a few phenolate-based ligands bearing tertamino substituent and their Zn(II) and Cu(II) metal complexes. Three mono/binuclear Zn(II) and Cu(II) complexes [Zn(L1)(H 2 O)].CH 3 OH.H 2 O (1) (H 2 L1 = 6,6-(((2-dimethylamino)ethylazanediyl)bis(methylene))bis(2, 4-dimethylphenol), [Zn 2 (L2) 2 ] (2) (H 2 L2 = 2,2-(((2-dimethylamino)ethyl)azanediyl)bis(methylene)bis(4methylphenol) and [Cu 2 (L3) 2 .CH 2 Cl 2 ] (3) (H 2 L3 = (6,6-(((2-(diethylamino)ethyl)azanediyl)bis(methylene)) bis(methylene))bis(2,4-dimethylphenol) were synthesized by using three symmetrical tetradendate ligands containing N 2 O 2 donor sites. These complexes are characterized by a variety of techniques including; elemental analysis, mass spectrometry, 1 H, 13 C NMR spectroscopic and single crystal X-ray analysis. The new complexes have been tested for the phosphotriesterase (PTE) activity with the help of 31 P NMR spectroscopy. The 31 P NMR studies show that mononuclear complex [Zn(L1)(H 2 O)].CH 3 OH.H 2 O (1) can hydrolyse the phosphotriester i.e., p-nitrophenyl diphenylphosphate (PNPDPP), more efficiently than the binuclear complexes [Zn 2 (L2) 2 ] (2) and [Cu 2 (L3) 2 .CH 2 Cl 2 ] (3). The mononuclear Zn(II) complex (1) having one coordinated water molecule exhibits significant PTE activity which may be due to the generation of a Zn(II)-bound hydroxide ion during the hydrolysis reactions in CHES buffer at pH 9.0.