Phosphatase activity and DNA binding studies of dinuclear phenoxo-bridged zinc(II) complexes with an N,N,O-donor ligand and halide ions in a rare cis-configuration

Abstract Three new dinuclear zinc(II) complexes of the types [Zn 2 (L) 2 (Cl) 2 ]·2(CH 3 OH) ( 1 ) and [Zn 2 (L) 2 (X) 2 ] (HL = 2-(((2-(dimethylamino)ethyl)amino)methyl)phenol; X = Br for 2 and I for 3 ), having a rare cis- configuration of the halide ions, were isolated using the one-pot synthesis of the building components in appropriate molar ratios and characterized. X-ray structural studies reveal that 1 – 3 contain a discrete dinuclear unit bridged by two phenoxo oxygen atoms of the deprotonated Schiff base ligand (HL) and adopt an overall rare cis- configuration where two halide ions are on the same side of the Zn–Zn axis and the ligand occupies the other side. Each Zn(II) centre in 1 – 3 has a distorted square pyramidal geometry with a ZnO 2 N 2 X chromophore (X = Cl for 1 ; Br for 2 ; I for 3 ). The initial rate values for the hydrolysis of 4-nitrophenylphosphate to 4-nitrophenolate by the complexes 1 – 3 are respectively 590, 334 and 705 min −1 . The complexes show an external binding propensity to calf thymus DNA with binding constant values 9.45 × 10 2 , 7.06 × 10 2 and 6.51 × 10 2  M −1 for 1 , 2 and 3 respectively.