Phosphatase-like activity of a newly synthesized and structurally characterized Zn(II) complex [ZnII2(L)(NCS)2] [LH2 = a Schiff base] in water and DMSO-water solvent systems

Abstract

Synthesis and single crystal X-ray diffraction characterization of a Zn(II) compound [Zn₂(L)(NCS)₂] (1) [H₂L = 6,6′-((propane-1,3-diylbis(azaneylylidene))bis(methaneyl-ylidene))bis(2-methoxyphenol)] has been reported. The two Zn(II) centres in 1 separately have distorted square pyramidal and distorted trigonal bipyramidal geometries. On employing 1 with the model substrate disodium salt of 4-nitrophenylphosphate (4-NPP), the title compound is found to show phosphatase-like activity in water and 95% (v/v) DMSO-water solvent systems. The reactions were monitored spectrophotometrically. Increase in absorption intensity separately at 405 nm (water) and 419 nm (DMSO-water) indicates the catalytic dissociation of NPP to 4-nitrophenol. Kinetic measurements revealed the K_cat (s⁻¹) as 4.92 × 10⁻² and 10.69 × 10⁻², respectively in water and 95% (v/v) DMSO-water system. The proposed reaction mechanism of the phosphatase-like reaction was supported by Density Functional Theory (DFT) calculations. The reaction-intermediate of the catalytic reaction was trapped by High Resolution Mass Spectrometry (HRMS).