New mixed ligand cobalt(II/III) complexes based on the drug sodium valproate and bioactive nitrogen-donor ligands. Synthesis, structure and biological properties

Abstract New cobalt valproate complexes with different nitrogen based ligands were synthesized and characterized using various techniques such as IR, UV–Vis, single crystal X-ray diffraction as well as other physical properties. The general formula of the prepared complexes is [Co n (valp) m (L) z ], (n = 1, 2 …; m = 1, 2, …; Z = 1, 2 …). The complexes [Co 2 (valp) 4 ] (1) , [Co(valp) 2 (2-ampy) 2 ] (2) and [Co 2 (valp) 4 (quin) 2 ] (3) showed different carboxylate coordination modes. The crystal structures of the complexes 2 and 3 were determined using single crystal X-ray diffraction. Kinetic studies of hydrolysis reactions of BNPP [ bis -(p-nitrophenyl)phosphate] with complexes 2 and 3 were performed. The hydrolysis rate of BNPP was studied at different temperatures, pH and concentrations by UV–Vis spectrophotometric method. The results showed that the hydrolysis rate of BNPP was 7.70 × 10 2  L mol −1  s −1 for ( 3) and 2.60 × 10 −1  L mol −1  s −1 for ( 2 ).