Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

Abstract

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2-(2,4-dichlorobenzamido)-N′-(3,5-di-tert-butyl-2-hydroxybenzylidene)benzohydrazide (LH 3 ) have been synthesized and characterized using various physico-chemical, spectroscopic and single crystal X-ray diffraction techniques. Structural studies of [Co(LH)(LH 2 )]·H 2 O (4) revealed the presence of both amido and imidol tautomeric forms of LH 3 , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni(LH)(H 2 O)]·H 2 O (5) and [Cu(LH)(H 2 O)]·H 2 O (6) are isomorphous structures and crystallize in the monoclinic P2 1 /c space group. The crystal structures of 4, 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C-H···π and π···π interactions. Complexes along with the ligand (LH 3 ) were screened for their in vivo anti-inflammatory activity (carrageenan-induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti-inflammatory and antioxidant potential.KEYWORDS anti-inflammatory activity, antioxidant activity, crystal structure, di-tert-butyl phenylhydrazone, isomorphous metal complexes