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

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 (LH3) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co(LH)(LH2)]·H2O (4) revealed the presence of both amido and imidol tautomeric forms of LH3, resulting in a distorted octahedral geometry around the Co(III) ion. [Ni(LH)(H2O)]·H2O (5) and [Cu(LH)(H2O)]·H2O (6) are isomorphous structures and crystallize in the monoclinic P21/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 (LH3) 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. 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide and its mononuclear Co(III), Ni(II) and Cu(II) complexes have been synthesized and characterized. Molecular structures of metal complexes were determined using single crystal X‐ray diffraction studies. Synthesized compounds were tested for their in vivo anti‐inflammatory activity and DPPH free radical scavenging activity. Metal complexes have shown significant anti‐inflammatory and antioxidant potencies.