Synthesis, characterization, spectroscopic properties and antihypertensive activity of 4-chlorobenzaldehyde hydralazine hydrazone and its metal complexes

A hydrazone ligand, 4-chlorobenzaldehyde hydralazine hydrazone (LH), has been synthesized. Our initial attempts to synthesize Co +2 , Ni +2 , Cu +2 and Zn +2 metal complexes of LH resulted in a cyclized triazole product (T). Structure of both the LH and T is characterized by single-crystal X-ray diffraction pattern analysis. Synthesis of desired metal complexes is achieved by using LH in its monohydrochloride salt form (LH.HCl), thus preventing cyclization of LH to T. Mass, IR, NMR, UV–Vis spectroscopic techniques, thermal and other physicochemical methods were used for the structural elucidation of the metal complexes. On the basis of electronic and magnetic properties of the complexes, four coordinate square-planar geometry for Ni +2 complex, while T d geometry for Cu +2 and Zn +2 complex was assigned. Around Co (II) ions, O h geometry was assigned. In vivo antihypertensive assay of the synthesized compounds is carried out in rats with fructose-induced hypertension to measure the blood pressure and tail pulse. Copper complex and the LH have exhibited antihypertensive activity at par with the well-known antihypertensive drug hydralazine.