Structural and Biological Activity Study of (E)-N’- (5-Chloro-2-Hydroxybenzylidene)Nicotinohydrazide) [H2L] and some of its Divalent Metal Complexes

Nicotinic acid hydrazide and 2-hydroxyl-5-chlorobenzaldehyde were condensed at 80oC to form an ONO coordination pattern ligand (H2L). The structure of the ligand was elucidated by using 1H NMR, 13C NMR, COSY, HSQC, CHN analyzer, ESI mass spectrometry and IR, Thereafter, five metal complexes [Cu(II), Fe(II), Zn(II), Mn(II) and Ni(II)] of the ligand were synthesized and their structural elucidation were achieved by using elemental analysis, infrared, EPR, molar conductivity and powder X-ray diffraction studies. Structural geometries of some of the compounds were predicted. Based on the analysis, octahedral geometry was suggested for the complexes. In vitro antitubercular activity study of the ligand and the metal complexes were evaluated against Mycobacterium tuberculosis, H37Rv, by using micro-diluted method. The results obtained (H2L- MIC = 0.86 µg/mL), (CuL- MIC = 0.64 µg/mL), (FeL- MIC = 0.77 µg/mL), (ZnL- MIC = 0.69 µg/mL), (MnL- MIC = 1.12 µg/mL) and (NiL- MIC = 0.92 µg/mL) revealed that all the compounds except (MnL- MIC = 1.12 µg/mL) possess better activity when compared with one of the first line drug (isoniazid) (INH- MIC = 0.9 µg/mL). H2Lexhibited higher antitubercular activity with MIC value of 0.86 µg/mL. However, the metal complexes displayed higher cytoxicity but were found to be non-significant different (P ˂ 0.05) to isoniazid drug.