3.3.2. Synthesis, crystal structure and biological activity of 1-(phthalazin-1(2H)-one)[(Pyridin-2-yl)ethylidene]hydrazone and its cobalt (III) complex

A new mononuclear complex of cobalt (III) (2) with 1-(phthalazin-1(2H)-one)[(Pyridin-2-yl) ethylidene] hydrazone ligand ( 1 ) has been synthesized and characterized by elemental analysis, IR and mass spectroscopic techniques. The crystal structures of the free ligand (1) and its complex ( 2 ) have been determined by single crystal X-ray diffraction technique. In complex 2 the hydrazone ligand chelates to the cobalt (III) ion through nitrogen atoms in a tridentate manner, giving an octahedral geometry where the cobalt (II) was oxidized to cobalt (III). The antifungal activity of ligand 1 and its complex 2 was studied against Aspergillus niger , Aspergillus flavus and Candida albicans . The results revealed modest activity of complex 2 against the tested organism with inhibition zones of 14, 15 and 14 mm, compared to the free ligand 1 with the inhibition zones of 12, 11 and 12 mm for A. niger, A. flavus, C. albicans respectively.