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

<span>A new mononuclear complex of cobalt (III) </span><strong>(2)</strong><span> with 1-(phthalazin-1(2H)-one)[(Pyridin-2-yl) ethylidene] hydrazone ligand (</span><strong>1</strong><span>) has been synthesized and characterized by elemental analysis, IR and mass spectroscopic techniques. The crystal structures of the free ligand </span><strong>(1)</strong><span> and its complex (</span><strong>2</strong><span>) have been determined by single crystal X-ray diffraction technique. In complex </span><strong>2</strong><span> 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 </span><strong>1</strong><span> and its complex </span><strong>2</strong><span> was studied against </span><em>Aspergillus niger</em><span>,</span><em> Aspergillus flavus</em><span> and </span><em>Candida albicans</em><span>. The results revealed modest activity of complex </span><strong>2</strong><span> against the tested organism with inhibition zones of 14, 15 and 14 mm, compared to the free ligand </span><strong>1</strong><span> with the inhibition zones of 12, 11 and 12 mm for </span><em>A. niger, A. flavus, C. albicans</em><span> respectively.