Synthetic aspects, crystal structure and antibacterial activity of two new Schiff base cobalt(III) complexes

Two new Schiff base complexes of cobalt(III) viz. [Co(L)(L1)(NCS)]ClO4 (1) and [Co(L2)(N3)]2·4H2O (2), where L = propane-1,2-diamine, L1 = 2-[N-(2-aminopropyl)ethanimidoyl]phenolate and L2 = 2,2′-[propane-1,2-diylbis(nitriloeth-1-yl-1-ylidene)]diphenolate ion, have been prepared and characterized. The syntheses have been achieved by reacting cobalt perchlorate either with the diamine (L) and 2-hydroxyacetophenone together or with their Schiff base H2L2 in presence of the respective pseudohalide. The same synthetic system has yielded two complexes of different nuclearity in presence of two different pseudohalides i.e. the mononuclear 1 with thiocyanate and the binuclear 2 with azide ion. The tridentate (L1) and tetradentate (L2) Schiff base anions were formed in situ to bind the Co(III) ion in case of the template syntheses. The complexes have been characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction studies. Structural studies reveal that the central Co(III) ions in both the complexes 1 and 2 adopt distorted octahedral geometry and weak intermolecular H-bonding or π…π interactions are operative to bind the complex units in the solid state. The antibacterial activity of the complexes and related compounds has been tested against some Gram(+) and Gram(−) bacteria.

Two new Schiff base complexes of cobalt(III) viz. [Co(L)(L1)(NCS)]ClO4 (1) and [Co(L2)(N3)]2·4H2O (2) where L = propane-1,2-diamine, L1 = 2-[N-(2-aminopropyl)ethanimidoyl]phenolate and L2 = 2,2′-[propane-1,2-diylbis(nitriloeth-1-yl-1-ylidene)]diphenolate ion have been prepared and characterized. In addition to the X-ray diffraction studies, the complexes and related ligands have been tested in vitro to assess their antibacterial activities.Figure optionsDownload as PowerPoint slideHighlights
► A mononuclear and a binuclear Schiff base complex of Co(III) have been prepared.
► Complexes of different nuclearity were obtained by changing the pseudohalide only.
► The central Co(III) ions are six-coordinated with distorted octahedral geometry.
► H-bonding and π…π interactions are operative in the supramolecular structures.
► The antibacterial activity of the complexes and related ligands has been evaluated.