Trinuclear Ce(IV) Salen Capped Complexes with bridging 2, 4, 6-Tris (4-Carboxyphenylimino-41-Formylphenoxy)-1, 3, 5- Triazine and 2,4,6-Tris(4-Carboxybenzimino)-1,3,5-Triazine: Synthesis, Characterization and Biological Studies

Abstract

Trinuclear Ce(IV) salen capped complexes of 2,4,6-tris(4-carboxyphenylimino-4¹-formylphenoxy)-1,3,5-triazine (H₃CT) and 2,4,6-tris(4-carboxybenzimino)-1,3,5-triazine(H₃MT) were synthesized. These were characterized using UV-Visible, IR, ¹H and ¹³C NMR spectroscopies, elemental analysis and molar conductivity measurements. The spectral studies indicate that both ligands are hexadentate and coordinates to the Ce(IV) ions through the oxygen atoms of the carboxylic group. The trinuclear Ce(IV) salen capped complexes were characterized as being bridged by carboxylate anions to the Ce(IV) salen centres and displays a coordination number of eight by involving two hydroxyl groups in the coordination sphere. The in vitro antimicrobial activities of the ligands and their Ce(IV) salen capped complexes were investigated against Gram-negative bacteria: Escherichia coli (ATCC 6749) and Pseudomonas aeruginosa (ATCC 9027), Gram-positive bacteria: Staphylococcus aureus (ATCC 6538P) and Bacillus cereus (ATCC 14579), and fungi: Candida albicans and Aspergillus niger by the agar well diffusion technique. In vitro antimicrobial test indicate that the tripodal ligand, H₃MT is more potent against the test micro-organisms relative to H₃CT, [{Ce(OH)₂(salen)}₃(CT)].3H₂O and [{Ce(OH)₂(salen)}₃(MT)].3H₂O. The MIC of H₃MT against Candida albicans is comparable to that of gentamycin. Amongst the Ce(IV) salen capped complexes, [{Ce(OH)₂(salen)}₃(MT)].3H₂O is more potent.