Synthesis, Characterization and Biological Studies of Trinuclear Ce(IV) Salen Capped Complex with 5-amino-2,4,6-tris(4-carboxybenzimino)-1,3-pyrimidine

Abstract

A novel tripodal Schiff base ligand, 5-amino-2,4,6-tris(4-carboxybenzimino)-1,3-pyrimidine (TTPS), was synthesized for the first time by the reaction of 2,4,5,6-tetraaminopyrimidine with 4-carboxybenzaldehyde. The prepared ligand was used to synthesize Ce(IV)  salen capped complex, [{Ce(OH)₂(salen)}₃(TTPS)].3H₂O. Both compounds were characterized using UV-Visible, IR, ¹H and ¹³C NMR spectroscopies, elemental analysis and molar conductivity measurements. The spectral studies indicate that the ligand is hexadentate and coordinates to Ce(IV) ions through the oxygen atoms of the carboxylic group. The trinuclear Ce(IV)  salen capped complex was 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 ligand and its Ce(IV) salen capped complex were investigated against Gram-negative bacteria: Escherichia coli (ATCC 6749) and Pseudomonas aeruginosa (ATCC 9027), Gram-positive: Staphylococcus aureus (ATCC 6538P) and Bacillus cereus (ATCC 14579), and fungi: Candida albicans and Aspergillus bacteria niger by the agar well diffusion technique. The ligand was found to be more potent against the test micro-organisms relative to the trinuclear Ce(IV) salen capped complex. The MIC of the new tripodal Schiff base ligand, TTPS, against Staphylococcus aureus was comparable to that of tetracycline and gentamycin