Group II complexes of N- and O-donors Mixed-ligands as anticancer agents

Abstract

Reactions of 1,10-phenanthroline (phen), p-amino benzoic acid (paba) and cinnamic acid (cina) with MCO3 (M = Mg, Ca, Sr) yielded two mononuclear magnesium complexes [{Mg(phen)(H2O)4}(phen)(paba)2] (1) and [{Mg(phen)(H2O)4}(phen)(cina)2] (2) and two one dimensional chains of both calcium and strontium [Ca(phen)(cina)]n (3), and [Sr(phen)(cina)]n (4) respectively. The structures were characterized by a variety of analytical techniques including IR, UV–Vis, 1H NMR, elemental analysis, and single crystal X–ray diffraction analysis. In these complexes, phen binds via an N,Ń–chelate pocket, while the monoanionic paba—/cina— ligands either remains uncoordinated (in case of 1 and 2) or coordinated in a tridentate fashion (in case of 3 and 4). Complexes 1, 3 and 4 crystallize in the same orthorhombic space group Pbcn while complex 2 crystallizes in triclinic space group P1. In complex 1 and 2, Mg2+ cation adopts a distorted six-coordinate octahedral geometry comprising an [N2O4] donor set while in complexes 3 and 4, Ca2+ and Sr2+ cations adopt a distorted eight-coordinate geometry comprising [N2O6] donor sets. Complexes 1, 2 and 4 were found to be potent anticancer against oral cancer cell line i.e. CAL-27 with IC50 1.85 ± 0.11 , 2.98 ± 1.2 and 5.05 ± 0.35 respectively while complex 3 was inactive.