Metal complexes derived from bidentate ligands: Synthesis, catalytic and biological applications

This review focusses on metal complexes containing bidentate ligands. The development in the synthesis and some applications of these complexes, reported mainly in the last two decades, are presented. Bidentate ligands are Lewis bases that donate 2 pairs of electrons to a central metal atom. Therefore bidentate ligands are often considered chelating agents because of their ability to bind to metal atoms at two points. This review focuses on metal complexes coordinated to different bidentate ligands such as 1,10-phenanthroline, chalcones, sulfonamides, Schiff base, 4-acylpyrazolones and β-diketones. Bidentate ligands and metal complexes containing bidentate ligands, have found applications as anticancer, antiproliferative, antimalarial, anti-inflammatory, antioxidant and antifungal agents where they inhibit the activities of metalloenzymes by selective complexation with its central metal atoms. Some metal complexes of bidentate ligands have been identified as versatile catalysts in organic synthesis. It's instructive to note that some of the metal complexes containing bidentate ligands reviewed showed better anticancer (when testing on human cancer cell lines) and biological activity than existing commercial therapeutic agents.