Synthesis of Six New Transition Metal Complexes: Structural Characterization and in vitro alpha-Glucosidase Inhibitions Studies

Three one-pot reactions leading to six new transition metal complexes are presented. The one-pot reactions involved transformations of 2-(N'-dicyanomethylene-hydrazino)-benzoic acid (DHB) into three new ligands (Lig-I)(2-), (Lig-II)(2-), and (Lig-III)(2-). The complex [Ni-2(Lig-I)(2)] . 3H(2)O (1) was prepared in a one-pot synthesis in which ligand, (Lig-I)(2-) was formed by the amination of DHB resulting from the nucleophilic attack of an amino group of ethylenediamine (en). The complex [Cu(Lig-II)(en)(H2O)] (2) was prepared in a one-pot synthesis in which ligand, (Lig-II)(2-) was formed by the nucleophilic attack of an amino group of en resulting in an imidazole ring formation. The dinunclear complexes [Zn-2(Lig-III)(2)(CH3OH)(2)] (3) and [Cu-2(Lig-III)(2)(CH3OH)(2)] (4), a linear trinuclear complex [Ni-3(Lig-III)(en)(2)(CH3OH)] (5), and a mononuclear complex [Mn(Lig-III)(CH3OH)(4)] (6) were synthesized using a preparation involving conversion of one of the nitriles on DHB into an imino-ester. The resulting complexes were characterized using a variety of analytical techniques including infra-red and UV-vis spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. The complexes displayed a-glucosidase enzyme inhibition with IC50 values in the range of 1.57-207 mu M.