Cationic Complexes of Magnesium with Phenanthroline: Synthesis, Structural Features, and Antibacterial Activity

Abstract

The reaction of magnesium oxide/magnesium pivalate with aromatic heterocyclic acids (3-indolecarboxylic (HInd); 2-thiophenecarboxylic (HTph)) and 1,10-phenanthroline (Phen) gave cationic complexes [Mg(Phen)(Ind)(H₂O)₃]⁺⋅Ind^–·2Phen·1.5H₂O (I) and [Mg(Phen)(H₂O)₄\(]_{3}^{{2 + }}\)·6Tph^–·2Phen (II). The structures of I and II were established by direct X-ray diffraction analysis (CCDC nos. 2422043 (I) and 2422042 (II)). According to X-ray diffraction data, the central atom in I and II has a distorted octahedral environment {MgN₂O₄}, with the magnesium coordination number being six. In the crystal packing of I, stacking interactions between the Phen aromatic rings give rise to parallel stacks held together by hydrogen bonds. The outer-sphere Tph^– in II form strong hydrogen bonds with the coordinated water molecules, thus forming 1D hydrogen-bonded framework. The antibacterial activity of I and II against a non-pathogenic Mycolicibacterium smegmatis strain and two lactobacillus strains, Lactobacillus brevis and Lactobacillus fermentum, was evaluated. The antiproliferative activity of I was determined against the human ovarian adenocarcinoma (SKOV3), breast adenocarcinoma (MCF7), and glioblastoma (A172) cells.