Synthesis and Characterization of Monomeric and Polymeric Hg(II) Complexes with 5-Methyl-5-(3-pyridyl)-2,4-imidazolidenedione Showing a Wide Spectrum of Effective Antibacterial Activities

Abstract

Three new mercury(II) coordination monomers, HgLX3 [X = Cl− (1) and Br− (2)], and polymer, [HgLI2]n, (3), L = 5-methyl-5-(3-pyridyl)-2,4-imidazolidenedione, have been synthesized and characterized by elemental analysis (C, H, and N %) and flame atomic absorption (Hg %), IR, and NMR spectroscopy. Complexes 1 and 2 have the same framework structure while the structure of complex 3 is an infinite 2D layers. According to X-ray diffraction analysis, complex 3 crystallizes in monoclinic system. In this polymeric complex, [Hg(C9H9N3O2)I(μ-I)2]n, HgII atom is coordinated by one L and three I− anions with a distorted tetrahedral geometry; one I− anion is in a monodentate coordination mode and the other two are bridging, linking HgII atoms into a one-dimensional chain. Classical hydrogen-bonding interactions (O···H–N) between adjacent ligands result in a zigzag type arrangement of one chain while consecutive polymeric chains are linked by non-classical ones (O···H–C) to form 2D supramolecular layers. The results indicate that the flexible ligand can form complexes with varied structures. In addition, the species of the halide were found to have great impact on the structure of the complexes. Antibacterial activity of L and the corresponding complexes investigated against six species of microorganisms. Testing was performed by disk diffusion method, and minimum inhibitory concentrations have been determined. Noteworthy antimicrobial activities for these complexes were observed.