A zinc iodide complex with two-dimensional supra-molecular network: new antimicrobial four coordinated zinc complexes

Abstract

Some novel Zn(II) complexes of a new long chain Schiff base ligand have been synthesized. The molecular formula of these complexes is suggested to be ZnLX2 (X = Cl−, Br−, I−, SCN− and N3 −). The ligand and its complexes were identified by elemental analysis, FT-IR, UV–Visible, 1H and 13C NMR spectra, thermogravimetry, conductometry, and melting point measurements. Moreover, the crystal structure of the zinc iodide complex was characterized by X-ray single-crystal analysis. This may be the first report on mononuclear four coordinated Schiff base complex based on 1,4-diaminobutane. The complex crystalizes in the triclinic system with space group P. The zinc ion is surrounded by two iminic nitrogen atoms from the ligand and two iodide anions. According to the angular index of Houser (τ 4) for description of the geometry of four coordinated centers, a distorted tetrahedron is suggested for the complex. Analysis of interactions between molecules of the ZnLI2 complex revealed the existence of intermolecular interactions such as C–H···I, C–H···π, and π···π interactions. There are three types of C–H···I interactions in the crystal packing. Each molecule forms six C–H···I hydrogen bonds with four neighbor molecules through aliphatic and alkenic carbons as donor and I atoms as acceptor. These various C–H···I interactions along with other ones lead to the formation of a supra-molecular structure in a two-dimensional network. After characterization of the complexes, thermal behavior and antimicrobial activities of the ligand and its complexes against some gram-positive and gram-negative bacteria as well as against two fungi were investigated by disk diffusion, MIC, and MBC methods.