Synthesis, structure and properties of [Zn(l-Tyr)2(bpy)]2⋅ 3H2O·CH3OH complex: Theoretical, spectroscopic and microbiological studies

The mixed ligand zinc(II) ion complex of the formula [Zn(l-Tyr)2(bpy)]2·3H2O·CH3OH (1), where l-Tyr and bpy are moieties of l-tyrosine and 2,2′-bipyridine (2,2′-bpy), has been isolated in a crystalline form. Crystal structure was determined and the spectroscopic (FTIR, Raman and near IR (NIR)–visible (vis)–UV) examinations were conducted. Additionally, the theoretical data of the molecular structure were obtained using the density functional theory (DFT) methods. Crystals of complex 1 adopt hexagonal form with a = b = 12.9307 (18) Å, c = 30.148 (6) Å and γ = 120 lattice parameters, and P3221 space group. The crystal structure is built of [Zn(l-Tyr)2(bpy)] units and disordered solvent molecules of water and methanol. Each l-tyrosine chelates the zinc(II) ion via carboxylate oxygen and amino nitrogen atoms. The donor atoms form the cis-[ZnN2N2′O2] chromophore with the distorted octahedral geometry around the Zn2 + ion. Complex 1 as well as [Zn(Im)(l-Tyr)2]2·5H2O (2) and {[Zn(l-Tyr)2(H2O)]·H2O}n (3) compounds were examined as potential inhibitors of the growth of plant and animal fungi, such as Fusarium solani, Penicillum verrucosum, Aspergillus flavus, and bacterial strains, such as Gram-negative Escherichia coli, Pseudomonas fluorescens, Serratia marcescens and Gram-positive Bacillus subtilis.

Graphical abstractThe crystal structure of [Zn(l-Tyr)2(bpy)]2·3H2O·CH3OH (1) was determined and the spectroscopic properties as well as the theoretical data of the molecular structure were studied. The biological activities of complex 1 against fungi (F. solani, P. verrucosum, A. flavus) and bacterial strains (E. coli, P. fluorescens, S. marcescens, B. subtilis) were also investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We have reported the synthesis, structural, spectroscopic and theoretical characterization of a new zinc(II) complex. ► The octahedral Zn2+ coordination is distorted. ► The biological activity of complexes is dependent of a secondary ligand molecule in the order of: imidazole>H2O>2,2′-bpy.