Synthesis, crystal structure, luminescent properties and antibacterial activities of zinc complexes with bipyridyl and salicylate ligands

Abstract

Two novel coordination complexes having salicylate and bidentate rigid organodiamine ligands, namely, [Zn(μ-bpp)2(Sal)2]n (1) and [{Zn(Sal)2}2(μ-bpe)]2 (2) [bpp = 1,3-bis(4-pyridyl)propane, bpe = 1,2-bis(4-pyridyl)ethane, and Sal− = salicylate anion] were synthesized under solvothermal condition. The complexes were investigated by single crystal X-ray diffraction (SCXRD), elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and photoluminescence spectroscopy. From structural analyses, 1 is a 1-D structure linked by bpp ligands with each Zn(II) atom in a tetrahedral coordination geometry while 2 is a dinuclear 0-D structure. All complexes were tested for their antibacterial activity by in vitro agar diffusion method against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Both 1 and 2 showed mediocre inhibition activity against the tested bacteria. Both complexes showed strong emission with λem at 393 nm (λex = 350 nm) and 390 nm (λex = 350 nm) for 1 and 2, respectively, in dimethyl sulfoxide (DMSO) solution. Metal ion sensing study showed that both complexes could be applied as a fluorescence sensor for detecting Cu2+ ion with good sensitivity and selectivity.