Syntheses, Crystal Structures, and Antibacterial Activity of New Tetranuclear Zinc(II) Complexes with Schiff Base Ligands

Two new tetranuclear zinc(II) complexes, [Zn-4(L-1)(2)(mu(2)-eta(1):eta(1)-CH3COO)(4)(mu(1,1)-N-3)(2)] (1) and [Zn-4(L-2)(4)(CH3CH2OH)(H2O)] (2), where L-1 and L-2 are the deprotonated forms of 4-fluoro-2-((pyridin-2-ylmethylimino)methyl)phenol (HO) and 4-fluoro-2-((2-(hydroxymethyl)phenylimino)methyl)phenol (H2L2), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, and single crystal X-ray diffraction. X-ray crystal structural study indicated that the distances between the adjacent Zn atoms are 3.160(1)-3.353(1) angstrom in 1 and 3.005(1)-3.168(1) angstrom in 2. All zinc atoms in 1 are pentacoordinated in trigonal bipyramidal geometry, and those in 2 are in square pyramidal and octahedral geometry. The complexes and the Schiff bases were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.