Syntheses, characterization and crystal structures of Schiff base nickel(II) complexes with antibacterial activity

Two nickel(II) complexes, [NiL1N3] (1) and [Ni(HL2)2(NCS)2)] (2), where L1 = 2-[(2-diethylaminoethylimino)methyl]-4,6-difluorophenolate, L2 = 2,4-difluoro-6-[(2-isopropylaminoethylimino)methyl]phenolate, have been prepared and structurally characterized by elemental analyses, IR and UV-Vis spectra, as well as single crystal X-ray determination. In complex 1, the Ni atom is in square planar coordination, with three donor atoms of the deprotonated Schiff base ligand L1 and the azido N atom. In complex 2, the Ni atom is in octahedral coordination, with the three donor atoms of the zwitterionic Schiff base ligand HL2 and two thiocyanato N atoms. The crystals are stabilized by hydrogen bonds. The complexes have strong antibacterial activity against B. subtilis, S. aureus and E. coli.