Nickel(II) Complexes Derived from Bis-Schiff Bases: Synthesis, Crystal Structures, and Antimicrobial Activity

Nickel(II) complexes derived from the bis-Schiff bases N,N'-bis(5-methylsalicylidene)-1,2-diaminocyclohexane (H2La), N,N'-bis(5-methylsalicylidene)-1,2-diaminoethane (H2Lb) and N,N’-bis(3,5-difluorosalicylidene)-1,2-diaminoethane (H2Lc), respectively, have been prepared and characterized by elemental analyses, IR, UV−Vis and single crystal XRD (CIF files CCDC nos. 1912770 (I), 1912771 (II), and 1912772 (III)). The bis-Schiff base ligands coordinate to the nickel atoms through phenolate O and imine N atoms. Each metal atom in the complexes is in square planar coordination. The effects of the complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied, which indicate that the fluoro-substituted groups are essential for the biological process.