title: Synthesis, structural characterization and antimicrobial activities of 4- and 6-coordinate nickel(II) complexes with three thiosemicarbazones and semicarbazone ligands.
abstract: To investigate the relationship between antimicrobial activities and the molecular structures of nickel(II) complexes with thiosemicarbazone and semicarbazone ligands, nickel(II) complexes with ligands Hmtsc, Hatsc, Hasc and H2dmtsc, were prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, magnetic susceptibility measurements, UV-Vis absorption spectra, TG/DTA and single-crystal X-ray analysis. Their antimicrobial activities were evaluated by the MIC against four bacteria (B. subtilis, S. aureus, E. coli and P. aeruginosa), two yeasts (C. albicans and S. cerevisiae) and two molds (A. niger and P. citrinum). The 4-coordinate, diamagnetic nickel(II) complexes showed antimicrobial activities which were different from those of free ligands or the starting nickel(II) compounds; [Ni(mtsc)(OAc)] 1 showed selective and effective antimicrobial activities against two Gram-positive bacteria (B. subtilis and S. aureus) and modest activities against a yeast (S. cerevisiae), [Ni(mtsc)Cl] 3 exhibited moderate activities against a Gram-positive bacterium (S. aureus), and [Ni(atsc)(OAc)] 5 showed modest activities against two Gram-positive bacteria (B. subtilis and S. aureus). On the other hand, the 6-coordinate, paramagnetic nickel(II) complexes with two protonated or deprotonated ligands ([Ni(mtsc)2] 2, [Ni(atsc)(mtsc)] 4, [Ni(atsc)2] 6, [Ni(Hatsc)2](NO3)(2)7, [Ni(Hatsc)2]Cl(2)8 and [Ni(Hasc)2](OAc)(2)9) and the sterically crowded 4-coordinate, diamagnetic nickel(II) complex ([Ni(dmtsc)] 10) did not inhibit the growth of the test organisms. The structure-activity correlation in this series of nickel(II) complexes was discussed based on their ligand-replacement abilities.
authors.affiliation: Department of Materials Science, Faculty of Science, Kanagawa University, Hiratsuka, Japan.
authors.forename: N C
authors.initials: NC
authors.lastname: Kasuga
authors.forename: K
authors.initials: K
authors.lastname: Sekino
authors.forename: C
authors.initials: C
authors.lastname: Koumo
authors.forename: N
authors.initials: N
authors.lastname: Shimada
authors.forename: M
authors.initials: M
authors.lastname: Ishikawa
authors.forename: K
authors.initials: K
authors.lastname: Nomiya
mesh_terms: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D018360:Crystallography, X-Ray; D005658:Fungi / Q000187:drug effects; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry* / Q000494:pharmacology*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D012664:Semicarbazones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D013882:Thiosemicarbazones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D015003:Yeasts / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D008024:Ligands; D009942:Organometallic Compounds; D012664:Semicarbazones; D013882:Thiosemicarbazones; D009532:Nickel