title: Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand.
abstract: New Co(II), Ni(II) and Cu(II) complexes derived from tetradentate macrocyclic nitrogen ligand, (1E,4E,8E,12E)-5,8,13,16-tetramethyl-1,4,9,12-tetrazacyclohexadeca-4,8,12,16-tetraene (EDHDH) have been synthesized. The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR and ESR (for Cu(II) complex)) mass, and magnetic as well as thermal analysis measurements. The complexes afforded the formulae: [Cu(EDHDH)Cl2]·2EtOH and [M(EDHDH)X2]·nH2O where M=Co(II) and Ni(II), X=Cl(-) or OH(-), n=1,0, respectively. The data revealed an octahedral arrangement with N4 tetradentate donor sites in addition to two Cl atoms occupying the other two sites. ESR spectrum of Cu(2+) complex confirmed the suggested geometry with values of a α(2)and β(2) indicating that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent, and are consistent with very strong σ-in-plane bonding in the complexes. The molecular modeling is drawn and showed the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all the title compounds using DFT method. Also, the thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. Moreover, the in vitro antibacterial studies of all compounds screened against pathogenic bacteria (two Gram +ve and two Gram -ve) to assess their inhibiting potential. The assay indicated that the inhibition potential is metal ion dependent. The ligand, EDHDH, Co(II) and Cu(II) complexes exhibited a remarkable antibacterial activity against Streptococcus Pyogenes as Gram +ve and Proteus vulgaris as Gram -ve bacterial strains. On the other hand, Ni(II) complex revealed a moderate antibacterial activity against both Gram +ve organisms and no activity against Gram -ve bacterial strain.
authors.affiliation: Department of Chemistry, Faculty of Science, Mansoura University, P.O. Box 70, Mansoura, Egypt. Electronic address: olaelgammal@yahoo.com.
authors.forename: O A
authors.initials: OA
authors.lastname: El-Gammal
authors.affiliation: Department of Chemistry, Faculty of Science, Mansoura University, P.O. Box 70, Mansoura, Egypt.
authors.forename: M M
authors.initials: MM
authors.lastname: Bekheit
authors.affiliation: Department of Chemistry, Faculty of Science, Mansoura University, P.O. Box 70, Mansoura, Egypt.
authors.forename: S A
authors.initials: SA
authors.lastname: El-Brashy
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D007700:Kinetics; D008024:Ligands; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D009532:Nickel / Q000494:pharmacology; D066244:Proton Magnetic Resonance Spectroscopy; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: D000900:Anti-Bacterial Agents; D056831:Coordination Complexes; D008024:Ligands; D047028:Macrocyclic Compounds; D003035:Cobalt; D003300:Copper; D009532:Nickel
keywords: In-vitro antibacterial; Macrocyclic; Octahedral complexes; Octahedral geometry; Spectral characterization; Thermal degradation