title: Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand.
abstract: Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH(2)O, where M=Co(II), Ni(II) and Cu(II), L=BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu(2+), Co(2+) and Ni(2+) complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu(2+), Ni(2+) and Co(2+) form 1:1 complexes.
authors.affiliation: Department of Chemistry, Faculty of Science, Cairo University, Cairo, Egypt. aelsherif72@yahoo.com
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: El-Sherif
authors.forename: Mohamed R
authors.initials: MR
authors.lastname: Shehata
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Shoukry
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Barakat
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D003035:Cobalt / Q000737:chemistry / Q000494:pharmacology*; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D003300:Copper / Q000737:chemistry / Q000494:pharmacology*; D004553:Electric Conductivity; D004583:Electrons; D005658:Fungi / Q000187:drug effects; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007700:Kinetics; D008024:Ligands; D060328:Magnetic Phenomena; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry / Q000494:pharmacology*; D012545:Schiff Bases / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics
chemical_list: D000890:Anti-Infective Agents; D056831:Coordination Complexes; D008024:Ligands; D012545:Schiff Bases; D003035:Cobalt; D003300:Copper; D009532:Nickel