title: Synthesis, spectroscopic characterization, electrochemical behaviour, reactivity and antibacterial activity of some transition metal complexes with 2-(N-salicylideneamino)-3-carboxyethyl-4,5-dimethylthiophene.
abstract: Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with a potentially tridentate Schiff base, formed by condensation of 2-amino-3-carboxyethyl-4,5-dimethylthiophene with salicylaldehyde were synthesized and characterized on the basis of elemental analyses, molar conductance values, magnetic susceptibility measurements, UV-vis, IR, EPR and NMR spectral data, wherever possible and applicable. Spectral studies reveal that the free ligand exists in a bifunctionally hydrogen bonded manner and coordinates to the metal ion in a tridentate fashion through the deprotonated phenolate oxygen, azomethine nitrogen and ester carbonyl group. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each complex. The EPR spectral data of the Cu(II) complex showed that the metal-ligand bonds have considerable covalent character. The Ni(II) complex has undergone facile transesterification reaction when refluxed in methanol for a lengthy period. X-ray diffraction studies of Cu(II) complex showed that the complex has an orthorhombic crystal lattice. In view of the biological activity of thiophene derivatives, the ligand and the complexes were subjected to antibacterial screening. It has been observed that the antibacterial activity of the ligand increased on chelation with metal ion.
authors.affiliation: Department of Chemistry, University of Kerala, Kariavattom Campus, Trivandrum 695581, Kerala, India.
authors.forename: Varughese P
authors.initials: VP
authors.lastname: Daniel
authors.forename: B
authors.initials: B
authors.lastname: Murukan
authors.forename: B Sindhu
authors.initials: BS
authors.lastname: Kumari
authors.forename: K
authors.initials: K
authors.lastname: Mohanan
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D004951:Esterification / Q000187:drug effects; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013055:Spectrophotometry, Infrared; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D028561:Transition Elements / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D008024:Ligands; D009942:Organometallic Compounds; D013876:Thiophenes; D028561:Transition Elements