Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1234035 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2010 | 9 Pages |
A series of N-benzoylated cyclam ligands incorporating three different benzoyl groups 1,4,8,11-tetra-(benzoyl)-1,4,8,11-tetraazacyclotetradecane (L1), 1,4,8,11-tetra-(2-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L2) and 1,4,8,11-tetra-(4-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L3) and their nickel(II) and copper(II) complexes are described. Crystal structure of L1 is also reported. The ligands and complexes were characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. N-benzoylation causes red shift in the λmax values of the complexes. The cyclic voltammogram of the complexes of ligand L1 show one-electron, quasi-reversible reduction wave in the region −1.00 to −1.04 V, whereas that of L2 and L3 show two quasi-reversible reduction peaks. Nickel complexes show one-electron quasi-reversible oxidation wave at a positive potential in the range +1.05 to +1.15 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment values μeff 1.70–1.73 BM which is close to the spin-only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. All the ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.