Supramolecular spectral studies on metal-ligand bonding of novel quinoline azodyes

A series of novel bidentate azodye quinoline ligands were synthesized with various p-aromatic amines like p-(OCH3, CH3, H, Cl and NO2). All ligands and their complexes have been characterized on the basis of elemental analysis, R-1, H-1 and C-13 NMR data and spectroscopic studies. IR and H-1 NMR studies reveal that the ligands (HL) exists in the tautomeric azo/hydrazo form in both states with intramolecular hydrogen bonding. The ligands obtained contain N=N and phenolic functional groups in different positions with respect to the quinoline group. IR spectra show that the azo compounds (HL) act as monobasic bidentate ligand by coordinating via the azodye (-N=N-) and oxygen atom of the phenolic group. The ESR (g(vertical bar vertical bar) and g(perpendicular to)) and bonding alpha(2) parameters of the copper ion were greatly affected by substituting several groups position of ring of quinoline and p-aromatic ring. The ESR spectra of copper complexes in powder form show a broad signal with values in order g(vertical bar vertical bar) > g(perpendicular to) > g(e) >2.0023. The value of covalency factor beta and orbital reduction factor K accounts for the covalent nature of the complexes. All complexes possessed an octahedral and square planar geometry. The thermal properties of the complexes were investigated using TGA and DSC. It is found that the change of substituent affects the thermal properties of complexes. (C) 2013 Elsevier B.V. All rights reserved.