Syntheses of copper complexes of nicotinohydroxamic and isonicotinohydroxamic acids.

Nicotinohydroxamic acid (NHA) and isonicotinohydroxamic acid (INHA) were synthesized, characterized by electronic and spectral studies,magnetic measurements and their pKa determined spectrophotometrically as 8.68 ± 0.02 in aqueous medium of 0.1mol dm-3 I=ionic strength. The composition of the complexes was determined by Job’s plot. The ratios of Cu2+ to ligands under investigation were ML2. The formation constants obtained and the possible binding modes for the complexes in solid states are discussed. Spectral studies of the isolated complexes indicate tetragonally distorted octahedral geometry via (O,O) and (N,O) coordination modes. The magnetic moments obtained for the complexes are in the range 1.57-1.79B.M. Microbial sensitivity test carried out on the ligands and their isolated complexes showed no activity on the microorganisms under investigation. Keywords: Nicotinohydroxamic acid, isonicotinohydroxamic acid, IR spectra, ionic strength, Job’s plot, pKa, microbial sensitivity