Spectrophotometric studies of complexing behavior of some organic ligands with selective metal ions

Abstract

The present work deals with the specrophotometric complexation studies of VO(II), Mn(II), Fe(III), Pb(II) and Bi(IIl) with ortho phenanthroline(o-Phen.) as primary and Eosin as secondary ligand. The spectra of these complexes were recorded under optimized pH conditions. The wavelength of maximun absorbance for these complexes were 550nm, 560nm,555nm,558nm and 552nm respectively. The stoichiometries of these complexes were determined by applying Job's method. It was found that Metal:o-phen.:Eosin ratios were 1:1:1,1:2:1,1:1:1,1:2:1 and 1:2:1 respectively for these complexes.. The molar absorption coefficient for these complexes were 1.73x 104L.morl.cm-I 1.95xl 04L.morl .cm-l, 2.8x 104L.morl .cm-l, 2.05xl 04L.morl .cm-l, and 1.92x 104L.morl.cm-l. The stability constants were also determined and log of stability constants were 5.94, 5.77, 6.11 , 6.93 and 6.93 respectively. The effect of time and temperature on these complexes was also studied. The effect of diverse ions on the intensity of these complexes was also investigated and the percentage decrease or increase in intensity along with the limiting concentration of these ions was determined. Calibration graphs were plotted to find out the range up to which these complexes obey the Beer's Law, a straight line was observed over the range 3-12 ppm, 0.4-2 ppm, 0.5-2 ppm, 0.5-2 ppm, and 0.4-4 ppm for these complexes respectively.