In the present investigation, the absorption difference and comparative absorption spectroscopic studies involving 4ƒ-4ƒ transitions of Pr(III) with acetyl acetone [Pr(acac)3(H2O)2] and their adducts with structurally related ligands like pyridine (py), bromopyridine (Brpy) and chloropyridine (Clpy) complexes in different solvents like CH3OH, CH3CN and DMF have been carried out. The intra 4ƒ-4ƒ transition spectra yield sharp bands which were analyzed individually by Gaussian curve analysis, the energy interaction parameters (FK,EK), Lande spin orbit coupling (ξ4f), nephelauxetic ratio (β), bonding parameter (b1/2), percent covalency (δ) were calculated and intensity parameters have been computed on computer using partial multiple regression analysis. The difference in the energy parameters with respect to ligands atoms and with various solvents reveals that the chemical environment around the Pr(III) ion has great influence on 4ƒ-4ƒ transition and any change in the environment results in modification of the absorption spectra.
