Absorption Spectral Study of 4f-4f Transitions for the Interaction of Nd(III) with Different Amino Acids in Presence and Absence of Ca(II)/Zn(II)

Abstract

By employing comparative absorption and quantitative spectral analysis of hypersensitive and pseudohypersensitive transitions using 4f-4f transitions as probe, the interaction of Nd(III) with L-leucine, L(-)-hydroxyproline and L-(+)-arginine in presence and absence of Ca(II)/Zn(II) has been studied in four different aquated organic solvents, i.e., methanol (CH₃OH), acetonitrile (CH₃CN), dimethylformamide (DMF), dioxane (C₄H₈O₂) and their equimolar mixtures. The various energy interaction parameters like Slator-Condon (F_K), Racah (E_K) and Lande (x_4f), nephelauxetic parameter (b), bonding parameter (b^1/2) and per cent covalency (¶) parameter are calculated using partial and multiple regression method. The values of oscillator strength (P) and computed values of Judd-Ofelt electric dipole intensity parameters (T_l) (l = 2, 4, 6) are also calculated for different 4f-4f transitions. The magnitude of changes in various energy interaction parameters as well as in the oscillator strength (P) and Judd-Ofelt intensity values (T_l) were used to explore the degree of inner and outer sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in binding with different ligands.