Comparative 4f–4f absorption spectral study for the interactions of Nd(III) with some amino acids: Preliminary thermodynamics and kinetic studies of interaction of Nd(III):glycine with Ca(II)

Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, l-alanine, l-phenylalanine and l-aspartic acid in the presence and absence of Ca2+ was carried out in some organic solvents; CH3OH, CH3CN, DMF and dioxane using comparative absorption spectra of 4f–4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator–Condon (Fk), Lande factor (ξ4f), nephelauxetic ratio (β), bonding parameter (b1/2), percent-covalency (δ) by applying partial and multiple regression analysis. The values of oscillator strength (Pobs) and Judd–Ofelt electric dipole intensity parameter Tλ (λ = 2, 4, 6) for different 4f–4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength (Pobs) and Tλ values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy (Ea) and thermodynamic parameters like ΔH°, ΔS° and ΔG° for the complexation are evaluated.

Comparative 4f–4f absorption spectra for the complexation of Nd(III) with different amino acids showing sensitivity of absorption bands towards coordination.Figure optionsDownload as PowerPoint slideHighlights
► Absorption 4f–4f transition analysis as a probe to investigate the coordination behaviour of the complexation of Nd(III) with some amino acids in the presence of Ca2+.
► Sensitivity of hypersensitive and nonhypersensitive bands of Nd(III) in solution state.
► Energy interaction parameters and intensity parameters.
► Change of intensity of different 4f–4f transition with time and calculation of rate of the reaction.
► Kinetics and thermodynamic studies of the complexation.