4f-4f Transition Spectra of the Interaction of Pr(III) with L-Valine in Solution: Kinetics and Thermodynamic Studies

Abstract

The 4f-4f transition spectra for the interaction of L-valine with praseodymium(III) in aqueous organic solvents (50% v/v) of CH3CN, DMF, CH3OH and C4H8O2 is investigated. The variation in the theoretically computed values of the absorption spectral parameters viz. energy interaction parameters-spin-orbit interaction (ξ4f), Slater-Condon (Fk), nephelauxetic ratio (β), Racah energy (Ek), bonding parameter (b1/2) and percentage covalency (δ) explained the nature of complexation. The values of evaluated intensity parameters viz. oscillator strengths (P) and Judd-Ofelt parameters (Ωt) (t = 2, 4, 6) were analyzed to see the possibility of outer and inner sphere coordination of Pr(III) with L-valine. Further, reaction pathways for Pr(III) with L-valine and consequently its thermodynamic parameters have been evaluated through 4f-4f transition spectra in the DMF solvent.

Absorption spectral study for the interaction of Pr(III) with L-Aspartic acid in various aquated organic solvents through 4f-4f transition spectra: Analysis of reaction pathways and thermodynamic parameters

“…Minor changes in the coordinating environment, on the other hand, had a considerable impact on the values of T4 and T6 parameters, which were both positive. Variation in the symmetry characteristics of the complex is connected to both 𝑇4 and 𝑇6 parameters [34]; therefore the significant changes in the values of 𝑇4 and 𝑇6 suggest changes in the symmetry of Pr(III), its complex systems and their immediate coordination environment. Outer-sphere coordination occurs between the ligand and metal ion when there are small variations in the values of oscillator strength and Judd Ofelt parameters, while inner-sphere coordination occurs when there are large variations in P and Tλ (λ=2,4,6).…”