Comparative Absorption Spectroscopy Involving 4f-4f Transitions to Explore the Interaction between the Pr(III) and Uracil in Presence and Absence of Zn(II)

Abstract

The interaction of Pr(III) with uracil has been explored in presence and absence of Zn(II) using comparative absorption spectroscopy involving 4f-4f transitions in different aquated organic solvents. The change in coordination in different medium is observed from the absorption intensity analysis when Pr(III) interacts with uracil. The interaction induced substantial changes in the intensities of 4f-4f bands and their perturbation was reflected through oscillator strength and Judd-Ofelt intensity (Tλ) parameters. Intensification of these bands became more prominent in presence of Zn(II) suggesting the stimulative effect of Zn(II) towards the complexation of Pr(III) with uracil. It is also suggested that the changes in the oscillator strengths of different 4f-4f bands and Judd-Ofelt intensity parameters can be used to predict in vivo intracellular complexation of uracil with Ca(II) through Pr(III)-uracil absorption spectral analysis studies in vitro as both Pr(III) and Ca(II) have unique similarity in their coordination behavior. Other parameters namely energy interaction parameters like Slator-Condon (Fk’s), spin-orbit Lande (ξ4f), Racah parameter (Ek), nephelauxetic effect (β), bonding (b1/2) and percent covalency (δ ) parameters are computed to correlate their simultaneous binding of metal ions with uracil.