Comparative 4f-4f Spectral Analysis of Simultaneous Complexation of Pr(III) with L-Tryptophan in Presence and Absence of Ca2+ and Zn2+ Ions in Aqueous Medium: Energy, Intensity and Kinetic Studies

The spectral analysis of the complexation of praseodymium (Pr3+) with L-tryptophan in various aqueous solvent applying a quantitative probe of 4f-4f transition spectra. The study is carried out by calculating various energy interaction parameters such as the nephelauxetic effect (β), percent covalency (δ), bonding parameter (b1/2), Slater-Condon (Fk) and intensity parameters like oscillator strength (P) and intensity of Judd-Ofelt parameters Tλ (λ = 2, 4, 6). The paramagnetic behaviour of Pr3+ shows 3H4→1D2, 3H4→3P0, 3H4→3P1, 3H4→3P2 types of specific 4f-4f absorption bands and are observed at the visible reason of 427-610 nm. The intensities of 4f-4f transition bands rise on the addition of Ca2+ and Zn2+ ions toward the complexation of praseodymium (Pr3+):Try and extended result in the case of Ca2+ ion compared to the Zn2+ ion due to increase in the interaction between ligand and 4f orbital of metal ions. These bands on immediate minor’s coordination change around praseodymium (Pr3+) found to be highly sensitive due to the formation of heterobimetallic complex between L-tryptophan (Try) with Pr3+ in the existence of Zn2+ and Ca2+ ions. The complexation of Try with Pr3+ in the presence of Zn2+ and Ca2+ ions are monitors simultaneously from the sensitivity of the bands using energy parameters and oscillator strength. The rate of heterobimetallic complexation of both Zn2+ and Ca2+ ions was calculated from the 4f-4f transition at different temperatures. The thermodynamic parameters and activation energy calculated from the rate constants from different temperatures are more favourable in case of Try form complex with Pr3+ in the presence of Ca2+ ion as compared to Zn2+ ion.