Theoretical Study of the Pr(III):DL-Serine:Ca2+ Complex Formation at Different pHs: 4f–4f Transition Spectra as PROBE

Abstract

The 4f–4f transition spectra for the complexation of Pr(III) with DL-serine amino acid and Ca²⁺ has been explored in aqueous organic solvents (v/v 50%) of methanol and dimethylformamide at different pHs 2, 4, and 6. The variation in the computed values of absorption spectral parameters (energy interaction): Slater–Condon (F_K), Lande spin orbit interaction (ξ_4f), Racah (E^K), nephelauxetic ratio (β), bonding (b^1/2), and percent covalency (δ) could provide the detailed information about the nature of complexation theoretically. The formation of covalent character has been validated by the elevated values of percent covalency (δ) 5.579–5.658 for MeOH and 5.779–5.820 for DMF. Values of root mean square deviation (RMS) ranges from 101.69 to 125.35, confirming the accuracy of the evaluated energy parameters. Further, the computed and observed values of evaluated oscillator strength(P) and Judd–Ofelt electric dipole intensity parameters T_λ (λ = 2,4,6) cm⁻² were analyzed to see the possibility of inner and outer sphere coordination of Pr(III) with DL-serine in the presence and absence of Ca²⁺ at different pHs. Of the three T_λ (λ = 2, 4, 6) cm⁻² parameters, T₆ is the most significant in all the pHs. Its values were 12.86–18.67 for MeOH and 11.30–20.87 for DMF. Interesting information about the effect of pH and solvents on complexation could be revealed.

Graphical Abstract

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