A Study on complexation
behavior of Lanthanides (III) with Pregabalin
Modi Niral, Sharma Sangita, Bishnoi Anjali and Bansal Rita
Res. J. Chem. Environ.; Vol. 29(12); 39-45;
doi: https://doi.org/10.25303/2912rjce039045; (2025)
Abstract
Lanthanide(III)-Pregabalin complexes were formed by interaction between Pregabalin
and Sm(III), Gd(III), Tb(III), Dy(III) & Ho(III) nitrates in aqueous medium. Stability
of binary complexes was studied in detail by using Irving Rossotti titration technique
at temperatures (30±0.1, 40±0.1 and 50±0.1°C) and ionic strength (0.1, 0.2, 0.3
and 0.4M). Protonation constants of Pregabalin have been evaluated using three different
methods PKAS, BEST and point wise calculation method with Fortran IV computer program.
Stability constants of Pregabalin lanthanide complexes have been obtained by BESTFIT
program with consideration of systematic errors.
ΔG0, ΔH0 and ΔS0 values were obtained to evaluate stability order of binary complexes
which were further investigated with the aid of speciation curves (SPEPLOT) plotted.
The value of overall stability constant of each complex obtained is relatively high,
indicating good stability for the complexes in the pH range 2-12. Critical analysis
of stability constant and their thermodynamic parameter indicate that stability
order is Sm(III) < Gd(III) < Tb(III) < Dy(III) < Ho(III).
