Vibrational Signatures of Calcium Oxalate Polyhydrates

Abstract

The vibrational signatures of the calcium oxalate polyhydrates are investigated using a combination of Density Functional Theory-Dispersion corrected, Fourier Transform- Raman and -Infrared (IR) spectroscopies. Most vibrational bands were assigned and the theoretical predictions were compared with in-house and other experimental data, for both, IR and Raman spectroscopies. Such an approach allowed a more accurate analysis of vibrational spectra helping in the completion of the band assignments of the vibrational bands of the mono, di, and tri hydrate calcium oxalate (COM, COD, and COT). Particular attention has been paid to the degree of hydration of COD, the low Raman wavenumbers, and the presence of oxalic acid in natural calcium oxalate polyhydrates. The obtained results are expected to be supportive in the detection of the different polyhydrates in natural samples, such as in kidney stones.