Structuring effect of some salts on glycerol carbonate: A near-infrared spectroscopy, small- and wide-angle X-ray scattering study

Alkylene carbonates such as ethylene, glycerol and propylene carbonates offer a valuable tool for the investigation of intermolecular interactions in polar non-aqueous liquids. Their physico-chemical properties suggest the presence of a strong structure that mainly depends on hydrogen bonds. The addition of salts bearing basic anions such as fluoride, carbonate and phosphate leads to the formation of free ions and ion pairs that are well accommodated in the solvent structure. In this work near infrared and attenuated total reflection Fourier-transform infrared spectroscopy, small- and wide-angle X-ray scattering were carried out on pure glycerol carbonate and on its solutions of saturated KF, K2CO3 and K3PO4 in order to probe the structure of the solvent. Linear and cyclic oligomeric clusters produced by the association of the liquid molecules are proposed. The different effectiveness of the studied anions in enhancing the internal arrangement of the liquid can be explained in terms of polarizability (i.e. of the delocalization of their charge), different basicity and hydrogen bonding (HB) accepting capacity and geometry of the anions.