In this study, the densities of pyrrole (1) + pyridine (2), pyridine (1) + quinoline (2), pyrrole (1) + quinoline (2), indoline (1) + quinoline (2), indoline (1) + pyridine (2), and indoline (1) + pyrrole (2) were measured over the entire composition range at temperatures T = 298.15–343.15 K and pressure p = 101.305 kPa. The data were used to calculate excess molar volume (VmE), partial molar volume (V̅i), excess partial molar volume (V¯iE), apparent molar volume (Vφ,i), and the isobaric thermal expansion (αp). Excess molar volumes (VmE) were fitted to a Redlich–Kister equation to evaluate the deviation from ideal mixing behavior. It was noted that indoline (1) + quinoline (2) has a negative (VmE) deviation from ideality. Whereas the pyridine (1) + quinoline (2), pyrrole (1) + quinoline (2), indoline (1) + pyridine (2), and indoline (1) + pyrrole (2) mixtures showed positive excess molar volume deviations from ideality due to dissimilar structures. The FT-IR spectra of all the studied binary mixtures showed the presence of N–H bonding within the molecules. Finally, the sigma profile and the sigma potential of individual compounds were generated and analyzed.
Sreekala et al. (Tue,) studied this question.