LAUSR

Abstract In this work, the fundamental nature of the interaction between pyrrole and pyridine with 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO 4 ]) was investigated using DFT theory and was confirmed with the sigma profile analysis via Co nductor-like S creening MO del for R eal S olvent (COSMO-RS) approach. Geometry optimization was performed at density functional theory with B3LYP functional, and 6–311 + G* basis set for individual species and complexes of neat [EMIM][EtSO 4 ] with pyrrole/pyridine. Thereafter, the partial charges and interaction energy were derived. The amount of charge transfers in [EMIM][EtSO 4 ] + pyrrole was found to be ~ 20% more than in [EMIM][EtSO 4 ] + pyridine, indicating that CH π interaction was stronger with pyrrole than with pyridine. The interaction energy for the complex [EMIM][EtSO 4 ] + pyrrole was more negative than that of [EMIM][EtSO 4 ] + pyridine, which implies that [EMIM][EtSO 4 ] has a more favourable interaction with pyrrole than with pyridine.