The nature of interactions between N-butylpyridinium tetrafluoroborate and thiophenic compounds: A theoretical investigation

In an effort to understand the nature of the interactions between pyridinium-based ionic liquids and thiophenic compounds, the electronic and topological properties of the interactions between N-butylpyridinium tetrafluoroborate ([BPY]+[BF4]−) and thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT) have been investigated by density functional theory. The most stable structure of the [BPY]+[BF4]− ion-pair indicated that hydrogen bonding interactions between fluorine atoms on [BF4]− anions and C2–H2 on the pyridinium ring play an important role in the formation of the ion-pair. The NBO and AIM analyses indicate the occurrence of π–π stacking interactions. The electron density at bond critical points and Wiberg bond indices are correlated with the interacting distances of H···F interactions, so electron density and Wiberg bond index can demonstrate the interacting strength of H···F hydrogen bonds. The interaction energies suggest that DBT adsorbs prior to the other compounds on N-butylpyridinium tetrafluoroborate ionic liquid.