Quantum chemical studies on the simultaneous interaction of thiophene and pyridine with ionic liquid

The simultaneous interaction of thiophene and pyridine with different ionic liquids:1‐butyl‐1‐methylpyrrolidinium tetrafluoroborate([BPYRO][BF4]),1‐butyl‐1‐methylpyrrolidinium hexafluoro‐phosphate ([BPYRO][PF6]), 1‐butyl‐4‐methylpyridinium tetrafluoroborate ([BPY][BF4]), 1‐butyl‐4‐methylpyridinium hexafluorophosphate ([BPY][PF6]) and 1‐benzyl‐3‐methylimidazolium tetrafluoroborate ([BeMIM][BF4]) were investigated using quantum chemical calculations. A three‐tier approach comprising of partial charges, interaction energies and sigma profile generation using conductor‐like screening model for real solvents (COSMO‐RS) was chosen to study the systems. A quantitative attempt based on the CH‐π interaction in ionic liquid; thiophene–pyridine complexes gave the interaction energies of ILs in the order: [BPY][BF4] > [BPYRO][PF6] > [BeMIM][BF4] > [BPY][PF6] > [BPYRO][BF4]. An inverse relation was observed between the activity coefficient at infinite dilution predicted via COSMO‐RS–based model and interaction energies. The dominance of CH‐π interaction was evident from the sigma profiles of ionic liquid together with thiophene and pyridine.