Proof of ion-pair structures in ammonium-based protic ionic liquids using combined NMR and DFT/PCM-based chemical shift calculations

摘要: The self-assembly of triethylammonium bis(trifluoromethylsulfonyl)imide, i.e. [(C2H5)3NH][TFSI], in chloroform and aqueous solutions has been investigated using 1H NMR spectroscopy computational (DFT/PCM prediction) methods. We have examined a number ion pairs formed between the [(C2H5)3NH]+ cation with different conformations alkyl substituents as well various dispositions multi-site [TFSI]− anion. Based on agreement calculated (DFT) observed chemical shifts, [(C2H5)3NH][TFSI] lipophilic complexes effective N+–H⋯N or N+–H⋯O hydrogen bonding, whereas hydrophilic Cα–H⋯O Cα–H⋯F bonding are found solutions. This study provides new insight into self-aggregation ammonium PILs incorporating widely used anion demonstrates importance solvent effects shifts. simulations explicit implicit dielectric continuum solvents to be most realistic method, yielding representative ensemble structures.