Capillary electrophoretic and nuclear magnetic resonance studies of interactions between halophenols and ionic liquid or tetraalkylammonium cations

Aqueous capillary electrophoretic studies were performed to investigate interactions between halophenols and 1-ethyl-3-methylimidazolium tetrafluoroborate or tetraethylammonium tetrafluoroborate electrolytes. In both cases, increased halogen size correlated with increased affinity for the electrolyte cation. For isomers, the ortho substituted isomer exhibited higher affinity than the para isomer. Irreproducible CE results for analyte pairs in the presence of the ionic liquid stimulated investigations of the interactions between halophenols as well as with the cations of the electrolyte. These interactions were explored by proton and fluorine one-dimensional NMR. The NMR results indicated differences in the interactions between tetraethylammonium/iodophenols and imidazolium/iodophenols. The NMR results indicate hydrophobic stacking interactions between the iodophenols and possible similar interaction among phenols and imidazolium.