Interaction of ionic liquids with the surface of silica gel using nanocluster approach: a combined density functional theory and experimental study

Silica gelaEuroconfined ionic liquid (IL) is a class of heterogeneous catalysts with broad catalytic applications. Leaching of the IL from the surface of the support is the major drawback of these catalysts, which reduce the catalyst efficiency during the chemical reactions. To investigate the effect of the hydrogen bonding on the leaching phenomena, the interaction between the 1aEuroethylaEuro3aEuromethylimidazoliumaEurobased IL with various anions (Cl-a?', Br-a?', HSO4a?', NO3a?', BF4a?', and PF6a?') and the surface of the silica gel were studied using density functional theory. Hence, a hydroxylated cageaEurolike cluster of silica gel, Si4O6(OH), was selected to mimic the surface. The values of iE-interaction show that ILs with halogen counter ions have stronger interactions than that of the IL with BF4a?' and PF6a?' counter ions. We also carried out stirringaEuro'filtration method for some prepared samples of IL@silica to experimentally explore the leaching phenomena. The results show good agreement with computational achievements. Copyright a (c) 2013 John Wiley & Sons, Ltd.