Modelling room temperature ionic liquids: charge environment, hydrogen bond dynamics and related phenomena

Abstract

In simple terM.S., room temperature ionic liquids (RTILs) are materials that are composed entirely of ions (without any charge neutral molecules) and also melt at low temperatures. [1 8] While 100oC is generally accepted as an arbitrary upper limit on melting point of RTILs, there is no fundamental difference between salts that melt at say 80oC and those at 120oC. [3] Low melting nature of RTILs does present a clear advantage over high temperature molten salts in terM.S. of ease of handling without the need of special equipment. [3] Paul Walden is credited to have synthesized in 1914 the earliest RTIL [EtNH3][NO3] which had a melting point of 12oC. [3, 9] There were many other independent scattered discoveries of other RTILs until early 1980s. These early RTILs were mainly based on chloroaluminate salts and had severe limitations with regards to their stability when exposed to air or moisture. It was in the early 1990s that air and moisture stable RTILs were developed and these diverse compounds started to be viewed under the single lens of RTILs. [3, 9]