Crystallographic view of fluidic structures for room-temperature ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate.

Shock-induced crystallization of the supercooled ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, C8H15N2+.PF6-, allows for the first time precise X-ray diffraction analysis directly pertinent to the fluid state. This intermediate-chain-length structure shows features of both short- and long-chain analogs. Two types of interplanar distances between imidazolium rings are observed. The anions are located in channels formed by the imidazolium rings and alkyl chains.