A “green” method for isolation of cucurbit[7]urilvia a solid state metathesis reaction

Abstract

A method to isolate CB[7] from a CB[5]/CB[7] mixture has been successfully developed by incorporating an alkyl-imidazolium ionic liquid guest of the type [C_nmim]Br which is only capable of binding with CB[7]. This CB[7]–[C_nmim]Br complex can be removed from the mixture and a subsequent solid state ion metathesis affords pure CB[7]. Moreover, the imidazolium ionic liquids can be recycled from the aqueous solution after the purification thus providing a ‘green’ process.