Acid–base indicators for non-polar solvents via anion-exchange of polymeric ionic liquids with anionic dyes

Abstract

This work reports the synthesis of acid–base indicators based on linear polymeric ionic liquids and their indicating behaviors in non-polar solvents. An acidic indicator PIL-MO, a basic indicator PIL-MB and an acid–base indicator PIL-MO–MB were prepared by attaching methyl orange (MO) and methyl blue (MB) to a linear polymeric ionic liquid, respectively or both. The obtained indicators showed significant acid–base indicating functions in dichloromethane. And these novel indicators exhibited some special properties when compared with the original anionic dyes.