Thermal reversion of spirooxazine in ionic liquids containing the NTf2 anion

We have compared the rate of thermal reversion of Spirooxazine (SO) from its merocyanine (MC) form within ionic liquids and molecular solvents. Et(30) and Kamlet-Taft parameter studies indicate ILs are comparable to polar protic and aprotic solvents. The observed reversion kinetics within the ionic liquids were slower than that of molecular solvents with similar polarity, indicating a greater degree of interactions between the ionic liquid ions and the zwitterionic MC isomer, which led to increased lifetimes for the MC-ion complexes. Pre-metathesis cleaning of precursor salts was found to be necessary in order to obtain spectroscopic grade ILs for physiochemical analysis using solvatochromic probe dyes.