Characterization of a Novel Intrinsic Luminescent Room-Temperature Ionic Liquid Based on [P-6,P-6,P-6,P-14][ANS]

Intrinsically luminescent room-temperature ionic liquids (RTILs) can be prepared by combining a luminescent anion (more common) or cation with appropriate counter ions, rendering new luminescent soft materials. These RTILs are still new, and many of their photochemical properties are not well known. A novel intrinsic luminescent RTIL based on the 8-anilinonaphthalene-1-sulfonate ([ANS]) anion combined with the trihexyltetradecylphosphonium ([P-6,P-6,P-6,P-14]) cation was prepared and characterized by spectroscopic techniques. Detailed photophysical studies highlight the in-fluence of the ionic liquid environment on the ANS fluorescence, which together with rheological and H-1 NMR experiments illustrate the effects of both the viscosity and electrostatic interactions between the ions. This material is liquid at room temperature and possesses a glass transition temperature (T-g) of 230.4 K. The fluorescence is not highly sensitive to factors such as temperature, but owing to its high viscosity, dynamic Stokes shift measurements reveal very slow components for the IL relaxation.