Aggregation-Induced Enhanced Emission of a Dimethylacridan Substituted Pyrimidine Derivative

A pyrimidine chromophore bearing an acridan fragment was synthesized and its photophysical properties were studied. In solution, this compound is characterized by an important positive emission solvatochromism with a shift of 5800 cm(-1) between nonpolar heptane and dichloromethane (DCM) associated with large Stokes shifts (up to 9100 cm(-1) in DCM). Mono-exponential fluorescence decays are observed in heptane whereas more complicated bi- or three-exponential decays are observed in more polar solvents due to an interplay between locally excited and charge transfer excited state. Additionally, an aggregation-induced enhanced emission process was demonstrated in THF/water mixtures. At low temperature (77 K), in a polymethylmethacrylate (PMMA) thin film, the presence of an accessible triplet state (T1) was demonstrated, which was not observed in solution. Finally, we show that it is possible to protonate the chromophore in thin film leading to panchromatic dual emission