Photophysics of 9,9‐dimethylacridan substituted phenylstyrylpyrimidines exhibiting long lived intramolecular charge transfer fluorescence and aggregation induced emission characteristics

Six pyrimidine-based push-pull systems substituted at positions C2 and C4/6 with phenylacridan and styryl moieties, employing methoxy or N , N -diphenylamino donors, have been designed and synthesized involving cross-coupling and Knoevenagel reactions. X-ray analysis confirmed their molecular structure featuring the acridan moiety arranged perpendicularly to the residual p-system. Photophysical studies revealed significant differences between the methoxy and N,N -diphenylamno chromophores. Solvatochromic studies revealed that the methoxy derivatives show dual emission in polar solvents. Time resolved spectroscopy revealed that the higher energy band involves very fast (<80 ps) prompt fluorescence while the lower energy one includes long components (~30 ns) due to  long lived ICT fluorescence. In contrast to N , N -diphenylamino chromophores, the methoxy derivatives also showed aggregation induced emission in THF/water mixtures as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates being not far from pure white light. These properties render the methoxy derivatives as very promising organic materials for WOLEDs.