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 through cross‐coupling and Knoevenagel reactions. X‐ray analysis confirmed that the molecular structure featured the acridan moiety arranged perpendicularly to the residual π system. Photophysical studies revealed significant differences between the methoxy and N,N‐diphenylamino chromophores. Solvatochromic studies revealed that the methoxy derivatives showed dual emission in polar solvents. Time‐resolved spectroscopy revealed that the higher energy band involved very fast (<80 ps) fluorescence, whereas the lower energy one included long components (≈30 ns) due to long‐lived intramolecular charge‐transfer fluorescence. In contrast to N,N‐diphenylamino chromophores, the methoxy derivatives also showed aggregation‐induced emission in mixtures of THF/water, as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates not far from that of pure white light. These properties render the methoxy derivatives as very promising organic materials for white organic light‐emitting diodes.
Highlights The protonation effect on the excited state dynamics is investigated Two pyrimidine chromophores, bearing the A-(π-D)2 and A-(π-D)3 structure, are used Time resolved fluorescence spectroscopy (fs and ns) is employed Protonation using three different acids, CSA, TFA and AcOH is studied The dynamics of the neutral chromophores become faster upon protonation with AcOH
The initial anisotropy of asymmetrically substituted tri-podal compounds is greatly dependent on the excitation wavelength indicating that the molecule behaves as pseudo-octupolar (λexc = 380 nm) or dipolar (λexc = 400 nm).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.