Synthesis and photophysical properties of 2-aryl-4-(morpholin-4-yl)quinazoline chromophores: The effect of π-linker moiety

A few-stages synthetic approach to novel 2-aryl-4-(morpholin-4-yl)quinazolines has been proposed. The photophysical properties of target compounds have been investigated in two solvents and compared with those for 2-thienyl-4-(morpholin-4-yl)quinazoline counterparts. The influence of nature, arrangement, and the length of π-linker moiety on the photophysical characteristics of dyes have been analyzed. In general, the replacement of thienylene ring with phenylene one results in blue-shifted absorption and emission maxima, whereas the compound with shortened π-system exhibits slight changes in both absorption and emission in toluene solution compared to the corresponding bi-phenylene counterpart. The compounds emit in solutions with quantum yield up to 75% in toluene and up to 46% in acetonitrile . Fluorescence colour and intensity change upon gradual addition of acid to the solution of the chromophore in toluene. It was found that (5-(4-diphenylaminophenyl)thiophen-2-yl)-4-(morpholin-4-yl)quinazoline is capable of generating white luminescence. Additionally, emission behaviour of quinazolines in the MeCN/water mixtures with different water content has been studied. The changes in position and intensity of the emission band were noted for all the compounds upon addition of water to the solution of quinazoline in MeCN; some chromophores show enhanced emission at 70–80 vol% of water fraction. Finally, 4-morpholinyl chromophores exhibit emission in the solid state. The biphenylene quinazolines emit deep-blue light in powder, while 2-(4-diphenylamino)phenylquinazoline and 2-(5-aminoaryl)thiophen-2-yl counterparts possess green or blue-green fluorescence. • Novel 2-aryl-4-(morpholin-4-yl)quinazolines were synthesized by few-stages approach. • Nature and length of π-linker moiety influence on the photophysical characteristics. • 2-(Ph 2 N-phenylthienyl) derivative can generate white luminescence. • Compounds exhibit blue or blue-green fluorescence in powder.