Effects of different substituted positions on the photophysical properties of pyrene-based sulfides

Abstract

A series of new pyrene-based sulfides were synthesized by the reaction between 4-methylbenzenethiol and R-bromopyrene (R = 1(1), 4(2), 2(3)). These compounds were structurally characterized and their properties were analyzed by spectroscopy, single crystal X-ray diffraction, electrochemistry and theoretical studies. Significant effect of substituted positions on photophysical properties were observed. The p-methylphenylthio group in 1- and 4-position significantly increases the absolute fluorescence quantum yield (ФF) in solid state, decreases the ФF in solution and almost does not change the ФF in film state compared to that of pyrene. However, this substituent in 2-position keeps the high ФF in solution, almost does not contribute to the ФF in solid state and significantly decreases the ФF in film state compared to that of pyrene. Moreover, compounds 1, 2 and 3 exhibit typical aggregation-induced emission (AIE) properties that were proved by time-resolved photoluminescence.