Effect of precipitant on the luminescent property of poly(phenylene ethynylene) with p-aminophenyl-ethynyl as side-group

The poly(phenylene ethynylene) (PAnPE) with p-aminophenyl-ethynyl as a side-group was synthesized through Pd-catalyzed Sonogashira coupling reaction between 4-[(2,5-dibromophenyl)ethynyl] aniline and 1,4-diethynyl-2,5-bis(pentyloxy) benzene. In THF solution, PAnPE exhibits two strong fluorescence emission peaks at 473 and 519 nm. The fluorescence properties of PAnPE are discussed when adjusting the kind and content of the precipitants, including methanol, acetic acid and dilute hydrochloric acid, which can influence the aggregation state of PAnPE. The experimental results exhibit that the intensity of the two fluorescence peaks of PAnPE display different downtrend due to the different aggregating structure of polymer molecular chain in mixed solvents which was ascribed to the different potency and type of the interaction between the precipitants molecules and PAnPE molecular chains. These results are helpful to achieve its application in chemo-sensors.