Fluorene–thiophene-based thin-film fluorescent chemosensor for methamphetamine vapor by thiophene–amine interaction

A fluorescence “turn-on” sensor for methamphetamine (MA) vapor sensing was realized. Two sensory materials, 9,9-dioctylfluorene-2,7-bisthiophene (FBT) and poly [(9,9-dioctylfuorenyl-2,7-diyl)-alt (3-hexylthiophene-2,5-diyl)] (PFT), were synthesized and their fluorescence sensing potential towards MA has been demonstrated. Both materials show high sensitivity and selectivity to MA vapor in solid state. Upon exposure to the saturated vapor of MA, the fluorescence could be increased 6.4 and 4.65 folds for FBT and PFT respectively and these changes could be readily distinguished by naked eyes. Taking a fluorescence intensity change as 1%, the detection limits of FBT and PFT for MA vapor were estimated to be 1.9 ppm and 6.4 ppm. The sensing mechanism was proposed to arise from fluorescence enhancement induced by a thiophene–amine interaction.