Enhanced Sensory Response of Quaterthiophene Bearing 1,2,3-Triazole Moiety to Explosives

Quaterthiophene (QT) with a 1,2,3-triazole moiety was found to have a high sensory response in solution toward a broad class of nitroaromatics, including DNT and TNT, and nitro esters, such as RDX and PETN. Fluorescence quenching in QT thin films was also high for vapors containing DNT or TNT in ppb levels. These results were unexpected based our earlier report that a polythiophene with triazole moiety as a side group does not show fluorescence quenching in solution with the same explosives. Remarkably, QT bearing a 1,2,3-triazole moiety, the oligomeric analog, shows fluorescence quenching in solution and in the solid state when exposed to nitroaromatic molecules used as explosives. We attribute the enhanced quenching observed in the oligomer in solution and in solid state to its lower aggregation propensity and thus enhanced access of the quenching sites to the analytes.