Porous Shape Persistent Fluorescent Polymer Films: An Approach to TNT Sensory Materials

Abstract

Fluorescence is a leading signal transduction method for the formation of chemosensory devices.1,2 Conjugated polymer-based fluorescent chemosensors have been proven to further amplify this inherently sensitive method.2 Although solid-state (thin film) fluorescent chemosensory devices are generally required, most systems have limited solid state utility with the lack of stable (reproducible) spectroscopic features and low fluorescence quantum yields, presumably due to the excimer formation and selfquenching.3,4 These processes have been an impediment to other applications of conjugated polymers and general solutions also have implications for electroluminescent polymer devices.4 We report herein an approach to stable fluorescent conjugated polymer films by the incorporation of the rigid three-dimensional pentiptycene moieties,5 1, which prevent π-stacking or excimer formation. In comparison to the planar model polymer 3, thin films of the pentiptycene polymer, 2, display enhanced fluorescence quantum yield and stability. Moreover, their potential for the trace detection of high explosives such as 2,4,6-trinitrotoluene (TNT) is also reported.6 Polymer 2 has unprecedented high sensitivity as an artificial fluorescent chemosensor for the vapors of TNT and 2,4-dinitrotoluene (DNT).