Nitroaromatic compounds sensing. Synthesis, photophysical characterization and fluorescence quenching of a new amorphous segmented conjugated polymer with diphenylfluorene chromophores

A new regularly segmented conjugated polymer bearing 2,7-diphenylfluorene chromophores tethered by isopropylidene connectors was synthesized by a relatively short synthetic route starting from easily available monomer synthons. Its photophysical properties were investigated using UV–vis absorption, steady state and time-resolved emission spectroscopies. The bent microstructure produces a highly soluble amorphous polymer and fluorescence depolarization showed that exciton mobility within the polymer film is not hindered. These properties are of practical significance in view of the high sensitivity and fast response of its fluorescence quenching by nitro aromatics. Half of the maximum quench (Q50%) of a polymer film occurred with dinitrobenzene in methanol solution at the micromolar range in less than 1 min in a reversible manner. We demonstrate that amorphous segmented conjugated polymers bearing relatively short chromophores can be used as sensing materials with performances comparable to those presented by conjugated polymers with more elaborate structural design.