Polyfluorene based fluorescent sensor for sensitive and selective detection of picric acid

A novel conjugated polyfluorene derivative (PCFSe) was successfully synthesized, with benzo[c][1,2,5]selenadiazole in polyfluorene backbone and N-alkylcarbazole in the side chain. PCFSe shows an orange-red fluorescence emission at 570 nm with a high glass transition temperature and excellent thermal stability. In the fluorescence titration experiments, PCFSe as fluorescent sensor exhibits varying degrees of fluorescence quenching towards different nitroaromatics, in which picric acid (PA) detection has the highest sensitive response with the Stern-Volmer quenching constant K-SV value of 1.2 x 10(4) M-1 and the calculated detection limit of 0.27 ppm. Meanwhile, the quenching effect of PA to PCFSe has no significant change even in the presence of other nitroaromatics, indicating a selective PA detection. Furthermore, the paper strips were also fabricated to detect PA, achieving a practical application in fast, easy and on-site detection of nitroaromatic explosives.