"Receptor free" inner filter effect based universal sensors for nitroexplosive picric acid using two polyfluorene derivatives in the solution and solid states.

Two "receptor-free" blue fluorescent conjugated polymers (CPs) of fluorene namely 9,9-bis(6-bromohexyl)-2-phenyl-9H-fluorene (PF1) and 9,9-bis(6-bromohexyl)-9H-fluorene (PF2) were synthesized using Suzuki cross coupling polymerization and oxidative coupling polymerization methods in high yields and well characterized by gel permeable chromatography, NMR, UV-vis, fluorescence and time-resolved photoluminescence (TRPL) spectroscopy. Both CPs explicitly recognized nitroexplosive picric acid (PA) and displayed a fluorescence quenching response in solution and on a solid support via the Inner Filter Effect (IFE) mechanism. Both CPs were highly selective and sensitive towards PA with high quenching constant values (K) of 5.