New imidazole‐functionalized polyfluorene derivatives: convenient postfunctional syntheses,sensitive probes for metal ions and cyanide,and adjustable output signals with diversified fluorescence color

Based on our previous work on the sensitive and selective conjugated fluorescent polymeric sensors toward cyanide, 2,1,3‐benzothiadiazole and 4,7‐bis(thiophen‐2‐yl)‐2,1,3‐benzothiadiazole were incorporated into the polyfluorene backbone to yield three new polymers bearing imidazole moieties in the side chains, with different fluorescence color. The fluorescence could be turned off by Cu²⁺ ions and then recovered on addition of cyanide, making them good cyanide sensors with the detection limit down to 1.9 μM. Moreover, by fully understanding this “turn off–turn on” strategy and using the cooperation of two polymers with different fluorescence color, the emission color of the mixture system of one of the imidazole‐containing polymers and one from the corresponding polymers without imidazole ones, could be adjusted by the concentrations of the added copper and cyanide ions, leading to the output fluorescent signals diversity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011