Aggregation-induced fluorescent response of urea-bearing polyphenyleneethynylenes toward anion sensing

A π-conjugated urea-bearing phenyleneethynylene polymer (Poly-2) was rationally designed by the Sonogashira coupling condensation reaction and had been demonstrated to have a unique fluorescent quenching effect for optical detection of all determined anions, especially CN−. The emission Poly-2 significantly quenched upon adding CN−, together accompanied with continuous red shift peak from 442 464 nm cyanide concentration increased 0 1.0 mM. On contrary, its precursor polymer, Poly-1, itself also displayed responsibility selected anions but no obvious selectivity tendency. For instance, addition highly basic N3−, AcO−, or F− Poly-1 solution in DMF/H2O (v/v = 1:1) led photoluminescence amplification, while weakly like Cl−, I−, Br− showed fluorescence effect. Both polymers were seriously self-aggregated state matter absence presence an anion. Interestingly, it found that exhibited aggregation-induced behavior, aggregation-caused effect, based on relationship between aggregation state. structural characterizations carried out NMR spectroscopy size exclusion chromatography measurements; properties anion sensing followed spectroscopy, behavior both investigated dynamic light scattering measurements.