A novel polythiophene derivative as a sensitive colorimetric and fluorescent sensor for anionic surfactants in water

A novel cationic polythiophene derivative, poly[N,N,N-trimethyl-4-(thiophen-3-ylmethylene)cyclohexanaminium chloride] (PTCA-Cl), has been prepared successfully and applied as a colorimetric and fluorometric probe for the detection of anionic surfactants. In particular, a new method for the polymerization of cationic polythiophene derivatives is found, which has not been reported previously. The colorimetric and fluorescent response of PTCA-Cl to anionic surfactants have been investigated by absorption and emission spectroscopy. The sensing interaction can be apparently observed by the naked eye, which presents a great advantage for its practical applications. Moreover, the sensor (PTCA-Cl) shows high selectivity towards anionic surfactants in the presence of other negatively charged analytes, as well as high sensitivity with a detection limit at 10(-9) M by using fluorimetry, which is the lowest ever achieved among all synthetic anionic surfactants sensors available. Therefore, the water soluble polythiophene derivative can be applied as a colorimetric and fluorescent probe for the detection of anionic surfactants with high selectivity and sensitivity.