Synthesis of a New Cationic Polythiophene Derivative and Its Application for Colorimetric and Fluorometric Detection of Iodide Ion and Anionic Surfactants in Water

A new cationic polythiophene derivative poly[3‐(1,1′‐dimethyl‐4‐piperidinemethylene)thiophene‐2,5‐diyl chloride] (PDPMT‐Cl) is synthesized and applied as a colorimetric and fluorometric probe for the detection of iodide ion and anionic surfactants with high selectivity and sensitivity. Upon adding iodide ion or anionic surfactant into the aqueous solution of PDPMT‐Cl, the maximum absorption of the polymer is blue‐shifted with a naked‐eye color change from red‐violet to yellow, signifying that iodide ion or anionic surfactants can cause the dissociation of PDPMT‐Cl aggregates. More sensitive results are obtained in the fluorometric detection to iodide ion or anionic surfactant, thereinto, the detection limit to surfactants can be extended to the order of 10−9 M.