Visual detection of copper(II) ions based on an anionic polythiophene derivative using click chemistry

We have developed a novel approach for the rapid visual detection of Cu²⁺ based on an anionic polythiophene derivative (sodium poly(2-(4-methyl-3-thienyloxy)propanesulfonate, PMTPS) using click chemistry. The method relies on the disassembly of PMTPS aggregates in the presence of cationic surfactant through electrostatic and hydrophobic interactions. In the assay of Cu²⁺ detection, a cationic surfactant was formed via a click reaction catalyzed by copper(I), which was derived in situ from copper(II) and promoted the disassembly of PMTPS aggregates leading to the distinct solution color change from purple to yellow. This polymer probe has excellent sensitivity and selectivity for Cu²⁺ with a detectable range in the micromolar regime by naked eyes and can be used for monitoring Cu²⁺ concentrations below the safety limit in real-world samples.