Thiol–Ene Click Post-Polymerization Modification of a Fluorescent Conjugated Polymer for Parts-per-Billion Pyrophosphate Detection in Seawater

Abstract

The evolution of conjugated polyelectrolytes (CPEs) that transduce analyte–receptor interactions into detectable fluorescent responses in complex aqueous environments is predicated on advancements in molecular design and improved synthetic accessibility. Here, we demonstrate a simple post-polymerization modification protocol, based on thiol–ene click chemistry, that results in the rapid installation of sodium sulfate terminated side-chains to a poly(fluorene-co-ethynyl) scaffold. The fluorescence of the resulting water-soluble CPE is quenched by Fe3+, dequenched selectively by pyrophosphate (PPi), and accurately quantifies PPi within ±6 nM in artificial seawater. The broad utility of thiol–ene click chemistry should offer the straightforward integration of diverse sensing elements.