Metal ion-sensing polymer in the weak binding monomer regime.

The field of conjugated polymer-based metal ion sensing has evolved rapidly with many systems developed via fluorescence quenching mechanism. Thus far, demonstrated polymer architectures invariably entail the main-chain or side-chain incorporation of strong binding sites. We show herein that extraordinary metal ion sensing systems could be created with monomer units in the weak binding regime. Poly(thienylene phenylene) exhibits highly selective fluorescence quenching response toward an environmentally toxic species, Hg2+. Our results offer important clues for expanding the chemical space of intelligent polymer systems.