Fluorescent conjugated polymer molecular wire chemosensors for transition metal ion recognition and signaling

Conjugated polymer molecular wires have advantages over small molecules for sensing applications due to enhancements associated with electronic communication along the polymer backbone. The majority of examples from the literature focus on fluorescence "turn-off" as the mechanism of sensor response. The energy transfer mechanism involved in these polymers focuses on energy transfer quenching and can be related to either a Dexter or Förster based mechanism. More recently, a series of chemosensors have been designed and synthesized which exhibit fluorescence "turn-on" behavior upon binding specific cations. The general assembly of both the turn-on and turn-off chemosensor structures involves assembling different organic receptor ligands onto the conjugated polymer backbones. Careful spectroscopic analysis of the energy and electron transfer mechanisms in these systems creates a myriad of opportunities for the design of new sensor materials.