Conjugated Polyelectrolyte-Based New Strategy for in Situ Detection of Carbon Dioxide

A conjugated polymer centered on fluorene and 2,1,3-benzothia-diazole (PFBT) is prepared for sensing CO₂ in situ with high sensitivity and low background. Upon introducing CO₂, the weaker electrostatic repulsion and stronger hydrophobic interactions between neighboring PFBT molecules enhance the interchain contacts compared to that without CO₂, leading to the energy transfer from fluorene to 2,1,3-benzothia-diazole sites and the emission color shift from blue to green, which is sensitive to sensing CO₂ in atmospheric air with a content of ∼400 ppm. Importantly, PFBT is employed to monitor photosynthesis and respiration upon cycling day and night in situ.