A water-soluble near-infrared (NIR) fluorescence activation probe for efficient detection of dissolved carbon dioxide

A near-infrared (NIR) fluorescent “turn-on” probe is presented for dissolved carbon dioxide (dCO 2 ) detection in aqueous medium. This probe is based on perylene bisimide-functionalized hyperbranched polyethylenimine (PBI-HPEI) polymer, which exhibits typical NIR fluorescence due to the excimer emission of π–π stacked PBI fluorophores. Both UV–vis absorption and fluorescent spectroscopy studies reveal that the PBI-HPEI polymer shows significantly dCO 2 -sensitive NIR emission via a known photoinduced electron transfer (PET) mechanism. Importantly, this sensory system is characterized with facile synthesis, fast response, excellent water-solubility and wide linear detection concentration range. It is thus capable of detecting dCO 2 even in real-world carbonated beverages and drinking water samples. Additionally, in view of the modular design principle of the present fluorescent polymer with typical NIR excimer emission of π–π stacked PBI molecules, the proposed strategy is expected to be applicable to the fabrication of novel versatile NIR-emitting sensory materials.