A novel pyrazolo[1,5- a ]pyridine fluorophore and its application to detect pH in cells.

A new fluorescent probe based on pyrazolo[1,5- a ]pyridine was synthesized and used to monitor the pH in cells. This probe exhibited a fast response to acidic pH (less than 10 s), a high quantum yield ( φ = 0.64), and high selectivity and sensitivity. The response mechanism of the fluorescent probes relies on the ICT change.