Based on a novel coumarin-quinolinium platform, probe 2 was rationally designed and synthesized as a novel ratiometric fluorescent sensor for sulfite anions. The probe exhibited a wide dynamic concentration range for sulfite anions in a PBS buffer (containing 1 mg mL−1 BSA). More importantly, the probe was suitable for ratiometric fluorescence imaging in living cells with high sensitivity, favorable selectivity, and minimal cytotoxicity.
