Rational development of a highly selective ratiometric fluorescent probe for hydrogen polysulfides

•A unique and specific H2Sn-mediated coumarindithiolone formation under mild condition was discovered.•By taking advantage of this unique H2Sn-mediated coumarindithiolone formation, a novel ratiometric fluorescent probe for H2Sn was rationally designed and synthesized.•This probe exhibited excellent sensitivity and selectivity toward H2Sn over other RSS such as biothiols and H2S. A novel ratiometric fluorescent probe, ACC-Cl, was developed by virtue of a unique H2Sn-mediated coumarindithiolone formation under mild condition. The probe ACC-Cl exhibited excellent sensitivity and selectivity toward H2Sn over other RSS such as biothiols and H2S. More importantly, titration of H2Sn to the solution of ACC-Cl under the existence of 1mM GSH, the obvious ratiometric fluorescence response still can be observed. Significantly, preliminary biological experiments indicated its potential for sensing H2Sn in living cells.