3.4. Proposed recognition mechanismIt has been reported that the C]C bond could be oxidized by ClO−to produce an aldehyde. A proposed reaction mechanism between probe CMM and ClO− was depicted in Scheme 2. In order to verify thesensing mechanism, mass spectra of probe CMM and the product wereperformed (shown in Fig. S4). With the reaction of ClO−, a new peak at227.0312 (m/z) corresponding to formylated coumarin ([M+Na]+)was found in mass spectra. It means that the transformation from probeCMM to the product of aldehyde took place, which regained the strongfluorescence.