1：Experimental Design and Method Selection:

The probe DHC was designed based on α,β-unsaturated ethanoylcoumarin fluorophore for H2S detection via a Michael addition reaction. Spectroscopic methods (fluorescence, UV-Vis, NMR, MS) were used to study the mechanism and properties.

2：Sample Selection and Data Sources:

Chemicals were obtained from ordinary suppliers. BHK cells were used for biological experiments.

3：List of Experimental Equipment and Materials:

JNM-ECS-400 MHz NMR instrument, LQC mass spectrometry system, HITACHI F-4600 spectrofluorometer, Lambda 35 UV-Vis spectrometer, PXSJ-226 pH meter, Bio-Rad model-680 microplate reader, and various chemicals including Na2S as H2S source.

4：Experimental Procedures and Operational Workflow:

Synthesis of probe DHC through multi-step reactions. Optical measurements in EtOH/H2O solution. Selectivity and competition tests with various analytes. Titration experiments with H2S. Time-dependent fluorescence studies. pH effect studies. MTT assays for cytotoxicity. Cell imaging with BHK cells.

5：2S. Time-dependent fluorescence studies. pH effect studies. MTT assays for cytotoxicity. Cell imaging with BHK cells. Data Analysis Methods:

5. Data Analysis Methods: Linear regression for LOD calculation, statistical analysis of fluorescence and absorbance data, and image analysis for cell experiments.