1：Experimental Design and Method Selection:

The study involved designing a fluorescent probe based on tetrahydro[5]helicene derivative with a 2,4-dinitrobenzenesulfonate group for H2S detection. The mechanism relies on thiolysis reaction induced by H2S, leading to fluorescence turn-on. Methods included synthesis, UV-vis and fluorescence spectroscopy, NMR analysis, DFT calculations, and cell imaging.

2：Sample Selection and Data Sources:

The probe H-DNP was synthesized and characterized. Analytes included H2S (using NaHS), various ions, amino acids, and biothiols. Solutions were prepared in PBS buffer with DMSO. HeLa cells were used for cytotoxicity and imaging studies.

3：List of Experimental Equipment and Materials:

Equipment included Bruker AV-500 spectrometer for NMR, PerkinElmer Lambda 950 spectrophotometer for UV-vis, LS-55 spectrofluorimeter for fluorescence, Delta 320 pH-meter, ZEISS LSM 710 Confocal Microscope. Materials included silica gel, various chemicals from suppliers like Heowns, Energy Chemical, Adamas-beta, and standard compounds.

4：Experimental Procedures and Operational Workflow:

Synthesis of H-DNP involved multiple steps with purification. Spectroscopic measurements were conducted in PBS/DMSO solutions. Titration experiments with H2S and other analytes were performed. Cell culture, incubation with probe and NaHS, and confocal imaging were carried out.

5：Data Analysis Methods:

Fluorescence intensities were measured and analyzed. Quantum yield was calculated using quinine sulfate as standard. Detection limit was determined using IUPAC method. NMR and DFT calculations were used to confirm mechanisms.