1：Experimental Design and Method Selection:

The study involved synthesizing a novel 8-hydroxylquinoline-benzothiazole conjugate (HQ-BT) and evaluating its fluorescence response to metal ions, particularly Cd2+, in aqueous methanol solutions. Theoretical calculations (DFT) and mass spectral analysis were used to understand the sensing mechanism.

2：Sample Selection and Data Sources:

Metal cation solutions were prepared from perchlorate, chloride, sulfate, or nitrate salts. The sensor HQ-BT was synthesized and dissolved in methanol for experiments. Living Hela cells were used for imaging studies.

3：List of Experimental Equipment and Materials:

Instruments included Edinburgh FS5 spectrofluorometer, SHIMADZU UV-1800 spectrophotometer, Bruker AVANCE III 400 MHz NMR spectrometer, AB Sciex 4700 MALDI TOF/TOF mass spectrometer, Mettler Toledo pH Meter, and Carl Zeiss LSM 700 microscope. Materials included 8-hydroxylquinoline, 2-aminobenzenethiol, hexamethylenetetramine, trifluoroacetic acid, hydrochloric acid, and various metal salts.

4：Experimental Procedures and Operational Workflow:

HQ-BT was synthesized via Duff reaction and condensation. Fluorescence spectra were measured with excitation at 313 nm. Titration experiments with Cd2+ were performed, and competition studies with other metal ions were conducted. pH effects and binding reversibility were tested. Confocal fluorescence imaging was done on Hela cells incubated with HQ-BT and Cd2+.

5：2+. Data Analysis Methods:

5. Data Analysis Methods: Fluorescence intensity changes were analyzed, linear relationships were established, detection limits were calculated (S/N=3), stoichiometry was determined using Job's plot, and DFT calculations were performed for structural optimization.