1：Experimental Design and Method Selection:

The study involved designing and synthesizing chemosensor 1 via a one-step reaction, followed by characterization using spectroscopic techniques. The sensing performance was evaluated through colorimetric, UV-vis, and fluorescence spectroscopy in a 9:1 (v/v) aqueous CH3CN solution with pH 7.0 HEPES buffer. DFT calculations and 1H NMR titrations were used to support the mechanism.

2：0 HEPES buffer. DFT calculations and 1H NMR titrations were used to support the mechanism. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Samples included chemosensor 1, various metal ions (e.g., Na+, K+, Mg2+, Al3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Hg2+, Cd2+), and amino acids (cysteine, methionine). Real water samples (drinking, tap, river water) were collected and filtered for application testing.

3：List of Experimental Equipment and Materials:

Equipment included a Shimadzu UV-240 spectrophotometer for UV-vis, HITACHI-7000 spectrofluorometer for fluorescence, BRUKER AVANCE 400 and 100 MHz NMR instruments, and Gaussian 03 for DFT calculations. Materials included benzil, 2-hydroxy-1-naphthaldehyde, ammonium acetate, glacial acetic acid, perchlorate salts of metal ions, cysteine, methionine, DMSO, acetonitrile (HPLC grade), and HEPES buffer.

4：Experimental Procedures and Operational Workflow:

Synthesis of 1 by refluxing reactants in glacial acetic acid. UV-vis and fluorescence titrations were performed by adding incremental amounts of analytes to the sensor solution. 1H NMR titrations involved mixing host and guest solutions in DMSO-d6. Data analysis used SPECFIT software for binding constants and stoichiometry.

5：Data analysis used SPECFIT software for binding constants and stoichiometry. Data Analysis Methods:

5. Data Analysis Methods: Spectral data were analyzed using SPECFIT for global analysis, DFT calculations for structural optimization and energy gaps, and standard equations for detection limits (LOD = 3σ/r).