1：Experimental Design and Method Selection:

The study involves the synthesis of a Schiff base probe (H2L) through formylation and condensation reactions, followed by characterization using spectroscopic and crystallographic methods. Sensing studies include UV-vis and fluorescence spectroscopy to detect ions, with mechanisms explained by DFT and TDDFT calculations.

2：Sample Selection and Data Sources:

The probe H2L is synthesized from 4-phenylphenol and 2-amino-4-methylphenol. Solutions are prepared in methanol-water (4:1, v/v, pH 7.2) using HEPES buffer. Metal ions (e.g., Al3+, Zn2+) and anions (e.g., F-) are used as analytes from their chloride or ammonium salts.

3：2) using HEPES buffer. Metal ions (e.g., Al3+, Zn2+) and anions (e.g., F-) are used as analytes from their chloride or ammonium salts. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a Perkin Elmer Lambda 25 spectrophotometer for UV-vis, Shimadzu RF-6000 fluorescence spectrophotometer for emission studies, Bruker 400 MHz FTNMR for NMR, Waters Xevo G2 Q-TOF mass spectrometer for HRMS, Perkin Elmer RX-1 IR spectrophotometer, and a nanosecond time-resolved fluorescence setup. Materials include 2-amino-4-methylphenol, 4-phenylphenol, trifluoroacetic acid, hexamine, ethanol, DMSO-d6, and various metal salts.

4：Experimental Procedures and Operational Workflow:

Synthesis involves refluxing reactants, purification, and characterization. For sensing, solutions of H2L and ions are titrated, and spectra are recorded. Procedures include Job plot analysis, pH dependence studies, competition experiments, and paper strip tests for practical application.

5：Data Analysis Methods:

Data analysis uses the Benesi-Hildebrand equation for association constants, calculation of LOD from fluorescence titration, and theoretical computations with DFT/TDDFT for electronic structures.