1：Experimental Design and Method Selection:

The study involved synthesizing two rhodamine B-based Schiff bases (RBF with –F and RBC with –COOH) and evaluating their sensing properties for metal ions using UV-Vis absorption and fluorescence spectroscopy in ethanol. The Benesi-Hildebrand method was used for binding constant calculations.

2：Sample Selection and Data Sources:

Stock solutions of RBF and RBC were prepared in ethanol (3 × 10^?6 mol/L), and metal ion solutions (Ag+, Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Hg2+, K+, Li+, Mg2+, Mn2+, Na+, Ni2+, Sr2+, Pb2+, Zn2+) were prepared in deionized water at various concentrations.

3：List of Experimental Equipment and Materials:

Instruments included a JEOL EX-400 spectrometer for NMR, a Thermo Scientific LC/MS spectrometer for mass spectra, a Lambda 35 spectrophotometer (Perkin Elmer) for UV-Vis spectra, and an LS-55 spectrofluorophotometer (Perkin Elmer) for fluorescence spectra. Materials included rhodamine B hydrazine, 4-carboxybenzaldehyde, 4-fluorobenzaldehyde, methanol, ethanol, and metal salts.

4：Experimental Procedures and Operational Workflow:

Synthesis involved refluxing rhodamine B hydrazine with aldehydes in methanol for 24 hours, followed by purification. Fluorescence and UV-Vis studies were conducted by adding metal ions to Schiff base solutions and recording spectra. Titration experiments involved adding incremental amounts of Al3+ to monitor changes.

5：Data Analysis Methods:

Fluorescence data were analyzed to determine enhancement factors, detection limits using the equation DL = 3σ/S, and binding constants using the Benesi-Hildebrand equation. Job's plot was used to determine stoichiometry.