1：Experimental Design and Method Selection:

The study involved synthesizing FPN via aromatic nucleophilic ipso nitro substitution, followed by characterization using UV-vis, fluorescence, FT-IR, NMR, and XRD. Solvatochromism was studied in various solvents, aggregation behavior in DMF-water mixtures, and chemosensing with metal ions using fluorescence spectroscopy. Computational methods (DFT-B3LYP) were used for theoretical analysis.

2：Sample Selection and Data Sources:

FPN was synthesized from fluorescein and 4-nitrophthalonitrile. Stock solutions were prepared in DMF for experiments. Metal ions (e.g., Fe3+) were used as chloride salts.

3：List of Experimental Equipment and Materials:

Equipment includes Schimadzu UV-Visible 2600 Spectrophotometer, Cary Eclipse Fluorescence Spectrophotometer (Agilent Technologies), JASCO FT-IR 4700 spectrometer, Bruker Avance III 400 MHz FT-NMR spectrometer, Bruker Kappa Apex II diffractometer. Materials include fluorescein, 4-nitrophthalonitrile, DMF, K2CO3, various solvents, and metal salts.

4：Experimental Procedures and Operational Workflow:

Synthesis involved stirring reactants in DMF with K2CO3 at 60°C under N2, followed by purification. For solvatochromism, FPN solutions in different solvents were analyzed. Aggregation studies involved varying water percentage in DMF. Chemosensing involved adding metal ions to FPN solutions and measuring fluorescence changes.

5：Data Analysis Methods:

Fluorescence quantum yield was calculated using comparative method with 2-aminopyridine as standard. LOD was determined from Stern-Volmer plot. Computational analysis used Gaussian 09 with DFT-B3LYP/6-31+G(d,p) basis set.