1：Experimental Design and Method Selection:

The study combined experimental synthesis and characterization with theoretical DFT/TD-DFT calculations to investigate ESIPT mechanisms. Methods included solvothermal synthesis, fluorescence spectroscopy, X-ray diffraction, and computational simulations.

2：Sample Selection and Data Sources:

Three aromatic aldehyde azines (compounds 1-3) were synthesized using commercially available reagents. Samples included polymorphs of P. Y. 101 obtained under different conditions (e.g., grinding, recrystallization).

3：List of Experimental Equipment and Materials:

Equipment included Agilent NMR Systems 400 MHz and 100 MHz Spectrometers, Agilent Cary 60 spectrophotometer, FluoroMax-4 spectrofluorometer, BRUKER SMART APEX Ⅱ CCD diffractometer, XD-2 Purkinje multi crystal X-ray diffractometer, UOP0500CC microscope, and Gaussian 09 software. Materials included 2-hydroxy-1-naphthaldehyde, salicylaldehyde hydrazone, solvents (toluene, n-butanol, EtOH, DMF, DMSO-d6), and other reagents from Energy Chemical and Sinopharm Chemical Reagent Co., Ltd.

4：Experimental Procedures and Operational Workflow:

Synthesis involved solvothermal reactions at 120°C for 12 hours. Characterization included NMR, UV/Vis diffuse reflectance, fluorescence emission spectroscopy, quantum yield and lifetime measurements, X-ray single crystal and powder diffraction, and fluorescence microscopy. Computational methods used DFT/TD-DFT with B3LYP functional and 6-311G(d,p) basis sets for geometry optimization and spectral calculations.

5：Data Analysis Methods:

Data were analyzed using shelx-97 for crystal structures, Gaussian 09 for computational results, and TCSPC for fluorescence decay analysis. Statistical fitting of decay curves used triple exponential models.