1：Experimental Design and Method Selection

Compounds 1?3 were synthesized by the hydrothermal method using similar procedures. The reactive mixtures were loaded into a Teflon-lined stainless steel autoclave and heated at 140 °C for 6 days.

2：Sample Selection and Data Sources

Single crystals of compounds 1?3 were obtained after cooling to 25 °C, rinsed with deionized water, and characterized by various techniques including XRD, IR spectra, UV?vis?NIR optical diffuse reflectance spectra, TGA, DSC, ICP elemental analyses, and luminescent studies.

3：List of Experimental Equipment and Materials

Panalytical X’pert Pro MPD diffractometer, JSM6700F field emission scanning electron microscope, Magna 750 FT-IR spectrometer, PerkinElmer Lambda 950 UV?vis?NIR spectrophotometer, NETZSCH STA449C instrument, Ultima 2 simultaneous ICP optical emission spectrometer, German Elementary Vario EL III instrument, Edinburgh FLS920 fluorescence spectrometer.

4：Experimental Procedures and Operational Workflow

The synthesis involved loading reactive mixtures into autoclaves, heating, cooling, rinsing products, and characterizing them. SHG measurements were performed using a modified method of Kurtz and Perry.

5：Data Analysis Methods

Data analysis included XRD pattern simulation, IR spectra interpretation, UV?vis?NIR spectra analysis using the Kubelka?Munk function, TGA and DSC curve analysis, and SHG signal measurement.