1：Experimental Design and Method Selection:

The study involved synthesis of the Schiff base compound NEH using slow evaporation solution growth technique, followed by characterization using various methods including single crystal X-ray diffraction, Kurtz-Perry powder technique for NLO efficiency, photoluminescence spectroscopy, Vicker's microhardness testing, dielectric measurements, photoconductivity studies, and quantum chemical calculations using DFT with Gaussian 09 software.

2：Sample Selection and Data Sources:

High-purity reagents from Sigma-Aldrich were used; single crystals were grown from methanol solution and recrystallized for purity.

3：List of Experimental Equipment and Materials:

Bruker Kappa Apex II diffractometer, Cary Eclipse fluorescence spectrophotometer, Shimadzu HMV-2T microhardness tester, Hioki LCR HiTester 3532-50, Keithley Electrometer 6517B/E, Q-switched Nd:YAG laser, halogen lamp, Gaussian 09 software, Crystal Explorer

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing equimolar solutions, slow evaporation for crystal growth; characterization steps included data collection at specific conditions (e.g., 293 K for XRD), measurements under varying loads, frequencies, temperatures, and light illumination.

5：Data Analysis Methods:

Data analyzed using standard formulas for hardness, dielectric properties, conductivity; quantum chemical calculations performed for molecular properties.