Uncovering the Molecular Stacking Patterns and Tuning Fluorescence Properties of Organic Molecular Crystals through Cocrystallization

Organic light-emitting materials have demonstrated their application potential in numerous fields, with their optoelectronic properties being profoundly influenced by molecular stacking patterns and intermolecular interactions. In this study, we utilized a mixed-solvent evaporation method and a solid grinding method to synthesize a series of meloxicam (MXM) cocrystals, whose structures and morphology were identified using single crystal X-ray diffraction and a polarization microscope. These crystals exhibited photoinduced fluorescence changes at a macroscopic level. Fluorescence spectral analysis indicated that, while the cocrystals prepared with different coformers displayed varying fluorescence intensities, they shared similar luminescence colors, which can be attributed to their comparable emission wavelengths. Density functional theory (DFT) calculations further elucidated the significant relationship between the fluorescence properties, molecular packing patterns, and charge transfers in MXM cocrystals. This research not only enhances the fluorescence performance of pure MXM crystals, but also offers novel insights and a robust experimental foundation for the advancement of multifunctional organic cocrystal materials.