Besides anisotropic grinding, hydrostatic pressure as an effective isotropic compression was used to realize in situ monitoring the MC behavior of crystals via diamond anvil cell (DAC) technique. As shown in Fig. , the pristine crystal of DCzPy exhibited brightly blue fluorescence under 365 UV light. During the compression process, the emission color of the crystal underwent a continuous and remarkable red-shift from blue to yellow to orange. Meanwhile, the absorption spectra were gradually red-shifted from around 400 nm to 510 nm (Fig. ). Moreover, the dominant wavelength of PL spectra was red-shifted from about 490 to 625 nm accompanied by a noticeable intensity decrease when the pressure was increased to 14.11 GPa (Fig. ). Notably, a large redshift by 135 nm in the PL spectra was attained. When the pressure was further increased to 16.15 GPa, the PL curve was almost parallel to the abscissa. In all, a large red-shifted and high-contrast fluorescence switching were achieved simultaneously upon increasing hydrostatic pressure. During the following decompression process, the emission peak was returned to the initial state along with the fluorescence intensity significantly enhanced (Fig. ). In addition, the absorption band of DCzPy reverted to its original position when the pressure was reduced to 0 GPa (Fig. ). This reversible process indicated that there was no obvious change of molecular phase or intermolecular packing mode during compression. As we know, MC materials with such distinct luminescence responses to anisotropic grinding and isotropic compression are rarely reported . In our system, the anisotropic grinding was applied to DCzPy to result in obvious hypsochromic-shift with enhanced solid-state emission efficiency, whereas the isotropic compression led to a bathochromic-shifted and weakened emission.