Fig. 4. Dynamic emission properties of X2A under various external stimuli. (A) Scheme of temperature sensor using the X2A-B-ClCH₂CH₂Cl crystal. (B) Ratio of excimer emission intensity (around 474 nm) to monomer emission intensity (around 428 nm) of the X2A-B-ClCH₂CH₂Cl crystal with temperature increasing from 288 K to 363 K (inset: photographs and CIE coordinates in CIE 1931 color space chromaticity diagram based on PL spectra). (C) ¹H NMR spectra of the X2A-B-ClCH₂CH₂Cl crystal in CDCl₃ at the initial state and after heating at 363 K (with the ratio of H_a and H_b). (D) Scheme of grinding of the X2A-B-ClCH₂CH₂Cl crystal. (E) Equipment for measuring the photoluminescence spectra during continuous grinding with time. Insert: photographs and CIE coordinates in CIE 1931 color space chromaticity diagram based on PL spectra of the X2A-B-ClCH₂CH₂Cl crystal during grinding. (F) PXRD patterns of the X2A-B-ClCH₂CH₂Cl crystal simulation, X2A-B-ClCH₂CH₂Cl ground state, as-prepared sample and X2A-G crystal simulation. (G) Scheme of isotropic compression on the X2A-B-ClCH₂CH₂Cl crystal. (H) Maximum fluorescence emission wavelength of the X2A-B-ClCH₂CH₂Cl crystal with the pressure increasing from 0.00 GPa to 11.13 GPa (inset: photographs and CIE coordinates in CIE 1931 color space chromaticity diagram based on PL spectra). (I) The relationship between maximum emission wavelength and pressure of the X2A-B-ClCH₂CH₂Cl crystal (up) and X2A-G crystal (down).