Fig. 2. (a) Photographs of d-Xyl crystals taken under various wavelengths of UV light or after stopping the irradiation at ambient conditions. (b) Prompt PL spectra of d-Xyl crystals with different λex values. (c) Decay profiles for d-Xyl crystals monitored at various emission wavelengths (λems). (d) Excitation–p-RTP mapping and p-RTP spectra with different excitations (td = 0.1 ms) for d-Xyl crystals. (e) Trajectory of tunable p-RTP colors, recorded by the change in the λex from 245 to 325 nm, in the CIE coordinate diagram. (f) Single crystal structure of d-Xyl with denoted intra- and inter-molecular O⋯O interactions. (g) Fragmental molecular packing of d-Xyl in crystals with denoted O⋯O short contacts. (h) HOMO and LUMO electron densities of monomer, dimer, trimer and tetramer of d-Xyl.
