The regulation of solid-state emission based on cocrystal engineering is an emerging strategy for developing next-generation luminescent materials. Here, three luminescent cocrystals (AA-DITFB, AA-TFTPA and AA-TCNB) of 9-anthraldehyde (9-AA) are reported, which exhibit a broad range of green-to-red emission. Tuning the photophysical properties of 9-AA via cocrystals is based on different mechanisms. Compared with single-component crystals, the difference in the emission properties of AA-DITFB and AA-TFTPA originates from the π–π interaction between chromophores. As for AA-TCNB, its prominent red-shifted emission is the result of the charge-transfer interaction, which is confirmed by infrared spectroscopy, “hole-electron” analysis and charge-transfer spectroscopy. This work not only reveals the relationship between molecular structure and fluorescent properties, but also proposes a strategy to develop multicolor luminescent systems with tunable efficiency and lifetime.

Thermosalient (TS) crystals have gained considerable attention due to their potential applications in various fields, including in actuators, sensors, energy harvesting, and artificial muscles. Herein, co-crystallization was employed to construct TS crystals by forming a twisted angle between aromatic rings. Two multicomponent trimethoprim (TMP) TS cocrystals, TMP-25HBA and TMP-OA, were obtained. Differential scanning calorimetry (DSC) and variable-temperature powder X-ray diffraction (VT-PXRD) revealed that TMP-OA undergoes a solid-to-solid phase transition, while TMP-25HBA does not exhibit any phase transition. To the best of our knowledge, TMP-25HBA is the first multicomponent TS crystal without phase transition. The TS effect of both crystals is a result of the unit cell’s anisotropic expansion.