Pressure-Induced Emission Enhancement and Multi-color for 1, 2, 3, 4-tetraphenyl-1, 3-cyclopentadiene (TPC)：Controlled Structure Evolution.

Mechanoresponsive luminescent (MRL) materials have attracted considerable attention due to their potential applications in mechanical sensors, memory chips, and security inks, especially for these possessing high-efficiency and multi-color qualities. In this letter, we found 1, 2, 3, 4-tetraphenyl-1, 3-cyclopentadiene (TPC) crystal exhibited both pressure-induced emission enhancement (PIEE) and multicolor behaviors. More excitingly, IR analysis indicated that ring-opening reaction of phenyl ring occurred when pressure was beyond 24.7 GPa. The reaction was promoted from 24.7 GPa to 35.9 GPa, which resulted in the redder irreversible color change for sample released from 35.9 GPa than it from 24.7 GPa. The study about mechanoresponsive behavior of TPC offered a deep insight into PIEE and multicolor from the point of structure and inspired an idea that capturing different color by hydrostatic pressure, which would facilitate the designing and searching for high-performance MRL materials.