A Benzene Ring-Linked Dimethylamino and Borate Ester-Based Molecule and Organic Crystal: Efficient Dual Room-Temperature Phosphorescence with Responsive Property

摘要

Pure organic crystal of N,N-di-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline (DMAB) exhibits efficient room-temperature phosphorescence(RTP) with an emission maximum at 387 nm and a high phosphorescenceefficiency of 35.2%. Significantly, DMAB shows an exceptional photo-inducedultra-long RTP (URTP) at 539 nm, which displays an afterglow time of 14 sin air. The two phosphorescent bands are attributed to the monomeric andaggregated RTP of DMAB, respectively. Continuous UV irradiation for ≈1 mincan dramatically improve the lifetimes for both of the monomeric and aggregatedphosphorescent emissions. The photo-induced URTP can be spontaneouslyswitched off after standing the crystal in air for 50 min, and this cyclicprocess has been repeated several times. The molecular packing based onmultiple intermolecular noncovalent interactions is adopted in DMAB crystal,which is beneficial to RTP. Upon UV irradiation, the consumption of oxygenin the crystal matrix accounts for the distinctive photo-induced URTP. Takingadvantage of the unique photo/oxygen-sensitive properties, DMAB crystalshave been successfully utilized in oxygen sensing and anticounterfeiting.