Ultralong Room‐Temperature Phosphorescence from Boric Acid

• Published in: Angewandte Chemie International Edition 2021-04, Vol.60 (17), p.9500-9506
• Main Authors: Zheng, Haoyue, Cao, Peisheng, Wang, Yanying, Lu, Xiaomei, Wu, Peng
• Format: Article
• Language: English
• Subjects: Boric acid; boron; Confined spaces; Conjugation; electronic communication; lone pair electrons; Metal ions; Molecular orbitals; N electrons; Organic materials; Phosphorescence; Phosphors; room temperature phosphorescence; Temperature; Transition metals
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202101923

For a long time, phosphors with long‐lived emission are dominated by rare earth/transition metal ion‐doped sulfides and oxides. Recently, organic materials capable of emitting long‐lived room‐temperature phosphorescence (RTP) are reported, carbon skeletons are almost the exclusive structural feature of the conjugated luminophores. Herein, we reported that boric acid, a non‐metal and C‐free material, could emit RTP with lifetime up to 0.3 s. Detailed investigations indicated the weak conjugation between the n electrons of the O atoms in the B‐O confined space was the possible origin of RTP. Similar RTP was also found in electron‐rich N/F systems, namely, BN and BF3 (BF4−). Importantly, the vacant pz0 orbital of B was found to contribute to the relevant unoccupied molecular orbitals involved in excitation, which is different from previous reports on phosphorescence from arylboronic acids. The results confirm the unique role of B as a versatile structure motif for construction of new RTP materials. The vacant pz0 orbital of boron contributes to the unexpected long‐lived room‐temperature phosphorescence of boric acid, boron nitride, and fluoborite.