The circularly polarized luminescence (CPL) switching is of significant interest for applications in security technologies and sensing devices. Small organic molecules (SOMs) show severala dvantages over metal complexes, supramolecular assemblies, and polymers. Therefore, the recent progress on the CPL switching in SOMs is here reviewed. The resultsa re summarized based on the strategies used to tune factors that influence the emission properties, and thus, to realize CPL switching. The strategies that have been adopted include promoting the excimer formation of fluorescent units, changing the conformation of fluorophores,t uning the electronic structure of the p-skeleton/ substituent, and modulating the intramolecular chargetransfer dynamics.[a] J.

In this paper, we have disclosed efficient room-temperature phosphorescence (RTP) in the amorphous state from a triarylborane-based biphenyl derivative, 4,4′-dibromo-2dimesitylboryl-2′-(N,N-dimethylamino)biphenyl (Br 2 -BN-BPh). The phosphorescence quantum yields of vigorously ground powder and drop-cast film are 0.36 and 0.22, respectively. Owing to the presence of two bulky substituents at the lateral positions, the existence of the intramolecular π−π interaction and the B•••N electronic interaction, this compound is intramolecularly rigid, which is helpful to retard the vibrational motions and thus suppress the nonradiative decay in the solid state. In addition, this compound has a very small ΔE S-T due to the well separation of HOMO and LUMO as a result of the significant twisting of the biphenyl skeleton. The combination of the small ΔE S-T and heavy atom effect of the bromo substituent is expected to enhance the spin−orbital coupling and thus increase intersystem crossing. Consequently, both the steric and electronic effects of the dimesitylboryl group are important for the efficient RTP property of Br 2 -BN-BPh, especially in the amorphous state.

The circularly polarized luminescence (CPL) switching is of great interest for applications in security technologies and sensing devices. Small organic molecules (SOMs) show several advantages over metal complexes, supramolecular assemblies, and polymers. Therefore, the recent progress on the CPL switching in SOMs is here reviewed. The results are summarized based on the strategies used to tune the factors that influence the emission properties, and thus, to realize CPL switching. For more details see the Minireview by J.‐L. Ma, Q. Peng, and C.‐H. Zhao on page 15441 ff.