Switching between Phosphorescence and Fluorescence Controlled by Chiral Self-Assembly

Helical self-assembly plays a unique role in regulating the localized excitations of π functional systems, which can also bring highly multi-scale orders, and show a special effect to tune the energy of electronics, vibration, and rotation of molecules. Due to controllable and dynamic property of chiral self-assembly, highly ordered and helical assemblies can be obtained to exhibit amplification effect and fascinating photophysical properties in photoluminescence. However, an effective control of singlet-triplet emissive switching in a unimolecular platform remains a great challenge. Recently, switchable singlet-triplet emission induced by helical self-assembly in a unimolecular platform has been developed. By taking advantage of the helical self-assembly driven by multiple intermolecular hydrogen bonding and strong π-π stacking interactions, reversible switching between fluorescence and phosphorescence could be efficiently achieved both in N,N-dimethylformamide/H2O solution and the solid state. The results will inspire the design of other intelligent luminescent materials through chiral self-assembly and be valuable for interdisciplinary development of supramolecular self-assembly and related materials science.