Optically active persistent luminescence in supramolecular nanoassemblies constructed from entirely achiral building blocks

Abstract

Optically active persistent luminescent materials have attracted significant attention due to their distinctive luminescent characteristics and ability to exhibit rich circular polarization information. Despite extensive efforts to develop circularly polarized persistent luminescence (CPPL) materials using chiral molecules or polymers, fabricating CPPL materials from achiral units remains a big challenge. In this work, we introduce an efficient co-assembly strategy to create CPPL materials using entirely achiral organic molecules. The optical activities of co-assembled complexes are attributed to structural chirality, which arises from chiral nanohelices formed during symmetry breaking in the self-assembly process of C₃-symmetric molecules. Achiral molecules with long-lasting phosphorescence can adhere to these chiral nanostructures via hydrogen bonding, and during the drying phase, form nanocrystals that align along helical fibers, resulting in circularly polarized, long-lasting phosphorescence. Enhanced CPPL efficiency, ranging from blue to yellow with a dissymmetry factor over 1.2 × 10⁻² and lifetime of up to 0.6 s at room temperature, is achieved through hydrogen bonding driven co-assembly. Additionally, the CPPL spectra of these co-assemblies are captured using a homemade time-resolved circularly polarized long afterglow detection platform. This study not only presents a new approach for the high-efficiency design of CPPL materials from achiral building blocks but also significantly broadens the research possibilities in real-time CPPL analysis, offering a horizon in the exploration of CPPL materials.