Uniform spherical chiral polyrotaxanes with steerable circularly polarized luminescence

Abstract

Spherical chiral polyrotaxanes (CPRs) with steerable circularly polarized luminescence (CPL) are intriguing as advanced chiroptical materials but have not been reported to date. Here, we constructed spherical chiral polyrotaxane (CPR) materials with steerable CPL by utilizing cyclodextrins (α-, β-, or γ-CyD) as the chiral wheel. Importantly, the structure and the CPL performance of the CPR materials can be regulated by varying the feeding amount and the type of cyclodextrin (α-, β-, or γ-CyD). It was found that the spherical reticular frame and the chiral polyrotaxane structure were indispensable for CPL generation of spherical CPRs due to the strengthening of confined chirality transfer, as shown by structural and spectral characterization. Remarkably, spherical β-CyD/CPR at feed_(C/B) = 4, 8, and 16 showed a higher quantum yield and a longer photoluminescence lifetime in comparison with those of α-CyD/CPR and γ-CyD/CPR. This work demonstrates an example of a CPL-active spherical CPR and provides insight into macrocyclic size-dependent CPL generation through a mechanically interlocked strategy and covalent reticular chemistry, which will be helpful for the future design of high-performance CPL materials.