Helical Chain Engineering in Chiral Metal–Organic Frameworks for Significantly Enhanced Circularly Polarized Luminescence
Azhar Abbas, Hongrui Zheng, Zhaoxing Wang, Bo Liu, Shangda Li, Jian Zhang
Abstract
The efficient amplification of molecular chirality into macroscopic chiroptical responses remains a key challenge in the development of circularly polarized photoluminescence (CPL) materials. Herein, we demonstrate that constructing well-defined helical chains within chiral metal–organic frameworks (CMOFs) serves as a powerful strategy to address this challenge. A pair of enantiomorphic CMOFs, D/L-Zn-2, featuring pronounced helical chains, and their nonhelical layered counterpart, D/L-Zn-1, were designed and synthesized from identical chiral ligands for a direct comparative study. Strikingly, the helical framework D/L-Zn-2 exhibits an order-of-magnitude enhancement in the luminescence dissymmetry factor (| g lum | = 3.67 × 10 –2 ), compared to that of D/L-Zn-1 . This dramatic enhancement is attributed to the helical superstructure, which acts as a chiral amplification matrix by providing a highly dissymmetric microenvironment for the emissive chromophores and promoting a more-delocalized excited state. This work not only presents high-performance CPL-active materials but also establishes helical engineering as a fundamental and effective design principle for advanced chiroptical systems.