Chiral metallomesogens and helical assemblies: advances in circularly polarized luminescence amplification and applications

Metallomesogens with unique triplet decay radiation, versatile arrangement, and interaction diversities are crucial for the emergence of novel functionalization, including phosphorescent organic light-emitting diodes (OLEDs), intelligent optical responsive materials, and liquid crystal electromagnetic switches. In this family of emitters, chiral metallomesogens consist of flexible chiral organic ligands and metal centers. The metal ions provide spin–orbit coupling to induce singlet–triplet mixing and intersystem crossing, and the chiral skeleton imparts structural asymmetry and chiroptical dichroism, enabling circularly polarized phosphorescence (CPP). Recently, hierarchical chiral architecture represents one important route to fabricate diverse higher-order helical superstructures to circumvent the inherent trade-off between quantum efficiency ( Փ ) and asymmetry factor ( g ) and achieve advanced chiroptical applications. In this review, we systematically review the structure−property relationships in chiral metallomesogens and related assemblies. Insight into the rational materials design of chiral metallomesogens based on metal coordination geometry, ligands, chelated configurations, and assembly methods, along with their helical liquid crystal (LC) stacking effects on circularly polarized luminescence (CPL) amplification. Lastly, challenges and future directions in purposeful material design and application are outlined. With an understanding of fundamental chemical structure design, molecular assembly features, and photophysical mechanisms, we hope that this review will propel the development and application scenarios of chiral metallomesogens for CPL devices.