Enantioresolution of Well‐Defined Au–Ag Clusters With Near‐Unity Phosphorescent Quantum Yields for Brilliant Circularly Polarized Luminescence

ABSTRACT

Luminescent chiral metal clusters represent promising materials for circularly polarized luminescence (CPL). However, assembling clusters exhibiting both robust photoluminescence (PL) and a high dissymmetry factor (| g _lum |) through conventional bottom‐up synthesis remains challenging. A straightforward approach is the enantioresolution of structurally well‐defined racemic clusters that demonstrate intense PL. By meticulously selecting chiral oxygen donor ligands and incorporating them into carbon‐centered Au ₆ Ag ₆ and Au ₆ Ag ₅ clusters, which are known to possess twisted yet racemic structures and near‐unity PL quantum yields (PLQYs) in solution, we successfully isolated three pairs of enantiopure clusters that display brilliant CPL. Notably, the phosphate‐protected C@Au ₆ Ag ₆ displayed a high PLQY (0.93) and a significant | g _lum | (0.008) in solution, surpassing the performance of C@Au ₆ Ag ₆ with carboxylate and C@Au ₆ Ag ₅ with sulfonate. Structural analysis coupled with theoretical calculations indicates that both the compact geometry and the localized orbital distributions within the chiral metal framework contribute to the elevated PLQY and considerable CPL observed in C@Au ₆ Ag ₆ with phosphate. Finally, we assembled metal cluster‐liquid crystal devices exhibiting enhanced CPL for an information encryption demonstration. This research introduces a series of clusters demonstrating notable CPL, with emphasis on chiral oxygen donor ligands, and proposes a straightforward and promising strategy for efficient fabrication of CPL materials.