Chiral Ligand Engineering for Modulating Circularly Polarized Luminescence in Families of Chiral Binuclear Lanthanide Clusters

ABSTRACT Three pairs of chiral lanthanide clusters R ‐ /S ‐Eu 2 ‐MPA , R ‐ /S ‐Eu 2 ‐PPA , and R ‐ /S ‐Eu 2 ‐NPA were synthesized using three pairs of chiral ligands ( R ‐HMPA = ( R )‐(−)‐ α ‐methoxyphenylacetic acid, S ‐HMPA = ( S )‐(+)‐ α ‐methoxyphenylacetic acid; R ‐HPPA = R ‐(−)‐2‐phenylpropanoic acid, S ‐HPPA = S ‐(+)‐2‐phenylpropanoic acid; R ‐/ S ‐HNPA = R ‐/ S ‐2‐(6‐methoxy‐2‐naphthol)) with varying steric hindrance and π‐conjugation effects, systematically investigating the regulatory mechanism of ligand structure on the chiral environment and the luminescent properties of Ln 3+ . Single‐crystal structural analysis reveals that the ligand R‐/S ‐HNPA, featuring an extended π‐conjugated naphthyl group, induces the lowest‐symmetry coordination geometry for Eu 3+ ion in R ‐ /S ‐Eu 2 ‐NPA , resulting in an enhanced luminescence dissymmetry factor ( g lum = ±0.006) compared with R ‐ /S ‐Eu 2 ‐MPA and R ‐ /S ‐Eu 2 ‐PPA . Moreover, the additional π–π interactions between R‐/S ‐HNPA and diph (diph = dipyridoacphenazinehemihydratemin) increase the molecular rigidity and effectively suppress non‐radiative transitions, thereby elevating the solid‐state luminescence quantum yield (Φ lum ) to 13.42% (compared with 6.88% for R ‐ /S ‐Eu 2 ‐MPA ). This work demonstrates that chiral ligand engineering can synergistically regulate both the asymmetry of the coordination field and the supramolecular interactions, offering a promising strategy for the development of high‐performance chiral luminescent materials.