Structural relaxation chirality transfer enhanced circularly polarized luminescence in heteronuclear CeIII–MnII complexes†

Circularly polarized luminescence (CPL) materials have developed rapidly in recent years due to their wide application prospects in fields like 3D displays and anti-counterfeiting. Utilizing energy transfer processes to transfer chirality has been proven as an efficient way to obtain CPL materials. However, the physics behind energy-transfer induced CPL is still not clear. Herein, in a well-designed heteronuclear Ce^III–Mn^II complex system [(Ce((R/S)-L)Br(μ-Br))₂]MnBr₄ [(R/S)-L = (2R,3R)- or (2S,3S)-2,3-dimethyl-1,4,7,10,13,16-hexaoxacyclooctadecane] with intra energy transfer from Ce^III to Mn^II, the luminescence dissymmetry factor of Mn^II obtained by excitation of Ce^III is around 10 times higher than that obtained by direct excitation of Mn^II, while the Ce^III center itself shows an almost negligible CPL. To address this unusual phenomenon, we proposed a new mechanism named structural relaxation chirality transfer (SRCT) where structural relaxation of the excited chiral donor amplified chirality transfer to the acceptor by intramolecular interactions. As an assistant proof, a mixture of Ce^III–Zn^II and La^III–Mn^II complexes with inter energy transfer showed no CPL amplification. These results will inspire more breakthroughs in the physics nature and development of energy-transfer induced CPL.