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Supramolecular Assembly of Chiral Lanthanide Triple-Decker Metallocyclophanes Ln 3 ( L meta ) 3 (L R / S ) 3 or Tetrahedral Cages Ln 4 ( L para ) 4 (L R / S ) 4 and Their Chiroptical Properties

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Two new ligands ( L meta: meta -tris-β-diketonate and L para: para -tris-β-diketonate) with meta and para orientations of coordinating bidentate β-diketonate units were synthesized in order to investigate their supramolecular formation behavior. When chiral ( R )- or ( S )-BINAPO (L R / S ) was used as a chiral inducer, trinuclear triple-decker metallocyclophane, Eu 3 ( L meta ) 3 (L R / S ) 3, was formed from L meta, whereas a tetranuclear tetrahedral cage Eu 4 ( L para ) 4 (L R / S ) 4 was formed with L para . The X-ray crystal of Eu 3 ( L meta ) 3 (L S ) 3 shows that all three Eu centers possess the same configuration, hence resulting in homochiral ΔΔΔ assembly. The triple-decker exhibited a longer luminescence lifetime (∼0.98 ms vs ∼0.74 ms) and higher quantum yields (∼66% vs ∼50%) than the tetrahedral cage. Moreover, chiroptical properties were observed for a lanthanide triple-decker metallocyclophane: Mirror-image circular dichroism of chiral Eu 3 ( L meta ) 3 (L R / S ) 3 or Eu 4 ( L para ) 4 (L R / S ) 4 discloses their enantiomeric behavior and chiral transmission from ( R )- or ( S )-BINAPO moiety to achiral L meta and L para . Furthermore, their circularly polarized luminescence indicated that the | g lum | can reach 0.13 for the triple-decker metallocyclophane and 0.16 for the tetrahedral cage.

Source: Inorganic Chemistry

DOI: 10.1021/acs.inorgchem.5c02534