Enantioselective assembly of tetrahedral Zr4(embonate)6 cages in zeolitic frameworks for synergetic circularly polarized luminescence

Abstract

Herein the chiral resolution of racemic Zr₄L₆ tetrahedral cages has been realized using luminescent enantiopure coordination cations. Accordingly, anionic ΔΔΔΔ-Zr₄L₆ and ΛΛΛΛ-Zr₄L₆ cages (L = embonate) were completely resolved using enantiopure [Ag(R-BINAP)₂]⁺ and [Ag(S-BINAP)₂]⁺ cations, respectively, and a pair of pure enantiomers (PTC-374(R,Δ) and PTC-374(S,Λ); PTC = polynuclear titanium cage) were easily prepared and structurally well-characterized, featuring an uncommon cage-supported supramolecular framework with zeolitic SOD topology. The stepwise transfer of homochirality can be clearly observed in the unusual resolution process. Moreover, the perfect combination of two functional components endows such co-assembled materials with synergistic circular dichroism performance, enhanced fluorescence and circularly polarized luminescence response.