Stereocontrolled Self-Assembly of a Helicate-Bridged Cu^I ₁₂L₄ Cage That Emits Circularly Polarized Light

Control over the stereochemistry of metal-organic cages can give rise to useful functions that are entwined with chirality, such as stereoselective guest binding and chiroptical applications. Here, we report a chiral (Cu12L4)-L-I pseudo-octahedral cage that self-assembled from condensation of triaminotriptycene, aminoquinaldine, and diformylpyridine subcomponents around Cu-I templates. The corners of this cage consist of six head-to-tail dicopper-(I) helicates whose helical chirality can be controlled by the addition of enantiopure 1,1 '-bi-2-naphthol (BINOL) during the assembly process. Chiroptical and nuclear magnetic resonance (NMR) studies elucidated the process and mechanism of stereochemical information transfer from BINOL to the cage during the assembly process. Initially formed Cu-I(BINOL)(2) thus underwent stereoselective ligand exchange during the formation of the chiral helicate corners of the cage, which determined the overall cage stereochemistry. The resulting dicopper-(I) helicate corners of the cage were also shown to generate circularly polarized luminescence.