Engineering Homochiral Dinuclear Ir(III)-Metallohelix-Based Porous Molecular Crystals for Atropisomer Enantioseparation

Porous molecular crystal materials offer promising applications for enantioselective separation and asymmetric catalysis, while regulating the chiral channel environment remains challenging yet. Herein, we report the introduction of homochiral dinuclear Ir(III) triple-stranded helicates as molecular blocks to fabricate chiral porous crystals for the effective enantioseparation of atropisomers. The chiral cyclohexylamine-functionalized robust helicates Δ2R6-H and Λ2S6-H exhibit remarkable stereochemical stability (>6 months) and present superb enantioseparation abilities toward atropisomers, yielding >99% ee for BINOL in only one adsorption and separation cycle. Importantly, these molecular crystals can provide consistent ee values (>99%) even after 10 cycles of enantioseparation. With simple regulation of the helicands with achiral ethylenediamine, the resulting helicates Δ2-H and Λ2-H display similar adsorption ability toward BINOL but no enantioselectivity. This study highlights that introducing and fine-tuning the configuration of homochiral helicates to fabricate porous molecular crystals is anticipated for enantioselective separation.