Multistep Chirality Transfer and Racemization Kinetics of Pillar [5]arenes by Tuning the Halogen Substituents on the Rims

Abstract

Halogen-substituted pillar[5]arenes exhibited hindered hydroquinone subunit flipping, enabling enantioseparation. An enantiopure conformer demonstrated a dissymmetric factor of 0.012 and an enantioselective binding ratio exceeding 1.92. Complexation with L-serine induced an enantiopreference in the pillar[5]arene, which persisted for a certain period after chiral inducer removal and reversed upon the addition of D-serine. This induced enantiopreference was subsequently transferred to a chromophore guest, achieving a multi-step chiral transfer process. This approach offers a potential alternative to traditional chiral HPLC methods, enabling the manipulation of chiral recognition and transfer through chiral inducers.