Dynamic selection in metallo-organic cube CdⅡ8L4 conformations induced by perfluorooctanoate encapsulation

Metallo-organic cages possess flexibility comparable to that of biological receptors and can alter their conformations to better accommodate guest species due to the dynamic reversibility of coordination bond. Induced fit is widely accepted involving conformation change of host, while few definitive examples are related to conformation selection. Herein, we reported the generation of metallo-organic cube CdII8L4 with the pre-existing of two conformations, which have fully been confirmed by NMR, ESI-MS and single-crystal X-ray diffraction analysis. The specific guest perfluorooctanoate PFOA selectively binds to the active conformer C2h-1 to form the PFOA⊂C2h-1 complex. Further, conformer D2-2 will isomerize to conformer C2h-1 in the presence of PFOA, for maximizing the guest binding affinity. This study provides an effective working paradigm for conformation selection, facilitating the understanding of fundamental mechanism of molecular recognition.