Solid-State Umbrella-type Inversion of a VO5 Square-Pyramidal Unit in a Bowl-type Dodecavanadate Induced by Insertion and Elimination of a Guest Molecule

摘要

Design of cavities for a target molecule and the elucidation of the corresponding host-guest interactions are important for molecular manipulation. A discrete dodecavanadate bowl, [V12O32](4-) (V12), with an entrance diameter of 4.4 angstrom and an electron-rich guest at the center of the bowl, was stabilized by electrostatic interactions. A characteristic of V12 is a solid-state polytopal rearrangement during guest elimination and recapture. A guest-free dodecavanadate, [V12O32](4-) (V12-free), was prepared by removal of the guest from CH2Cl2-inserted V12 under vacuum at 50 degrees C. Single-crystal X-ray analysis revealed that one of the VO5 square pyramids at the bottom of V12-free was inverted to fill the void of the bowl cavity. The exposure of V12-free to the guest molecule vapors of CH2Cl2, 1,2-dichloroethane, MeNO2, MeCN, and MeBr resulted in the selective insertion of the guest to reform the guest-inserted V12 structure. Whereas CO2 could be inserted in the V12 bowl, CH4 and CO could not.