Encapsulation of a Porous Organic Cage into the Pores of a Metal–Organic Framework for Enhanced CO(2) Separation

We present a facile approach to encapsulate functional porous organic cages (POCs) into a robust MOF by an incipient‐wetness impregnation method. Porous cucurbit[6]uril (CB6) cages with high CO(2) affinity were successfully encapsulated into the nanospace of Cr‐based MIL‐101 while retaining the crystal framework, morphology, and high stability of MIL‐101. The encapsulated CB6 amount is controllable. Importantly, as the CB6 molecule with intrinsic micropores is smaller than the inner mesopores of MIL‐101, more affinity sites for CO(2) are created in the resulting CB6@MIL‐101 composites, leading to enhanced CO(2) uptake capacity and CO(2)/N(2), CO(2)/CH(4) separation performance at low pressures. This POC@MOF encapsulation strategy provides a facile route to introduce functional POCs into stable MOFs for various potential applications.