Endo-functionalization of tailored-adaptive nanospace for efficient binding of organic molecules in non-aqueous media

Precision in controlling the microenvironment of nanospaces is a potent strategy for exploring architecture‒function relationships. Herein, a face-capped tetrahedral cage, featuring Pd‒Pd-bonded vertices, with a tailored nanospace surrounded by 12 ethyl units, was facilitated to adaptively accommodate a library of guests with different sizes and shapes, including C6 cyclic hydrocarbons, adamantane derivatives, S₈ and P₄. This nanocavity can achieve strong binding with cyclohexane in non-aqueous media in contrast to reported structurally similar non-endo-functionalized cages by an increase of four orders of magnitude. The crystal structures of free cage and host‒guest complexes demonstrate that the aliphatic units within the nanospace are allowed to adaptively deform to stabilize the guests or serve as grippers to form unique interactions. This work indicates the achievability of both efficient organic guests and elemental sulfur/phosphorus binding in a non-aqueous system with minimal synthetic efforts, by modifying inward-facing aliphatic units to the inner face of the nanospace.