image: Schematic diagram of the adaptive guest-binding process of the endo-functionalized coordination cage.
Credit: ©Science China Press
In nature, living cells can selectively encapsulate substrates in closed pockets of enzyme or protein receptors. Similarly, artificially synthesized confined nanospaces also have outstanding potential for application in various fields. During the self-assembly process, constructing well-defined and precise nanocavities often requires the use of rigid linkers to ensure directionality during the coordination process, as flexible structures typically cause the collapse of nanospaces. To address this issue, the research team implanted multiple aliphatic "grippers" within the confined nanocavities of a clustered basal coordination cage, creating a unique atmosphere that enables them to perfectly and adaptively adjust the conformation of the guest according to its shape to achieve the best match and the highest affinity.
This edited confined nanocavity can encapsulate C6 cyclohydrocarbon compounds, adamandane derivatives, and elemental sulfur/phosphorus in non-aqueous media, while also providing a cavity efficiency far exceeding that of non-functionalized ones. Among the currently known coordination cages, this structure exhibits the strongest affinity for cyclohexane in the organic phase. This demonstrates the significant importance of the implanted flexible aliphatic gripper in improving the affinity of the cage, and also positions this interesting nanocavity as a promising candidate for developing efficient host-guest partnerships.