Biomimetic Recognition of Quinones in Water by an Endo-Functionalized Cavity with Anthracene Sidewalls

Selective molecular recognition in water is the foundation of numerous biological functions but is a challenge for most synthetic hosts. We employ the concept of endo-functionalized cavity and the strategy of simultaneous construction to address this issue. The concept and the strategy were demonstrated in the construction of a biomimetic host for selectively recognizing quinones in water. The host was synthesized by joining two pieces of bent anthracene dimer through amide bond formation, affording a deep hydrophobic cavity and inward-directing hydrogen bonding sites. The host can recognize quinones over their close analogues in water, and its association affinity to p-benzoquinone is the highest among all the known hosts and is even comparable to that of the bioreceptor. The binding with an anthraquinone reaches nanomolar affinity. Shielded hydrogen bonding, C-H⋅⋅⋅π, and charge transfer interactions, and the hydrophobic effect are responsible for the high binding affinity and selectivity.