Endohedral Coordination of Bulky Substrates in Metalloenzyme-Like Organometallic Nanotubes.

Artificial receptors inspired by metalloenzymes share three key properties: a structurally flexible cavity, substrate binding via metal-ligand coordination, and metal-based redox activity. Herein, we report an organometallic nanotube with such features based on our supramolecular pillarplex platform, incorporating eight Cu centers in its cavitand walls. The structurally adaptable cavity of this receptor enables the endohedral coordination of tetrahydrofuran (THF) as a hydrophilic model substrate with remarkable binding affinity despite a steric mismatch between the host and guest. Evidence from SC-XRD, H NMR titration in aqueous solution, and DFT modelling confirms that metal-ligand coordination governs substrate binding. Electrochemical analysis of a derived rotaxane reveals metal-centered redox activity.