Endohedral Coordination of Bulky Substrates in Metalloenzyme-Like Organometallic Nanotubes

Abstract

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^I 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, ¹H 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.

Keywords: cavitands; metalloenzymes; nanotubes; organometallic; pillarplex.