Smart Covalent Organic Frameworks with Intrapore Azobenzene Groups for Light-Gated Ion Transport

Abstract

Constructing gated ion transport channels is of profound significance for a variety of applications but remains challenging. Covalent organic frameworks (COFs), as a new class of reticular materials, have demonstrated superiority in controllable transport and precise separation of fine species including ions. Herein, we engineer a light-responsive COF featuring intrapore azobenzene groups for highly efficient and adjustable transport of multivalent ions. Such azobenzene-tagged channels afford a customizable configuration that is precisely switchable at an angstrom level without compromising crystallinity. The membrane-shaped COFs exhibit an exceptional discrimination capability between monovalent and multivalent ions, rendering a K⁺/Al³⁺ selectivity of above 6000. Particularly, the azobenzene-decorated ordered nanochannels empower reversible, remote-controlled ion transport, implementing the tailor-made recycling of ionic adjuvants used for antibiotic production. This study reports the design and synthesis of a stimulus-responsive COF and demonstrates the efficient separation of ions by light-gated nanochannels of the smart COF.