Proton transport in crystalline, porous covalent organic frameworks: a NMR study

Abstract

Herein, we demonstrate proton transport in two crystalline covalent organic frameworks with different surface chemistries – a hydrocarbon and a carbon surface, mainly using NMR techniques. While proton diffusion of the immobilized H₂O layer in direct contact with the hydrocarbon surfaces is slower, the diffusion of H₂O molecules which are not directly in contact with the surfaces is enhanced, resulting in a diffusion coefficient significantly higher than that of the bulk water. This study also highlights the importance of the persistence length of the crystalline mesopores in COFs, which must be sufficiently long, and percolate at a macroscopic level in order to promote long range proton transport.