Chemically Gradient Hydrogen‐Bonded Organic Framework Crystal Film

Abstract Hydrogen‐bonded organic frameworks (HOFs) are ordered supramolecular solid structures, however, nothing much explored as centimetre‐scale self‐standing films. The fabrication of such crystals comprising self‐supported films is challenging due to the limited flexibility and interaction of the crystals, and therefore studies on two‐dimensional macrostructures of HOFs are limited to external supports. Herein, we introduce a novel chemical gradient strategy to fabricate a crystal‐deposited HOF film on an in situ ‐formed covalent organic polymer film (Tam‐Bdca‐CGHOF). The fabricated film showed versatility in chemical bonding along its thickness from covalent to hydrogen‐bonded network. The kinetic‐controlled Tam‐Bdca‐CGHOF showed enhanced proton conductivity (8.3×10 −5 S cm −1 ) compared to its rapid kinetic analogue, Tam‐Bdca‐COP (2.1×10 −5 S cm −1 ), which signifies the advantage of bonding‐engineering in the same system.