Metalo Hydrogen‐Bonded Organic Frameworks (MHOFs) as New Class of Crystalline Materials for Protonic Conduction

Recently, proton conduction has been a thread of high potential owing to its wide applications in fuel‐cell technology. In the search for a new class of crystalline materials for protonic conductors, three metalo hydrogen‐bonded organic frameworks (MHOFs) based on [Ni(Imdz)6]2+ and arene disulfonates (MHOF1 and MHOF2) or dicarboxylate (MHOF3) have been reported (Imdz=imidazole). The presence of an ionic backbone with charge‐assisted H‐bonds, coupled with amphiprotic imidazoles made these MHOFs protonic conductors, exhibiting conduction values of 0.75×10−3, 3.5×10−4 and 0.97×10−3 S cm−1, respectively, at 80 °C and 98 % relative humidity, which are comparable to other crystalline metal‐organic framework, coordination polymer, polyoxometalate, covalent organic framework, and hydrogen‐bonded organic framework materials. This report initiates the usage of MHOF materials as a new class of solid‐state proton conductors. Conduct protons: Metalo hydrogen‐bonded organic frameworks (MHOFs) self‐assembled through charge‐assisted H‐bonding interactions between cationic metal‐imidazole and anionic diarene sulfonate/carboxylate exhibit super‐protonic conduction and inaugurate the usage of MHOFs as new class of solid‐state proton conductors.