Molecular Assemblies and Proton Conductivity of Triazole-Fused Tetraphenylene

A nonplanar molecule, triazole-fused tetraphenylene (TrzTP), was examined for its potential in proton-conducting organic crystals. Depending on the solvent, TrzTP yielded two distinct structures: TrzTP-I (TrzTP·2Et2O), featuring a three-dimensional (3D) intermolecular hydrogen-bonded and π–π stacked host lattice, and TrzTP-II (TrzTP·4H2O), characterized by a two-dimensional (2D) network bridged by water molecules. Upon dehydration and subsequent rehydration, TrzTP·nH2O exhibited humidity-dependent conductivity, reaching 8.63 × 10–7 S cm–1 at 363 K and RH = 98% (Ea = 0.38 eV). This proton conductivity is 2 orders of magnitude lower than that of the imidazole-fused analog (ImTP). While ImTP maintains stable one-dimensional (1D) channels during water adsorption–desorption cycle, TrzTP undergoes structural rearrangement upon guest removal, which modulates long-range conduction pathways. These findings highlight how the flexibility of molecular assemblies can be utilized to develop switchable proton-conducting materials, wherein macroscopic proton conductivity can be reversibly switched ON and OFF driven by hydration and dehydration processes.