2D conjugated metal-organic framework as a proton-electron dual conductor

Abstract

<h2>Summary</h2> Herein, we report a Zn-based dual-conductive metal-organic framework (MOF), Zn-HHTP-H₂O, that simultaneously conducts electrons and protons. We employed an octahedral Zn node with axial H₂O ligands to induce proton transport while in-plane HHTP coordination provides d-π conjugation for electron transport. The axial H₂O as a weak binding ligand served as functionalizable sites through post-synthetic ligand substitution. Zn-HHTP-H₂O shows 4.5 × 10⁻² and 1.6 × 10⁻⁵ S cm⁻¹ of electrical and proton conductivities, respectively, at 343 K and 95% RH. Upon post-synthetic urea treatment of Zn-HHTP-H₂O, the proton conductivity was 10 times higher than the pristine MOF, while electrical conductivity remained in the same order. We believe that our system provides a chemically intriguing platform, valuable for the further development of dual-conducting materials.