Sulfonate-Functionalized Polyoxovanadate-Based Metal-Organic Polyhedra for Enhanced Proton Conduction via the Synergy of Linker and Metal Cluster Vertex

Abstract

Metal-organic polyhedra (MOPs) have emerged as novel porous platforms for proton conduction, however, the concerted employment of both linker and metal cluster vertex is rarely applied for the fabrication of MOPs-based high conducting materials. Herein we report the synthesis of sulfonate-functionalized polyoxovanadate-based MOPs for enhanced proton conduction via the synergistic effect from linker and metal cluster node. MOPs 1 and 2 exhibit octahedral cage configuration constructed from {V5O9Cl} vertex and 5-sulfoisophthalate linker. Owing to the ordered packing of octahedral cages along three axes, 3D interpenetrated open channels that are lined with high-density sulfonates are thus formed within 2. Coupled with the proton-conductive {V5O9Cl} vertexs as well as protonated counterions, an extensive H-bonded network is therefore generated for facile proton transfer. 2 exhibits high proton conductivity of 3.02×10−2 S cm−1 at 65 °C under 90% RH, recording the highest value for MOPs pellet sample. This value is enhanced ~1 order of magnitude compared with that of carboxylate-functionalized analogue 3, clearly illustrating the advantage of combining linker and metal cluster node for enhanced proton conduction. This work will further promote the exploitation of high proton conductive MOPs-based materials by the synergy design strategy.