Redox-Active Ruthenium-Organic Polyhedra with Tunable Surface Functionality and Porosities

Dinuclear ruthenium paddlewheel complexes exhibit high structural stability in redox reactions. The use of these chemical motifs for the construction of Ru-based metal-organic polyhedra (RuMOPs) provides a route for redox-active porous materials. However, there are few studies on the synthesis and characterization of RuMOPs due to the difficulty in controlling the assembly process via the ligand-exchange reaction of equatorial acetates of the diruthenium tetraacetate precursors with dicarboxylic acid ligands. In this study, we synthesized three novel cuboctahedral RuMOPs based on the Ru₂(II/III)-paddlewheel units with different alkyl functionalizations on the benzene-1,3-dicarboxylate moieties. We evaluated the effect of external functionalization on the molecular packing and the porous and redox properties. The electrochemical measurements revealed the multielectron transferred redox process where the electron-donating/-withdrawing nature of the functional groups allows the control of the redox behavior.