Proton-Conducting Supramolecular Metallogels from the Lowest Molecular Weight Assembler Ligand: A Quote for Simplicity

Oxalic acid has been proven to be the lowest molecular weight organic ligand able to form robust supramolecular metallogel networks in the presence of metal salts. In particular, two novel multifunctional metallogels were readily prepared at room temperature by simple mixing of stock solutions of CuII acetate monohydrate or CuII perchlorate hexahydrate and oxalic acid dihydrate. Formation of different polymorphs and unprecedented proton conduction under anhydrous conditions were also demonstrated with some of these materials. Small change: Multifunctional and robust Cu‐based metallogels have been prepared by simply mixing solutions of a CuII salt and oxalic acid (see figure). For the first time, proton conductivity is demonstrated under anhydrous conditions for some of these metallogels and their corresponding xerogels with σ values in the range 10−3–10−4 S cm−1. Oxalic acid is the smallest ligand able to build up stable metallogel networks.