Multifunctional Supramolecular Gels with Strong Mechanical\nProperties Formed by Self-Assembly of Polyoxometalate-Based Coordination\nPolymers

Metallogels built\nin a bottom-up approach by metal coordination\nand supramolecular interactions have important potential for the elaboration\nof smart materials. In this context, we present here the formation\nof supramolecular coordination polymers driven by the complexation\nof cobalt(II) or zinc(II) ions with polyoxometalate-based hybrids\ndisplaying two terpyridine ligands in a linear arrangement. Thanks\nto the electrostatic interactions between the polyoxometalate cores\nand metal nodes, the polymer chains self-assemble into fibers that\nphysically cross-link to form gels above a critical concentration.\nUsing spectroscopy, microscopy, X-ray scattering, and rheometry, complemented\nby molecular dynamics simulations, we investigated the supramolecular\norganization of the chains in the fibers and the resulting processes\nleading to gelation. Compared to previously reported systems, these\ngels have improved rheological features and appealing properties,\nsuch as birefringence, luminescence, and spin crossover, paving the\nway for their use as building blocks for multifunctional smart materials.