Chemical Transformations in Supramolecular Hydrogels

Time and again, nature utilizes the available building blocks for the preparation of molecules and ordered architectures for vital processes such as cell motility and intercellular transport. As biological catalyst, enzymes allow these chemical transformations at their active sites with high efficiency and selectivity. Importantly, these chemical transformations take place in aqueous media. To mimic the activity of natural enzymes, control over the reactivity of reactants (or intermediates) is necessary for artificial catalytic systems in aqueous media. Altering the selectivity of aqueous chemical reactions could be feasible with an organized and confined media in which reactants or intermediates would possess specific orientations, similar to active sites of an enzyme. Supramolecular hydrogels could be such organized media, where the fibrillar hydrogel network can provide active surface area with efficient diffusion properties. Herein, we summarize the use of supramolecular hydrogels in catalysis and as nanoreactors for efficient chemical transformations in aqueous media. The advantages of carrying out reactions in supramolecular hydrogels and key factors for hydrogel-phase catalysis are discussed. Overall, characteristics of supramolecular hydrogels and molecular engineering over the catalytic microenvironment within a hydrogel are key in the development of efficient chemical transformations with selectivity. However, this field is its infancy, as there is a limited set of chemical transformations resembling enzymatic activity. Based on recent developments in this field, we expect a promising future for cleverly designed chemical transformations in supramolecular hydrogels and encourage applications in biological systems and the pharmaceutical industry.