Soft and dispersed interface-rich aqueous systems that promote and guide chemical reactions

Although aqueous solutions are considered to be sustainable, environmentally friendly reaction media, their use is often limited by poor reactant solubility. This limitation can be overcome by converting aqueous solutions into soft, dispersed interface-rich systems such as polyelectrolyte solutions, micellar solutions, oil-in-water microemulsions or vesicle dispersions. All consist of homogeneously distributed dynamic structures that, in a fashion reminiscent of enzymes, provide local environments that are different from the bulk solution. The presence of soft, dispersed interface-rich structures leads to not only selective reaction accelerations but also changes in reaction pathways, whereby chemical reactions are guided towards desired products. Once again, the analogy to enzyme-catalysed transformations is enticing. In this Review, we illustrate the general concepts applied in such systems and illustrate them with selected examples, ranging from enzyme mimics, the preparation of conductive polymers and transition-metal-catalysed organic syntheses on the industrial scale to the chemistry of prebiotic systems.