Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry.
AbstractOn planet Earth, water is everywhere: the majority of the surface is covered with it; it is a key component of all life; its vapor and droplets fill the lower atmosphere; even rocks contain it and undergo geomorphological changes because of it. A community of physical scientists largely drives studies of the chemistry of water and aqueous solutions, with expertise in biochemistry, spectroscopy, and computer modeling. More recently however, supramolecular chemistry -with its expertise in macrocyclic synthesis and measuring supramolecular interactions -have renewed their interest in water-mediated non-covalent interactions. These two groups offer complementary expertise that, if harnessed, offers to accelerate our understanding of aqueous supramolecular chemistry and water writ large. This review summarizes the state-of-the-art of the two fields, and highlights where there is latent chemical space for collaborative exploration by the two groups.
4Water is ubiquitous and essential to life on planet Earth. A full understanding of aqueous solutions is therefore of significance to a wide range of fields within the atmospheric, environmental, biological and geological sciences. Within the chemical sciences, a deeper appreciation of how non-covalent interactions and chemical transformations are influenced by water would benefit a variety of fields. However, as we highlight here, there are many open questions regarding the chemical and physical properties of aqueous solutions.The aqueous realm is frequently bifurcated into the Hofmeister and hydrophobic effects, phenomena that respectively deal with the properties of solutions of salts and relatively nonpolar molecules. However, it is becoming increasingly evident that these areas do in fact frequently overlap; two prime examples being the accumulation of large polarizable anions at the air-water interface, 1-5 and the favorable interactions of polarizable anions with non-polar surfaces. [6][7][8][9][10][11][12][13][14][15] Thus the hydrophobic and Hofmeister effects are but part of a greater continuum of aqueous supramolecular chemistry, with many important and outstanding questions regarding the influence of the different kinds of non-covalent interactions involved.Studies of water and aqueous solutions have mostly been driven by the physical sciences community, a broad range of scientists whose expertise in spectroscopy, computer modeling, and biochemistry (to name just three areas) has generally not involved macrocycles or host molecules in general. However, for some time now, supramolecular chemists -with their expertise in macrocyclic synthesis and measuring weak non-covalent interactions -have been travelling a parallel course of exploration. This Review, inspired by discussions between sixteen members of each community at a recent workshop, 16 is an attempt to summarize what we know about aqueous solutions, what we do not know about them, and where the two communit...