Since the discovery that Diels-Alder reactions proceed faster (as high as 700-fold) and have greater structural selectivity in water than in organic solvents, extensive experimental and theoretic studies have been carried out on this topic. The small size and high polarity of a water molecule, as well as a three-dimensional hydrogen-bonded network system of bulk water, provide some unique properties that include a large cohesive energy density, a high surface tension and a hydrophobic effect. These unique properties are believed to be responsible for the rate and selectivity enhancements of certain classes of reactions. The hydrogen bonding between water and organic molecules is also believed to play an important role in the rate accelerations of some organic reactions in water. Unique chemistry in water is also no doubt involved in catalytic reactions designed to remove industrial organic contaminants from water supplies. Furthermore, acid-base chemistry (i.e. pH not equal to 7) is required as much changes when conditions are not pH neutral. Models and simulations at the molecular level at organic and inorganic surfaces and non neutral pH levels can contribute to understanding photo-catalytic splitting of water in an area where clear cut experiments are still rather difficult to perform.
Materials science brings its own set of issues involving water, ranging from the formation and properties of crystalline and amorphous ice, to understanding solvation to the role of water in properties of solids. At one end of the spectrum, environmental applications would benefit from design and synthesis of advanced polymeric materials capable of chelating heavy metals, and ordered aqueous polyelectrolytes could provide the basis for development of novel ultrafiltration systems or ion conducting media for energy storage devices. At the other end of the spectrum, understanding the role of water in facilitating crystallization and accelerating organic molecule degradation could enable delivery and long-term storage of probiotics and pharmaceuticals in underdeveloped parts of the world. Furthermore, the issues that arise in organic solids are also present in inorganic materials, where corrosion continues to be a problem with few solutions. Significant progress can be made computationally in understanding these matters with reliable potentials for describing interactions.