Unexpected appearance of water makes a big difference to supramolecules

Water can play an important role in the self-assembly of molecular structures – even when it is not supposed to be present. This curious discovery was made accidentally by researchers in the Netherlands, when they inadvertently dried a sample in a spectrometer – only to find that the structures they were investigating had disappeared. The discovery could help researchers to control the production of next-generation catalysts.

Although organic chemistry is usually performed in organic solvents like alkanes, even these contain tiny quantities of residual water. Researchers have known for decades that this water comprises almost entirely individual molecules: ‘They’d like to form hydrogen bonds but there’s too much of an energetic cost to create a cavity big enough to hold a dimer of water,’ explains Nathan Van Zee of the University of Eindhoven. As they are present in such minuscule quantities, however (usually less than 0.01% weight at room temperature), such frustrated, high-energy water molecules are often assumed to have a negligible effect on reactions.