Case closed -- where the missing proton goes
H2O is the molecule everybody knows, and nobody can live without. But for all its familiarity and import for life, aspects of water's behavior have been hard to pin down, including how it conducts positive charge. In the current issue of the journal Science, Yale University chemists report tracing how a cluster of water molecules adapts to the presence of an extra proton, the positively charged subatomic particle. Water constantly encounters stray protons - in biological contexts, as when light impinges on the eye's retina, for example, or in purely chemical contexts, as when water is split by electrolysis, or in technological contexts, as in the operation of fuel cells. The new research results provide long-sought experimental data that advance understanding of water's ability to conduct charge, and researchers expect the data to help theoretical chemists simulate how positive charge propagates through a more extended three-dimensional water network. This in turn will shed light on the way positive charge moves in biological systems. "Getting this right is one of the grand challenges of contemporary physical chemistry research, and we believe we've taken a big step," said Yale chemist Mark Johnson, the lead investigator.
