Microhydration of Protonated Biomolecular Building Blocks: IR Spectra of Protonated Imidazole–Watern Complexes

The sequential microhydration process of protonated imidazole (ImH+) was studied by resonant IR photodissociation spectroscopy of mass-selected ImH+⋅(H2O)n clusters (see figure). The IR spectra directly probe the effects of both protonation and stepwise hydration on the acidity of the NH groups of ImH+ with relevance to proton transport in biochemical processes and ionic liquids.