Unique Solvating Effect in Azabenzene Clathrate Hydrates

The water solvent is a well-known solvating medium which can stabilize unstable species in bulky water or molecular clusters, but little is known about the solvating performance of the clathrate hydrate cages and changes of molecular properties of the solutes. In this work, on the basis of the experimentally observed clathrate hydrate structures, we theoretically explore their structures and properties, taking azabenzenes (pyridazine, pyrimidine, pyrazine, and pyridine) and benzene as the guests which have negative electron affinities, focusing on stability, electron affinity, vibrational shifts, proton transfer, and especially unique solvating effect of the clathrate hydrate cavity, using the density functional theory calculations. Calculations indicate that inclusion of the guest azabenzene/benzene in the clathrate hydrate cages could considerably change the structures and properties including stability increase, the C–H stretching blue shifts of the guests, and electron affinity conversion from the negative to considerably large positive values, acting as better electron carriers. This work characterizes a unique solvating model for stabilizing azabenzenes and their anions and provides novel insights into the guest–host interaction including the electrostatic, H-bonding, and confining interactions and the structure and property changes of the clathrate hydrates. Clearly, this information is useful in designing novel icy materials and finding their practical applications.