Hydrogen Bonding Interaction between Adsorbate Molecules and Surface Hydroxyl Groups on Silica

The interactions of the surface hydroxyl groups on amorphous silica with two series of adsorbates, the methylbenzenes and the chloromethanes, have been studied. A correlation is demonstrated between the frequency shifts of the surface hydroxyl stretching vibration and the ionization potential of the adsorbate. A similar correlation is found for the interaction of the hydroxyl group of a carbinol with the methylbenzene series. The importance of charge-transfer interaction in hydrogen bonding, which is indicated by these correlations, is discussed.