An IETS study of the adsorption of 1,2-, 1,3- and 1,4-benzenedimethanol, 2-, 3- and 4-hydroxyphenethyl alcohol, and 2-, 3- and 4-hydroxybenzyl alcohol, on thin-film plasma-grown aluminium and magnesium oxides

Abstract

Abstract The IET spectra of 1,2-benzenedimethanol and 2-hydroxyphenethyl alcohol adsorbed on thin-film aluminium and magnesium oxide suggest that seven-membered chelate ring formation is probable at both oxide surfaces. In like manner, 2-hydroxybenzyl alcohol adsorption may involve six-membered chelate ring formation at both the aluminium and magnesium oxide surfaces. For the analogous meta -substituted systems, i.e. 1,3-benzenedimethanol, 3-hydroxyphenethyl alcohol and 3-hydroxybenzyl alcohol, the IET spectra suggest that the surface adsorption—chemisorption process follows a similar pattern to that of the 1,2-systems, though now the 1,3-disposition of the functional groups precludes chelated geometries at the oxide surface under examination. Of the corresponding 1,4-molecules only 1,4-benzenedimethanol was found to bind to either oxide. The IET spectra for this adsorbate do not indicate clearly the mode of adsorption at the oxide surfaces other than to suggest that either only one end of the molecule is chemisorbed leaving the “free” hydroxyl group to contribute to the background ν(OH) signal of each oxide or both methanolic hydroxyl groups are interacting with the oxide surfaces. These alternatives separately or in combination cannot be distinguished further.