“…[31][32][33][34] Indeed, the observed frequency for the hydrogen bonded conformer of DMG was found to fit well a linear plot of tC-O vs. nOH (Fig. 6) derived for a series of other carboxylic acids isolated in inert matrices, including several molecules that also exhibit intramolecular hydrogen bonds (formic, pyruvic, glycolic, oxalic, maleic, malonic 25,31,32,[34][35][36] ). This fact gives further support to the assignments made here, although this particular correlation is not a universal one, since besides hydrogen bonding other effects (e.g., different vibrational coupling and packing) might affect the frequencies, in particular that of the torsional mode.…”