Investigation of intramolecular hydrogen bonds in ortho-hydroxytropolone

The S0–S1 electronic spectra of ortho-hydroxytropolone (o-OHTR) in supersonic jets were measured in order to study its isomerism. Only one isomer has been detected in a supersonic jet. A blue shift of electronic origin due to deuteration of two -OH groups was twice as large as that of one -OH group, suggesting that the configurations of the two -OH groups in o-OHTR are equivalent. This finding is consistent with the results of the ab initio calculations. The origin bands of the complexes with water and acetone were red-shifted from that of the bare molecule. The red-shift was explained in terms of two opposite effects of formation of an intermolecular hydrogen bond on each of two intramolecular hydrogen bonds.