IR-UV double-resonance spectroscopic study of 2-hydroxypyridine and its hydrogen-bonded clusters in supersonic jets

Infrared spectra of 2-hydroxypyridine (2HP) and its hydrogen-bonded clusters with water and methanol have been observed by IR-UV double-resonance spectroscopy. The OH stretching vibrations of the 2-HP site as well as either the water or methanol site were observed. The spectra were compared with those of the corresponding clusters of 2-pyridone (2PY), which have been reported in J. Chem. Phys. 1999, 110, 8397. The OH stretching vibration of bare 2HP was observed at 3600 cm^-1, representing a clear difference from the NH stretching vibration of 2PY (3441 cm^-1). On the other hand, the IR spectra of the 2HP-water and -methanol clusters were found to be very similar to those of the corresponding clusters of 2PY, indicating a solvation-mediated tautomerization between 2HP and 2PY. The cluster structures were examined using ab initio molecular orbital calculations.