Infrared spectroscopy of OH stretching vibrations of hydrogen-bonded tropolone-(H2O)n (n=1–3) and tropolone-(CH3OH)n (n=1 and 2) clusters

Infrared spectra of jet-cooled tropolone-(H2O)n (n=1–3) and tropolone-(CH3OH)n (n=1 and 2) clusters were observed in the OH stretching region by using infrared-ultraviolet double resonance techniques. Size separated electronic spectra of these clusters were also observed with hole-burning spectroscopy in which the infrared laser was used as hole light. Both the infrared and hole-burning spectra of the tropolone-methanol clusters were found to be quite similar to those of the corresponding tropolone-water clusters, indicating that a similar structure is expected for both the clusters. Structure of the n=1 and 2 clusters of tropolone-water and -methanol is discussed. The infrared (IR) spectra suggest that the intramolecular hydrogen bond of tropolone OH is not destroyed in tropolone-(H2O)n (n≤2) and -CH3OH, while the intermolecular hydrogen bond dominates in tropolone-(H2O)3 and -(CH3OH)2. The transformation of the intramolecular to intermolecular hydrogen bond induced by the solvation is also discussed.