Infrared Spectroscopy of Hydrogen-Bonded Phenol−Amine Clusters in Supersonic Jets

We report infrared spectra of hydrogen-bonded phenol−amine clusters, phenol−NH 3, −N(CH 3 ) 3, −NH(C 2 H 5 ) 2, and −N(C 2 H 5 ) 3, prepared in jet expansions. The OH, NH, and CH stretching fundamentals were studied. Infrared−ultraviolet double-resonance techniques were utilized for vibrational spectroscopy of size-selected clusters. The OH stretch frequencies of the phenol moieties showed extremely large red-shifts from that of bare phenol, reflecting the strong proton affinities of the amines. Moreover, non-proton-transferred structures of the clusters were confirmed. The detailed structure of phenol−NH 3 was examined by ab initio calculations, which reproduced the observed infrared spectrum.