Formation of hydrogen-bonded bridges in jet-cooled complexes of a chiral chromophore as studied by IR/UV double resonance spectroscopy. (±)2-Naphthyl-1-ethanol/(methanol)n=1,2 complexes

The structure of (±)2-naphthyl-1-ethanol and its 1∶1 or 1∶2 complexes with methanol has been studied by IR fluorescence dip spectroscopy, combined with DFT calculations. The bare molecule exhibits a gauche conformation of the OH group and exists as two conformers which differ by a rotation of the aromatic plane by 180° around the C2–Cα axis. When associated with methanol, both conformers form complexes which can be discriminated by the shift of their first electronic transition and which exhibit very similar structures. The 1∶1 complexes have been assigned to a structure in which methanol accepts a proton from the OH group of the chromophore and is involved in a OH⋯π interaction with the aromatic ring. A bridged structure which contains a methanol dimer inserted between the OH group of the chromophore and the aromatic ring has been proposed for the 1∶2 complexes.