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

Abstract

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–C_α 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.