Hydrogen bonding in 1,1'-Bi-2-naphthol within the polarizable continuum model.

Intra- and intermolecular hydrogen bonding of 1,1'-bi-2-naphthol in a series of solvents and in solid phase has been investigated by means of mid-IR spectroscopy and DFT reaction field calculations. The polarizable continuum model has been used to estimate the relative stability of isomers differing in the positions of the hydroxyl groups. The height of the potential barriers between them was also calculated and the corresponding transition states characterized. In hydrogen bond nonaccepting solvents, the isomer preference does not change relative to the gas phase, although the less stable isomers are more probable in solvents of higher relative permittivity. In hydrogen bond forming solvents, the least stable isomer is most probably prevalent due to the additional stabilization through intermolecular hydrogen bonds with solvent molecules. A detailed vibrational analysis revealed the spectral regions specific to the OH vibrations with the observed solvent effects concerning the redistribution of vibrational intensities rather than wavenumber shifts.