Vibrational circular dichroism of the OH-stretching vibration in 2,2′-dihydroxy-1,1′-binaphthyl

Abstract

Vibrational circular dichroism (VCD) spectra in the near-IR region of (R)-2,2′-dihydroxy-1,1′-binaphthyl have been obtained in various organic solvents. It is found that the VCD feature of the OH-stretching vibration exhibits a remarkable change with solvent polarity reflecting different states of the hydrogen bond. A strong negative VCD band accompanying a weak positive band on the low-wavenumber side is observed for the OH-stretching vibration in dilute CCl₄ solution. The strongly negative-biased bisignate feature is interpreted as the sum of the conservative bisignate couplet and the negative monosignate term. The strong negative VCD is attributed to the dynamic polarization mechanism due to the large anisotropy of polarizability of the naphthalene ring in the intramolecular hydrogen-bond structure. The bisignate feature is found to originate in the three-centre dynamic polarization coupling mechanism as well as the classical electric dipole–dipole coupling mechanism in the degenerate coupled-oscillator system.