Molecular structure and the indirect spin-spin coupling constants in azulene - A proton NMR study in the nematic phase

Abstract

The proton NMR spectrum of azulene has been investigated in the nematic phase of a liquid crystal. Spectral analysis provided the direct dipole-dipole coupling constants which were used to derive the structural information. It was found that the relative proton-proton distances in the 7- and 5-membered rings deviate significantly from those for regular heptagons and pentagons. Indirect spin-spin couplings were also obtained. Many of the inter-ring and long-range couplings have magnitudes between 0.2-0.8 Hz