Analysis of single and multiple quantum NMR spectra of 1,3-dichloro-2-ethenylbenzene in liquid crystal solvents

Abstract

The single and multiple quantum NMR spectra of 1,3-dichloro-2-ethenylbenzene as solute in two different nematic liquid crystals have been measured and analysed in terms of dipolar couplings and chemical shift differences. Because the single quantum spectra did not yield to straightforward analysis, normal and frequency selective multiple quantum experiments were used to aid the analysis. The results from four spectra were combined to yield structural information and the order matrix in each solution. The structure of the ring is very close to that of 1,3-dichlorobenzene, and that of the ethenyl group very close to that of ethenylbenzene. The dihedral angle between the ethenyl group and the aromatic ring is found to be 45·4±1·0°, and the C - C = C angle is found to be 127·3±0.3°.