Conformations of 3,5-dichloroanisole and 3,5-dibromoacetophenone determined from 1H nuclear magnetic resonance spectra of nematic solutions

Abstract

The ¹H n.m.r. spectra of samples of 3,5-dichloroanisole and 3,5-dibromoacetophenone dissolved in the liquid crystal Merck Phase V have been analysed to yield sets of dipolar coupling constants. For both molecules the dipolar couplings are consistent only with structures having the side chain groups, COC and CCC, and phenyl rings coplanar, and with one CH bond of the methyl group in this plane and pointing away from the ring. It is also shown that the molecules reorient rapidly in the liquid crystals during each rotation about the C–X bonds.