The Determination Of The Conformation Of The Aromatic Rings In A Lateral Fluoro-Substituted Liquid Crystal By C-13 Nmr Spectroscopy

A C-13-{H-1} NMR spectrum of 2,2'-difluoro-4"-hexoxy-4-pentyl-[1,1': 4',1"]-terphenyl in the nematic phase has been obtained and analysed to yield a set of partially-averaged dipolar couplings, D-ij(CF), which are used to determine the relative conformation of the two fluorinated rings. The probability distribution for the inter-ring angle is found to be peaked at 47.5+/-2.5degrees and 122.5+/-2.5degrees. The integrated, normalised probability that the inter-ring angle is less than 90degrees is 0.43.