A maximum-entropy analysis of the problem of the rotameric distribution for substituted biphenyls studied by 1H nuclear magnetic resonance spectroscopy in nematic liquid crystals

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Abstract
The statistical principle of maximum entropy is applied to the analysis of dipolar couplings from 1H NMR of nonrigid molecules dissolved in liquid‐crystalline phases. A distribution function for the orientational and inter‐ring angles is so obtained. The most probable internal angle φ is determined for 4,4’‐dichlorobiphenyl (φ=34°) in the nematic phase of I52, 4‐pentyl‐4’‐cyanobiphenyl (φ=32°) and 4’‐Br‐4‐Cl‐2,6‐difluorobiphenyl (φ=42°) in EBBA. The physical reliability of the distributions determined is discussed. The maximum‐entropy treatment seems to indicate a limit for the information on the internal motion obtainable from the experimental data.