The statistical principle of maximum entropy is applied to the analysis of dipolar couplings from H-1 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 phi is determined for 4,4'-dichlorobiphenyl (phi = 34-degrees) in the nematic phase of I52, 4-pentyl-4'-cyanobiphenyl (phi = 32-degrees) and 4'-Br-4-Cl-2,6-difluorobiphenyl (phi = 42-degrees) 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.
A maximum-entropy approach analysis of the problem of the rotameric distribution for substituted biphenyls studied by 1H nuclear magnetic resonance spectroscopy in nematic liquid crystals
CATALANO, DONATA INES MARIA;DI BARI, LORENZO;VERACINI, CARLO ALBERTO;
1991-01-01
Abstract
The statistical principle of maximum entropy is applied to the analysis of dipolar couplings from H-1 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 phi is determined for 4,4'-dichlorobiphenyl (phi = 34-degrees) in the nematic phase of I52, 4-pentyl-4'-cyanobiphenyl (phi = 32-degrees) and 4'-Br-4-Cl-2,6-difluorobiphenyl (phi = 42-degrees) 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
