A MAXIMUM-ENTROPY ANALYSIS OF THE PROBLEM OF THE ROTAMERIC DISTRIBUTION FOR SUBSTITUTED BIPHENYLS STUDIED BY H-1 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY IN NEMATIC LIQUID-CRYSTALS

被引:53
作者
CATALANO, D [1 ]
DIBARI, L [1 ]
VERACINI, CA [1 ]
SHILSTONE, GN [1 ]
ZANNONI, C [1 ]
机构
[1] UNIV BOLOGNA,DIPARTIMENTO CHIM FIS & INORGAN,I-40136 BOLOGNA,ITALY
关键词
D O I
10.1063/1.460669
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
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.
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收藏
页码:3928 / 3935
页数:8
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