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Order parameters of ,-diphenylpolyenes in a nematic liquid crystal from an integrated computational and NMR spectroscopic approach
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10.1063/1.2363994
/content/aip/journal/jcp/125/17/10.1063/1.2363994
http://aip.metastore.ingenta.com/content/aip/journal/jcp/125/17/10.1063/1.2363994

Figures

Image of FIG. 1.
FIG. 1.

Sample spectra of DPH dissolved in ZLI-1167. (A) (isotropic), (B) , (C) , and (D) . The common scale is in relative ppm, referred to the position of the –CN peak of the solvent in the isotropic phase. Carbon assignments are also reported (see text).

Image of FIG. 2.
FIG. 2.

Temperature dependence and assignments of the chemical shifts (ppm) of BP in the isotropic and nematic phase of ZLI-1167, referred to the chemical shift of the –CN group of the liquid crystal in the isotropic phase. Nematic-isotropic temperature . Dashed lines connect the peaks belonging to the same carbon at the various temperatures. Carbon labeling is also reported.

Image of FIG. 3.
FIG. 3.

The same as in Fig. 2 but for DPE. . Carbons which are experimentally equivalent are marked with a overbar.

Image of FIG. 4.
FIG. 4.

The same as in Fig. 2 but for DPB. . Carbons which are experimentally equivalent are marked with a overbar. Both the -trans and -cis (gray) structures are shown.

Image of FIG. 5.
FIG. 5.

The same as in Fig. 2 but for DPH. . Carbons which are experimentally equivalent are marked with a overbar. Both the all--trans and all--cis (gray) structures are shown.

Image of FIG. 6.
FIG. 6.

The same as in Fig. 2 but for DPO. . Carbons which are experimentally equivalent are marked with a overbar. Both the all--trans and all--cis (gray) structures are shown.

Image of FIG. 7.
FIG. 7.

Molecular frame embedded on the phenyl rings of each structure. The definition of the angle specifying the tensor principal axis is also shown.

Image of FIG. 8.
FIG. 8.

Comparison between experimental and calculated isotropic chemical shifts in ZLI-1167, relative to the chemical shift of carbon 1 of each structure (see Figs. 1–5 for carbon labelings).

Image of FIG. 9.
FIG. 9.

Crosses: reference benzene for carbons . Empty circles: reference ab initio for carbons . Shielding tensors for carbons taken as averages of carbons and , respectively. The error bars are estimated by assuming that the shielding tensors of the reference carbons differ from true ones with a root-mean-square deviation of for the principal value components and of 2° for the orientation of the principal frame in the phenyl plane.

Image of FIG. 10.
FIG. 10.

Order parameters (solid lines) and (dashed lines) at three reduced temperatures in the nematic range: (circles), (diamonds), and (squares). Full symbols correspond to order parameters derived from time-dependent fluorescence depolarization experiments and are taken either from Refs. 29 and 71 (DPH) or Refs. 30 and 72 (DPO).

Tables

Generic image for table
Table I.

Calculated carbon isotropic shifts and shielding tensors principal values (ppm) for biphenyl (BP), trans-stilbene (DPE), 1,4-diphenyl-butadiene (DPB), 1,6-diphenyl-hexatriene (DPH), and 1,8-diphenyl-octatetraene (DPO), in an anisotropic solvent with and , with oriented along the axis. (deg) is defined in Sec. III A.

Generic image for table
Table II.

Comparison between the shielding components obtained from experiment and from ab initio calculations.

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/content/aip/journal/jcp/125/17/10.1063/1.2363994
2006-11-07
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Order parameters of α,ω-diphenylpolyenes in a nematic liquid crystal from an integrated computational and C13 NMR spectroscopic approach
http://aip.metastore.ingenta.com/content/aip/journal/jcp/125/17/10.1063/1.2363994
10.1063/1.2363994
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