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).
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.
The same as in Fig. 2 but for DPE. . Carbons which are experimentally equivalent are marked with a overbar.
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.
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.
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.
Molecular frame embedded on the phenyl rings of each structure. The definition of the angle specifying the tensor principal axis is also shown.
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).
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.
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).
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.
Comparison between the shielding components obtained from experiment and from ab initio calculations.
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