Cyano biphenyl molecules

The cyano biphenyl molecules illustrate the effect of sequence structure on the abihty to form various phases. The cyano biphenyl molecules form a very important group of materials being widely used in many liquid crystal display appKcations. Two examples are as follows ... 

There are a number of factors working within this series of molecules. Firstly, a Sc phase appears at n = 4, the Sb and Se being also only observed for n = 3. The alkyl cyano biphenyl molecules, structure (8), all have the same absolute... 

Figure 16, A typical cyano-biphenyl nematic liquid crystal molecule.

The third material, MES, behaves differently. In this case the adsorbed LC film does show an anisotropy (Fig. 5.4b) the 5CB molecules follow the rubbing direction. The surface alignment is characterized by Qa 0.3 and 0 w 71°. The value of the surface in-plane order parameter is in the lowest range of the usual values for rubbed polymer surfaces Qa 0.3 — 0.5 [29,35,36]. The observed tilt angle is the same as for the other silanes and comparable with alignment angles of cyano-biphenyl monolayers usually found on substrates that induce a planar macroscopic alignment [15,22]. 

Molecules that form liquid crystalline phases are often oblate or prolate in shape, with aspect ratios of three or more, and have some rigidity, conferred, for example, by rigid biphenyl or terphenyl groups. Figure 10-1 shows some examples of liquid-crystal formers, namely, A-(p-methoxybenzylidene)-/ -butylaniline (MBBA), p-n-hexyloxybenzilidene-/ -aminobenzonitrile (HBAB), and the 4-cyano-4 alkylbiphenyl series, or kCB, where n is... 

The polarized triplet-triplet absorption spectra of biphenyl, carbazole, and phenanthrene have been compared, and phenanthrene has been found to differ considerably from the other two molecules.290 T-T Absorption spectra of cyano-substituted benzenes,291 several aromatic vapours,292 tetracene in THF,293 and hexachloroacetone 294 have been reported, and an interesting use of the triplet state of anthracene as a probe for measuring the rates of lateral diffusion of molecules of biological interest has been described.295 Absorption spectra of... 

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