Nematic liquid crystals synthesis

Perfluoroalloxy liquid crystals were prepared by the Williamson ether synthesis using perfluoro iodopropene. These materials can be mixed with nematic liquid crystal materials to provide liquid crystal compositions having low viscosity, low refractive index anisotropy, high dielectric anisotropy, and broad nematic phase ranges. 

The next major improvement in sample quality was the result of developments in direct synthesis. Oriented samples were obtained by the polymerisation of acetylene with the conventional titanium catalyst on a single crystal substrate and in nematic liquid crystals, see Tsukamoto (1992). Heat-treating the catalyst was found to produce polymer that could be stretched to give oriented samples. This resulted in a higher electrical conductivity along the orientation direction, up to 2xl05 fl-lm-1 being obtained. Naarman and co-workers heat treated the catalyst at 393 K and carried out the reaction in silicone oil at room temperature (Theophilou et al., 1986). Silicone oil was chosen as it has the same viscosity at room temperature as the usual solvents... 

Tosoni M, Laschat S, Baro A. Synthesis of novel chiral hquids and their phase behavior in mixtures with smectic and nematic liquid crystals. Helv. Chim. Acta. 2004. 87, 2472-2479. 

H.M.P. Chen, D. Katsis, S.H. Chen, Deterministic synthesis and optical properties of glassy chiral-nematic liquid crystals. Chem. Mater. 15, 2534—2542 (2003)... 

J.H. Wild, K. Bartle, N.T. Kirkman, S.M. Kelly, M. O NeiU, T. Stirner and R.P. Tuffin, Synthesis and investigation of nematic liquid crystals with flexoelectric properties, Chem. Mater. 17(25), 6354-6360, (2005). 

The synthesis of conjugated polymers in chiral nematic liquid crystal fields has been reviewed [9]. 

Piao, G., et al. 2001. Synthesis of well-controlled helical polyacetylene films using chiral nematic liquid crystals. Curr Appl Phys 1 121. 

K. Akagi, S. Katayama, M. Ito, H. Shirakawa, K. Araya, Direct synthesis of ahgned cis-rich polyacetylene films using low-temperature nematic liquid crystals, Synth. Met., 28, 51-56 (1989). 

Y. Arakawa, S. Nakajima, S. Kang, M. Shigeta, G. Konishi, J. Watanabe, Synthesis and evaluation of dinaphthylacetylene nematic liquid crystals for high-birefringence materials, Liq. Cryst. 39 (2012) 1063. 

Synthesis of Nematic Liquid Crystals and Chiral Dopants... 

The synthesis of a great number of materials that exhibit the nematic phase has achieved many different goals. Firstly, much knowledge has been acquired of the effect of stmctural features and various combinations of stmctiual features on melting points, mesophase morphology, and stability. Secondly, many physical properties have been evaluated for a great niunber of nematic liquid crystals and the resrrlts have been linked to the stmcture. Thirdly, mixtures of nematic materials have been formulated that have been... 

Kirsch, P, and Bremer, M. "Nematic Liquid Crystals for Active Matrix Displays Molecular Design and Synthesis." Angew. Chem. Int. Ed. Eng., 39,4216-4235 (2000). 

Kirsch, R Bremer, M. Nematic liquid crystals for active matrix displays Molecular design and synthesis, Angew. Chem., Int. Ed. 2000, 39, 4216-4235, and references therein. 

This brief account of methods for the synthesis of nematic liquid crystals concentrates on the most frequently encountered core systems, linking and terminal groups the synthetic methods presented are often applicable to more unusual nematogens and to compounds showing other mesophases (see V. Vill in Volume 1, Chapter IV on General Synthetic Strategies). 

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