121219-25-8Relevant articles and documents
New low polar tolane cholesterics designed for infrared applications
Herman, Jakub,Kula, Przemys?aw
, p. 84231 - 84235 (2016/10/06)
We have designed, synthesized and evaluated the physical properties of new fluorinated phenyltolane based chiral liquid crystal materials with 2-methylbutyl terminal chain. The 2- or 2,6-fluorosubstitution in combination with the phenyltolane core brings surprising improvement of mesomorphic properties. The investigated compounds are characterized by a broad temperature range of the cholesteric (chiral nematic N?) phase, very low melting temperatures and easy thermal control of selective reflection in the near infrared region. The moderate helical twisting power β, high optical anisotropy and source of a blue phase make these compounds attractive for cholesteric mixture formulations.
The Synthesis and Transition Temperatures of Some Fluoro-Substituted 4-Cyanophenyl and 4-Cyanobiphenyl-4'-yl 4-Pentyl- and 4-Butoxy-Benzoates
Gray, G. W.,Hird, M.,Lacey, D.,Toyne, K. J.
, p. 165 - 190 (2007/10/02)
A series of 4-cyanophenyl 4-X-benzoates and a series of 4-cyanobiphenyl-4'-yl 4-X-benzoates (X= pentyl, butoxy) have been prepared without fluoro-substitution and with mono-fluoro to tetra-fluoro-substitution; all possible combinations of substitution patterns at the positions ortho- to the cyano group and ortho- to the carboxylate group have been obtained in an attempt to determine the structural features which are responsible for some members of these series showing very large positive values of dielectric anisotropy.The synthesis of novel precursors required for the preparation of these esters is described and the melting points and transition temperatures of the esters are discussed and an explanation is provided for the variation of Tn-1 values with position and extent of fluoro-substitution. - Keywords: Fluoro-substitution, phenyl and biphenyl benzoates, terminal cyano namatogens.