95759-51-6Relevant academic research and scientific papers
Synthesis and Liquid Crystal Behaviour of Further 4,4"-Disubstituted 2'-Fluoro-1,1':4',1"-Terphenyls
Chan, L. K. M.,Gray, G. W.,Lacey, D.,Toyne, K. J.
, p. 209 - 240 (2007/10/02)
Further to earlier work on the liquid crystal properties of fluoro-1,1':4',1"-terphenyls we have now extended this series to include terminally fluoro- and cyano-substituted 2'-fluoro-1,1':4',1"-terphenyls, chiral 2'-fluoro-1,1':4',1"-terphenyls, and esters derived from 2'-fluoro-1,1':4',1"-terphenyls and incorporating the alkylcyclobutyl group.The preparations and transition temperatures for these series of compounds are presented and their transition temperatures and mesophase types are discussed.An interesting result from this work was the appearence of an S*C phase for one chiral homologue and of SC phases for the esters incorporating the alkylcyclobutyl group.The SC formation is attributed to the presence of the fluoro-substituent.Keywords: terphenyls, fluoroterphenyls, smectic C phases, cyclobutyl esters.
Reentrant Nematic and Injected Smectic Behaviour in Binary Mixtures Including Those of Terminally Non-Polar Compounds
Chan, L. K. M.,Gray, G. W.,Lacey, D.,Srithanratana, T.,Toyne, K. J.
, p. 335 - 360 (2007/10/02)
Some new examples of injected smectic hehaviour for binary mixtures of strong terminally polar mesogens (CBs, PCHs, BCOs, and CCHs) with a range of terminally non-polar esters are presented.Variations in the strength of the injected behaviour are discussed.Examples of SB as well as SA injection occur.Studies of mixtures of terminally non-polar 4,4"-dialkyl-2'-fluoro-p-terphenyls (I) with cyano-substituted mesogens are also described and provide an example of injection of SA and SE phases.Of greater interest is the observation that binary mixtures consisting solely of homologues of (I) can exhibit reentrant nematic behaviour, providing further evidence that reentrant phenomena are not a special feature of terminally polar mesogens and their mixtures.An isomeric mixture of two compounds of structure (I) also gives an interesting case of an injected SC phase, and enhanced SC properties are recorded for other mixtures of homologues of (I).Mixtures involving alkyl/alkoxy analogues of (I) also provide examples of SC phase injection or enhancement, and in one case some evidence for injected S1 behaviour.Keywords: mixtures of terminally non polar mesogens, reentrant nematics, injected SA phases, injected SC phases, lateral fluoro-substitution.
Synthesis and Evaluation of Some 4,4''-Disubstituted Lateral Fluoro-1,1':4',1''-terphenyls
Chan, L. K. M.,Gray, G. W.,Lacey, D.
, p. 185 - 204 (2007/10/02)
A number of laterally fluorinated 4,4''-di-n-alkyl-, 4,4''-di-n-alkoxy- and 4-n-alkyl-4''-n-alkoxy-1,1':4',1''-terphenyls of structure (I) have been synthesised, with the lateral fluoro-substituent in the central benzene ring. The nematic and smectic thermal stabilities for all three series of compounds, have been examined.A typical example is (I), X = n-C5H11, Y = n-C3H7, C-N 50 deg C and N-I 140.6 deg C.For the 4,4''-di-n-alkyl-1,1':4',1''-terphenyls, the position of the lateral fluoro-substituent with respect to the longest n-alkyl chain is found to be important in determining the smectic behaviour of this class of compound.By using a combination of optical microscopy, X-ray diffraction and miscibility studies, the complex smectic behaviour of the higher homologues of this series has also been investigated.A comparison of the liquid crystal behaviour of the laterally fluorinated terphenyls of structure (I) with their non-fluorinated analogues is also given.A selected number of these compounds, have been further examined to assess their usefulness as high TN-I additives for multiplexed mixtures used in electro-optic display devices.
