- Anisotropic organic compounds
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STR1 The invention describes liquid crystalline compounds or formula (I), where A, D and G are independently selected from phenyl, thiophene, hydrogenated phenyl, chlorinated phenyl and fluorinated phenyl, B and E are independently selected from a single bond C= C. C C.C00, azoxy and diazo, k and m are independently selected from 1 and 0, such that m+n is 1 or 2, and R1 and R2 are independently selected from R, R0, alkynyl, thioalkyl, hydrogen, CN, NCS and SCN; provided that at least one of R1 and R2 is selected from CN, NCS and SCN and that at least one of A, D and G is phenyl; and excluding where at least one of R1 and R2 is independently selected as CN and one of A, D or G is not thiophene, and where m is 0, A, and D are phenyl, B is a single bond and only one of R1 or R2 is NCS. Also described are compounds suitable for inclusion in a device utilizing pretransitional characteristics of liquid crystalline materials in the isotropic phase, of general formula (II) where J and Y are independently selected from phenyl, thiophene, hydrogenated phenyl, chlorinated phenyl and fluorinated phenyl, X is selected from C= C. C C.COO azoxy and diazo, k is 1 or 0 and R3 and R4 are independently selected from R, RO, alkynyl, thioalkyl, hydrogen, CN, NCS and SCN; provided that at least one of R3 and R4 is selected from CN, NCS and SCN and that at least one of J and Y is phenyl.
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- The Synthesis of Several Lateral Difluoro-substituted 4,4''-Dialkyl- and 4,4''-Alkoxyalkyl-Terphenyls and a Rationalisation of the Effect of Such Substitution on Mesophase Type and Transition Temperatures
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In recent years we have prepared a large number of mono-fluoro- and ortho-difluoro-substituted 4,4''-dialkyl- and 4,4''-alkoxyalkyl-terphenyls.The synthesis and transition temperatures of a variety of related difluoro compounds is presented here so that it is now possible to identify (i) broadening of the molecule, (ii) twisting about an inter-annular bond, and (iii) the presence of an "inner" (2-, 2'-, 3'- or 2''-substituent) or an "outer" (3- or 3''-substituent) fluorine, as being the major factors which influence the type and the thermal stability of the mesophases obtained.
- Gray, G. W.,Hird, M.,Toyne, K. J.
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