- CHARACTERIZATION OF THE HEXATIC B AND CRYSTAL B PHASES BY OPTICAL MICROSCOPY.
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Recent investigations concerning the structure of the B phase have unearthed a variety of packing arrangements of the molecular layers for this smectic modification. Two general structures have been discovered; one in which the B phase has three-dimensional crystalline order (crystal B), and one that is characterized by short-range in-plane positional ordering of the constituent molecules, and long-range bond orientational order, both within and between the layers (hexatic B). In this present study n-hexyl 4 prime -n-pentyloxybiphenyl-4-carboxylate (650BC) has been synthesized and its smectic phases characterized. Typically, this ester exhibits an A,B,E phase sequence, with the B phase being of the hexatic type. The synthesis, microscopic textures, and miscibility studies are reported here. The results show that while the two types of B phase appear co-miscible by conventional optical methods, in fact X-ray diffraction studies show that a transition occurs between the two phases in certain binary mixtures. Thus, the hexatic B and crystal B modifications are thermodynamically distinct phases.
- Goodby,Pindak
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- Synthesis of Mesogenic Compounds, Catalyzed by Metal Complexes. I. Monoalkylation and Monoarylation of 1,4-Dibromobenzene in the Synthesis of 4-n-Alkyl- and 4-n-Alkoxy-4'-Cyanobiphenyls Catalyzed by Palladium
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New methods of synthesis of mesomorphic 4-n-alkyl- and 4-n-alkoxy-4'-cyanobiphenyls are developed, based on the palladium catalyzed highly selective reactions of 1,4-dibromobenzene with alkyl and aryl Grignard reagents.
- Bumagin, N. A.,Luzikova, E. V.,Beletskaya, I. P.
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p. 1480 - 1486
(2007/10/03)
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- SYNTHESIS OF 4-ALKOXY-4'-CYANOBIPHENYLS
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A preparative method was developed for the synthesis of liquid crystals of the 4-alkoxy-4'-cyanobiphenyl group.It involves the nitration of 4-cyanobiphenyl to 4-nitro-4'-cyanobiphenyl, reduction of the latter, diazotization of the obtained 4-amino-4'-cyanobiphenyl, and alkylation of the 4-hydroxy-4'-cyanobiphenyl formed during decomposition of the diazonium salt.
- Ruolene, Yu. I.,Adomenas, P. V.,Adomenene, O. K.,Denis, G. I.
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p. 1192 - 1195
(2007/10/02)
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