A novel dimesogen with a cholesteric phase of wide temperature range : Synthesis and characterisation

Abstract Dimesogenic compounds consisting of two non-identical mesogenic units connected through a polymethylene spacer are now of interest in the area of liquid crystal research. Previous studies have shown that dimesogens made up of a cholesteryl ester unit and a Schiff's base unit connected through a central alkyl spacer give rich mesomorphism. We have taken up investigations to study the effects of replacing the Schiff's base moiety with a tolan unit. As an example, the dimesogen; cholesteryl 6-[4-(4-n-butyloxyphenylethynyl)phenoxy]hexanoate was synthesized and studied for its liquid crystalline properties. Although this compound shows only one mesophase, viz., the cholesteric phase, the temperature range of the mesophase is very wide, perhaps one of the largest ranges reported to date.

[1]  G. R. Luckhurst,et al.  Symmetric and non-symmetric liquid crystal dimers with branched terminal alkyl chains : racemic and chiral , 1997 .

[2]  T. Endo,et al.  Synthesis and thermal properties of dimeric alkoxy-substituted tolans , 1996 .

[3]  E. Białecka-Florjańczyk,et al.  Synthesis and liquid crystalline properties of cholesteryl bisesterimides with poly(ethylene oxide)s as central spacers , 1996 .

[4]  Jung‐Il Jin,et al.  From Incommensurability to Commensurability in Smectic Phases for a Series of Dimesogenic Liquid Crystals , 1995 .

[5]  I. Nishiyama,et al.  Coupling between chirality and odd-even effect of twin materials in smectic liquid-crystalline phases , 1995 .

[6]  Jung‐Il Jin,et al.  Novel sequence with incommensurate SA phases in a new dimesogenic liquid crystal , 1994 .

[7]  J. Watanabe,et al.  Thermotropic liquid crystals of polyesters having a mesogenic 4,4-bibenzoate unit Smectic mesophase properties and structures in dimeric model compounds , 1993 .

[8]  G. W. Gray,et al.  Palladium-catalysed cross-coupling reactions in the synthesis of some high polarizability materials , 1993 .

[9]  G. R. Luckhurst,et al.  Smectogenic dimeric liquid crystals. The preparation and properties of the α,ω-bis(4-n-alkylanilinebenzylidine-4′-oxy)alkanes , 1992 .

[10]  G. R. Luckhurst,et al.  Non-symmetric dimeric liquid crystals The preparation and properties of the α-(4-cyanobiphenyl-4′-yloxy)-ω-(4-n-alkylanilinebenzylidene-4′-oxy)alkanes , 1988 .

[11]  A. I. Galatina,et al.  Structure and Mesomorphism of Cholesteric Liquid Crystals , 1986 .

[12]  A. Griffin,et al.  Effect of molecular structure on mesomorphism. 12. Flexible-center Siamese-twin liquid crystalline diesters - a "prepolymer" model , 1981 .

[13]  K. Sonogashira,et al.  A Convenient Synthesis of Ethynylarenes and Diethynylarenes , 1980 .

[14]  J. Jacques,et al.  Recherches sur les Substances Mésomorphes III. Tolanes Nématiques , 1973 .