Chiral liquid crystal tetramers

Cholesteryl-based liquid crystal dimers containing a sulfur–sulfur link in the flexible spacer

“…The authors attributed this behaviour to the relative rotational barriers about S−S and C−C bonds. In order to study the role of the disulfide link in determining the properties of liquid crystal dimers further, we report here the synthesis and characterisation of the first examples of chiral dimers containing the disulfide link, 2.2 Cholesteryl 5-bromopentanoate, 2 (n = 5) 2 (n = 5, 6,8,10,11,12) were prepared according to the method described by Donaldson et al [39]. Thus, for 2 (n = 5), cholesterol (2.0 g, 5.2 mmol), DCC (1.6 g, 7.7 mmol) and DMAP (trace) were added to a solution of 5-bromovaleric acid (0.94 g, 5.2 mmol) in dry dichloromethane (40 mL), and the mixture was stirred at room temperature for 12 h. The dicyclohexylurea formed was removed by filtration and the filtrate concentrated under reduced pressure.…”

“…These consist of molecules containing two or more mesogenic units interconnected via flexible spacers, usually in a linear fashion. The simplest oligomers, termed liquid crystal dimers, contain just two liquid crystal units interconnected by a single spacer and these have been by far the most widely studied oligomers [2,3] although higher oligomers such as trimers and tetramers have been reported (for recent examples, see [5][6][7][8][9]). The intense interest in liquid crystal dimers has arisen because they exhibit very different properties to conventional low molar mass liquid crystals and recent investigations have included the observation of nematic-nematic transitions [10][11][12][13]; siloxanebased dimers [14]; studies of their light emitting [15] and flexoelectric properties [16,17]; the effects of spacer length and linking groups [18,19]; bent corecalamitic dimers [20,21]; anthracene-based [22] and discotic dimers [23]; H-shaped [24,25] and cyclic dimers [26]; intercalated [27,28] and biaxial smectic phases [29].…”

1,2-Propanediol-linked chiral symmetric and non-symmetric liquid crystal dimers containing trifluoromethyl

“…The crude product was obtained by filtration and washed with water several times to remove the excess PD out. The white powder 1-hydroxypropan-2-yl 4ʹ-(4-(trifluoromethyl) benzoyloxy) biphenyl-4-carboxylate (4) …”

“…Chiral liquid crystals (LCs), including chiral smectic phase, [1][2][3][4][5][6] chiral nematic phase, [2,[5][6][7][8][9] cholesteric phase, [4,[10][11][12] blue phase [12][13][14][15] and so on, have attracted much interest because of their unique optical and electrical properties, such as the selective reflection of light, [3,5,7,8,12] thermochromism [16,17] and ferroelectricity. [1,6,18,19] Fluorinated LCs are a class of important LCs for their fascinating properties such as the high polarity, dielectric anisotropy, optical anisotropy and viscoelastic properties.…”

Synthesis and phase behaviour of new biodegradable liquid crystalline polycarbonate derived from side chain cholesteryl derivative

“…So far, the many LC compounds based on cholesterol or its derivatives have been reported to study optical-electric properties, thermochromism and circular dichroism. [31][32][33][34][35][36] Besides, LC materials containing cholesteryl groups have especially attracted more and more attention in the biomaterials fields. [3,[21][22][23][24][37][38][39][40][41] Stupp et al first reported the synthesis of cholesterol end functionalised oligo(L-lactic acid) and their interactions with cells.…”