Kristallin‐flüssige Heterocycloalkane. I. Synthese und Eigenschaften substituierter 1,3‐Dioxane

Abstract

Liquid‐crystalline Heterocycloalkanes. I. Synthesis and Properties of Substituted 1,3‐Dioxanes The synthesis of 2,5‐disubstituted 1,3‐dioxanes is described, their melting and clearing points and their physical properties (dielectric anisotropy, viscosity, transition enthalpies, optical birefringence) are investigated. The cyano substituted 1,3‐dioxans 5 and 7 are valuable materials for application in displays.

Mesogenic, optical, and dielectric properties of 5-substituted 2-[12-(4-pentyloxyphenyl)-p-carboran-1-yl] [1,3]dioxanes

“…The low polarizability anisotropy and a moderate molecular dipole moment 1 of 2.13 ¡ 0.03 D, oriented at 47u relative to the C2-C5 axes, make [1,3]dioxane an attractive structural element for the preparation of liquid crystals with positive dielectric anisotropy, low birefringence, and minimal absorption in the UV region. [2][3][4][5][6] Analysis of the available data 7 shows that the dioxane ring has a smectogenic character and even two-ring compounds often exhibit smectic phases. 2 While this property of [1,3]dioxane is useful for the development of SmC* materials, 6,8,9 it is undesirable for formulation of nematic materials.…”

From the discovery of the partially bilayer smectic A phase to blue phases in polar liquid crystals

“…In homologous series 11 and 3 the SmA d phase is observed for members with shorter chains: n = 4 [45] and n = 7, [49] respectively, while for dioxane 7, it is not seen even in n = 11. [50] In the case of homologous ester series 12 and 13 (nCN, nOCN), the SmA d phase is observed for members with a minimum chain length n = 10, but for the isomeric ester 15 (CNOn) with the lower dipole moment, it appears with a shorter terminal chain, n = 8. [43] The SmA d phase is also observed in compounds with terminal nitro (NO 2 ) and formyl (COH) groups.…”

The influence of lateral substituents on the phase behavior of side-chain liquid crystalline polysiloxanes containing trans-2,5-disubstituted-1,3-dioxane based mesogenic side groups

“…2,5-Disubstituted 1,3-dioxane [1][2][3][4][5][6], 1,3-dithianes 17-11], 1,3-oxathianes [12][13][14], 1,2,3-dioxaborinane 1115-161 and 2,5-disubstituted phenyl-pyrimidine units have been reported as being new types of liquid crystalline compounds. These kinds of liquid crystals which usually show very wide nematic ranges and some favourable properties, are useful for liquid crystal display application.…”