photochromic biindenylidenedione derivatives containing two mesogenic biphenyl units connected with flexible alkyl chains were designed and synthesized. All of them exhibited photochromism in solid states on UV-Vis irradiation accompanied by the simultaneous generation of stableorganicradicals, two of them displayed monotropic liquidcrystalsproperties. These were the first examples which had three
A compound having ferroelectric liquid crystal properties of the formula:
wherein A is the residue of a liquid crystal material or a liquid crystal compatible material;
X is 0 or S;
n is 0 or 1;
Y is any inert group which does not cause the melting point of the compound of Formula I to exceed 200°C;
R1 is selected from H, C1-4-alkyl and halogen; and
R2 is C1-4-alkyl or halogen;
provided that R1 and R2 are different. In a suitable environment the compound is capable of alignment in two metastable states and is therefore suitable for use in multiplex-addressed, liquid crystal devices, such as flat bed large area screens and displays.
一种具有铁电液晶特性的化合物,其式如下
其中 A 是液晶材料或液晶兼容材料的残留物;
X 是 0 或 S
n 是 0 或 1;
Y 是任何惰性基团,不会导致式 I 化合物的熔点超过 200℃;
R1 选自 H、C1-4-烷基和卤素;以及
R2 是 C1-4-烷基或卤素;
条件是 R1 和 R2 不同。在合适的环境中,该化合物能够以两种析出状态排列,因此适用于多址液晶设备,如平板大面积屏幕和显示器。
A liquid crystal like difluoroterphenyl chiral dopant was synthesized to match the dimensions of a host chiral dopant mixture. The melting point of the chiral dopants was decreased by increasing the length of the alkyl chain. The melting point of the chiral dopants also decreased when fluorine was on the same ring as the ester i.e. at 2 '', 3 '' position. These dopants were formulated with terphenyl host mixture and liquid crystal properties were assessed. New dopants, when added to the host mixture, maintain SmA(1) but the SmC2 phase was reduced markedly. There was a decrease in spontaneous polarisation when fluorine was on the same ring as the ester i.e. at 2 '', 3 '' position. As the molecular weight of the chiral dopant increased (pentyl -> heptyl -> nonyl), spontaneous polarisation decreased. (C) 2012 Elsevier B.V. All rights reserved.
Synthesis of 4-Alkyl-2′′, 3′′ difluoro terphenyl nitrile using coupling reactions
作者:Zohra N. Kayani、Robert A. Lewis、Shahzad Naseem
DOI:10.1016/j.molliq.2012.08.012
日期:2012.11
Study of chirality in liquid crystals is one of the most interesting areas of liquid crystal science. Liquid crystalline terphenyls with two lateral fluoro substituent and alkyl substituent in the 4- have been synthesised. Convergent approach was applied which involved the use of arylboronic acids and aryl halides in palladium-catalysed cross-couplingreactions. All the diifluoroterphenyls generate