New optically active tetra-ortho-substituted biphenyl chiral dopants for nematic liquid crystals are described. It was shown, with respect to our previous results, that biphenyl chiral dopants bearing only mesogenic residues on their 2,2'-positions and without any substituents on their 4,4'-positions gave rise to very high twisting powers in nematic liquid crystals. This powerful and unconventional chiral dopant molecular architecture allowed the design of new tetra-ortho-substituted biphenyl derivatives, easier to prepare in optically active form. This simplification of the molecular architecture still affords chiral dopants for nematic liquid crystals with large helical twisting powers and allows more economical large-scale preparation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

中文翻译：

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新的 2,2'-取代的 6,6'-二甲基联苯衍生物在液晶中诱导强螺旋扭曲能力

描述了用于向列液晶的新型光学活性四邻位取代联苯手性掺杂剂。相对于我们之前的结果表明，联苯手性掺杂剂在其 2,2'-位置仅带有介晶残基并且在其 4,4'-位置没有任何取代基在向列液晶中产生非常高的扭曲能力. 这种强大且非常规的手性掺杂剂分子结构允许设计新的四邻位取代联苯衍生物，更容易以光学活性形式制备。这种分子结构的简化仍然为具有大螺旋扭曲能力的向列液晶提供手性掺杂剂，并允许更经济的大规模制备。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)