Synthesis of 4-Alkyl-2′′, 3′′ difluoro terphenyl nitrile using coupling reactions

Abstract

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-coupling reactions. All the diifluoroterphenyls generate the smectic C phase. Mixture of 4-Alkyl-2′′, 3difluoro terphenyl nitrile in achiral host mixture HM1 generates ferroelectric liquid crystal properties. Ferroelectric properties were found to be highly dependent upon the relative lengths of the alkyl chain attached to chiral dopant. The compounds were studied using optical polarisation microscopy, differential scanning calorimetric, nuclear magnetic resonance, and Instec elecro-optical device to find ferroelectric liquid crystal properties.