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Alkynyl and isocyanobiphenyls : new thermotropic liquid crystals Bailey, Austin Lou

Abstract

The presence of mesomorphism in 4-n-alkyl-4'-isocyanobiphenyls 4 and 4-n-alkyl-4'-alkynylbiphenyls 5 was investigated, based on the liquid-crystallinity of the cyanobiphenyls 2 (R = n-alkyl). Compound 4 (R = n-butyl) is non-mesomorphic, whereas 4 (R = n-pentyl) is a virtual liquid crystal melting at 34-35°C and supercooling to a nematic phase at 30°C, and 4 (R = n-hexyI) is a nematic liquid crystal from 9 to 19°C. Compounds of structure 5 (R = n-pentyl, X = Si(CH₃)₃, H, CH₃, CI) are not liquid crystals. The corresponding bromo- and iodoalkynes (5, R = n-pentyl, X = Br, I) are liquid crystals with mesomorphic ranges of 88-108°C and 110-119°C, respectively. [See Thesis for Diagram]

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