A. Bailey, G. S. Bates
Apr 1, 1991
Citations
1
Influential Citations
11
Citations
Journal
Molecular Crystals and Liquid Crystals
Abstract
Abstract 4-n-Alkyl-4′-cyanobiphenyls (1) have achieved widespread application as stable thermotropic liquid crystals with mesophases at room temperature. The importance of the cyano functional group in the liquid-crystalline behaviour of these compounds is not clearly defined. By modifying this functional group with minimal changes in molecular geometry, we have found two new classes of mesomorphs. 4-n-Alkyl-4′-isocyanobiphenyls (2) and 4-n-alkyl-4′-(haloalkynyl)biphenyls (3). The synthesis of these compounds is described. Compound 2a (R = n-butyl) is non-mesomorphic, whereas compound 2b (R = n-pentyl) is a virtual liquid crystal melting at 34-5°C and supercooling to a nematic phase at 30°C, and 2c (R = n-hexyl) is a nematic liquid crystal from 9 to 19°C. Compounds of structure 3 (R = n-. pentyl, X = Si(CH3)3. H, CH3, Cl) are not liquid crystals. The corresponding bromo- and iodoalkynes (3, R = n-pentyl, S = Br, 1) are liquid crystals with mesomorphic ranges of 88-108°C and 110-119°C. respectively.