Studies on some smectogenic compounds with large bilayer spacings

Madhusudana, N. V. ; Srikanta, B. S. ; Ursa, M. Subramanya Raj (1983) Studies on some smectogenic compounds with large bilayer spacings Molecular Crystals and Liquid Crystals, 97 . pp. 49-75. ISSN 1058-725X

PDF - Publisher Version

Official URL:

Related URL:


In mesomorphic compounds with strongly polar end groups, near neighbor molecules have antiparallel correlations. This results in a bilayer structure which in turn leads to several interesting phenomena like reentrance and smectic polymorphism. After a brief review of the development of this subject, we report some unusual properties in several compounds with relatively large bilayer spacings (≥ 1.6 times the molecular length). For example, 4-n-decylphenyl-3'-methyl-4'-(4"-nitrobenzoyloxy)benzoate (10 PMNBB) shows a remarkably large expansion (~20%) of the bilayer spacing on cooling in the SA phase, the rate of expansion increasing with decrease of temperature. Further, the dielectric anisotropy reverses sign, becoming negative at lower temperatures. When the nitro group is replaced by a cyano group (10 PMCBB), (a) the rate of expansion of the bilayer spacing decreases with decrease of temperature, and (b) an SA - SA transition takes place with a jump of ~0.4 Å in the layer spacing at TAN - T ≈ 15°. We present results on several homologues of both the compounds as also on compounds with a lateral methoxy substituent.

Item Type:Article
Source:Copyright of this article belongs to Taylor and Francis Ltd.
ID Code:20882
Deposited On:20 Nov 2010 13:24
Last Modified:17 May 2016 05:08

Repository Staff Only: item control page