Unusual odd-even effects depending on the monomer chain length in nematic liquid crystals made of rod-like dimers

Kundu, Brindaban ; Pal, Santanu Kumar ; Kumar, Sandeep ; Pratibha, R. ; Madhusudana, N. V. (2009) Unusual odd-even effects depending on the monomer chain length in nematic liquid crystals made of rod-like dimers Europhysics Letters, 85 (3). 36002_1-36002_6. ISSN 0295-5075

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Official URL: http://iopscience.iop.org/0295-5075/85/3/36002/

Related URL: http://dx.doi.org/10.1209/0295-5075/85/36002

Abstract

We report physical studies on the nematic phase exhibited by five members of a homologous series of symmetric dimers which have cyanobiphenyl end groups and, a disulphide bridging group in the spacer. All of them have rod-like conformations in the nematic phase, but unusually, the nematic-isotropic transition temperature, the birefringence and the dielectric anisotropy exhibit "odd-even" effects depending on the number of carbon atoms in the alkyl chain of a monomeric moiety. Further, the lowest "even" homologue exhibits a nematic-nematic transition. We argue that these phenomena arise from the relatively facile rotational fluctuations of the two monomeric moieties around the central S-S bond, whose orientation with respect to the long molecular axis changes between the "even" and "odd" members.

Item Type:Article
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ID Code:20949
Deposited On:20 Nov 2010 13:18
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