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Dependence of Mesomorphic Behaviour of Methylene‐Linked Dimers and the Stability of the N TB /N X Phase upon Choice of Mesogenic Units and Terminal Chain Length
Author(s) -
Mandle Richard J.,
Goodby John W.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201601146
Subject(s) - mesogen , mesophase , liquid crystal , crystallography , phase (matter) , methylene , materials science , chain (unit) , stereochemistry , chemistry , liquid crystalline , organic chemistry , physics , optoelectronics , astronomy
Twelve symmetrical dimeric materials consisting of a nonamethylene (C9) spacer and either phenyl 4‐(4′‐alkylphenyl)benzoate, phenyl 4‐(4′‐alkylcyclohexyl)benzoate or phenyl 4‐(4′‐alkylbicyclohexyl)carboxylate mesogenic units were prepared and their mesogenic behaviour characterised by POM, DSC and XRD. All of the materials exhibited nematic phases with clearing points in excess of 200 °C. Four compounds were found to exhibit the twist‐bend nematic phase, with one material exhibiting a transition from the N TB phase into an anticlinic smectic ‘X’ phase. Across all three series of compounds the length of terminal chain is seen to dictate, to some degree, the type of mesophase formed: shorter terminal chains favour nematic and N TB mesophases, whereas longer terminal aliphatic chains were found to promote smectic phases.