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

作者：Mandle Richard J; Goodby John W

来源：Chemistry - A European Journal, 2016, 22(27): 9366-9374.

DOI：10.1002/chem.201601146

• bimesogens
• liquid-crystalline dimers
• mesomorphism
• nematic phase
• X-ray diffraction

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 degrees C. Four compounds were found to exhibit the twist-bend nematic phase, with one material exhibiting a transition from the NTB 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.

• 出版日期2016-6-27