Abstract
The properties of six chiral non-symmetric dimers belonging to the family of (S)-(benzylidene-4'-substitutedaniline)-2 ''-methylbutyl-4'''-(4 ''''-phenyloxy)benzoate-oxy)hexanoates are described. The terminal substituents on the 4-benzylidene-4'-substituted fragment are H, Cl, Br, I, CH3 and C2H5. All six dimers exhibit an enantiotropic chiral nematic phase. The relationship between the chiral nematicisotropic transition temperature and the terminal substituent is discussed in terms of the size of the substituent and its effect of the molecular shape, and its ability to interact with mesogenic group to which it is attached. The C2H5-substituted dimer also shows an enantiotropic monolayer chiral smectic C phase, the formation of which is attributed to the enhanced molecular inhomogeneity arising from the longer alkyl chain. The weak smectic tendencies seen for the halogen-substituted dimers are attributed to potentially repulsive interactions between the ester links that would occur in an intercalated smectic arrangement which would be expected for dimers of this type. (C) 2016 Elsevier B.V. All rights reserved.
Original language | English |
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Pages (from-to) | 118-125 |
Number of pages | 8 |
Journal | Journal of Molecular Structure |
Volume | 1111 |
Early online date | 20 Jan 2016 |
DOIs | |
Publication status | Published - 5 May 2016 |
Bibliographical note
AcknowledgementsThe author (G.Y.Yeap) would like to thank Universiti Sains Malaysia (Account Number 1001/PKIMIA/811159) for providing the research facilities and financial support under RU Research Grant (Account No. 203/PKIMIA/6711192) and PRGS Postgraduate Research Grant (Account No. 1001/KIMIA/835010). Authors also thank Ms Anna Zep and her supervisor Prof E. Gorecka for the powder X-ray diffraction measurement.
Keywords
- Liquid crystal dimers
- Non-symmetric dimers
- Chirality
- Bend nematic phase
- Mesogenic linking unit
- Behavior
- Tetramers
- Oligomers
- Azobenzene
- Trimers
- Spectroscopy
- Intercalate
- Moiety