Synthesis and mesomorphic properties of nonsymmetric liquid crystalline dimers containing azobenzene groups

Rahman, Lutfor; Asik, Jahimin; Kumar, Sandeep; Silong, Sidik; Rahman, Mohamad Zaki Ab.

doi:10.1080/01411590802642406

Cited by 20 publications

(4 citation statements)

References 31 publications

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“…[39] Since the procedure used to synthesise the entire series of 2a-2g is unchanged, therefore, the experimental details can be described by based on a representative compound 2a.…”

Section: Syntheses Of 6-bromo[4-(4-acetylphenylazo) Phenoxy]hexane (2a)mentioning

confidence: 99%

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Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

et al. 2015

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New non-symmetrical dimers which contain respective side units of azobenzene and 1,2,3-triazole-choloesteral have been synthesised from the reaction between 6-azido-[4-(4-acetylphenylazo)phenoxy]alkane and cholesteryl-4-(prop-2-ynyloxy)benzoate. The results show that the derivatives of 6-bromo[4-(4-acetylphenylazo)phenoxy] alkanes which possess the odd alkyl spacers exhibit dimesomorphism of N and SmA phases whilst the members with even numbers are non-mesogenic. However, the 6-azido-[4-(4-acetylphenylazo)phenoxy]-alkanes show N and SmA phases in a wide temperature range. On heating and cooling the target compounds cholesteryl 4-[(1-(6-(4-(4ʹ-acetylphenylazo)phenoxy)alkyl)-1H-1,2,3-triazol-4-yl)methoxy]benzoate show chiral nematic (oily streak and fanshaped texture) and focal conic texture characteristics of smectic A phases with high thermal stability. Present investigation also reveals the effect of the spacer length upon the phase transition temperature. Intercalated arrangement is favoured by the molecules in the smectic phase. The observation is well established by XRD measurement wherein the actual molecular length is smaller than the theoretical value.

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“…[39] Since the procedure used to synthesise the entire series of 2a-2g is unchanged, therefore, the experimental details can be described by based on a representative compound 2a.…”

Section: Syntheses Of 6-bromo[4-(4-acetylphenylazo) Phenoxy]hexane (2a)mentioning

confidence: 99%

“…Intermediary compound 1 was prepared according to the method described by Lutfor et al [39]. Dilute hydrochloric acid [conc.…”

Section: Synthesis Of 4-(4-hydroxyphenylazo) Acetophenone (1)mentioning

confidence: 99%

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

et al. 2015

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“…All intermediate compounds 1-3 were synthesized according to our earlier paper (Scheme 1). [30][31][32][33] Ethyl…”

Section: Synthesis Of Intermediate Compoundsmentioning

confidence: 99%

Liquid Crystals Decorated Gold Nanoparticles for Photoswitching Properties

Rahman¹,

Sarjadi²,

Sarkar³

et al. 2018

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Liquid crystals decorated gold nanoparticles are synthesized as the molecular architecture consists of the azobenzenes moieties with alkene as the peripheral units, which are connected to gold nanoparticles (Au-NPs) via thiolated phenolic units are in the middle. The morphology and mesomorphic properties were investigated by the field emission scanning electron microscope, high-resolution transmission electron microscopy, differential scanning calorimetry, and polarizing optical microscopy. The aromatic thiolated azobenzene moieties with gold nanoparticles showed smectic A phase with monotropic nature only appeared in the cooling cycle. HR-TEM measurement showed that the functionalized Au-NPs are well dispersed without any aggregation. However, the absorption spectrum of peripheral azobenzene units shows strong absorption maxima in the ultraviolet region at 378 nm due to π-π* transition. For n-π* transition, a weak absorption band is observed in the visible region at 472 nm. The photo-isomerization characteristic is measured using absorption spectroscopy. The photosaturation of Au-NPs is found at the time duration of 16 s. The thermal back relaxation is completed after the time interval of 70 min. Moreover, Au-NPs showed excellent stability towards photo-decay. Therefore, Au-NPs compound is suitable in the field of optical storage and molecular switching.

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“…The molecules of mesogenic materials are geometrically constructed by linking two identical or unidentical units with a flexible spacer, generally a polymethylene unit [1,2]. Dimers consisting of two identical units are known as symmetric dimmers [3,4].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Mesomorphism in Symmetric and Nonsymmetric Dimers

Kotadiya

Khunt

Bhoya

2015

Molecular Crystals and Liquid Crystals

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A homologous series consisting of 12 homologue symmetrical dimers, viz., bis(4-nalkoxy benzoyloxy) 2,2-diphenyl propanes was synthesized, studied, and evaluated to establish the relation between molecular structure and mesomorphic properties on comparative basis with nonsymmectric dimers. The methoxy to pentyloxy homologue dimers, the novel symmetric series, are nonmesogenic. Mesomorphism commences from the hexyloxy homologue as smectic and nematic. The hexyloxy to decyloxy dimers possess smectogenic character with nematogenic character and the dodecyloxy to hexadecyloxy homologue dimers exhibit nematogenic character without the exhibition of smectogenic character. All the mesogenic homologues are enantiotropic mesomorphs. The smectic and nematic thermal stability of series is 129.0 • C and 147.7 • C, respectively, and mesomorphic phase length varies between 18 • C for the hexadecyloxy homologue and 56 • C for the heptyloxy homologue.

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Synthesis and mesomorphic properties of nonsymmetric liquid crystalline dimers containing azobenzene groups

Cited by 20 publications

References 31 publications

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

Liquid Crystals Decorated Gold Nanoparticles for Photoswitching Properties

A Comparative Study of Mesomorphism in Symmetric and Nonsymmetric Dimers

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