Photo-responsive and electrically switchable mesophases in a novel class of achiral bent-core azo compoundsElectronic supplementary information (ESI) available: colour versions of Figs. 3, 4, 7 and 8. See http://www.rsc.org/suppdata/jm/b3/b314482h/

Prasad, Veena; Kang, Shin‐Woong; Qi, Xianghong; Kumar, Satyendra

doi:10.1039/b314482h

Cited by 62 publications

(32 citation statements)

References 16 publications

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“…[27][28][29][30][31][32][33] Alteration of the binding sites of the supramolecules is simple and effective way to change the shape of SMHBLCs [34][35][36][37] in order to design new materials with new mesomorphic properties. Herein, we extend our systematic study to investigate the effect of introducing additional azobenzene unit to the angular supramolecular complexes previously reported by us [36] through hydrogen-bond formation between 4-alkoxyphenylazo benzoic acids (In) [38,39] as proton donors and 4-(3ʹ-pyridylazo)-4ʹʹ-alkoxybenzoates (IIm) as proton acceptors (see Figure 1).…”

Section: In/iimmentioning

confidence: 99%

Mesophase behaviour of azobenzene-based angular supramolecular hydrogen-bonded liquid crystals

Ahmed

Naoum

2015

Liquid Crystals

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New types of angular 1:1 hydrogen-bonded supramolecular complexes via hydrogen-bond formation between 4-alkoxyphenylazo benzoic acids (In) and 4-(3ʹ-pyridylazo)-4ʹʹ-alkoxybenzoates (IIm) with various alkoxy chains (from 6 to 16 carbons) were prepared and investigated for their mesophase behaviour by differential scanning calorimetry (DSC) and polarised-light microscopy (PLM). All prepared homologues were found to be dimorphic, possessing smectic C and nematic mesophases. The formation of 1:1 hydrogen-bonded supramolecular liquid crystals (LCs) complexes was confirmed by FTIR and UVʹvisible (UVʹvis) absorption spectroscopy. The study revealed that nematic transition enhancement (ΔT) decreases with the increase of the alkoxy chain length on the base complement, while it increases with the increase of the chain attached to the acid complement of the complex, that is the stability of the nematic phase is more dependent on the length of the acid component.

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Section: In/iimmentioning

confidence: 99%

Mesophase behaviour of azobenzene-based angular supramolecular hydrogen-bonded liquid crystals

Ahmed

Naoum

2015

Liquid Crystals

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“…The non-symmetry of the molecular structure was introduced, for example, by different length and type of the terminal chain (14)(15)(16)(17)(18)(19)(20)(21)(22)(23), by different functionalities in the central unit (14)(15)(16)(24)(25)(26)(27)(28)(29)(30), different number and lateral substitution of the benzene units in the arms (16,18,19,27,(29)(30)(31)(32)(33), the type, number and orientation of the linking groups (28,(34)(35)(36)(37)(38)(39)(40), and combination of all these factors. A special sub-type of non-symmetrical bent-shaped liquid crystals are the hockey-stick mesogens, denomination of which was introduced for five-ring materials with non-symmetrical position of the bend (41).…”

Section: Introductionmentioning

confidence: 99%

Novel hockey‐stick mesogens with the nematic, synclinic and anticlinic smectic C phase sequence

et al. 2008

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New hockey-stick mesogens have been synthesised and their mesomorphic properties studied. The molecular structure consists of a laterally substituted central naphthalene unit prolonged by two non-symmetrical arms, both of which contain ester units of identical orientation. The shorter arm possesses only one and the longer arm three benzene rings. Nematic, synclinic smectic C and anticlinic smectic C phases were identified and their physical properties studied. No banana-type ordering producing dipolar phases has been found.

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“…The first compounds forming electrically switchable and photo-responsive mesophases have also been reported [46]. The authors studied the influence of light action on the phase transition temperatures of these compounds and found that the formation of Z-isomers during photo-irradiation results in a small decrease of the phase transitions temperatures (Cr to B 2 phase as well as B 2 phase to the isotropic one).…”

Section: Introductionmentioning

confidence: 97%

Photochromic azobenzene functionalised banana–calamitic dimers and trimers: mesophase behaviour and photo-orientational phenomena

et al. 2011

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Azobenzene functionalised banana-calamitic dimers and a novel type of banana-calamitic-banana trimers have been synthesised. Their thermotropic behaviour and the structure of the mesophases have been characterised by differential scanning calorimetry, polarising optical microscopy and X-ray diffractions measurements. Electro-optical studies evidence the polar properties of the smectic phases. A rare anticlinic-synclinic smectic CP (SmCP) phase transition could be proven for two of the twins upon cooling without an electric field although the molecules are not optically active. Remarkably, the phase sequence SmC a -SmC s has been observed upon cooling, the inverse sequence to that reported for non-chiral compounds up to now. A comparative study of the photochemical properties of dilute solutions and of thin films of two compounds has been performed. Irradiation with polarised ultra-violet (365 nm) and visible light (473 nm) induces a photo-orientation process of the chromophores in a direction perpendicular to the polarisation plane of the exciting light. For a trimeric compound bearing an azobenzene bridge between both bent-core mesogenic units this process is associated with cycles of the E-Z-E isomerisation of the azobenzene groups followed by rotational diffusion of molecules in the films. For a bis(azobenzene) containing dimer the E-Z isomerisation in films is strongly suppressed and the photo-induced orientation has a rotational diffusion mechanism.

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Photo-responsive and electrically switchable mesophases in a novel class of achiral bent-core azo compoundsElectronic supplementary information (ESI) available: colour versions of Figs. 3, 4, 7 and 8. See http://www.rsc.org/suppdata/jm/b3/b314482h/

Cited by 62 publications

References 16 publications

Mesophase behaviour of azobenzene-based angular supramolecular hydrogen-bonded liquid crystals

Mesophase behaviour of azobenzene-based angular supramolecular hydrogen-bonded liquid crystals

Novel hockey‐stick mesogens with the nematic, synclinic and anticlinic smectic C phase sequence

Photochromic azobenzene functionalised banana–calamitic dimers and trimers: mesophase behaviour and photo-orientational phenomena

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