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

Ahmed, Hoda A.; Naoum, Magdi M.

doi:10.1080/02678292.2015.1096970

Cited by 33 publications

(40 citation statements)

References 54 publications

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“…An/II16) that, an independent effect of the alkoxy chain length of the acid on a monotropic nematic phase covered all supramolecular complexes. From the present investigation, it would be expected that, the increment in the molecular anisotropy due to the orientation of the lateral electron-withdrawing Cl atom in the supramolecular geometry impacted the stability of nematic phase that agrees with our previous work[31,61].Furthermore, the addition of lateral Cl atom in supramolecular architectures weakens the side by side cohesion interactions thus enhances a nematic phase for all 1:1 complexes. In addition, the molecular geometry and size of the lateral substituent impact the mesophase stability and the polarizability of whole molecule[19,20,62].…”

supporting

confidence: 90%

“…[25][26][27][28][29]Designing of photosensitive SMLCs through intermolecular interactions using the suitable H-bond donors and acceptors are concerns of our area of interest. [30][31][32][33][34][35][36]Anisotropic structures are produced from the overall molecular shape of architectures and the combination of rigid (aromatic) and flexible segments (alkyl chains). Those changes in the characteristics of the LCs may be impact the mesomorphism as well as the properties essential for technical uses.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and theoretical approaches of new nematogenic chair architectures of supramolecular H-bonded liquid crystals

Hagar

Ahmed

2019

Proceedings of the 23rd International Electronic Conference on Synthetic Organic Chemistry

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New four isomeric chair architectures of 1:1 H-bonded supramolecular complexes were prepared through intermolecular interactions between 4-(2-(pyridin-4-yl)diazenyl-(2-(or 3-)chlorophenyl) 4-alkoxybenzoates and 4-n-alkoxybenzoic acids. The H-bond formation of all complexes was confirmed by differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). Mesomorphic characterization was carried by DSC and polarized optical microscopy (POM). It was found that, all prepared laterally choro substituted supramolecular complexes were nematogenic exhibited pure nematic phase and low melting temperature. The thermal stability of the nematic mesophase observed depends upon the location and spatial orientation of the lateral Cl-atom in as well as the length of terminal chains. The density functional theory (DFT) theoretical calculations were discussed to predict the molecular conformation for the formed complexes as well as their thermal parameters. The results of the computational calculations revealed that the H-bonded complexes were in a chair form molecular geometry. Moreover, the results explained the effect the position and orientation of the lateral group as well as the alkoxy chain length on the type and the stability of the nematic mesophase. In addition, their impacts on the estimated thermal parameters of H-bonded complex and how these play an important role in influencing thermal and optical properties.

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confidence: 90%

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical approaches of new nematogenic chair architectures of supramolecular H-bonded liquid crystals

Hagar

Ahmed

2019

Proceedings of the 23rd International Electronic Conference on Synthetic Organic Chemistry

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“…Thermotropic liquid crystals based on intermolecular hydrogen-bonded interactions are mostly used in display devices as well as sensor applications [9][10][11][12][13]. Most binary H-bonded mixtures are based on pyridine and carboxylic derivatives [14][15][16][17][18][19][20][21][22][23][24]. Recently, our research group [25][26][27][28]…”

Section: Introductionmentioning

confidence: 99%

New Symmetrical U- and Wavy-Shaped Supramolecular H-Bonded Systems; Geometrical and Mesomorphic Approaches

et al. 2020

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New mesomorphic symmetrical 2:1 supramolecular H-bonded complexes of seven phenyl rings were prepared between 4-n-alkoxyphenylazobenzoic acids and 4-(2-(pyridin-3-yl)diazenyl)phenyl nicotinate. Mesomorphic studies of the prepared complexes were investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fermi bands of the formed H-bonded interactions were confirmed by FT-IR spectroscopy. Geometrical parameters for all complexes were performed using the density functional theory (DFT) calculations method. Theoretical results revealed that the prepared H-bonded complexes are in non-linear geometry with U-shaped and wavy-shaped geometrical structures; however, the greater linearity of the wavy-shaped compounds could be the reason for their stability with respect to the U-shaped conformer. Moreover, the stable, wavy shape of supramolecular H-bonded complexes (SMHBCs) has been used to illustrate mesomeric behavior in terms of the molecular interaction. The experimental mesomorphic investigations revealed that all complexes possess enantiotropic smectic C phase. Phases were confirmed by miscibility with a standard smectic C (SmC) compound. A comparison was constructed to investigate the effect of incorporating azophenyl moiety into the mesomeric behavior of the corresponding five-membered complexes. It was found that the addition of the extra phenylazo group to the acid moiety has a great increment of the mesophase stability (TC) values with respect to the monotropic SmC phase of the five aromatic systems to the high stable enantiotropic SmC mesophase.

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“…Several H-bonded mesogenic complexes containing azo, ester, and Schiff base central linkages have been widely reported [42][43][44][45][46][47]. Most of them are based on the linear intermolecular H-bonding interactions [48][49][50][51][52][53], and there are an attractive area of interest toward the formation of nonlinear SMHBLCs [54][55][56]. Further, the terminal alkoxy chains have important roles in the temperature range and stability of the mesophase of the LC compounds.…”

Section: Introductionmentioning

confidence: 99%

Chair- and V-Shaped of H-bonded Supramolecular Complexes of Azophenyl Nicotinate Derivatives; Mesomorphic and DFT Molecular Geometry Aspects

et al. 2020

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New geometrical architectures of chair- and V-shaped supramolecular liquid crystalline complexes were molded through 1:1 intermolecular hydrogen bonding interactions between 4-(4-(hexyloxy)phenylazo)methyl)phenyl nicotinate and 4-alkoxybenzoic acids. The length of terminal alkoxy acid chains varied, n = 6 to 16 carbons. The mesomorphic behaviour of these complexes was examined through differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fourier-transform infrared spectroscopy (FT-IR) was carried out to confirm the presence of Fermi bands that appeared for the hydrogen bonding formation. Enantiotropic nematic phases were observed and covered all lengths of alkoxy chains. The geometrical structures of the prepared supramolecular complexes geometries were estimated by Density functional theory (DFT) calculations. The supramolecular complexes I/An are projected to exhibit a nonlinear geometry with V-shaped and chair-shaped geometry. The chair-shaped conformers of I/An were found to be more stable than V-shaped isomeric complexes. Moreover, the effect of the change of the mesogenic core on the mesophase thermal stability (TC) has been investigated by a comparative study of the present azo supramolecular H-bonding LCs (SMHBCs) I/An and our previously reported their Schiff base analogue complexes, II/An. The findings of the DFT illustrated the high impact of CH=N as a mesogenic core on the mesomorphic behavior in terms of the competitive lateral and terminal intermolecular interactions as well as the molecular electrostatic potential (MEP).

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

Cited by 33 publications

References 54 publications

Experimental and theoretical approaches of new nematogenic chair architectures of supramolecular H-bonded liquid crystals

Experimental and theoretical approaches of new nematogenic chair architectures of supramolecular H-bonded liquid crystals

New Symmetrical U- and Wavy-Shaped Supramolecular H-Bonded Systems; Geometrical and Mesomorphic Approaches

Chair- and V-Shaped of H-bonded Supramolecular Complexes of Azophenyl Nicotinate Derivatives; Mesomorphic and DFT Molecular Geometry Aspects

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