Mesophase behavior of four ring ester/azomethine/ester liquid crystals in pure and mixed states

Alhaddad, Omaima A.; Khushaim, Muna; Gomha, Sobhi M.; Ahmed, Hoda A.; Naoum, Magdi M.

doi:10.1080/02678292.2022.2037768

Cited by 15 publications

(9 citation statements)

References 39 publications

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“…The entropy value of the N transition was small due to the short length of the alkyl chain of compound I 5 , while the entropy of SmC transitions for both I 9 and I 15 derivatives had higher magnitude than I 5 . These results are in accordance with previous findings [ 34 ]. In addition, the terminal alkyl chains play an important role in multiconformational changes in the molecule [ 35 ].…”

Section: Resultssupporting

confidence: 94%

“…Table 1 and Figure 3 reveal that the derivate with the shortest alkyl chain ( I 5 ) exhibited pure nematic (N) phase, while the other two longer homologues ( I 9 and I 15 ) were smectogenic and possessed the SmC mesophases. Generally, the mesomorphic behavior of any designed liquid crystalline molecular architecture is determined by the type of linking spacers, the length of the terminal chains, and the size of the attached substituents [ 34 , 35 ]. The melting transitions followed a random pattern, as seen in Table 1 and Figure 3 .…”

Section: Resultsmentioning

confidence: 99%

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New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer

et al. 2022

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In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (–CH=N-N=CH–), namely ((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (In), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared compounds were determined using elemental analysis, NMR, and FT-IR spectroscopy. The mesophase transitions were detected by differential scanning calorimetry (DSC), and the mesophases were identified using polarized optical microscopy (POM). The results indicated that the derivative with the shortest length (I5) was purely nematogenic, while the other homologues (I9 and I15) possessed SmC mesophases. The optimal geometrical structures of the investigated group were derived theoretically. The estimated results demonstrated that all homologues were mesomorphic, and their type depended on the length of the terminal chains. Computations based on density functional theory (DFT) were used to explain the experimental data. The calculated dipole moment, polarizability, thermal energy, and molecular electrostatic potential all showed that it was possible to predict the mesophase type and stability, which varied according to the size of the molecule.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer

et al. 2022

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“…The strategy utilized to construct the title compounds I n includes two sequentially steps that start with the synthesis of (E)-4-((4-hydroxybenzylidene)amino)phenol 3 [ 34 ], by reacting 4-hydroxy aniline 1 with the respective 4-hydroxybenzaldehyde 2 . Compound 3 could then be converted to their corresponding targets (E)-4-((4-hydroxybenzylidene)amino)phenyl 4-(alkoxy)benzoate I n through reaction with 4-alkoxybenzoic 4 in dry methylene chloride containing N , N′ − dicyclohexylcarbodiimide (DCC) and catalytic amounts of 4 − dimethylaminopyridine (DMAP) ( Scheme 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…The basic symmetrical and nonsymmetrical configurations of the designed molecule are affected by the number of aromatic units, the length of terminal chains, the alteration of polar spacers in elongating wings, and the mesomeric character of the central molecular core [ 32 ]. There have also been reports on the materials with two and three rings, as well as non-symmetrical molecular shapes and a core unit with one or two different linkages [ 33 , 34 ]. We recently looked into the thermal stability of symmetrical materials having the azomethine linkage as the central connecting group, 4-alkoxybenzoyloxy 4’-phenylmethineazophenyloxy 4”-alkoxybenzoate, in the mesophase [ 35 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Investigations of Three-Ring Ester/Azomethine Materials

et al. 2022

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New three-ring ester/azomethine homologues series, (E)-4-((4-hydroxybenzylidene)amino)phenyl 4-(alkoxy)benzoate In, were prepared and their properties were investigated experimentally and theoretically. FT-IR, NMR, and elemental analyses were used to confirm the chemical structures of the synthesized compounds. The mesomorphic activities of the planned homologues were evaluated using differential scanning calorimetry (DSC) and polarized optical microscopy. All of the homologous examined were found to have non-mesomorphic properties. Theoretical calculations using the density functional theory (DFT) were used to validate the experimental data and determine the most stable conformation of the synthesized compounds. All calculated conformers’ thermal properties, dipole moments, and polarizability were discussed. The results show that the terminal alkoxy chain length affects the thermal parameters of the conformers. The correlations between these parameters’ values and the conformer type were demonstrated. The base component was expected to be in two conformers according to the orientation of the N atom of imine-linkage. DFT calculations revealed the more probable of the two possible conformers, and the incorporation of the alkoxy terminal chain in one position affect its geometrical and mesomerphic characteristics.

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“…The mesophase behavior of non-symmetrical biphenyl derivatives [13,14] has been recently explored. Moreover, the addition of a new connecting group and a change to the rigid component stabilized the mesomorphic behavior and may have resulted in the development of new phases [15,16].…”

Section: Introductionmentioning

confidence: 99%

Wide Nematogenic Azomethine/Ester Liquid Crystals Based on New Biphenyl Derivatives: Mesomorphic and Computational Studies

et al. 2022

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The thermal stability and mesomorphic behavior of a new biphenyl azomethine liquid crystal homologues series, (E)-4-(([1,1’-biphenyl]-4-ylmethylene)amino)phenyl 4-(alkoxy)benzoate, In, were investigated. The chemical structures of the synthesized compounds were characterized using FT-IR, NMR, and elemental analyses. Differential scanning calorimetry (DSC) and polarized optical microscopy were employed to evaluate the mesomorphic characteristics of the designed homologues. The examined homologues possessed high thermal stability and broad nematogenic temperature ranges. Furthermore, the homologues were covered by enantiotropic nematic phases. The experimental measurements of the mesomorphic behavior were substantiated by computational studies using the density functional theory (DFT) approach. The reactivity parameters, dipole moments, and polarizability of the studied molecules are discussed. The theoretical calculations demonstrated that as the chain length increased, the polarizability of the studied series increased; while it did not significantly affect the HOMO–LUMO energy gap and other reactivity descriptors, the biphenyl moiety had an essential impact on the stability of the possible geometries and their thermal as well as physical parameters.

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Mesophase behavior of four ring ester/azomethine/ester liquid crystals in pure and mixed states

Cited by 15 publications

References 39 publications

New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer

New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer

Experimental and Theoretical Investigations of Three-Ring Ester/Azomethine Materials

Wide Nematogenic Azomethine/Ester Liquid Crystals Based on New Biphenyl Derivatives: Mesomorphic and Computational Studies

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