Effect of the Relative Positions of Di-Laterally Substituted Schiff Base Derivatives: Phase Transition and Computational Investigations

Alamro, Fowzia S.; Ahmed, Hoda A.; Popoola, Saheed A.; Altaleb, Hamud A.; Al-Ola, Khulood A. Abu; Gomha, Sobhi M.

doi:10.3390/cryst11080870

Cited by 9 publications

(6 citation statements)

References 46 publications

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“…On the other hand, the second phenyl ring and the alkoxy oxygen at the LUMO level were found to be electron deficient while electron clouds distribution only covered the carbon atoms of the pyridyl and the first phenyl rings as well as their C=N linkage. On the part of the molecular electrostatic potential (MEP) presented in the Figure 5, the carbonyl oxygen of the ester linkage in each of the Tn series has high electron density but low electrostatic potential as reflected by the red cloud over its region [53][54][55]. Similarly, an appreciable electron density was observed for the pyridyl nitrogen heteroatom, C=N linkage nitrogen atom and alkoxyl oxygen of the derivatives.…”

Section: Mesomorphic Behaviormentioning

confidence: 99%

Synthesis, Phase Behavior and Computational Simulations of a Pyridyl-Based Liquid Crystal System

et al. 2021

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A homologous set of liquid crystalline materials (Tn) bearing Schiff base/ester linkages were prepared and investigated via experimental and theoretical techniques. Terminal flexible groups of different chain lengths were connected to the end of phenylbenzoate unit while the other end of molecules was attached to the heterocyclic pyridine moiety. The molecular structures of the designed molecules were evaluated by FT-IR, NMR spectroscopic analyses, whereas their mesomorphic properties were investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). They all exhibited dimorphic properties with the exception of the members having the shortest and longest terminal flexible chains (n = 6 and 16), which were monomorphic. The T16 derivative was further found possessing purely smectic A (SmA) mesophase while others have their lengths covered by nematic (N) phase. Moreover, the computational evaluation of the azomethine derivatives was carried out using a DFT approach. The polarity of the investigated derivatives was predicted to be appreciably sensitive to the size of the system. Furthermore, the Frontier molecular orbitals analysis revealed various distributions of electron clouds at HOMO and LUMO levels.

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Section: Mesomorphic Behaviormentioning

confidence: 99%

Synthesis, Phase Behavior and Computational Simulations of a Pyridyl-Based Liquid Crystal System

et al. 2021

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“…The magnitude of any system’s thermodynamic dynamic parameters, as well as its energy, is proportional to its length. This conclusion is supported by Table 2 , which shows that the values of all estimated parameters increased as the length of the terminal alkyl chain increased [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ].…”

Section: Resultsmentioning

confidence: 55%

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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“…The magnitude of any of thermodynamic dynamic parameters as well as energy of a system is size-dependent. This assertion is reflected in the results presented in Table 4 for which the values of all the calculated parameters increase with the increasing chain length of terminal alkoxy chain [ 44 , 45 , 46 , 47 , 49 ]. Moreover, the similar values predicted for the energy indicators of the corresponding members of the two isomers is due fact that they have the same molecular formula but only differ in configurations which do not significantly affect the energy.…”

Section: Resultsmentioning

confidence: 80%

“…On the part of the molecular electrostatic potential (MEP) presented in Figure 6 , the red cloud above the carbonyl and phenolic oxygen atoms indicates low electrostatic potential but high electron density. On the other hand, the blue cloud over the phenolic hydrogen portrays high electrostatic potential with low electron density [ 45 , 46 , 47 , 48 , 49 ].…”

Section: Resultsmentioning

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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Effect of the Relative Positions of Di-Laterally Substituted Schiff Base Derivatives: Phase Transition and Computational Investigations

Cited by 9 publications

References 46 publications

Synthesis, Phase Behavior and Computational Simulations of a Pyridyl-Based Liquid Crystal System

Synthesis, Phase Behavior and Computational Simulations of a Pyridyl-Based Liquid Crystal System

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

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

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