scholarly journals Optical and Geometrical Characterizations of Non-Linear Supramolecular Liquid Crystal Complexes

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 701 ◽  
Author(s):  
Hoda A. Ahmed ◽  
Mohamed Hagar ◽  
Omaima A. Alhaddad ◽  
Ayman A. Zaki
Keyword(s):  
Self Assembly ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Theoretical Calculations ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
The Density Functional Theory ◽  
Different Temperatures ◽  
Ft Ir ◽  
Liquid Crystalline Materials

Nonlinear architecture liquid crystalline materials of supramolecular 1:1 H-bonded complexes (I/II and I/III) were prepared through a self-assembly intermolecular interaction between azopyridine (I) and 4-n-alkoxybenzoic acid (II) as well as 4-n-alkoxyphenylazo benzoic acid (III). The H-bond formation of the prepared supramolecular hydrogen bonded (SMHB) complexes was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Optical and mesomorphic behaviors of the prepared complexes were studied by polarized optical microscopy (POM) as well as DSC. Theoretical calculations were performed by the density functional theory (DFT) and used to predict the molecular geometries of the synthesized complexes, and the results were used to explain the experimental mesomorphic and optical properties in terms of their estimated thermal parameters. Ordinary and extraordinary refractive indices as well as birefringence at different temperatures were investigated for each sample using an Abbe refractometer and modified spectrophotometer techniques. Microscopic and macroscopic order parameters were calculated for individual compounds and their supramolecular complexes.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

scholarly journals Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

2013 ◽  
Vol 9 ◽  
pp. 425-436 ◽  
Author(s):  
Alexej Bubnov ◽  
Miroslav Kašpar ◽  
Věra Hamplová ◽  
Ute Dawin ◽  
Frank Giesselmann
Keyword(s):  
Liquid Crystalline ◽  
Molecular Structures ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Smectic Phases ◽  
Chiral Nematic ◽  
Nematic Phases ◽  
Liquid Crystalline Materials ◽  
Hydroxy Groups ◽  
Mesomorphic Properties

Several new calamitic liquid-crystalline (LC) materials with flexible hydrophilic chains, namely either hydroxy groups or ethylene glycol units, or both types together, have been synthesized in order to look for new functional LC materials exhibiting both, thermotropic and lyotropic behaviour. Such materials are of high potential interest for challenging issues such as the self-organization of carbon nanotubes or various nanoparticles. Thermotropic mesomorphic properties have been studied by using polarizing optical microscopy, differential scanning calorimetry and X-ray scattering. Four of these nonchiral and chiral materials exhibit nematic and chiral nematic phases, respectively. For some molecular structures, smectic phases have also been detected. A contact sample of one of the prepared compounds with diethylene glycol clearly shows the lyotropic behaviour; namely a lamellar phase was observed. The relationship between the molecular structure and mesomorphic properties of these new LCs with hydrophilic chains is discussed.

Synthesis of Dendrimers Liquid Crystalline Materials based on 1,3,5-triphenylbenzene

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Linh I Awad ◽  
Nasreen R Jber
Keyword(s):  
Differential Scanning Calorimeter ◽  
Liquid Crystalline ◽  
Spectroscopic Method ◽  
Optical Microscope ◽  
Crystalline Materials ◽  
Liquid Crystalline Phases ◽  
Ft Ir ◽  
Liquid Crystalline Materials ◽  
New Compounds ◽  
Liquid Crystalline Dendrimers

In this study, new compounds of discotic liquid crystalline dendrimers are prepared which is derived from 1,3,5-triphenylbenzene. The synthesis of these compounds shows the effect of dendrimer unit on the mesogenic properties. The structures of prepared compounds characterized by using spectroscopic method e.g. FT-IR and 1HNMR. The liquid crystalline phases of prepared compounds was identified by using the hot-stage polarizing optical microscope (POM) and differential scanning calorimeter (DSC).

Synthesis and Liquid Crystalline Properties of New Chiral Monomers and Polysiloxanes

2013 ◽  
Vol 815 ◽  
pp. 747-751
Author(s):  
Jian She Hu ◽  
Yi Nan Liu ◽  
Ya Ting Song ◽  
Di Wang
Keyword(s):  
Liquid Crystalline ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Crystalline Materials ◽  
H Nmr ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Liquid Crystalline Materials

To study the structure-property relationships of new chiral liquid crystalline materials based on menthol and explore their potential applications, a monomer 4-(4-allyloxybenzoyloxy) phenyl-4-menthyl-oxyacetyloxybiphenyl-4-carboxylate (LCM) and the corresponding homopolymer (LCP) were synthesized. The chemical structure was characterized by FT-IR and 1H NMR. The liquid crystalline properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The monomer LCM formed a cholesteric phase when a flexible linkage chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. The homopolymer LCP exhibited a batonnet texture of a smectic A phase.

scholarly journals Chiral Photoresponsive Liquid Crystalline Materials Derived from Cyanoazobenzene Central Core: Effect of UV Light Illumination on Mesomorphic Behavior

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1161
Author(s):  
Anna Poryvai ◽  
Alexej Bubnov ◽  
Michal Kohout
Keyword(s):  
Liquid Crystalline ◽  
Uv Light ◽  
Structural Type ◽  
Optical Microscope ◽  
Light Illumination ◽  
Aromatic System ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

One of the most frequently utilized liquid crystalline (LC) materials is a rod-like (calamitic) compound 4-cyano-4′-pentylbiphenyl (5-CB). The main objective of this work is to enhance its functionality by introducing a photoresponsive diazenyl spacer in the aromatic core and replace the non-chiral pentyl chain with various chiral alkyl carboxylate units. The mesomorphic properties of the prepared materials have been studied using polarizing optical microscopy and differential scanning calorimetry. It has been found that materials with an extended aromatic system possess the liquid crystalline behavior. The studied LC materials have shown mesophases at lower temperatures than previously reported analogous substances. Furthermore, one of them exhibits a chiral orthogonal frustrated twist grain boundary smectic phase, which has not been previously observed for this structural type of materials. We also investigated photoresponse of the mesophases under illumination with UV-light (365 nm) using a polarizing optical microscope. A non-conventional photoresponse of the prepared materials in a crystalline phase is presented and discussed.

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

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6416
Author(s):  
Fowzia S. Alamro ◽  
Hoda A. Ahmed ◽  
Saheed A. Popoola ◽  
Asmaa Aboelnaga
Keyword(s):  
Liquid Crystalline ◽  
Molecular Structures ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Pyridine Moiety ◽  
Computational Evaluation ◽  
Liquid Crystal System ◽  
Homo And Lumo ◽  
Liquid Crystalline Materials ◽  
Chain Lengths

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.

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

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1420 ◽  
Author(s):  
Laila A. Al-Mutabagani ◽  
Latifah Abdullah Alshabanah ◽  
Hoda A. Ahmed ◽  
Mohamed Hagar ◽  
Khulood A. Abu Al-Ola
Keyword(s):  
Density Functional ◽  
Geometrical Parameters ◽  
Scanning Calorimetry ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Smectic C ◽  
The Density Functional Theory ◽  
Phenyl Rings ◽  
Ft Ir ◽  
Bonded Complexes

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.

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

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1510 ◽  
Author(s):  
Omaima A. Alhaddad ◽  
Khulood A. Abu Al-Ola ◽  
Mohamed Hagar ◽  
Hoda A. Ahmed
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Molecular Geometry ◽  
Supramolecular Complexes ◽  
Scanning Calorimetry ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Ft Ir ◽  
Nematic Phases

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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