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).

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 Synthesis, Optical and DFT Characterizations of Laterally Fluorinated Phenyl Cinnamate Liquid Crystal Non-Symmetric System

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1145
Author(s):  
Laila A. Al-Mutabagani ◽  
Latifah A. Alshabanah ◽  
Hoda A. Ahmed ◽  
Mohamed A. El-Atawy
Keyword(s):  
Density Functional ◽  
Liquid Crystalline ◽  
Theoretical Calculations ◽  
Symmetric System ◽  
Scanning Calorimetry ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Computational Tools ◽  
Meta Position ◽  
Chain Lengths

 A new laterally fluorinated unsymmetric liquid crystalline homologous series, based on cinnamate linkage, named 2-fluoro-4-(4-(alkoxy)phenyl)diazenyl)phenyl cinnamate (In), was synthesized and evaluated via different experimental and computational tools. The series had different terminal alkoxy-chain lengths with a lateral F atom in the meta position with respect to the azo moiety. The experimental mesomorphic and optical investigations were carried out using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Theoretical calculations and geometrical parameter predictions were conducted using the DFT program method at B3LYP/6-311G** level of theory. The results revealed that all the designed compounds exhibited the nematic (N) mesophase enantiotropically. The nematic stability and temperature range were impacted by the terminal alkoxy chain length. Compounds with the shortest chains (I6 and I8) showed a monotropic smectic A (SmA) phase, while the longest chain derivative, I16, possessed enantiotropic Sm A phase. Theoretical density functional theory (DFT) predictions were correlated with the practically observed data from the mesomorphic investigations. Data revealed that the terminal alkoxy and lateral F groups had an essential impact on the total energy of possible geometrical structures and their physical and thermal parameters. 

scholarly journals New nematogenic conical-shaped supramolecular H-bonded complexes for solar energy investigations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sobhi M. Gomha ◽  
Hoda A. Ahmed ◽  
Mohamed Shaban ◽  
Tariq Z. Abolibda ◽  
Khalid Abdulaziz Alharbi ◽  
...  
Keyword(s):  
Solar Energy ◽  
Density Functional ◽  
Geometrical Structure ◽  
Energy Gap ◽  
Supramolecular Complexes ◽  
Geometrical Parameters ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Ft Ir ◽  
Flexible Core

AbstractNew conical-shaped geometrical supramolecular H-bonded liquid crystal complexes were formed through 1:2 intermolecular interactions of H-bonding between flexible core (adipic acid, A) and lateral chloro-substituted azopyridines (Bn). The chains of the terminally alkoxy substituted base (n) were changed between 8 and 16 carbons. Mesomorphic and optical examinations of the prepared complexes were measured via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fourier-transform infrared spectroscopy (FT-IR) was used to confirm the Fermi bands of the H- bonding interactions. Induced nematogenic mesophases that cover the whole lengths of alkoxy-chains were detected. The non-linear geometries of the designed supramolecular complexes were also confirmed via Density functional theory (DFT) calculations. It was found that the length of terminal alkoxy chain of the base moiety highly affects the geometrical structure of the investigated complexes. Moreover, it increases the thermodynamic energy and influences the geometrical parameters. The electrical properties of each of the acid component (A), the base (B16) and their 1:2 complex (A/2B16) were evaluated using the Keithley measurement-source unit. The optical properties studies showed that the influences in the optical absorption and the reduction of the energy gap of the complex compared to its individual components made the resulted supramolecular H-bonded complex soft material suitable for solar energy investigations.

scholarly journals Measurements, Thermodynamic Modeling, and a Hydrogen Bonding Study on the Solubilities of Metoprolol Succinate in Organic Solvents

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2469 ◽  
Author(s):  
Jian Shen ◽  
Xianrui Liang ◽  
Hao Lei
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonding ◽  
Ethyl Acetate ◽  
Density Functional ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Fixed Temperature ◽  
Functional Theory ◽  
Metoprolol Succinate ◽  
Bonding Structure

The solubilities of metoprolol succinate (a cardioselective β1 adrenergic receptor) in methanol, ethanol, n-propanol, isopropanol, n-butanol, ethyl acetate, and acetone were measured at temperatures ranging from (278.2 to 318.2) K using a solid–liquid equilibrium method. The solubility of metoprolol succinate increases with increasing temperature. At a fixed temperature, the solubility decreases in the order methanol > ethanol > n-butanol > n-propanol > isopropanol > acetone > ethyl acetate. The enthalpy of fusion and the melting point of metoprolol succinate were determined by differential scanning calorimetry. The thermodynamic properties of the dissolution process, determined by a van’t Hoff analysis, have been obtained and are discussed. The modified Apelblat equation, Wilson model, and non-random two-liquid (NRTL) model were employed to correlate the solubilities of metoprolol succinate in different solvents. Finally, a quantitative structure–property relationship (QSPR) study of physical properties of solvents and density functional theory simulations of hydrogen-bonding structure were carried out to give the explanation for the sequence of solubility in alcohols. The density functional theory (DFT) calculations well illustrated that the solubility of metoprolol succinate in various alcohols can be mainly attributed to the intra- and intermolecular hydrogen bonds in metoprolol succinate-solvent complexes.

scholarly journals New Rod-Like H-Bonded Assembly Systems: Mesomorphic and Geometrical Aspects

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 795
Author(s):  
Laila A. Al-Mutabagani ◽  
Latifah Abdullah Alshabanah ◽  
Hoda A. Ahmed ◽  
Khulood A. Abu Al-Ola ◽  
Mohamed Hagar
Keyword(s):  
Density Functional ◽  
Polarized Light ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Ft Ir ◽  
Ir Spectroscopic ◽  
Thermal Stability Of ◽  
Bonded Complexes

Experimental and geometrical approaches of new systems of mesomorphic 1:1 supramolecular H-bonded complexes (SMHBCs) of five rings are discussed. The H-bonding between 4-alkoxyphenylimino benzoic acids (An, as proton acceptor) and 4-(4′–pyridylazophenyl) 4′′-alkoxybenzoates (Bm, as proton donor) were investigated. Mesomorphic behaviors were analyzed by differential scanning calorimetry (DSC) and mesophase textures were identified by polarized light microscopy (POM). H-bonded assembly was established by FT-IR spectroscopic measurements via Fermi band discussion. Thermal and theoretical factors were predicted for all synthesized complexes by density functional theory (DFT) predictions. The results revealed that all prepared complexes were monomorphic, with a broad range of smectic A phases with a high thermal stability of enantiotropic mesophase. Furthermore, DFT stimulations illustrated the experimental results in terms of the influence of the chain length either of the acid or the base component. Many parameters, such as the calculated stability, the dipole moment and the polarizability of the H-bonded complexes, illustrate how these parameters work together to enhance the smectic mesophases with the obtained stability and range.

scholarly journals New Liquid Crystal Assemblies Based on Cyano-Hydrogen Bonding Interactions

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohamed Hagar ◽  
Hoda A. Ahmed ◽  
Rua B. Alnoman ◽  
Mariusz Jaremko ◽  
Abdul-Hamid Emwas ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Crystal ◽  
Density Functional ◽  
Scanning Calorimetry ◽  
Hydrogen Bonding Interactions ◽  
Temperature Ranges ◽  
Dimensional Parameters ◽  
Ft Ir ◽  
Experimental Findings ◽  
Chain Lengths

A new selection of supramolecular liquid crystal complexes based on complementary molecules formed via hydrogen-bonding interactions is reported. All prepared complexes were prepared from 4-n-alkoxybenzoic acid (An) and N-4-cyanobenzylidene-4-n-(hexyloxy)benzenamine (I). FT-IR, temperature gradient NMR, Mass Spectrometer and Chromatography spectroscopy were carried out to confirm the -CN and −COOH H-bonded complexation by observing their Fermi-bands and the effects of the 1H-NMR signals as well as its elution signal from HPLC. Moreover, binary phase diagrams were established for further confirmation. All formed complexes (I/An) were studied by the use of differential scanning calorimetry and their phase properties were validated through the use of polarized optical microscopy Results of mesomorphic characterization revealed that all presented complexes exhibited enantiotropic mesophases and their type was dependent on the terminal lengths of alkoxy chains. Also, the mesomorphic temperature ranges decreased in the order I/A6 > I/A8 > I/A10 > I/A16 with linear dependency on the chain length. Finally, the density functional theory computational modeling has been carried out to explain the experimental findings. The relation between the dimensional parameters was established to show the effect of the aspect ratio on the mesophase range and stability. The normalized entropy of the clearing transitions (∆S/R) was calculated to illustrate the molecular interaction enhancements with the chain lengths.

Synthesis and Properties of Thermotropic Main-Chain Type Liquid Crystalline Polyurethanes Containing Biphenyl Mesogen

2007 ◽  
Vol 342-343 ◽  
pp. 729-732
Author(s):  
Jong Baek Lee ◽  
Byung Won Kang
Keyword(s):  
Liquid Crystalline ◽  
Main Chain ◽  
Scanning Calorimetry ◽  
New Type ◽  
Ft Ir ◽  
Nematic Phases ◽  
Stage Properties ◽  
Ir Study ◽  
Optical Polarizing Microscopy ◽  
Tolylene Diisocyanate

A new type of thermotropic main-chain liquid crystalline polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4′-Bis(8-hydroxyoctoxy)biphenyl (BP8). The structure of the monomer and the corresponding polymers were confirmed using FT-IR and 1H-NMR spectroscopic methods. BP8 exhibited a smectic type mesophase, however, nematic phases were found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP8 based polyurethane. For example, polyurethane 2,5-TDI/BP8 exhibited monotropic liquid crystallinity in the temperature ranging from 172 to 160 °C on the cooling stage. Properties of these polyurethanes were studied by differential scanning calorimetry (DSC), and optical polarizing microscopy. The FT-IR study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism.

scholarly journals Pyridine-Based Three-Ring Bent-Shape Supramolecular Hydrogen Bond-Induced Liquid Crystalline Complexes: Preparation and Density Functional Theory Investigation

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 628
Author(s):  
Sayed Z. Mohammady ◽  
Daifallah M. Aldhayan ◽  
Mohamed Hagar
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Compact Groups ◽  
Geometrical Structures ◽  
Thermal Stabilities ◽  
Functional Theory ◽  
Aspect Ratios ◽  
Enthalpy Changes ◽  
Chain Lengths

A series of new supramolecular three-ring bent-shape Schiff base liquid crystal (LC) complexes were prepared and studied. On one side, two alkoxy chain lengths of the carboxylic acids were used, namely eight and sixteen carbons. Moreover, on the other side, terminal small compact groups, which substituted aniline, with different polarities were utilized. Furthermore, the hydrogen-bonding interactions in the formed complexes were elucidated by Fourier-transform infrared (FT–IR) spectroscopy. The mesomorphic thermal and optical characteristics of the samples were determined by differential thermal analysis (DSC) and polarized optical microscopy (POM). The complexes exhibited enantiotropic and dimorphic mesophase behaviors. The results indicate that the polarity of the compact groups and the lengths of the alkoxy chains greatly impacted the mesomorphic characteristics and thermal stabilities of the mesophases. The observed values of the enthalpy changes (ΔH) associated with the crystalline smectic-A (TCr-SmA) transitions were extremely small compared with the conventional values that characterize supramolecular hydrogen-bonded liquid crystalline complexes. ΔH, which corresponded to the nematic isotropic transitions (TN-I), varied from 0.13 to 9.54 kJ/mol depending mainly on the polarity of the groups that were para-attached to the aniline moiety. Finally, the theoretical results obtained by density functional theory (DFT) calculations were discussed. The DFT geometrical structures showed non-coplanar structures. The mesomorphic range was correlated with the calculated dipole moment, polarizability and the aspect ratios of the investigated compounds.

scholarly journals Experimental and Theoretical Approaches of New Nematogenic Chair Architectures of Supramolecular H-Bonded Liquid Crystals

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 365 ◽  
Author(s):  
O. A. Alhaddad ◽  
H. A. Ahmed ◽  
M. Hagar
Keyword(s):  
Nematic Phase ◽  
Density Functional ◽  
Molecular Conformation ◽  
Theoretical Calculations ◽  
Molecular Geometry ◽  
Supramolecular Complexes ◽  
Scanning Calorimetry ◽  
Theoretical Approaches ◽  
Computational Calculations ◽  
The Stability

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 chloro-substituted supramolecular complexes were nematogenic, and exhibited 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. Theoretical calculations were carried out within the paradigm of the density functional theory (DFT) in order to establish the molecular conformation for the formed complexes and estimate their thermal parameters. The results of the computational calculations revealed that the H-bonded complexes were in a chair form molecular geometry. Additionally, out of the acquired data, it was possible to designate the influence of the position and orientation of the lateral group as well as the alkoxy chain length on the stability of the nematic phase.

scholarly journals Heterocycle Effects on the Liquid Crystallinity of Terthiophene Analogues

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2314 ◽  
Author(s):  
David Ester ◽  
Declan McKearney ◽  
Khrystyna Herasymchuk ◽  
Vance Williams
Keyword(s):  
Density Functional Theory ◽  
Organic Semiconductors ◽  
Self Assembly ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
Phase Behaviour ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Thiadiazole Ring

Liquid crystalline self-assembly offers the potential to create highly ordered, uniformly aligned, and defect-free thin-film organic semiconductors. Analogues of one of the more promising classes of liquid crystal semiconductors, 5,5”-dialkyl-α-terthiophenes, were prepared in order to investigate the effects of replacing the central thiophene with either an oxadiazole or a thiadiazole ring. The phase behaviour was examined by differential scanning calorimetry, polarized optical microscopy, and variable temperature x-ray diffraction. While the oxadiazole derivative was not liquid crystalline, thiadiazole derivatives formed smectic C and soft crystal lamellar phases, and maintained lamellar order down to room temperature. Variation of the terminal alkyl chains also influenced the observed phase sequence. Single crystal structures revealed the face-to-face orientation of molecules within the layers in the solid-state, a packing motif that is rationalized based on the shape and dipole of the thiadiazole ring, as corroborated by density functional theory (DFT) calculations. The solution opto-electronic properties of the systems were characterized by absorption and emission spectroscopy, cyclic voltammetry, and time-dependent density functional theory (TD-DFT).

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