scholarly journals Synthesis, Thermal and Optical Characterizations of New Lateral Organic Systems

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 551
Author(s):  
Laila Ahmed. Al-Mutabagani ◽  
Latifah A. Alshabanah ◽  
Sobhi M. Gomha ◽  
Hoda A. Ahmed
Keyword(s):  
Methoxy Group ◽  
13C Nmr Spectroscopy ◽  
Molecular Structures ◽  
Phenyl Ester ◽  
Scanning Calorimetry ◽  
1H And 13C Nmr ◽  
Polarized Optical Microscopy ◽  
Organic Systems ◽  
Temperature Ranges ◽  
Ft Ir

New laterally OCH3-substituted optical organic Schiff base/ester series, namely 4-(4-(hexyloxyphenyl)iminomethyl)-3-methoxyphenyl 4-alkoxybenzoates, were prepared and characterized with different thermal, mesomorphic, and photoactive techniques. The prepared group constitutes five homologues that differ from each other in the number of carbons in the terminal alkoxy chain (n), which varies between n = 6, 8, 10, 12, and 16 carbons. The laterally protruded methoxy group is attached to the central benzene ring that makes an angle of 120° with the molecular long axis. Molecular structures of all newly prepared homologues were fully elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic transitions were determined via differential scanning calorimetry (DSC) and the phases identified by polarized optical microscopy (POM). Independent of the length of the terminal alkoxy chain attached to phenyl ester ring, only a monomorphic nematic (N) phase was observed for all the synthesized compounds. A comparative study was made between the present lateral methoxy-substituted homologues and their corresponding laterally-neat analogues. The results revealed that, depending on the length of the alkoxy chain and the presence or absence of the lateral methoxy group, different mesophases with different thermal stability and temperature ranges were observed. Finally, UV-vis spectra showed that the present nematogenic series possess photoactive properties that are of importance for many applications.

scholarly journals Optical and Thermal Investigations of New Schiff Base/Ester Systems in Pure and Mixed States

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1687
Author(s):  
Abeer S. Altowyan ◽  
Hoda A. Ahmed ◽  
Sobhi M. Gomha ◽  
Ayman M. Mostafa
Keyword(s):  
13C Nmr Spectroscopy ◽  
Molecular Structures ◽  
Mixed States ◽  
Scanning Calorimetry ◽  
1H And 13C Nmr ◽  
Meta Position ◽  
Binary Phase Diagrams ◽  
Thermal Investigations ◽  
Ester Moiety ◽  
Ft Ir

New mesomorphic series, 4-hexadecyloxy phenyl-imino-4′-(3-methoxyphenyl)-4″-alkoxybenzoates (An), were prepared and investigated with different thermal and mesomorphic techniques. The synthesized homologous series constitutes four members that differ from each other in the terminal length of flexible chain (n) attached to phenyl ester moiety, which varies between n = 6, 8, 10, and 12 carbons. A lateral CH3O group is attached to the central benzene ring in the meta position with respect to the ester moiety. Molecular structures of all newly prepared homologues were elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic and thermal properties were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the mesophases identified by polarized optical microscopy (POM). DSC and POM examinations revealed that all members of the present series (An) exhibit a purely enantiotropic nematic (N) phase. Comparative evaluations and binary phase diagrams were established between the present homologues and their corresponding shorter one (Bn). The examination revealed that, the length of the flexible alkoxy chain incorporated into the phenylimino moiety is highly effective on the temperature range and stability of the mesophase observed. With respect to the binary mixtures An/Bn, the exhibited N phase showed to cover the whole composition range with eutectic behavior.

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

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 870
Author(s):  
Fowzia S. Alamro ◽  
Hoda A. Ahmed ◽  
Saheed A. Popoola ◽  
Hamud A. Altaleb ◽  
Khulood A. Abu Al-Ola ◽  
...  
Keyword(s):  
Molecular Structures ◽  
Experimental Measurements ◽  
Positional Isomers ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Schiff Base Derivatives ◽  
Elemental Analyses ◽  
Ft Ir ◽  
Mesomorphic Properties ◽  
Ft Ir Spectroscopy

Two new laterally di-substituted derivatives namely, (E)-4-(((2-Chlorophenyl)imino)methyl)-3-methoxyphenyl 4-(alkoxy)benzoate, were designed and investigated for their mesomorphic properties. Elucidation of their molecular structures was carried out by elemental analyses, NMR and FT-IR, spectroscopy. Phase transitions were examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The optimized geometrical architectures of both compounds were deduced theoretically using GAUSSIAN 09 program. In order to establish the most probable conformation for each compound, four probable conformations were predicted for their positional isomers which vary according to the orientations of the two lateral groups. The results were used to correlate the experimental measurements with the predicted conformations. The study revealed that the investigated derivatives are non-mesomorphic and the orientations, as well as positions of the two-lateral groups, have a significant effect on the molecular packing of the molecules, their geometrical and thermal parameters.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

Trimesic Acid-Based Star Mesogens with Flexible Spacer: Synthesis and Mesophase Characterization

2012 ◽  
Vol 65 (10) ◽  
pp. 1426 ◽  
Author(s):  
A. Shanavas ◽  
T. Narasimhaswamy ◽  
A. Sultan Nasar
Keyword(s):  
13C Nmr Spectroscopy ◽  
Steric Repulsion ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Analysis Techniques ◽  
Trimesic Acid ◽  
Smectic A ◽  
Flexible Spacer ◽  
Ft Ir ◽  
Alkoxy Groups

A series of trimesic acid-based star mesogens containing an octamethylenoxy spacer and two-ring containing side arms with terminal alkoxy groups were synthesised by a divergent approach. A structurally similar mesogen containing a three-ring side arm was also synthesised. All the mesogens and intermediates were characterised thoroughly using FT-IR, 1H NMR, 13C NMR spectroscopy, and elemental analysis techniques. The mesophase characteristics were identified by hot stage optical polarising microscopy (HOPM) and differential scanning calorimetry (DSC), while X-ray was used to confirm the existence of a smectic A (SA) phase. The HOPM and DSC results revealed the presence of rich polymesomorphism in the star mesogens. The dominance of a SA phase in the series is attributed to the steric repulsion associated with steric asymmetry. The change of the side arm from two rings to three rings was found to increase the mesophase stability.

scholarly journals Synthesis, Mesomorphic, and Solar Energy Characterizations of New Non-Symmetrical Schiff Base Systems

2021 ◽  
Vol 9 ◽  
Author(s):  
Fowzia S. Alamro ◽  
Hoda A. Ahmed ◽  
Sobhi M. Gomha ◽  
Mohamed Shaban
Keyword(s):  
Schiff Base ◽  
Solar Energy ◽  
Methoxy Group ◽  
Energy Gap ◽  
Molecular Structures ◽  
Ortho Position ◽  
Electric Resistance ◽  
Scanning Calorimetry ◽  
Energy Applications ◽  
Terminal Chain

New asymmetrical Schiff base series based on lateral methoxy group in a central core, (E)-3-methoxy-4-(((4-methoxyphenyl)imino)methyl)phenyl 4-alkoxybenzoate (An), were synthesized and their optical and mesomorphic characteristics were investigated. The lateral OCH3group was inserted in the central ring in ortho position with respect to the azomethine linkage. FT-IR, and NMR spectroscopy as well as elemental analyses were used to elucidate their molecular structures. Their mesomorphic behaviors were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). These examinations indicated that all the designed series were monomorphic and possessed nematic (N) mesophase enantiotropically, except A12 derivative which exhibited monotropic N phase. A comparative study was made between the present investigated series (An) and their corresponding isomers (Bn). The results revealed that the kind and stability of the mesophase as well as its temperature range are affected by the location and special orientation of the lateral methoxy group electric-resistance, conductance, energy-gap, and Urbach-energy were also reported for the present investigated An series. These results revealed that all electrodes exhibit Ohmic properties and electric-resistances in the GΩ range, whereas the electric resistance was decreased from 221.04 to 44.83 GΩ by lengthening the terminal alkoxy-chain to n = 12. The band gap of the An series was reduced from 3.43 to 2.89 eV by increasing the terminal chain length from n = 6 to n = 12 carbons. Therefore, controlling the length of the terminal chain can be used to improve the An series’ electric conductivity and optical absorption, making it suitable for solar energy applications.

scholarly journals Surface Properties of Poly(Hydroxyurethane)s Based on Five-Membered Bis-Cyclic Carbonate of Diglycidyl Ether of Bisphenol A

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5184
Author(s):  
Mariusz Tryznowski ◽  
Zuzanna Żołek-Tryznowska
Keyword(s):  
Bisphenol A ◽  
Surface Properties ◽  
Rheological Characteristic ◽  
13C Nmr Spectroscopy ◽  
Cyclic Carbonate ◽  
Contact Angles ◽  
Diglycidyl Ether ◽  
Scanning Calorimetry ◽  
Static Contact ◽  
Ft Ir

Poly(hydroxyurethane)s (PHU) are alternatives for conventional polyurethanes due to the use of bis-cyclic dicarbonates and diamines instead of harmful and toxic isocyanates. However, the surface properties of poly(hydroxyurethane)s are not well known. In this work, we focus on the analysis of the surface properties of poly(hydroxyurethane) coatings. Poly(hydroxyurethane)s were obtained by a catalyst-free method from commercially available carbonated diglycidyl ether of bisphenol A (Epidian 6 epoxy resins) and various diamines: ethylenediamine, trimethylenediamine, putrescine, hexamethylenediamine, 2,2,4(2,4,4)-trimethyl-1,6-hexanediamine, m-xylylenediamine, 1,8-diamino-3,6-dioxaoctane, 4,7,10-trioxa-1,13-tridecanediamine, and isophorone diamine, using a non-isocyanate route. The structures of the obtained polymers were confirmed by FT-IR, 1H NMR and 13C NMR spectroscopy, and thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses were performed. The rheological characteristic of the obtained polymers is presented. The static contact angles of water, diidomethane, and formamide, deposited on PHU coatings, were measured. From the measured contact angles, the surface free energy was calculated using two different approaches: Owens–Wendt and van Oss–Chaudhury–Good. Moreover, the wetting envelopes of PHU coatings were plotted, which enables the prediction of the wetting effect of various solvents. The results show that in the investigated coatings, a mainly dispersive interaction occurs.

scholarly journals New Nitro-Laterally Substituted Azomethine Derivatives; Synthesis, Mesomorphic and Computational Characterizations

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1927
Author(s):  
Mohamed A. El-atawy ◽  
Magdi M. Naoum ◽  
Salma A. Al-Zahrani ◽  
Hoda A. Ahmed
Keyword(s):  
Experimental Data ◽  
Molecular Geometry ◽  
Alkoxy Group ◽  
Molecular Structures ◽  
The Other ◽  
Molecular Architecture ◽  
Scanning Calorimetry ◽  
Elemental Analyses ◽  
Ft Ir ◽  
Chain Lengths

Two new homologues series, based on two rings of the azomethine central group bearing the terminal alkoxy group of various chain lengths, were prepared. The alkoxy chain length varied between 6 and 16 carbons. The other terminal wing in the first series was the F atom, and the compound is named N-4-florobenzylidene-4-(alkoxy)benzenamine (In). The second group of compounds included a lateral NO2 substituent in addition to the terminal F atom, named N-(4-fluoro-3-nitrobenzylidene)-4-(alkyloxy)aniline (IIn). Mesomorphic and optical properties were carried out via differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Elemental analyses, FT-IR, and NMR spectroscopy were carried out to elucidate the molecular structures of the synthesized groups. Mesomorphic investigations indicated that all the synthesized homologues (In) were monomorphic, possessing the smectic A (SmA) phase monotropically, while the second group (IIn) members were non-mesomorphic. The experimental data indicated that the formation of the mesophase is affected by the protrusion of the lateral nitro group. The disruption of the mesophase in the second group was attributed to the increase of its molecular width, which affects its lateral intermolecular interactions. The computational simulations were in agreement with the experimental data. On the other hand, the location of NO2 group within the molecular geometry increased the melting temperature of the molecule, and thus, affected their thermal and physical properties. By discussing the estimated parameters, it was found that the molecular architecture, the dipole moment, and the polarizability of the investigated compounds are highly affected by the electronic nature and position of the terminal and lateral substituents as well as their volumes.

scholarly journals Induced Nematic Phase of New Synthesized Laterally Fluorinated Azo/Ester Derivatives

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4546
Author(s):  
Fowzia S. Alamro ◽  
Hoda A. Ahmed ◽  
Mohamed A. El-Atawy ◽  
Salma A. Al-Zahrani ◽  
Alaa Z. Omar
Keyword(s):  
Theoretical Data ◽  
Molecular Structures ◽  
Scanning Calorimetry ◽  
Polar Groups ◽  
Ir And Nmr Spectroscopy ◽  
Terminal Substituent ◽  
Computational Calculations ◽  
Elemental Analyses ◽  
Ft Ir ◽  
Polar Substituents

A new series of laterally fluorinated mesomorphic compounds, namely 2-fluoro-4-((4-(alkyloxy)phenyl)diazenyl)phenyl 4-substitutedbenzoate (Inx) were prepared and evaluated for their mesophase behavior. The synthesized series constitutes five members that possess different terminally attached polar groups (X). Their molecular structures were confirmed by elemental analyses and both FT-IR and NMR spectroscopy. Examination of the prepared derivatives was conducted via experimental and theoretical tools. Mesomorphic investigations were carried by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). DSC and POM measurements indicated that except for the un-substituted analogue, all other derivatives were purely nematogenic, possessing their nematic (N) mesophase enantiotropically. This is to say that insertions of terminal polar substituents on their mesogenic structures induced the N phase. In addition, the location of lateral and terminal polar moieties played a considerable role in achieving good thermal N stability. Computational calculations were investigated to determine the deduced optimized molecular structures. Theoretical data indicated that both size and polarity of the terminal substituent (X) have essential impact on the thermal parameters and optical properties of possible geometries.

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.

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