scholarly journals Polar Alkoxy Group and Pyridyl Effects on the Mesomorphic Behavior of New Non-Symmetrical Schiff Base Liquid Crystals

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1832
Author(s):  
Sayed Z. Mohammady ◽  
Daifallah M. Aldhayan ◽  
Mohammed A. Alshammri ◽  
Ayoub K. Alshammari ◽  
Mohammed Alazmi ◽  
...  
Keyword(s):  
Schiff Base ◽  
Liquid Crystals ◽  
Chain Length ◽  
Density Functional ◽  
Theoretical Calculations ◽  
13C Nmr Spectroscopy ◽  
Alkoxy Group ◽  
Thermal Stabilities ◽  
New Compounds ◽  
Base Liquid

A series of non-symmetrical Schiff base liquid crystals were prepared and investigated. Schiff bases of p-alkyloxy aniline derivatives and 4-phenyl pyridine-4′-carbaldehyde were synthesized. The terminal alkoxy groups substituting aniline are of varied chain length, namely C6, C8, and C16. The structures of the compounds were confirmed via 1H NMR and 13C NMR spectroscopy. Different mesophases of the samples were thermally and optically characterized by differential thermal analysis (DSC) and polarized optical microscopy (POM). All samples revealed enantiotropic smectic B (SmB) and smectic A (SmA) mesophases. The results obtained were further correlated with the density functional theory (DFT) theoretical calculations. The results are compared to a series of compounds bearing biphenyl moiety in their mesogens. The thermal stabilities of the different mesophase reduced upon the increment of the alkoxy chain length. The temperature ranges of both the smectic mesophases of new compounds bearing the 4-phenyl pyridine moiety are generally expanded higher than the other series. In addition, the total mesophase range is greater in the new compounds when compared to their biphenyl analogues. The DFT results were investigated in terms of the molecular geometries and the frontier molecular orbitals as well as the charge distribution mapping to show and illustrate the difference in the mesomorphic properties.

scholarly journals Mesomorphic Behaviour and DFT Insight of Arylidene Schiff Base Liquid Crystals and Their Pyridine Impact Investigation

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 978
Author(s):  
Mohamed A. Zakaria ◽  
Mohammed Alazmi ◽  
Kanubhai D. Katariya ◽  
Yeldez El Kilany ◽  
El Sayed H. El Ashry ◽  
...  
Keyword(s):  
Schiff Base ◽  
Chain Length ◽  
Schiff Bases ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Strong Impact ◽  
Polarization Optical Microscopy ◽  
Thermal Stabilities ◽  
New Compounds ◽  
Base Liquid

A new series of Schiff base liquid crystal have been prepared and studied. Schiff bases of p-alkyl aniline derivatives and 4-phenyl pyridine-4′-carbaldehyde were prepared. The terminal alkyl groups substituting aniline are of varied chain length, namely C8, C12 and C14. The structures of the compounds were elucidated by 1H NMR and 13C NMR. The mesomorphic thermal and optical characteristics of the samples were determined via differential thermal analysis (DSC) and polarization optical microscopy (POM). All compounds exhibit enantiotropic dimorphic mesophase behaviour, referred to as smectic X1 (SmX1) and smectic X2 (Sm A). Experimental results obtained for the mesophases were correlated with density functional theory (DFT) theoretical calculations. The results of the new series are further compared to two series of compounds bearing pyridine (two ring Schiff bases) and biphenyl, respectively, in their mesogens. The series of compounds of one pyridine ring are generally not mesomorphic. The results indicate that the alkyl chain length has a strong impact on the mesomorphic characteristics and thermal stabilities of the different mesophases. As a trend, the temperature ranges of both of smectic mesophases of all compounds are higher in new compounds bearing the 4-phenyl pyridine moiety. In addition, the total mesophase range is generally higher in the new compounds when compared to their biphenyl analogues. Finally, theoretical DFT calculations were performed to illustrate the experimental finding of the mesomorphic behaviour in terms of the molecular geometry and aromaticity, π–π stacking and LOL-π.

scholarly journals Schiff Base liquid Crystals with Terminal Alkoxy Group Synthesis and Thermotropic Properties

2017 ◽  
Vol 17 (2) ◽  
pp. 64-72 ◽  
Author(s):  
Nasreen R. Jber ◽  
◽  
Mohammad M. Shukur ◽  
Ahmed A. Najaf ◽  
◽  
...  
Keyword(s):  
Schiff Base ◽  
Liquid Crystals ◽  
Alkoxy Group ◽  
Thermotropic Properties ◽  
Base Liquid

scholarly journals Synthesis, Optical, and Geometrical Approaches of New Natural Fatty Acids’ Esters/Schiff Base Liquid Crystals

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4293 ◽  
Author(s):  
Alnoman ◽  
Al-Nazawi ◽  
Ahmed ◽  
Hagar
Keyword(s):  
Fatty Acids ◽  
Schiff Base ◽  
Liquid Crystals ◽  
Density Functional ◽  
Optical Transition ◽  
Molecular Structures ◽  
Frontier Molecular Orbital ◽  
Computational Calculations ◽  
Base Liquid ◽  
Methyl Phenyl

Schiff base liquid crystals, known as [4-(hexyloxy)phenylimino)methyl]phenyl palmitate (IA), [4-(hexyloxy)phenylimino)methyl]phenyl oleate (IIA) and [4-(hexyloxy)phenylimino)methyl]phenyl linoleate (IIIA), were synthesized from palmitic, oleic, and linoleic natural fatty acids. The prepared compounds have been investigated for their thermal and optical behavior as well as phase formation using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Molecular structures of all studied compounds were confirmed via elemental analysis, FT-IR, 1H NMR, and 13C NMR. Smectic phase is the observed mesophase for all compounds; however, their type and range depend upon the terminal alkanoate chains attached to the phenyl ring. Computational calculations, Density functional theory (DFT), energy difference of the frontier molecular orbital (FMOs), as well as the thermodynamic parameters of different molecular configurations isomers were discussed. It was found that the mesophase behavior and the geometrical characteristics were affected by the degree of unsaturation of fatty terminal chains. Furthermore, the geometrical structure of the CH=N linkage plays an important role in the thermal stability and optical transition temperature.

Structure and molecular packing in smectic BCr and Ad phases of Schiff base liquid crystal compounds through the analyses of layer spacing, entropy and crystal structure

2017 ◽  
Vol 19 (29) ◽  
pp. 19434-19441 ◽  
Author(s):  
Yasuhisa Yamamura ◽  
Takahito Murakoshi ◽  
Sakiko Iwagaki ◽  
Natalia Osiecka ◽  
Hideki Saitoh ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Schiff Base ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Chain Length ◽  
Molecular Packing ◽  
Smectic Liquid Crystals ◽  
Layer Spacing ◽  
Alkyl Chains ◽  
Base Liquid

Chain-length dependence of layer spacing reveals the packing of molten alkyl chains in smectic liquid crystals.

New two rings Schiff base liquid crystals; ball mill synthesis, mesomorphic, Hammett and DFT studies

2020 ◽  
Vol 299 ◽  
pp. 112161 ◽  
Author(s):  
Sherif S. Nafee ◽  
Mohamed Hagar ◽  
Hoda A. Ahmed ◽  
O.A. Alhaddad ◽  
Reda M. El-Shishtawy ◽  
...  
Keyword(s):  
Schiff Base ◽  
Liquid Crystals ◽  
Ball Mill ◽  
Dft Studies ◽  
Base Liquid

scholarly journals New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches

RSC Advances ◽  
2020 ◽  
Vol 10 (16) ◽  
pp. 9643-9656 ◽  
Author(s):  
Nagwa H. S. Ahmed ◽  
Gamal R. Saad ◽  
Hoda. A. Ahmed ◽  
Mohamed Hagar
Keyword(s):  
Schiff Base ◽  
Liquid Crystals ◽  
Base Liquid ◽  
Dsc Thermograms

DSC thermograms of some prepared compounds: (a) recorded from second heating and (b) from cooling at a rate of ±10 °C min−1.

Influence of meta-extended rigid-core, complementary hydrogen bonding and flexible chain on polymorphism in Schiff-base liquid crystals: (4)MeOBD(3)AmBA:nOBAs

2019 ◽  
Vol 47 (4) ◽  
pp. 582-603
Author(s):  
AVSN Krishna Murthy ◽  
M. Srinivasulu ◽  
AVN Ashok Kumar ◽  
YV Rao ◽  
DM Potukuchi
Keyword(s):  
Hydrogen Bonding ◽  
Schiff Base ◽  
Liquid Crystals ◽  
Rigid Core ◽  
Flexible Chain ◽  
Base Liquid

scholarly journals Role of Pyridine Nitrogen in Palladium-Catalyzed Imine Hydrolysis: A Case Study of (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2609 ◽  
Author(s):  
Ahmad ◽  
Rasool ◽  
Rizwan ◽  
Altaf ◽  
Rashid ◽  
...  
Keyword(s):  
Schiff Base ◽  
Transition Metal ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Coupling Reaction ◽  
Suzuki Coupling Reaction ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Hydrolysis Of ◽  
Insight Into

In the present study, 4-methylpyridin-2-amine was reacted with 3-bromothiophene-2-carbaldehyde and the Schiff base (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine was obtained in a 79% yield. Coupling of the Schiff base with aryl/het-aryl boronic acids under Suzuki coupling reaction conditions, using Pd(PPh3)4 as catalyst, yielded products with the hydrolysis of the imine linkages (5a–5k, 6a–6h) in good to moderate yields. To gain mechanistic insight into the transition metal-catalyzed hydrolysis of the compounds, density functional theory (DFT) calculations were performed. The theoretical calculations strongly supported the experiment and provided an insight into the transition metal-catalyzed hydrolysis of imines.

SF5-Terminated Fluorinated Schiff Base Liquid Crystals

2004 ◽  
Vol 108 (52) ◽  
pp. 19940-19948 ◽  
Author(s):  
Jeremy A. Smith ◽  
Robert A. DiStasio ◽  
Nicole A. Hannah ◽  
Rolf W. Winter ◽  
Timothy J. R. Weakley ◽  
...  
Keyword(s):  
Schiff Base ◽  
Liquid Crystals ◽  
Base Liquid
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