Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

A new liquid crystalline, optical material-based Schiff base core with a near to room-temperature mesophase, (4-methoxybenzylideneamino)phenyl oleate (I), was prepared from a natural fatty acid derivative, and its physical and chemical properties investigated by experimental and theoretical approaches. The molecular structure was confirmed by elemental analysis, FT-IR (Fourier-Transform-Infrared Spectroscopy) and NMR (nuclear magnetic resonance) spectroscopy. Optical and mesomorphic activities were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results show that compound (I) exhibits an enantiotropic monomorphic phase comprising a smectic A phase within the near to room-temperature range. Ordinary and extraordinary refractive indices as well as birefringence with changeable temperatures were analyzed. Microscopic and macroscopic order parameters were also calculated. Theoretical density functional theory (DFT) calculations were carried out to estimate the geometrical molecular structures of the prepared compounds, and the DFT results were used to illustrate the mesomorphic results and optical characteristics in terms of their predicted data. Three geometrical isomers of the prepared compound were investigated to predict the most stable isomer. Many parameters were affected by the geometrical isomerism such as aspect ratio, planarity, and dipole moment. Thermal parameters of the theoretical calculations revealed that the highest co-planar aromatic core is the most stable conformer.

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

Molecules ◽

10.3390/molecules25020365 ◽

2020 ◽

Vol 25 (2) ◽

pp. 365 ◽

Cited By ~ 15

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.

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NEW ELASTOMERIC MATERIALS FROM BIOMASS: STEREOSELECTIVE POLYMERIZATION OF LINEAR TERPENES AND THEIR COPOLYMERIZATION WITH BUTADIENE BY USING A COBALT COMPLEX WITH PHOSPHANE LIGANDS

Rubber Chemistry and Technology ◽

10.5254/rct.20.79972 ◽

2020 ◽

Vol 93 (4) ◽

pp. 605-614

Author(s):

David Hermann Lamparelli ◽

Veronica Paradiso ◽

Carmine Capacchione

Keyword(s):

Room Temperature ◽

Cobalt Complex ◽

Size Exclusion ◽

Resonance Spectroscopy ◽

New Materials ◽

Scanning Calorimetry ◽

Wide Range ◽

Elastomeric Materials ◽

Exclusion Chromatography ◽

Stereoregular Polymers

ABSTRACT The polymerization of bio-renewable terpenes such as β-ocimene (O), β-myrcene (M), and β-farnesene (F) promoted by CoCl2(PCyPh2)2 (1) in combination with modified methylalumoxane at room temperature is reported. Stereoregular polymers of O, M, and F were obtained. 1 also promoted, showing good stereoselectivity, the copolymerization of O and M with butadiene (B) in a wide range of compositions by suitably varying the alimentation feed: up to 67 and 75 mol% of O and M incorporated for poly(ocimene-butadiene) and poly(myrcene-butadiene) copolymers, respectively. These new materials with elastomeric properties (glass transition temperatures observed in the range of −5.7 to −72.5 °C) were fully characterized by differential scanning calorimetry, size exclusion chromatography, and nuclear magnetic resonance spectroscopy (1H, 13C, and two-dimensional experiments).

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Room-temperature quantum interference in single perovskite quantum dot junctions

Nature Communications ◽

10.1038/s41467-019-13389-7 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 4

Author(s):

Haining Zheng ◽

Songjun Hou ◽

Chenguang Xin ◽

Qingqing Wu ◽

Feng Jiang ◽

...

Keyword(s):

Quantum Interference ◽

Density Functional ◽

Room Temperature ◽

Transport Theory ◽

Theoretical Calculations ◽

Interference Effects ◽

Perovskite Materials ◽

Metal Halide Perovskite ◽

Perovskite Quantum Dots ◽

Quantum Transport Theory

AbstractThe studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge. Herein, we provide the observation of room-temperature quantum interference effects in metal halide perovskite quantum dots (QDs) using the mechanically controllable break junction technique. Single-QD conductance measurements reveal that there are multiple conductance peaks for the CH3NH3PbBr3 and CH3NH3PbBr2.15Cl0.85 QDs, whose displacement distributions match the lattice constant of QDs, suggesting that the gold electrodes slide through different lattice sites of the QD via Au-halogen coupling. We also observe a distinct conductance ‘jump’ at the end of the sliding process, which is further evidence that quantum interference effects dominate charge transport in these single-QD junctions. This conductance ‘jump’ is also confirmed by our theoretical calculations utilizing density functional theory combined with quantum transport theory. Our measurements and theory create a pathway to exploit quantum interference effects in quantum-controlled perovskite materials.

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Defect-Induced Gas-Sensing Properties of a Flexible SnS Sensor under UV Illumination at Room Temperature

Sensors ◽

10.3390/s20195701 ◽

2020 ◽

Vol 20 (19) ◽

pp. 5701

Author(s):

Nguyen Manh Hung ◽

Chuong V. Nguyen ◽

Vinaya Kumar Arepalli ◽

Jeha Kim ◽

Nguyen Duc Chinh ◽

...

Keyword(s):

Density Functional ◽

Room Temperature ◽

Surface Defects ◽

Gas Sensing ◽

Theoretical Calculations ◽

Tin Sulfide ◽

Sensing Properties ◽

Uv Illumination ◽

Gas Sensing Properties ◽

Key Factor

Tin sulfide (SnS) is known for its effective gas-detecting ability at low temperatures. However, the development of a portable and flexible SnS sensor is hindered by its high resistance, low response, and long recovery time. Like other chalcogenides, the electronic and gas-sensing properties of SnS strongly depend on its surface defects. Therefore, understanding the effects of its surface defects on its electronic and gas-sensing properties is a key factor in developing low-temperature SnS gas sensors. Herein, using thin SnS films annealed at different temperatures, we demonstrate that SnS exhibits n-type semiconducting behavior upon the appearance of S vacancies. Furthermore, the presence of S vacancies imparts the n-type SnS sensor with better sensing performance under UV illumination at room temperature (25 °C) than that of a p-type SnS sensor. These results are thoroughly investigated using various experimental analysis techniques and theoretical calculations using density functional theory. In addition, n-type SnS deposited on a polyimide substrate can be used to fabricate high-stability flexible sensors, which can be further developed for real applications.

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Synthetic, Mesomorphic, and DFT Investigations of New Nematogenic Polar Naphthyl Benzoate Ester Derivatives

Materials ◽

10.3390/ma14102587 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2587

Author(s):

Salma A. Al-Zahrani ◽

Hoda A. Ahmed ◽

Mohamed A. El-atawy ◽

Khulood A. Abu Al-Ola ◽

Alaa Z. Omar

Keyword(s):

Density Functional ◽

Energy Gap ◽

Molecular Structures ◽

Experimental Investigations ◽

Geometrical Parameters ◽

Polar Group ◽

Scanning Calorimetry ◽

Structural Shape ◽

Elemental Analyses ◽

Ft Ir

Four new non-symmetrical derivatives based on central naphthalene moiety, 4-((4–(alkoxy)phenyl) diazenyl)naphthalen–1–yl 4–substitutedbenzoate (In/x), were prepared, and their properties were investigated experimentally and theoretically. The synthesized materials bear two wing groups: an alkoxy chain of differing proportionate length (n = 6 and 16 carbons) and one terminal attached to a polar group, X. Their molecular structures were elucidated via elemental analyses and FT-IR and NMR spectroscopy. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were carried out to evaluate their mesomorphic properties. The results of the experimental investigations revealed that all the synthesized analogues possess only an enantiotropic nematic (N) mesophase with a high thermal stability and broad range. Density functional theory (DFT) calculations were in accordance with the experimental investigations and revealed that all prepared materials are to be linear and planar. Moreover, the rigidity of the molecule increased when an extra fused ring was inserted into the center of the structural shape, so its thermal and geometrical parameters were affected. Energy gap predictions confirmed that the I16/c derivative is more reactive than other compounds.

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Binary Liquid Crystal Mixtures Based on Schiff Base Derivatives with Oriented Lateral Substituents

Crystals ◽

10.3390/cryst10040319 ◽

2020 ◽

Vol 10 (4) ◽

pp. 319 ◽

Cited By ~ 3

Author(s):

Rua B. Alnoman ◽

Mohamed Hagar ◽

Hoda A. Ahmed ◽

Magdi M. Naoum ◽

Hanefah A. Sobaih ◽

...

Keyword(s):

Schiff Base ◽

Binary Mixtures ◽

Density Functional ◽

Theoretical Calculations ◽

Geometrical Parameters ◽

Scanning Calorimetry ◽

Functional Theory ◽

Schiff Base Derivatives ◽

Lateral Group ◽

Molecular Stacking

Binary mixtures of the laterally substituted Schiff base/ester derivatives, namely 4-((2- or 3-) substituted phenyl imino methyl) phenyl-4”-alkoxy benzoates, Ia–d, were prepared and mesomorphically studied by differential scanning calorimetry (DSC) and their mesophases identified by polarized optical microscopy (POM). The lateral group (1-naphthyl, 2-F, 2-Br, 3-F in Ia–d, respectively) is attached to different positions of the phenyl Schiff moiety. The mixtures investigated were made from two differently shaped compounds that differ from each other in the polarity, size, orientation, and relative positions of the lateral group. The results revealed that the binary mixture Ia/Ib (bearing the naphthyl and 2-flouro substituents) exhibited the SmA phase, which covered the whole composition range. For the mixtures Ib/Id (2-F and 2-Br), the isomeric lateral F-group in compound Ib distributed the SmA arrangement of Id. In the Ic/Id mixture bearing two positionally and structurally different substituents, the addition of Ic to Id resulted in solid binary mixtures where its behavior may be attributed to the negligible steric effect of the small electronegative fluorine atom compared to the Br atom. Density functional theory (DFT) theoretical calculations were carried out to estimate the geometrical parameters of individual components and to show the effect of these parameters in the mesophase behavior of the binary system, where the higher dipole moment of Id (6 Debye) may be the reason for its high π–π molecular stacking, which influences its mesophase range and stability.

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Synthesis, Mesomorphic and Computational Characterizations of Nematogenic Schiff Base Derivatives in Pure and Mixed State

Molecules ◽

10.3390/molecules26072038 ◽

2021 ◽

Vol 26 (7) ◽

pp. 2038

Author(s):

Laila A. Al-Mutabagani ◽

Latifah A. Alshabanah ◽

Hoda A. Ahmed ◽

Hafsa H. Alalawy ◽

Mayada H. Al alwani

Keyword(s):

Density Functional ◽

Molecular Structures ◽

Geometrical Parameters ◽

Molecular Architecture ◽

Aromatic Rings ◽

Scanning Calorimetry ◽

Binary Phase ◽

Schiff Base Derivatives ◽

Elemental Analyses ◽

Ft Ir

Homolog series based on three aromatic rings bearing terminal alkoxy chain of various lengths named 4-(4-(alkoxy)phenylimino)methyl)phenyl nicotinate (An) were synthesized. The alkoxy-chain length changed between 6, 8 and 16 carbons. 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 prepared derivatives. Mesomorphic results indicated that all the synthesized homologs (An) are monomorphic possessing the nematic (N) phase enantiotropically with wide thermal stability. Computational simulations were measured via density functional theory (DFT) theoretical calculation tool. The estimated thermal and geometrical parameters are in agreement with the experimental data. By discussing the estimated parameters, it was found that the molecular architecture, dipole moment and the polarizability of the investigated compounds are highly affected by the length of the attached terminal flexible chain and the location of the nitrogen atom in the other terminal aromatic ring. Binary phase diagrams of two corresponding homologs with different proportionating terminals were constructed, and their binary phase physical properties were discussed in terms of the temperature range and stability of the N phase.

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

Symmetry ◽

10.3390/sym13071145 ◽

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.

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High-resolution electron spectroscopy and molecular structures of Cu–(2,2′-bipyridine) and Cu-(4,4′-bipyridine)

Canadian Journal of Chemistry ◽

10.1139/cjc-2012-0543 ◽

2013 ◽

Vol 91 (7) ◽

pp. 613-620 ◽

Cited By ~ 1

Author(s):

Xu Wang ◽

Jung Sup Lee ◽

Dong-Sheng Yang

Keyword(s):

Ground State ◽

Metal Binding ◽

Electron Spectroscopy ◽

Density Functional ◽

Copper Complexes ◽

Theoretical Calculations ◽

Molecular Structures ◽

Laser Vaporization ◽

Binding Modes ◽

Mp2 Calculations

Copper complexes of 2,2′-bipyridine (22BIPY) and 4,4′-bipyridine (44BIPY) were prepared in a laser-vaporization supersonic molecular beam source and identified by laser photoionization time-of-flight mass spectrometry. Electronic spectra and molecular structures were studied with pulsed-field ionization zero electron kinetic energy (ZEKE) electron spectroscopy, density functional theory (DFT) and second-order Møller–Plesset perturbation (MP2) calculations, and spectral simulations. Adiabatic ionization energies and metal–ligand and ligand-based vibrational frequencies of Cu–22BIPY and Cu–44BIPY were measured from the ZEKE spectra. Ground electronic states and molecular structures of the two complexes were determined by comparing the spectroscopic measurements with the theoretical calculations. The ground state of Cu–22BIPY ( 2 B1, C2v) has a planar bidentate structure with Cu binding to two nitrogen atoms and two pyridine molecules in the cis configuration. The ground state of Cu–44BIPY ( 2 A, C2) has a monodentate structure with Cu binding to one nitrogen and two pyridines in a twisted configuration. The ionization energy of Cu–22BIPY is considerably lower and its bond energy is much higher than that of Cu–44BIPY. The different ionization and dissociation energies are attributed to the distinct metal binding modes of the two complexes. It has been found that the DFT calculations yield the correct structures for the Cu–22BIPY complex, whereas the MP2 calculations produce the best structures for the Cu–44BIPY complex.

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Preparation and DFT Study for New Three-Ring Supramolecular H-Bonded Induced Liquid Crystal Complexes

Frontiers in Chemistry ◽

10.3389/fchem.2021.679528 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sayed Z. Mohammady ◽

Daifallah M. Aldhayan ◽

Mohamed Hagar

Keyword(s):

Liquid Crystal ◽

Density Functional ◽

Theoretical Calculations ◽

Compact Groups ◽

Scanning Calorimetry ◽

Thermal Stabilities ◽

Functional Theory ◽

Enthalpy Changes ◽

Bonding Interaction ◽

Chain Lengths

Supramolecular three-ring Schiff base novel liquid crystal complexes have been prepared and investigated. Schiff bases of para-substituted aniline derivatives and para-pyridine carbaldehyde have been prepared and then mixed in equimolar quantities with para-alkoxy benzoic acids. On one side, the alkoxy chain length varies from 8 to 16 carbon atoms. On the other side, terminal small compact groups substituting aniline with various polarities are used. Hydrogen-bonding interaction was elucidated by FTIR spectroscopy. The mesomorphic thermal and optical characteristics of the samples were obtained by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). All samples exhibit enantiotropic mesophases. Experimental results obtained for the induced mesophases were correlated with density functional theory (DFT) theoretical calculations. The results revealed that both the polar compact groups’ polarity and the alkoxy chain lengths contribute strongly to mesomorphic characteristics and thermal stabilities of the mesophases. Surprisingly, the observed values of enthalpy changes associated with the crystalline mesomorphic transitions lie in the range of 2.2–12.5 kJ/mol. However, the enthalpy changes corresponding to the mesomorphic–isotropic transitions vary from 0.9 to 13.9 kJ/mol, depending on the polarity of para-attached groups to the aniline moiety.

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