scholarly journals Thermal and Photophysical Studies of Binary Mixtures of Liquid Crystal with Different Geometrical Mesogens

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 223 ◽  
Author(s):  
Omaima A. Alhaddad ◽  
Hoda A. Ahmed ◽  
Mohamed Hagar ◽  
Gamal R. Saad ◽  
Khulood A. Abu Al-Ola ◽  
...  
Keyword(s):  
Binary Mixtures ◽  
Density Functional ◽  
Binary Systems ◽  
Uv Spectroscopy ◽  
Twist Angle ◽  
Optical Microscope ◽  
Geometrical Parameters ◽  
Scanning Calorimetry ◽  
Photophysical Studies ◽  
The Individual

Three binary systems were prepared by mixing of two different mesogenic derivatives, homologues, the first is azo/ester, namely 4-alkoxyphenylazo-4′-phenyl-4″-alkoxybenzoates (IIn+m) and the second is Schiff base/ester, namely 4-(arylideneamino)phenyl-4″-alkoxy benzoates (In+m). The two corresponding analogues from both series in the binary mixtures investigated are of the same terminal alkoxy chain length. Mesomorphic properties were investigated by differential scanning calorimetry (DSC) and phases identified by polarized optical microscope (POM). Photophysical studies were investigated by UV spectroscopy connected to a hot stage. Results were discussed based on constructed binary phase diagrams. All mixtures were found to exhibit eutectic compositions, with linear or slightly linear nematic and smectic A stability/composition dependences. Geometrical parameters were predicted applying density functional theory (DFT) calculations. Twist angle (θ), aspect ratio, dipole moment and the polarizability of the individual compounds were discussed and correlated with the experimental results to illustrate the enhanced the mesophase stability and the mesophase range of the mixture at the eutectic composition compared with those of their individual components.

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

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 319 ◽  
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.

scholarly journals Characterization of New H-Bonded Liquid Crystalline Complexes Based on Iminophenyl Nicotinate

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 499 ◽  
Author(s):  
Rua B. Alnoman ◽  
Mohamed Hagar ◽  
Hoda A. Ahmed ◽  
Khulood A. Abu Al-Ola ◽  
Magdi M. Naoum ◽  
...  
Keyword(s):  
Terephthalic Acid ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Uv Spectroscopy ◽  
Isophthalic Acid ◽  
Geometrical Parameters ◽  
Scanning Calorimetry ◽  
Acid Complex ◽  
Smectic A

Two new 1:2 supramolecular H-bonded liquid crystalline complexes (SMHBCs) were prepared through double H-bond interactions between either isophthalic acid (A) or terephthalic acid (B) and a nicotinate Schiff base (I6). The formed complexes were thermally investigated by differential scanning calorimetry (DSC), and their phases were identified by polarized optical microscopy (POM) and UV-spectroscopy. The formation of 1:2 hydrogen-bonded complexes was confirmed through their Fermi-bands observed by FT-IR spectroscopy. The first system (I6/A) was found to possess enantiotropic smectic A and nematic mesophases. Induced broad range of smectic A phase was observed in I6/A complex which is not shown by their individual components. The second complex system (I6/B) was purely nematogenic. Density functional theory (DFT) calculations were applied to predict their geometrical parameters. Theoretical studies revealed that the isophthalic complex adopted the W-shape; while the U-shape was adopted by the terephthalic acid complex (I6/B). The linear geometry of the complex based on the isophthalic acid enhanced the mesomorphic behavior observed by the terephthalic complex; I6/B. Actually; the orientation of the two carboxylic groups was shown to highly affect the softness of the derived complex. On the other hand; the mapping orientation of the charge distribution can be used to explain the mesophase behavior. The photophysical characterization of isophthalic complex (I6/A) is also discussed

scholarly journals Powder properties of binary mixtures of chloroquine phosphate with lactose and dicalcium phosphate

2010 ◽  
Vol 46 (3) ◽  
pp. 531-537
Author(s):  
Michael Ayodele Odeniyi ◽  
Collins Chidi Onyenaka ◽  
Oludele Adelanwa Itiola
Keyword(s):  
Binary Mixtures ◽  
Internal Flow ◽  
Optical Microscope ◽  
Volume Reduction ◽  
Dicalcium Phosphate ◽  
Flow Properties ◽  
Maximum Volume ◽  
Cohesive Properties ◽  
Particle Size And Shape ◽  
The Individual

A study was conducted on the packing and cohesive properties of chloroquine phosphate in binary mixtures with lactose and dicalcium phosphate powders. The maximum volume reduction due to packing as expressed by the Kawakita constant, a, and the angle of internal flow, θ, were the assessment parameters. The individual powders were characterized for their particle size and shape using an optical microscope. Binary mixtures of various proportions of chloroquine phosphate with lactose and dicalcium phosphate powders were prepared. The bulk and tapped densities, angles of repose and internal flow, as well as compressibility index of the materials were determined using appropriate parameters. The calculated and determined values of maximum volume reduction for the binary mixtures were found to differ significantly (P< 0.05), with the Kawakita plot being more reliable in determining the packing properties. Diluent type was found to influence the flow properties of the mixtures, with dicalcium phosphate giving predictable results while mixtures containing lactose were anomalous with respect to flow. The characterization of the packing and cohesive properties of the binary mixtures of chloroquine with lactose and dicalcium phosphate would be useful in the production of powders, tablets, capsules and other drug delivery systems containing these powders with desirable and predictable flow properties.

scholarly journals Electrical Conductivities and Interactions in Binary Mixtures of Imidazolium-Based Ionic Liquids with Acetonitrile and Dimethyl Sulfoxide

2020 ◽  
Vol 71 (2) ◽  
pp. 392-402
Author(s):  
Oana Ciocirlan ◽  
Amalia Stefaniu
Keyword(s):  
Electrical Conductivity ◽  
Ionic Liquids ◽  
Dimethyl Sulfoxide ◽  
Binary Mixtures ◽  
Density Functional ◽  
Binary Systems ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Electrical Conductivities ◽  
Anion Type

This paper reports experimental electrical conductivities data of eight binary systems of four ionic liquids: 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4], 1-hexyl-3-methylimidazolium tetrafluoroborate, [Hmim][BF4], 1-butyl-3-methylimidazolium hexafluorophosphate, [Bmim][PF6] and 1-butyl-2,3-dimethyl-imidazolium tetrafluoroborate, [Bmmim][BF4] with the organic solvents dimethyl sulfoxide (DMSO) and acetonitrile (ACN) at atmospheric pressure and temperatures from 298.15 to 328.15 K. It was found that conductivities in the investigated ionic liquids follow the order: [Bmim][BF4] ] [Bmim][PF6] ][Bmmim][BF4] ] [Hmim][BF4]. Experimental results demonstrate that the binary mixtures possess higher electrical conductivity compared with pure components. Electrical conductivity data were correlated using Casteel�Amis and Arrhenius equations. The molar conductivity was derived from experimental data and fitted to Walden rule. The influence of the cation structure and anion type on the conductivity was discussed, which help understanding the intermolecular interactions in the binary systems. A deeper understanding of the transport behavior of ILs is given by means of density functional theory calculations (DFT)

Effect of the Compatibility of Rubbers on the Viscous Flow Properties of Their Binary Mixtures

1973 ◽  
Vol 46 (5) ◽  
pp. 1188-1192 ◽  
Author(s):  
G. S. Kongarov ◽  
G. M. Bartenev
Keyword(s):  
Strain Rate ◽  
Viscous Flow ◽  
Binary Mixtures ◽  
Binary Systems ◽  
Flow Properties ◽  
Entrance Effect ◽  
The Individual

Abstract The viscosity of binary systems of incompatible polymers is lower than that of the individual rubbers. In the case of compatible polymers, the viscosity of the systems changes additively with its composition or may increase somewhat. The degree of compatibility of the polymers affects the size of the entrance effect and the character of its dependence on strain rate.

Binary Mixtures of Hydrogen-Bonded Ferroelectric Liquid Crystals: Thermal Span Enhancement in Smectic X* Phase

2015 ◽  
Vol 70 (9) ◽  
pp. 757-774 ◽  
Author(s):  
Gopal Sangameswari ◽  
Nataraj Pongali Sathya Prabu ◽  
Mathukumalli Lakshmi Narayana Madhu Mohan
Keyword(s):  
Binary Mixtures ◽  
Thermal Equilibrium ◽  
Optical Microscope ◽  
Stability Factor ◽  
Benzoic Acids ◽  
Scanning Calorimetry ◽  
Ferroelectric Liquid Crystals ◽  
Binary Liquid ◽  
Smectic C ◽  
Hydrogen Bonded

AbstractThermotropic hydrogen-bonded ferroelectric binary liquid crystal mixtures comprising of N-carbamyl-l-glutamic acid (CGA) and p-n-alkyloxy benzoic acids (BAO) are investigated. Variation in the molar proportion of X and Y (where X=CGA+5BAO and Y=CGA+9BAO, CGA+10BAO, CGA+11BAO, and CGA+12BAO) comprising of four series yielded 36 binary mixtures. Optical and thermal properties of these mixtures are meticulously studied in the present article. In addition to the traditional phases, a novel smectic ordering namely smectic X* is observed in all the four series. The aim of the investigation is to obtain abundance occurrence of smectic X* with a large thermal span, and hence, the proportions of the binary mixtures are so chosen that the prelude task is accomplished. Optical tilt angle in smectic X* and smectic C* phases is experimentally determined, and a theoretical fit is performed. Phase diagrams of the four series are constructed from the data obtained from the differential scanning calorimetry and correlated with the phases recorded by the polarising optical microscope studies. Thermal stability factor and thermal equilibrium are also premeditated.

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.

Observation of Induced Luminescence and Thermochromism in Achiral Hydrogen Bonded Liquid Crystal Complexes

2020 ◽  
Vol 234 (10) ◽  
pp. 1709-1733
Author(s):  
A. Ramya ◽  
V. Balasubramanian ◽  
R. Jayaprakasam ◽  
V. N. Vijayakumar
Keyword(s):  
Liquid Crystal ◽  
Nematic Phase ◽  
Density Functional ◽  
Atomic Charge ◽  
Optical Microscope ◽  
Band Gap Energy ◽  
Stability Factor ◽  
Scanning Calorimetry ◽  
Interesting Phenomenon ◽  
Hydrogen Bonded

AbstractA novel hydrogen bonded liquid crystal (HBLC) complexes are obtained from the non-mesogenic (benzylmalonic acid) and mesogenic (p-n-alkyloxybenzoic acid, where n = 6, 7 and 8) compound via intermolecular hydrogen bonds (H-bond). H-bonds are experimentally confirmed by the Fourier transform infrared spectroscopic (FT-IR) studies and the same is validated using density functional theory (DFT). Induced thermochromism is observed by the polarizing optical microscope (POM) and its possible applications are reported. Phase transition temperature and their analogous enthalpy values, stability factor and span width are determined by the differential scanning calorimetry (DSC) studies. Band gap energy is calculated using UV-visible and photoluminescence spectrum. Hyper conjugative stabilization energy and atomic charge distribution is studied by the natural bond orbital (NBO) studies. Mulliken analysis clearly reveals the intermolecular interaction and steric effect of the HBLC complexes. An interesting phenomenon is that the observation of luminescence and thermochromism in the highly fluidity nematic phase. This peculiar behavior is attributed due to the intermolecular H-bonding interaction between the BMA and nOBA compounds and the effect of rotatory motion of the molecules in nematic phase. Luminescence increases when the spacer moiety decreases in the present complexes is also reported. In nematic phase, the molecules are in different degrees of the excited state which is correlated with the hyper conjugative energy through NBO studies.

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

Materials ◽  
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.

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

Molecules ◽  
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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