The Synthesis of New Thermal Stable Schiff Base/Ester Liquid Crystals: A Computational, Mesomorphic, and Optical Study

Abstract

A Schiff base supramolecular 4-[(4-(hexyloxy)phenylimino)methyl]benzoic acid and a new series of Schiff base/ester linkages named 4-substitutedphenyl 4-[(4-(hexyloxy)phenylimino)methyl]benzoate liquid crystals were synthesized. The thermal stability, mesomorphic, and optical behavior of the prepared compounds were characterized by differential scanning calorimetry (DSC), Thermogravemetric analysis (TGA), polarized optical microscopy (POM), and UV spectroscopy. FT-IR, 1H-NMR, 13C-NMR, and elemental analyses were carried out to elucidate and confirm the molecular structures of the synthesized compounds. The investigated series comprising different sized terminal polar groups changed between CH(CH3)2, H, I, and F. It was found that the supramolecular imino acid dimer is enantiotropic dimorphic, with a wide SmA phase and a good N phase range. The other series of terminally substituted Schiff base/esters are mesomorphic with a high thermal stable SmA phase, except the iodo derivative, which showed dimorphic SmA and N phases. The effect of the position and the orientation of the cores, as well as the terminal substituent of the type and the stability of the mesophase, were studied. A computational theoretical study of the effects of the van der Waal’s volume, the Hammett substituent coefficient, the inductive sigma constant, and other geometrical parameters were discussed. The study revealed that the planarity of the two phenyl rings attached with an imino linking group impacted the resonance effect of the terminal substituents rather than their inductive effect. A detailed study on the effect of the estimated thermal parameters, as well as their geometrical planarity with the type and stability of the formed mesophase, was discussed.

Chair- and V-Shaped of H-bonded Supramolecular Complexes of Azophenyl Nicotinate Derivatives; Mesomorphic and DFT Molecular Geometry Aspects

“…Recently, azopyridine has been used in the formation of nano-fiber supramolecular self-assembling and hydrogen/halogen-bonding LCs with photo-induced transition phenomena [11][12][13][14][15][16][17]. They are particularly interesting due to their ability for trans-cis photo-isomerization molecular geometries upon irradiation with UV light [18]. In addition, the incorporation of the azobenzene moiety into the geometrical structure of liquid crystalline materials resulted in photo-switchable applications [2,19].…”

“…Finally, a comparison is made between the present complexes and our previously reported Schiff base analogues to demonstrate briefly experimentally and theoretically in terms of the effect of the mesogen on the geometry as well as thermal parameters. for trans-cis photo-isomerization molecular geometries upon irradiation with UV light [18]. In addition, the incorporation of the azobenzene moiety into the geometrical structure of liquid crystalline materials resulted in photo-switchable applications [2,19].…”

“…The prepared complexes I/An 2Preparation of 4-(4-(Hexyloxy)phenylazo)methyl)phenyl Nicotinate[18,56].…”

Design, Molecular Modeling and Synthesis of Metal-Free Sensitizers of Thieno Pyridine Dyes as Light-Harvesting Materials with Efficiency Improvement Using Plasmonic Nanoparticles

“…Computational modeling study has also been performed in order to predict the reactive sites of the dyes' molecules and their ability to serve in the field of solar cell applications. Density functional theory (DFT) method exhibits outstanding explanation of the structural, spectral and electronic properties of the studied molecules [17][18][19]. The B3LYP calculation functional method has been chosen to predict the energetic, electronic and spectral properties for many molecules in high precision [20][21][22].…”

New Symmetrical U- and Wavy-Shaped Supramolecular H-Bonded Systems; Geometrical and Mesomorphic Approaches

“…Recently, density functional theory (DFT) has become an effective tool due to its excellent performance and consistent results with respect to experimental evidence. Furthermore, the molecular geometries and thermal parameters, such as the dipole moment, polarizability, and energy difference between the molecular orbitals of the compound are interesting investigations [5,[45][46][47][48][49][50][51][52][53][54].The goal of our present work is to design new structural seven-ring 2:1 supramolecular H-bonded complexes, as well as to conduct a theoretical (DFT) and experimental investigation on the effect of the possible geometrical orientations of prepared binary mixtures. Moreover, our goal is to analyze their mesomorphic, optical, and photophysical properties and correlate the evaluated variables with the predicted geometrical parameters.…”