Synthesis, characterization and mesomorphic properties of new unsymmetrical azomethine-type liquid crystals derived from 4-biphenyl carboxaldehyde (original) (raw)
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Acta chimica Slovenica, 2020
This study examines the effects of substituents and hydrogen bonding, orientations of imine linkage on the behavior of benzylidene aniline compounds as liquid crystals (LC). Compounds 4-carboxy benzylidene-4-X-aniline (X = H, F, Cl, Br, CH3, OCH3) 1a-6a were synthesized by the reaction of aniline and its substituted derivatives with 4-formylbenzoic acid. Compounds 4-X-benzylidene-4-carboxy aniline (X = H, F, Cl, Br, CH3, OCH3) 1b-6b were synthesized by the reaction of benzaldehyde and its substituted derivatives with 4-aminobenzoic acid using absolute ethanol as the solvent. Synthesized compounds were characterized by FT IR and 1H NMR spectroscopy, liquid crystal properties were inves-tigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Based on the mesomorphic properties, it was proven that the compounds 2b-4b are dimorphic exhibiting a smectic and nematic phase, compounds 5b, 6b are monomorphic exhibiting a nematic phase, while ...
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Journal of Molecular Liquids, 2012
A new thermotropic liquid crystals containing azobenzene unit and imine linkages were synthesized via condensation of 4- (4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde with 4-aminoazobenzene (AzoAz-1) and 4,4′-diaminoazobenzene (AzoAz-2). The structures of compounds were characterized by means of NMR, FTIR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. The mesomorphic behavior of the unsymmetrical AzoAz-1 and symmetrical AzoAz-2 azobenzeneimines was investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Based on the POM and DSC measurements AzoAz-1 exhibited smectic phases (SmX, SmA), while AzoAz-2 showed smectic (SmX1, SmX2, SmA) and nematic (N) mesophases. Optical properties of the azobenzeneimines were tested by UV-vis and photoluminescence (PL) spectroscopy in various solvents. Preliminary investigations of electrical properties of the new compounds were carried out by current-voltage (I-V) measurements performed on ITO/compound/Al device.
Synthetic Metals, 2010
One series of symmetrical azine-type liquid crystals were synthesized and their chemical structure identified by FTIR, NMR, high resolution mass spectrometry-electro spray ionization (MS-ESI) and elemental analysis. The absorption (UV-vis), photoluminescence (PL) and thermoluminescence (TL) features of the compounds are documented. X-ray diffraction was employed to evaluate their phase transitional behaviour. Their mesomorphic properties were investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). Terminal groups of the liquid crystals had an effect on their mesomorphic properties. Azine with alkoxysemiperfluorinated end-groups (A1) exhibited smectic C (SmC) phase, whereas azine with octadecyloxy end chains (A3) showed SmC and SmA phases. Azine with 5octyl-2,2 :5 ,2-terthiophene groups (A2) exhibited only nematic phase. Different types of N and SmC textures were found and investigated by POM technique. Azine with thiophene groups (A2) has an absorption band about 138 nm batochromically shifted compared to the analogous band of other compounds. The lowest optical band gap value (2.34 eV) was detected for A2. Azines emitted violet or green light. The thermoluminescence emission of azines occurred at about 390-440 nm wavelengths. Current-voltage measurements were performed on ITO/compound/Alq 3 /Al and ITO/TiO 2 /compound/Alq 3 /Al devices before and after light irradiation. To prepare TiO 2 layer, sol-gel technique was applied.
Journal of Molecular Structure, 2010
Three discotic-shaped azomethines were prepared by condensation reactions of 4,4 0 ,4 00 -triformyltriphenylamine with various aliphatic monoamines. Their chemical structures were confirmed by FTIR, 1 H, 13 C NMR spectroscopies, as well as elemental analysis. Thermal properties of the azomethines were examined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXRD, SAXRD). Moreover, UV-vis properties of the thin films of the compounds were investigated on the quartz substrate without and with [6,6]-phenyl C 61 butyric acid methyl ester (PC 61 BM). Current-voltage (I-V) measurements were performed on ITO/compound/Al, ITO/compound:PC 61 BM/Al and ITO/PEDOT:PSS/compound:PC 61 BM/Al devices in the dark and during irradiation with light (under illumination 1000 W/m 2 ). Additionally, the compounds were tested using various AFM techniques.
Journal of Molecular Structure, 2010
The synthesis, characterization and mesomorphism of new thermotropic imine prepared via condensation of biphenyl-4-carboxaldehyde with poly(1,4-butanediol)bis(4-aminobenzoate) was reported. The structure of imine was characterized by means FTIR, 1 H, 13 C NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. The differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXRD, SAXRD) were employed to evaluate their phase transitional behavior. The imine exhibited smectic A (SmA) and smectic B (SmB) mesophases. Liquid crystalline properties of the azomethine were studied additionally via UV-vis spectroscopy in the function of temperature (UV-vis(T)). The compound has one emission band at 360 nm and thermoluminescence emission occurs at about 500-600 nm wavelengths. Current-voltage measurements were performed on ITO/AZ/Alq 3 /Al device with three different thickness of the film.
Journal of Molecular Structure, 2010
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