scholarly journals Mesomorphic Behavior of Symmetric Azomethine Dimers Containing Different Chromophore Groups

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2183
Author(s):  
Elena Perju ◽  
Luminita Marin
Keyword(s):  
Aromatic Amines ◽  
1H Nmr Spectroscopy ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Optoelectronic Devices ◽  
Polarized Light ◽  
The Other ◽  
Scanning Calorimetry ◽  
Intense Luminescence ◽  
Photophysical Behavior

A series of new azomethine dimers was synthesized by the condensation reaction of flexible bis-benzaldehydes with four aromatic amines containing phenyl, naphthyl, anthracene and pyrene groups. Their right structure was confirmed by FTIR and 1H-NMR spectroscopy and their thermal properties were investigated by thermogravimetric analysis, differential scanning calorimetry and polarized light optical microscopy. A view on their photophysical behavior was gained by UV-vis and photoluminescence spectroscopy. The dimers containing pyrene and anthracene presented liquid crystalline behavior, while the other dimers were crystalline compounds. Two dimers containing pyrene moieties formed mesomorphic glasses and had intense luminescence, promising properties for applications in building optoelectronic devices.

scholarly journals LIQUID CRYSTALLINE PROPERTIES OF HYDROXYPROPYL CELLULOSE PREPARED FROM DISSOLVED EGYPTIAN BAGASSE PULP

2021 ◽  
Vol 55 (1-2) ◽  
pp. 13-22
Author(s):  
ABOU-ZEID RAGAB E. ◽  
NAHLA A. EL-WAKIL ◽  
AHMED ELGENDY ◽  
YEHIA FAHMY ◽  
ALAIN DUFRESNE
Keyword(s):  
Molecular Structure ◽  
1H Nmr Spectroscopy ◽  
Liquid Crystalline ◽  
Critical Concentration ◽  
Polarized Light ◽  
Hydroxypropyl Cellulose ◽  
Scanning Calorimetry ◽  
Dimethyl Acetamide ◽  
Ft Ir ◽  
Bagasse Pulp

"Egyptian agricultural wastes were used for preparing advanced cellulosic derivatives possessing liquid crystalline properties. Cellulose was successfully isolated in pure form from Egyptian bagasse pulp. Hydroxypropylation was carried out on the obtained cellulose and the liquid crystalline properties were investigated. The prepared hydroxypropyl cellulose (HPC) was esterified with 4-alkyloxybenzoic acids, giving products with liquid crystalline properties. The molecular structure of HPC and a series of its esters – 4-alkoxybenzoloxypropyl cellulose (ABPC-m) – was confirmed by Fourier transform infrared (FT-IR) and 1H NMR spectroscopy. The liquid crystalline (LC) phases and transition behaviors were investigated using differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The lyotropic behavior in dimethyl acetamide (DMA) was investigated using an Abee refractometer, and the critical concentration was determined by measuring the refractive index of the solutions in DMA."

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

scholarly journals The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

2020 ◽  
Vol 16 ◽  
pp. 175-184 ◽  
Author(s):  
Itamar L Gonçalves ◽  
Rafaela R da Rosa ◽  
Vera L Eifler-Lima ◽  
Aloir A Merlo
Keyword(s):  
Liquid Crystal ◽  
Relative Position ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Ammonium Thiocyanate ◽  
The Other ◽  
Amide Derivatives ◽  
Crystal Properties ◽  
Benzoyl Chlorides ◽  
Membered Heterocycle

A series of novel thiourea and amide liquid crystals containing 5-membered isoxazoline and isoxazole rings were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material. Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered heterocycle.

scholarly journals Substituted Azolium Disposition: Examining the Effects of Alkyl Placement on Thermal Properties

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 34 ◽  
Author(s):  
Karel Goossens ◽  
Lena Rakers ◽  
Tae Shin ◽  
Roman Honeker ◽  
Christopher Bielawski ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Polarized Light ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Imidazolium Chloride ◽  
X Ray ◽  
Smectic A ◽  
X Ray Scattering ◽  
Thermal Phase ◽  
Azolium Salts

We describe the thermal phase characteristics of a series of 4,5-bis(n-alkyl)azolium salts that were studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized-light optical microscopy (POM), and synchrotron-based small- to wide-angle X-ray scattering (SWAXS) measurements. Key results were obtained for 1,3-dimethyl-4,5-bis(n-undecyl)imidazolium iodide (1-11), 1,3-dimethyl-4,5-bis(n-pentadecyl)- imidazolium iodide (1-15), and 1,2,3-trimethyl-4,5-bis(n-pentadecyl)imidazolium iodide (2), which were found to adopt enantiotropic smectic A mesophases. Liquid-crystalline mesophases were not observed for 1,3-dimethyl-4,5-bis(n-heptyl)imidazolium iodide (1-7), 3-methyl-4,5-bis(n-penta-decyl)thiazolium iodide (3), and 2-amino-4,5-bis(n-pentadecyl)imidazolium chloride (4). Installing substituents in the 4- and 5-positions of the imidazolium salts appears to increase melting points while lowering clearing points when compared to data reported for 1,3-disubstituted analogues.

scholarly journals Liquid Crystalline Compounds in the Thiophene Series, Part 6+ Synthesis and Characterization of Azomethines and Vinylenes with Two Mesogenic Groups and Different Alkylene Spacer Lengths

1993 ◽  
Vol 48 (6) ◽  
pp. 826-843 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Frank Dirk Hoppe ◽  
Barbara Hirsch
Keyword(s):  
Aromatic Amines ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Alkyl Chains ◽  
Liquid Crystalline Phases ◽  
Smectic Mesophase ◽  
Methylene Groups

Compounds which have two mesogenic groups with and without terminal alkyl chains containing thiophene systems, were prepared from α.ω-bis(5-formyl-2-thienyl)alkanes (3a-3n) and various aromatic amines or 2-fluorenyl-Wittig-salt (10). The liquid crystalline properties of these compounds were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Only the series of α.ω-bis{5-[N-(4′-butyloxybiphenyl-4-yl)imino]formyl-2-thienyl}alkanes (7a-71) showed enantiotropic smectic and nematic mesophases. The series of E,E-α.ω-bis[5-(2-fluorenylvinyl)-2-thienyl]alkanes (8a-81) showed enantiotropic nematic mesophases for the compounds with 4 and 6 methylene groups, monotropic nematic mesophases for the compounds with 7—12 methylene groups and no liquid crystalline phases for compounds with 3, 5, 16 methylene groups in the connecting alkylene chain. In contrast to the compounds 8a-81, E-l-(5-butyl-2-thienyl)-2-(2-fluorenyl)ethylene has a smectic mesophase.

Liquid Crystalline Compounds in the Thiophene Series, Part 11+ Liquid Crystalline Thiophene Carboxylic Esters

1995 ◽  
Vol 50 (8) ◽  
pp. 1265-1274 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Barbara Hirsch
Keyword(s):  
Liquid Crystalline ◽  
Polarized Light ◽  
Scanning Calorimetry ◽  
Crystalline Phases ◽  
H Nmr ◽  
Smectic Phases ◽  
Liquid Crystalline Phases ◽  
Nematic Phases ◽  
Optical Textures ◽  
Carboxylic Esters

The new series of ten 4,4'-bis(5-alkyl-2-thienylcarbonyloxy)azobenzenes (2a -2j) and ten 2,5-bis(5-alkyl-2-thienylcarbonyloxy)toluenes (3a -3j) were prepared. These, as yet unknown esters were characterized in relation to their structures by elemental analyses, IR, UV, 1H NMR spectra and MS. The azobenzene-esters 2a -2j which form liquid crystalline phases were studied by microscopy under polarized light and DSC (differential scanning calorimetry). Through the observation of the optical textures nematic phases were monitored. Only 2j has an additional smectic phase; 2h and 2i form monotropic smectic phases during cooling. The toluene-esters 3a -3j do not form liquid crystalline phases.

Synthesis and Characterization of Novel Arylidene and Cardo Ester Bismaleimides and Poly(aminoaspartimide)s Therefrom

2003 ◽  
Vol 15 (3) ◽  
pp. 301-318 ◽  
Author(s):  
Vasile Cozan ◽  
Mitica Sava ◽  
Luminita Marin ◽  
Maria Bruma
Keyword(s):  
Thermal Stability ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Analysis Data ◽  
Synthesis And Characterization ◽  
Elemental Analysis Data ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
H Nmr

Six new bismaleimides (BMIs) having arylidene or cardo cycloaliphatic internal moieties were prepared by reacting 4-maleimidobenzoyl chloride with various arylidene or cardo bisphenols. The structures of BMIs were confirmed using elemental analysis data and spectroscopic (IR, 1H-NMR) characterizations. Two poly(aminoaspartimide)s (PAAs) were synthesized to exemplify one of the post-reaction abilities of the BMIs. Thermotropic liquid crystalline behavior was observed by differential scanning calorimetry and polarized light microscopy. The thermal stability of BMIs and PAAs was determined by thermogravimetric analysis and they showed good thermal stability except BMI 10, containing a cyclopentanone unit, which decomposed around 235°C. In this paper, we discuss the synthesis and characterization of these materials.

New Liquid Crystalline Material with an Azo Group in the Molecular Core

2011 ◽  
Vol 130-134 ◽  
pp. 1520-1522
Author(s):  
Si Chen ◽  
Si Pei Li ◽  
Xu Wang
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Crystalline Material ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Phase Structures ◽  
Molecular Core ◽  
Azo Group ◽  
Liquid Crystalline Material

A new kind of liquid crystalline material with an azo group in the molecular core was synthesized successfully. The chemical structures of the compounds were confirmed by mass spectrometry and 1H NMR. Their phase structures and transitions were investigated by differential scanning calorimetry. And the liquid crystalline behaviors were researched with polarized light microscopy experiments. The experimental results suggested that the compounds with a azo group in the molecular core can develop into a well-defined nematic phase.

Design of new Schiff base polymers containing thiadiazole rings and study of their liquid crystalline behavior

2019 ◽  
Vol 28 (2) ◽  
pp. 100-111
Author(s):  
Omer Y Thayee Al-Janabi ◽  
Ahmed K Hussein ◽  
Emaad T Bakir Al-Tikrity ◽  
Osamah A Hussein ◽  
Hana’a K Salih
Keyword(s):  
Potassium Salt ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Aromatic Diamines ◽  
Polarized Optical Microscopy ◽  
Chemical Structures ◽  
Smectic Mesophase ◽  
Schiff Base Polymers

New liquid crystalline thiadiazole dibenzaldehyde monomers labeled as THDB1–THDB3 were successfully synthesized by alkylation of thiadiazole’s potassium salt with 4-(bromomethyl) benzaldehyde. A number of polymers consisting of thiadiazole and azomethine coded PTDAZ1–PTDAZ5 were synthesized via condensation reaction of the presynthesized monomers THDB1–THDB3 with aromatic diamines. The chemical structures of the prepared materials were confirmed using Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance techniques. The liquid crystalline behavior of the studied monomers and polymers was examined by differential scanning calorimetry and hot stage polarized optical microscopy (POM) techniques. All these compounds were found to demonstrate mesomorphic transitions belonging to smectic and nematic liquid crystals. The studied monomers exhibited fan-like texture of smectic mesophase under POM cooling investigation. Fan-like texture of smectic and nematic mesophases was observed under POM for PTDAZ1 and PTDAZ2, while PTDAZ3 and PTDAZ4 revealed clay and schlieren textures of the smectic and nematic mesophases, respectively, and nematic texture has been found for the polymer PTDAZ5.

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