scholarly journals New azobenzene liquid crystal with dihydropyrazole heterocycle and photoisomerization studies

2020 ◽  
Vol 7 (7) ◽  
pp. 200474
Author(s):  
Xiaoxuan Wang ◽  
Zhaoxia Li ◽  
Haiying Zhao ◽  
Shufeng Chen
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Ester Group ◽  
Azo Compounds ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Mesogenic Unit ◽  
Crystal Properties ◽  
Azobenzene Derivatives ◽  
Long Chain

New azobenzene derivatives with dihydropyrazole heterocycle have been prepared and characterized. According to thermal polarizing microscopy and differential scanning calorimetry studies, the compounds consisting of four linearly linked rings and a long alkoxy chain on the azobenzene side ( 3a-8 and 3a-14 ) displayed no liquid crystal properties. When the length of mesogenic unit increased to five rings, except for compound 5a-8 , all compounds from 5a-10 to 5a-16 containing a long chain of 10–16 carbon atoms on the side of ester group displayed liquid crystalline properties, and the mesogenic domain gradually narrowed with increase of the chain length. However, in the case of the molecule with long alkoxy chains on both sides, only 5c-16 with a long chain of 16 carbon atoms exhibited liquid crystal behaviour. In addition, these azo compounds underwent isomerization from E to Z under ultraviolet irradiation and then thermal back relaxation slowly in the dark, which can be recycled many times.

scholarly journals An unsymmetrical porphyrin and its metal complexes: Synthesis, spectroscopy, thermal analysis and liquid crystal properties

2009 ◽  
Vol 74 (10) ◽  
pp. 1097-1104 ◽  
Author(s):  
Changfu Zhuang ◽  
Xuexin Tang ◽  
Dong Wang ◽  
Aiqing Xia ◽  
Wenhui Lian ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Liquid Crystalline ◽  
Thermal Studies ◽  
Luminescent Properties ◽  
Quantum Yields ◽  
Scanning Calorimetry ◽  
Crystal Properties

The synthesis and characterization of a new unsymmetrical porphyrin liquid crystal, 5-(4-stearoyloxyphenyl)phenyl-10,15,20-triphenylporphyrin (SPTPPH2) and its transition metal complexes (SPTPPM, M(II) = Zn, Fe, Co, Ni, Cu or Mn) are reported. Their structure and properties were studied by elemental analysis, and UV-Vis, IR, mass and 1H-HMR spectroscopy. Their luminescent properties were studied by excitation and emission spectroscopy. The quantum yields of the S1 ? S0 fluorescence were measured at room temperature. According to thermal studies, the complexes have a higher thermal stability (no decomposition until 200?C). Differential scanning calorimetry (DSC) data and an optical textural photograph, obtained using a polarizing microscope (POM), indicate that the porphyrin ligand had liquid crystalline character and that it exhibited more than one mesophase and a low-lying phase transition temperature, with transition temperatures of 19.3 and 79.4?C; the temperature range of the liquid crystal (LC) phase of the ligand was 70.1?C.

scholarly journals Synthesis and Determination of Thermotropic Liquid Crystalline Behavior of Cinnamaldehyde-Based Molecules with Two Schiff Base Linking Units

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3780
Author(s):  
Zuhair Jamain ◽  
Nor Faizawani Omar ◽  
Melati Khairuddean
Keyword(s):  
Schiff Base ◽  
Liquid Crystal ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Crystal Properties ◽  
Structure Property Relationship

A series of liquid crystal molecules with two Schiff base linking units and a cinnamaldehyde core with different terminal groups were synthesized and characterized. The intermediates of 4-heptyloxybenzaldehyde (1a) and 4-dodeyloxybenzaldehyde (1b) were synthesized through the alkylation of 4-hydroxybenzaldehyde with a series of bromoalkane. A condensation reaction of cinnamaldehyde, 1,4-phenylenediamine and a series of substituted benzaldehydes with different terminal groups such as bromo, chloro, hydroxy, cinnamaldehyde, hydrogen, methoxy, heptyloxy and dodecyloxy produced a series of new cinnamaldehyde-based compounds, 2–9, respectively. All these compounds were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and CHN elemental analysis. The liquid crystal properties of these compounds were determined using polarized optical microscopy (POM), and their transitions were further confirmed using differential scanning calorimetry (DSC). Compounds with chloro, bromo, methoxy, heptyloxy, and dodecyloxy substituents are mesogenic compounds with nematic phase behavior. However, the other compounds were found to be non-mesogenic without any mesophase transitions. The structure–property relationship was investigated in order to study the effect of different terminal groups and Schiff base linking units on the liquid crystalline behavior of these compounds.

Synthesis and Properties of Novel Thiophene-Based Liquid Crystalline Conducting Polymers

2017 ◽  
Vol 25 (9) ◽  
pp. 669-676 ◽  
Author(s):  
Danesh Roudini
Keyword(s):  
Magnetic Field ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Electronic Properties ◽  
Liquid Crystalline ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystal Properties

Side-chain liquid crystalline polythiophenes were synthesised and the effects of the mesogenic units on the structure and electronic properties of the polymers were studied. The liquid crystal properties of the polymer films were studied using polarised hot-stage optical microscopy and differential scanning calorimetry, and X-ray diffractometry was used to investigate the effect of a magnetic field on the monomers and polymers.

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

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.

Synthesis of Segmented Anisotropic-Isotropic Poly(Aryl Ester)Poly(Arylene Ether) Copolymers

1989 ◽  
Vol 175 ◽  
Author(s):  
J. E. McGratn ◽  
K. L. Cooper ◽  
W. Waehamad ◽  
H. Huang ◽  
G. L. Wilkes
Keyword(s):  
Molecular Weight ◽  
Liquid Crystal ◽  
Benzoic Acid ◽  
Liquid Crystalline ◽  
Average Molecular Weight ◽  
Nucleophilic Aromatic Substitution ◽  
Copolymer Composition ◽  
Aromatic Substitution ◽  
Scanning Calorimetry ◽  
Arylene Ether

AbstractCarboxyl functional poly(arylene ether) oligomers of controlled number average molecular weight were synthesized via nucleophilic aromatic substitution step polymerization using p-hydroxy benzoic acid as the molecular weight and end group controlling reagents. The subsequent functionalized polyarylene ethers were copolymerized with acetoxy benzoic acid or acetoxyphenoxy benzoic acid via melt acidolysis procedures. Successful copolymers were generated using chlorobenzene as a solvent for the first s age of the reaction followed by melt reaction at temperatures as high as 325°C. Resulting copolymer composition and segment size were investigated. It was possible to prepare improved solvent resistant copolymers through incorporation of the liquid crystal polyester (LCP) segment. Extraction tests using boiling chloroform showed that a high percentage of segmented copolymer were generated. Swelling characteristics were also noted and were observed to decrease as a function of the LCP concentration utilized. Multiple transitions were observed in differential scanning calorimetry consistent with Tg's, Tm's and possibly with liquid crystal transitions. Optical microscopy showed an ordered microstructure developed which is consistent with the presence of liquid crystalline phases. The materials were successfully compression molded to afford tough coherent films at all compositions, implying the likelihood of improved compressive strength relative to the LCP homo- or copolyesters.

Synthesis and Characterization of Stilbene Derivatives for Possible Incorporation as Smart Additives in Polymers Used as Packaging Films.

1997 ◽  
Vol 50 (4) ◽  
pp. 425 ◽  
Author(s):  
Gary M. Day ◽  
Owen T. Howell ◽  
Michael R. Metzler ◽  
Paul D. Woodgate
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Packaging Films ◽  
Multiple Phase ◽  
Liquid Crystalline Phases ◽  
Crystal Properties ◽  
Stilbene Derivatives

Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.

Chiral Liquid Crystalline Polymers Containing Isosorbide Groups

2013 ◽  
Vol 781-784 ◽  
pp. 403-406
Author(s):  
Mei Tian ◽  
Zhi Xin Xu ◽  
Li Gao ◽  
Dan Shu Yao ◽  
Xiao Zhi He ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Main Chain ◽  
Liquid Crystalline Polymers ◽  
Optical Microscope ◽  
Liquid Crystal Polymers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystalline Polymers

A series of new main-chain liquid-crystal polymers (LCPs) were prepared from sebacoyl chloride (SD) and various amount of 4, 4-Dihydroxy-2, 2-dimethyl Benzalazine (DDBA) and isosorbide (ISO). The liquid crystal (LC) properties were investigated by polarized optical microscope (POM), differential scanning calorimetry (DSC) and X-ray diffraction measurements. P1 exhibited a typical nematic thread texture, which contains no ISO. P2-P7 are Sc* and N LCPs, which exhibited broken fan-shaped texture and droplet texture. The introduction of chiral units into the polymers led to a change of mesomorphase, as compared with P1.

Synthesis, Characterization and Adsorption Performance of Semi-crystalline/Liquid Crystalline Polyether Chelating Resins

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Shuangqing Zhang ◽  
Chaocan Zhang ◽  
Changhai He ◽  
Jun Xu
Keyword(s):  
Adsorption Capacity ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Selective Adsorption ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Adsorption Ability ◽  
H Nmr ◽  
Chelating Resins ◽  
Crystal Polymer

AbstractA series of polyether chelating resins with pendent biphenyl mesogenic groups were synthesized, and the chemical structure of monomers and polymers were confirmed by IR and 1H NMR detection. The thermal properties of resins were investigated by the Differential Scanning Calorimetry (DSC) and Polarizing Microscopy (POM), and the results showed that only the product of polyepichlorohydrin grafted with 4-cyano-4’-hydrobiphenyl, i.e., HPCN resin, was a kind of nematic liquid crystal polymer with typical schlieren texture (70-130 0C) and other resins were semi-crystalline. The results of adsorption experiments showed that all five resins exhibited a higher adsorption capacity (>1.0 mmol/g) for Cu (II) and Hg (II) and medium adsorption ability for Cd (II), Zn (II), Pb (II) and Co (II), however, a poor adsorption capacity (<0.3 mmol/g) for Mg (II), indicating that this type of polyether resins have a better selective adsorption for above metal ions. In addition, the adsorption capacity of HPnCP resins was generally higher than that of HPd and HPCN owing to the existence of terminal pyrrole coordination groups in HPnCP resins.

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