Discotic liquid crystals of transition metal complexes, part 36: syntheses and mesomorphic properties of very large discotic liquid crystals based on triphenylenocyanine and 1,4-diazatriphenylenocyanine

2006 ◽  
Vol 10 (09) ◽  
pp. 1145-1155 ◽  
Author(s):  
Masahiro Ichihara ◽  
Masakazu Miida ◽  
Bernhard Mohr ◽  
Kazuchika Ohta
Keyword(s):  
Liquid Crystals ◽  
Room Temperature ◽  
Optical Microscope ◽  
Decomposition Temperature ◽  
Discotic Liquid Crystals ◽  
Large Area ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
Homeotropic Alignment ◽  
Mesomorphic Properties

Two series of very large discotic complexes of tetrakis (2,3,6,7-tetraalkoxy)triphenylenocyaninato copper(II) (abbreviated as ( C n O )16 TcCu ; n = 8, 10, 12 and 14) and tetrakis(2,3,6,7-tetraalkoxy)-1,4-diazatriphenylenocyaninato copper(II) (abbreviated as ( C n O )16 TzCu ; n = 8, 10, 12 and 14), were synthesized to investigate their mesomorphic properties by differential scanning calorimetry, thermogravimetry analysis, polarizing optical microscope observation and temperature-dependent X-ray studies. The results show that each of the ( C n O )16 TcCu derivatives exhibits two or three disordered rectangular columnar ( Col rd ) mesophases from room temperature to the decomposition temperature at ca. 330-340°C under nitrogen gas. However, each of the ( C n O )16 TzCu complexes exhibits only one ordered tetragonal columnar ( Col tet.o ) mesophase in an extremely wide temperature region from room temperature to the decomposition temperature at ca 300°C and ca. 340-350°C under the atmosphere and nitrogen gas, respectively. It is very interesting that the Col tet.o mesophase of ( C n O )16 TzCu for n = 10, 12 and 14 shows remarkable spontaneous homeotropic alignment in a large area, without disclinations and polydomains, in the temperature range from room temperature to the decomposition temperature. As far as we know, these discotic liquid crystals are the first examples to show homeotropic alignment at room temperature. Furthermore, the difference between the mesomorphic properties of ( C n O )16 TcCu and ( C n O )16 TzCu originated only from the additional eight nitrogen atoms in the central core in ( C n O )16 TzCu .

scholarly journals Effect of Flexible Chain on Mesomorphic Properties of Alkyloxy Substituted 4-Chloroazobenzene Liquid Crystals

2021 ◽  
Vol 33 (5) ◽  
pp. 1159-1164
Author(s):  
Kamruzzaman ◽  
Roushown Ali ◽  
Rabiul Karim ◽  
Samiul Islam Chowdhury ◽  
Tariqul Hasan
Keyword(s):  
Liquid Crystals ◽  
Optical Microscope ◽  
Scanning Calorimetry ◽  
Flexible Chain ◽  
Spacer Length ◽  
Smectic A ◽  
Alkyl Bromides ◽  
Dsc Analyses ◽  
Azobenzene Derivatives ◽  
Mesomorphic Properties

Three rod-shaped alkyloxy substituted 4-chloroazobenzene liquid crystals, 1-(4-chlorophenyl)-2-[4- (alkyloxy)phenyl]diazene (hexayl, octyl and nonyl as flexible oxyalkyl chain) have been synthesized by diazotization of p-chloroaniline with phenol and subsequently performed etherification reaction with different alkyl bromides. The structures of the substituted 4-chloroazobenzene liquid crystals have been characterized by spectroscopic methods. The mesomorphic properties of the liquid crystals were examined by polarizing optical microscope (POM) and differential scanning calorimetry (DSC). All the oxyalkyl homologues of chloro substituted azobenzene showed enantiotropic smectic A (SmA) mesophase, which was understood clearly by the texture of the compounds employing polarizing optical microscope (POM) analysis. During heating scan in DSC analyses melting points, SmA-isotropic temperature and enthalphy changes associated with SmA-isotropic transition showed a remarkable impact on the spacer length of 4-chloro azobenzene derivatives.

Discotic liquid crystals of transition metal complexes 44: synthesis of hexaphenoxy-substituted phthalocyanine derivatives showing spontaneous perfect homeotropic alignment

2012 ◽  
Vol 16 (10) ◽  
pp. 1114-1123 ◽  
Author(s):  
Masaaki Ariyoshi ◽  
Makiko Sugibayashi-Kajita ◽  
Ayumi Suzuki-Ichihara ◽  
Takayuki Kato ◽  
Tenpei Kamei ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystals ◽  
Transition Metal ◽  
Transition Metal Complexes ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Homeotropic Alignment

We have synthesized novel hexaphenoxy-substituted phthalocyanine derivatives, 2-(12-hydroxydodecyloxy)-3-methoxy-9,10,16,17,23,24-hexakis(3,4-di-n-alkoxyphenoxy)phthalocyaninato copper(II) (abbreviated as Cn(OC12OH)PcCu : n = 10, 12, 14), and investigated their columnar mesomorphism and homeotropic alignment property. These hexaphenoxy-substituted Pc derivatives could be successfully isolated and purified from the mixture products by polarity difference. It was revealed by using polarizing optical microscopic observations, differential scanning calorimetry and temperature-dependent X-ray diffraction studies that each of the hexaphenoxy-substituted Pc derivatives has plural mesophases, and that the tetragonal columnar (Coltet) mesophase shows spontaneous perfect homeotropic alignment between two non-surface-treated glass plates without any defects and polydomain boundaries.

Discotic liquid crystals of transition metal complexes, 54: Rapid microwave-assisted synthesis and homeotropic alignment of phthalocyanine-based liquid crystals

2017 ◽  
Vol 21 (07n08) ◽  
pp. 476-492 ◽  
Author(s):  
Toshiyuki Akabane ◽  
Kazuchika Ohta ◽  
Tokihiro Takizawa ◽  
Takehiro Matsuse ◽  
Mutsumi Kimura
Keyword(s):  
Liquid Crystals ◽  
Reaction Time ◽  
Microwave Heating ◽  
Phase Transfer ◽  
Difficult Problem ◽  
Phase Transfer Catalyst ◽  
Microwave Assisted Synthesis ◽  
Aliquat 336 ◽  
Large Area ◽  
Homeotropic Alignment

The most difficult problem on syntheses of the phthalocyanine-based liquid crystals is the long reaction time. In order to shorten the reaction time, we have developed novel Methods A, B and D, for the syntheses of phthalocyanine-based liquid crystals by using microwave heating and/or adding a phase transfer catalysis of Aliquat 336. A series of phthalocyanine derivatives C[Formula: see text]PcZn(1) ([Formula: see text] 10, 12, 14, 16 and 18: a, b, c and e) could be successfully synthesized in a dramatically short reaction time of 30–60 min using Methods A and B by microwave heating. On the other hand, anothor series of the derivatives C[Formula: see text](OH)PcZn (2a–2e) could not be synthesized by microwave heating. Therefore, all these derivatives were synthesized using conventional Method C by oil bath heating, but the reaction took a very long time (22.5–88 h). To shorten the reaction time, we have developed Method D by oil bath heating with adding a phase transfer catalyst of Aliquat 336. In this method, we successfully shortened the reaction time from 88 h to 3 h for the synthesis of the derivative 2a. Thus, the reaction time for oil bath heating can be also greatly shortened by adding the phase transfer catalyst of Aliquat 336. Furthermore, we have established from POM, DSC and temperature-dependent X-ray diffraction measurements that the derivative C[Formula: see text]PcZn (1a) shows a very rare pseudohexagonal columnar (Col[Formula: see text] phase, and that the derivatives C[Formula: see text]PcZn (1b–1e) and C[Formula: see text](OH)PcZn (2b–2e) exhibit spontaneous perfect homeotropic alignment in a large area between two glass plates in their Col[Formula: see text] phases.

scholarly journals Discotic Liquid Crystals Based on Cu(I) Complexes with Benzoylthiourea Derivatives Containing a Perfluoroalkyl Chain

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Monica Iliş ◽  
Viorel Cîrcu
Keyword(s):  
Liquid Crystalline ◽  
Large Temperature ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
Ir And Nmr Spectroscopy ◽  
Hexagonal Columnar ◽  
Mesomorphic Properties

Mesomorphic three-coordinate copper(I) complexes ([Cu(BTU)2X], where X = Cl or Br) based on a new N-benzoylthiourea (BTU) ligand with two decyloxy and one perfluorooctyl groups at its periphery were designed and prepared. The BTU ligand coordinates via the S atom in a neutral monodentate fashion as confirmed by IR and NMR spectroscopy data. The liquid crystalline behavior of these copper(I) complexes was investigated by a combination of polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction analysis (XRD), while their thermal stability was studied by thermogravimetric analysis (TGA). These new copper(I) complexes have mesomorphic properties and exhibit a hexagonal columnar mesophase over a large temperature range, more than 100°C.

Discotic liquid crystals of transition metal complexes 38†: peripheral chain substituent position effect on columnar mesophase and stacking structures of novel phthalocyanine-based liquid crystals

2007 ◽  
Vol 11 (07) ◽  
pp. 503-512 ◽  
Author(s):  
Masahiro Ichihara ◽  
Ayumi Suzuki ◽  
Kazuaki Hatsusaka ◽  
Kazuchika Ohta
Keyword(s):  
Liquid Crystals ◽  
Position Effect ◽  
Optical Microscope ◽  
Central Core ◽  
Ortho Position ◽  
Discotic Liquid Crystals ◽  
Isotropic Liquid ◽  
X Ray ◽  
Phenoxy Group ◽  
Columnar Mesophases

In order to clarify the peripheral chain substitution position effect on columnar mesophase and stacking structures, we have synthesized three novel series of discotic liquid crystals (1-3) having octakis(phenoxy)phthalocyaninato copper(II) as a central core and one peripheral chain at the para position (1), meta position (2) or ortho position (3) of each phenoxy group, and three more novel series of discotic liquid crystals (4-6) having the same central core and two peripheral chains at para and meta positions (4), meta and meta positions (5) or ortho and meta positions (6) of each phenoxy group. Their columnar mesophase and stacking structures were investigated with a polarizing optical microscope, a differential scanning calorimeter and a temperature-dependent X-ray diffractometer. According to the results, their columnar mesophase and stacking structures strongly depended on the peripheral chain substitution positions and the number of peripheral chains. Derivatives 3 and 5 are viscous isotropic liquid at room temperature. Derivatives 1, 2, 4 and 6 exhibit various kinds of columnar mesophases: 1 Colhd; 2 Colhd and Colho; 4 Colhd, Colrd(P21/a), Coltet.d and Cub ( Pn [ three bar ] m ); 6 Colhd, Colrd(P21/a) and Colrd(X). Moreover, derivatives 1, 4 and 6 exhibit disordered columnar mesophases. However, derivative 2 only exhibits an ordered columnar mesophase and its X-ray diffraction pattern shows a sharp reflection corresponding to a very short intracolumnar stacking distance of 3.33 Å. Thus, we can drastically change the mesophase and stacking structures by the peripheral chain substitution positions and the number of peripheral chains at each phenoxy group. This is a new way of controlling mesomorphic structure.

scholarly journals Image Analysis Studies for Phase Transitions of Ferroelectric Liquid Crystals

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
S. Sreehari Sastry ◽  
B. Gowri Sankara Rao ◽  
K. B. Mahalakshmi ◽  
K. Mallika ◽  
C. Nageswara Rao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Image Analysis ◽  
Liquid Crystals ◽  
Optical Microscope ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Statistical Parameters ◽  
Ferroelectric Liquid Crystals ◽  
Phase Transition Temperatures ◽  
Parameter Values

Phase transition temperatures of ferroelectric liquid crystals ((S)-(-)-2-methylbutyl 4′-(4″-n-alkanoyloxybenzoyloxy) biphenyl-4-carboxylates (where n=16 and 18)) are studied through two techniques of image analysis. One is a statistical method, applied to compute the statistical parameters from the textures of each sample and the other, computation of Legendre moments being applied as image moment analysis, both of which are considered as a function of temperature. The textures of the samples are recorded with the polarizing optical microscope (POM) attached to the hot stage and high resolution camera. The phase transition temperatures of samples are inferred by the abrupt changes in the computed parameter values. The results obtained from the present methodology are in good agreement with those published in earlier literature done by the different techniques, like differential scanning calorimetry (DSC).

Synthesis and Mesomorphic Properties of a Series of Cholesteric Liquid Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 759-762 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Phase Transition Temperatures ◽  
Second Category ◽  
Mesomorphic Properties

A series of cholesterol liquid crystal compounds was synthesized. Phase-transition temperatures and mesomorphic textures of these synthesized compounds were characterized with differential scanning calorimetry and polarized optical microscopy, respectively. In these molecules the terminal ester chains CnH2n-1COO-, where n was the number of carbon atoms in the terminal ester chains, were linked to the cholesterol core. All of the synthesized cholesterol compounds exhibited mesophases for the first heating. However, as temperature decreased from their clearing points, their micrographs can also be divided into two categories, the first category exhibits branch-like mesophase textures for n in the range of 1-10 while the second category exhibits branch-like crystal textures for n in the range of 11-18.

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