scholarly journals Saddle-shaped tetraphenylenes with peripheral gallic esters displaying columnar mesophases

2009 ◽  
Vol 5 ◽  
Author(s):  
Eugen Wuckert ◽  
Constanze Hägele ◽  
Frank Giesselmann ◽  
Angelika Baro ◽  
Sabine Laschat
Keyword(s):  
Chain Length ◽  
X Ray Diffraction ◽  
X Ray ◽  
Columnar Mesophases ◽  
Chain Lengths ◽  
Hexagonal Columnar ◽  
Mesomorphic Properties

Tetraphenylenes 2 with eight peripheral gallic esters were prepared in two steps from octamethoxytetraphenylene 1 in 19–72% yield. Investigation of the mesomorphic properties of 2 by DSC, POM and X-ray diffraction revealed that derivatives 2a–d with short alkoxy chain lengths (C5–C8) did not show any mesomorphic properties, whereas compounds 2e–i with C9–C13 chains displayed rectangular columnar mesophases and compounds 2j–l with C14–C16 chains displayed hexagonal columnar mesophases. Furthermore an anomalous odd-even effect of the clearing points of compounds 2e–l versus chain length was detected.

scholarly journals Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

2009 ◽  
Vol 5 ◽  
Author(s):  
Gundula F Starkulla ◽  
Elisabeth Kapatsina ◽  
Angelika Baro ◽  
Frank Giesselmann ◽  
Stefan Tussetschläger ◽  
...  
Keyword(s):  
Terminal Group ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Phase ◽  
X Ray ◽  
Smectic A ◽  
Polar Groups ◽  
Chain Lengths ◽  
Mesomorphic Properties ◽  
Phase Width

Based on 5-(4-hydroxyphenyl)-2-octylpyrimidine 8, 5-phenylpyrimidine derivatives 3–7, 9 with different spacer chain lengths (C2 up to C6) and different terminal polar groups (Br, Cl, N3, OH, CN) were synthesized by etherification and nucleophilic substitution. The mesomorphic behaviour of these compounds was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS) and revealed smectic A mesophases for bromides, chlorides and azides 3, 4 and 6. For these compounds a maximum phase width was observed for the C5 spacer regardless of the terminal group, whereas the hydroxy- and cyano-substituted derivatives 5 and 7, respectively, were non mesomorphic and showed only melting transitions.

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.

Liquid crystalline alkylthia-substituted novel phthalocyanines: synthesis and characterization

2014 ◽  
Vol 18 (01n02) ◽  
pp. 139-148 ◽  
Author(s):  
Buket S. Erdoğan ◽  
Devrim Atilla ◽  
Ayşe G. Gürek ◽  
Vefa Ahsen
Keyword(s):  
Liquid Crystalline ◽  
Metal Salt ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Elemental Analyses ◽  
Diffraction Patterns ◽  
Columnar Mesophases ◽  
New Compounds ◽  
Hexagonal Columnar

Methylene-bridged tetra- and octa-alkylthia substituted metal free- and Ni ( II ) phthalocyanines were synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt ( NiCl 2) or a strong organic base. The new compounds were fully characterized by elemental analyses, UV-vis, IR, NMR and mass spectra. The mesogenic properties of these materials were studied by differential scanning calorimetry, optical microscopy and X-ray diffraction investigations. X-ray diffraction patterns of the mesophase confirmed that the tetra- and the octa-substituted compounds formed hexagonal columnar mesophases (Colh). The mesogenic properties of these compounds were compared to that of their octa alkythia substituted phthalocyanine derivatives in the literature.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

scholarly journals Temperature-Dependent X-Ray Studies of Discotic Hexagonal Columnar Mesophases in Trinuclear Gold(I) Pyrazolate Complex

2021 ◽  
Vol 17 (3) ◽  
pp. 285-294
Author(s):  
Mohamad Azani Abd Khadir Jalani ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee ◽  
Juan Matmin ◽  
Nur Fatiha Ghazalli ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
Gold Complex ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling ◽  
Depth Study ◽  
Columnar Mesophases ◽  
Hexagonal Columnar

Gold(I) pyrazolate complex ([Au3Pz3]C10TEG) has been widely studied due to its interesting liquid crystalline properties by exhibiting the discotic hexagonal columnar arrangement. Generally, the liquid crystalline properties of the gold complex were confirmed based on their differential scanning calorimetry thermogram and polarized optical microscopy (POM) images. However, there is still no in-depth study on the phase transition in liquid crystals of [Au3Pz3]C10TEG especially on its structural change at variable temperature. In this study, the resulting liquid crystalline properties of [Au3Pz3]C10TEG upon being heated and cooled was extensively demonstrated via variable-temperature POM (VT-POM) and small angle X-ray scattering (VT-SAXS). Based on the VT-POM images, it was indicated that [Au3Pz3]C10TEG displayed a fan-shaped texture for typical arrangements of discotic hexagonal columnar of liquid crystals. Moreover, VT-SAXS results was in good agreement with the VT-POM images as it showed that [Au3Pz3]C10TEG might consist of two types of stacking system, which are ordered and disordered hexagonal discotic arrangements. Likewise, VT-SAXS analysis also demonstrated that hexagonal columnar mesophase of [Au3Pz3]C10TEG could be recovered even after the heating and cooling for two cycles.

The nonlinear effect of alkyl chain length in the membrane interactions of phenolipids: Evidence by X-ray diffraction analysis

2017 ◽  
Vol 119 (8) ◽  
pp. 1600397 ◽  
Author(s):  
Erwann Durand ◽  
Robert F. Jacob ◽  
Samuel Sherratt ◽  
Jérôme Lecomte ◽  
Bruno Baréa ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Chain Length ◽  
Nonlinear Effect ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Membrane Interactions ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals X-Ray Diffraction Studies on Alicyclic Saturated Discotic Liquid Crystals

1987 ◽  
Vol 42 (6) ◽  
pp. 631-635 ◽  
Author(s):  
H. W. Neuling ◽  
H. Stegemeyer ◽  
K. Praefcke ◽  
B. Kohne
Keyword(s):  
Liquid Crystalline ◽  
Optical Observations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
New Class ◽  
X Ray Scattering ◽  
Oriented Samples ◽  
Hexagonal Columnar

The discotic liquid crystalline phase of a new class of disc-like molecules (hexa-O-alkanoylscyllo- inositoles) is studied by small angle X-ray scattering, DSC and optical observations. Comparison of these three methods allows the determination of the structural arrangement. X-ray film exposures of oriented samples clearly demonstrate the hexagonal columnar ordered type of mesophases. A simple model calculation shows that the alkyl chains of neighbouring columns interpenetrate each other to a small extent.

Star mesogens — Synthesis and structural characterization using 1D and 2D solution NMR techniques and mesophase characterization

2013 ◽  
Vol 91 (3) ◽  
pp. 196-205 ◽  
Author(s):  
A. Shanavas ◽  
T. Narasimhaswamy ◽  
B.V.N. Phani Kumar ◽  
A. Sultan Nasar
Keyword(s):  
Chain Length ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
2D Nmr ◽  
Smectic Layer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Techniques ◽  
Terminal Chain

Novel star mesogens based on trimesic acid and symmetrical side arm cores with terminal alkoxy groups were synthesized via a divergent approach. The central core and side arms were connected through alkyl spacers. All the synthesized mesogens and their intermediates were characterized thoroughly using Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), 13C NMR, and mass spectrometers. One representative mesogen was subjected to the two-dimensional (2D) NMR experiments to ascertain the structure of the mesogens. The mesophase characterization was carried out using hot-stage optical polarizing microscopy (HOPM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques. Many of the molecules with an ethyloxy spacer were found to be nonmesogenic, whereas all the molecules with a butyloxy spacer showed liquid crystalline phases. The increase of terminal chain length decreased the transition temperatures. The nematic phase was observed for the mesogens with short terminal chain length, whereas smectic polymorphism was observed on increasing the terminal chain length. The results of a variable temperature powder X-ray diffraction of the representative sample support the smectic layer ordering.

Synthesis and characterization of some octaalkyl substituted lead phthalocyanines and unexpected variations in lead lability arising from the position of substituents and their chain length

2013 ◽  
Vol 17 (06n07) ◽  
pp. 511-521 ◽  
Author(s):  
Lydia X. Sosa-Vargas ◽  
Isabelle Chambrier ◽  
Colin J. MacDonald ◽  
Simon J. Coles ◽  
Graham J. Tizzard ◽  
...  
Keyword(s):  
Chain Length ◽  
Alkyl Chain ◽  
Lead Ion ◽  
X Ray ◽  
H Nmr ◽  
Alkyl Groups ◽  
Nmr Spectrometry ◽  
Acid Catalyzed ◽  
Chain Lengths

The preparation of some peripherally substituted (2,3,9,10,16,17,23,24) and non-peripherally substituted (1,4,8,11,15,18,22,25) octaalkyl lead(II) phthalocyanines with different alkyl chain lengths (6, 7, 8 or 9 carbons) is described and a comparison of some of their properties reported. X-ray structure analyses of the isomeric peripheral and non-peripheral octakis(octyl)phthalocyaninato lead(II) compounds reveal a greater degree of distortion of the ligand ring system from planarity in the former derivative. The series of peripherally substituted octaalkyl lead(II) phthalocyanines exhibit columnar liquid crystal behavior whereas the non-peripherally substituted isomers do not. The lability of the lead ion was investigated using 1 H NMR spectrometry under a specific set of conditions (8.8 × 10-4 M solutions of the phthalocyanine in d8-toluene containing d4-acetic acid 2.06 × 10-5 M). All the compounds underwent acid catalyzed demetalation at rates dependent upon the location of the substituents and, more surprisingly, the chain length of the alkyl groups. Under these conditions the lead ion within each of the peripherally substituted octaalkyl lead phthalocyanines was more labile than that in the non-peripherally substituted isomer.

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