scholarly journals Novel banana-discotic hybrid architectures

2009 ◽  
Vol 5 ◽  
Author(s):  
Hari Krishna Bisoyi ◽  
H T Srinivasa ◽  
Sandeep Kumar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Optical Microscopy ◽  
Elemental Analysis ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
Spectral Techniques ◽  
Design And Synthesis ◽  
Chemical Structures ◽  
Crystalline Property ◽  
Liquid Crystalline Property

Here we present the design and synthesis of novel banana-discotic dimers and banana-bridged discotic dimers. The chemical structures have been characterized by spectral techniques and elemental analysis. The thermal behaviors of the compounds have been investigated by polarizing optical microscopy and differential scanning calorimetry. None of these synthesized compounds exhibit any liquid crystalline property probably because of the incompatibility of the bent-core with the discotic core.

scholarly journals Synthesis and Spectral Studies of Some Homo Dinuclear Lanthanide(III) Complexes of a Mesogenic Schiff Base

2021 ◽  
Vol 68 (4) ◽  
pp. 904-912
Author(s):  
Prem Kumar Shrestha ◽  
Pawan Raj Shakya
Keyword(s):  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Schiff Base ◽  
Elemental Analysis ◽  
Spectral Studies ◽  
Scanning Calorimetry ◽  
Spectral Techniques ◽  
Zwitterionic Form ◽  
Smectic A ◽  
Wide Range

A mesogenic Schiff base, N,N’-di(4-decyloxysalicylidene)-1’,8’-diamino-3’,6’-dioxaoctane (H2L) and a series of homo dinuclear lanthanide(III) complexes of the type [Ln2(LH2)3(NO3)4](NO3)2, (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) were synthesized and characterized by elemental analysis, mass spectrometry, FTIR, and NMR spectral techniques. The IR and NMR spectral evidences imply bonding of a neutral bidentate H2L species through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Differential scanning calorimetry (DSC) and polarizing optical icroscopic (POM) studies reveal mesogenic properties (smectic-X, smectic-A and nematic mesophases) in the ligand over a wide range of temperature but none mesomorphism in the LnIII complexes synthesized under this study. Luminescence studies exhibit emissions of H2L and TbIII complex.

scholarly journals Synthesis and Structural Characterization of Some Lanthanide(III) Nitrate Complexes with a Mesogenic Schiff-Base, N,N’-di-4-(4’-heptadecyloxybenzoate) salicylidene-1,3-diaminopropane Derived from 2,4- dihydroxybenzaldehyde

2020 ◽  
Vol 41 (1) ◽  
pp. 16-25
Author(s):  
Prem Kumar Shrestha ◽  
Pawan Raj Shakya
Keyword(s):  
Schiff Base ◽  
Liquid Crystalline ◽  
Molar Conductance ◽  
Scanning Calorimetry ◽  
1H And 13C Nmr ◽  
Spectral Techniques ◽  
Crystalline Property ◽  
Elemental Analyses ◽  
Overlap Parameter

Complexes of La(III), Pr(III), Nd(III), Sm(III), Gd(III) and Dy(III) with the Schiff-base, N,N′-di-4-(4’-heptadecyloxybenzoate)salicylidene-1,3-diaminopropane, (abbreviated as H2L) have been synthesized and characterized on the basis of elemental analyses, molar conductance, magnetic, electronic, infrared, 1H and 13C NMR spectral techniques. The nephelauxetic ratio (β), the bonding parameter (b1/2), Sinha’s parameter (%δ) and angular overlap parameter (η) have been calculated from the electronic spectra of Pr(III), Nd(III), Sm(III) and Dy(III) complexes. Infrared and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as LH2) to the Ln(III) ions through two phenolate oxygens, rendering the overall geometry around Ln(III) to distorted square antiprism. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) shows the liquid crystalline property of the ligand with a nematic (N) mesophase. Among the metal complexes, only that of the Gd(III) exhibits smectic B (SmB) and nematic (N) phases. 

scholarly journals Thermotropic Liquid-Crystalline Properties of Viologens Containing 4-n-alkylbenzenesulfonates

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 77 ◽  
Author(s):  
Pradip Bhowmik ◽  
Anthony Chang ◽  
Jongin Kim ◽  
Erenz Dizon ◽  
Ronald Principe ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Liquid Crystalline ◽  
Metathesis Reaction ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Melting Transitions

A series of viologens containing 4-n-alkylbenzenesulfonates were synthesized by the metathesis reaction of 4-n-alkylbenzenesulfonic acids or sodium 4-n-alkylbezenesulfonates with the respective viologen dibromide in alcohols. Their chemical structures were characterized by Fourier Transform Infrared, 1H and 13C Nuclear Magnetic Resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. They formed LC phases above their melting transitions and showed isotropic transitions. As expected, all the viologen salts had excellent stabilities in the temperature range of 278–295 °C as determined by thermogravimetric analysis.

Effect of Spacer Length on the Liquid Crystalline Property of Azobenzene-Containing ABA-Type Triblock Copolymers via ATRP

2010 ◽  
Vol 428-429 ◽  
pp. 67-70
Author(s):  
Xin De Tang ◽  
Long Cheng Gao ◽  
Nian Feng Han
Keyword(s):  
Liquid Crystalline ◽  
Triblock Copolymers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Spacer Length ◽  
Polymer Main Chain ◽  
Flexible Spacer ◽  
Crystalline Property ◽  
Liquid Crystalline Property ◽  
Methylene Groups

The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl methacrylates with varying methylene groups (n = 0, 2, 6) were used to synthesize a series of azobenzene-containing amphiphilic triblock copolymers PAnC-PEG-PAnC by atom transfer radical polymerization (ATRP). Differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and one-dimensional X-ray diffraction (1D WAXD) have shown that the glass transition temperatures of these copolymers decreased as n increases. PA0C-PEG-PA0C has no mesophase, while both PA2C-PEG-PA2C and PA6C-PEG-PA6C have a nematic mesophase. These differences derive of the length of spacer groups between the polymer main chain and side chain.

scholarly journals New cholesteryl containing bent core liquid crystals

2013 ◽  
Vol 78 (5) ◽  
pp. 669-680 ◽  
Author(s):  
Cosmin-Constantin Huzum ◽  
Irina Carlescu ◽  
Gabriela Lisa ◽  
Dan Scutaru
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Liquid Crystalline ◽  
Benzoic Acids ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Acyl Chlorides ◽  
Esterification Reactions

The paper presents the synthesis and mesomorphic behavior of two new series of bent core liquid crystalline compounds based on a 1,3-dihydroxybezene core and containing a cholesteryl 6-oxyhexanoate wing. The two series were obtained by the esterification of the cholesteryl 6-(3-hydroxyphenoxy)hexanoate core with some 4-((4-(n-alkyloxy)phenyl)azo)benzoic acids (n-alkyl = n-hexyl ? n-dodecyl) or 4-(4-(n-alkyloxy)benzoyloxy)benzoic acids (n-alkyl = n-hexyl ? n-decyl). The esterification reactions were performed via the corresponding acyl chlorides or with the DCC / DMAP system. All the synthesized compounds evidenced enantiotropic liquid crystalline properties, with smectic type textures, when investigated by means of differential scanning calorimetry and polarized optical microscopy. Isotropisation and isotropic to liquid crystal transitions were relatively low (between 89 ? 1460C). The compounds containing the azo-aromatic linking group presented the largest range of stability of the mesophases (between 42 and 870C). All the investigated compounds were thermally stable in the existence range of the mesophases.

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.

Synthesis and Characterization of Polyamidoamine-Based Liquid Crystalline Dendrimers

1998 ◽  
Vol 10 (3) ◽  
pp. 231-240 ◽  
Author(s):  
Kazuhiro Suzuki ◽  
Osamu Haba ◽  
Ritsuko Nagahata ◽  
Koichiro Yonetake ◽  
Mitsuru Ueda
Keyword(s):  
Mass Spectroscopy ◽  
Elemental Analysis ◽  
Liquid Crystalline ◽  
Lithium Bromide ◽  
Synthesis And Characterization ◽  
Crystalline Property ◽  
Liquid Crystalline Property ◽  
Crystalline Nature ◽  
Liquid Crystalline Dendrimers

Poly(amidoamine)-based liquid crystalline dendrimers (LCDs) with mesogenes on the surface were successfully prepared by the reaction of poly(amidoamine) dendrimers with 40-cyanobiphenyl hydrogen glutarate in the presence of a condensing agent, diphenyl(2,3- dihydro-2-thioxo-3-benzoxazolyl)phosphonate. The structures of LCDs were characterized by IR, 1H-NMR and MALDI-TOF mass spectroscopy and elemental analysis. These LCDs did not show a thermotropic liquid crystalline nature but exhibited a lyotropic liquid crystalline property in the 80 wt% DMF solutions of LCDs containing lithium bromide.

Influence of the Terminal Substituent of Azobenzene on the Liquid Crystalline Property of ABA Triblock Copolymers

2010 ◽  
Vol 428-429 ◽  
pp. 122-125
Author(s):  
Xin De Tang ◽  
Long Cheng Gao ◽  
Nian Feng Han
Keyword(s):  
Liquid Crystalline ◽  
Triblock Copolymers ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Nematic Mesophase ◽  
Terminal Substituent ◽  
Crystalline Property ◽  
Weight Distributions ◽  
Liquid Crystalline Property

The influence of the terminal substituent of azobenzene on the liquid crystalline property of ABA triblock copolymers was studied. Three kinds of azobenzene-containing monomers with different terminal substituents were respectively used to synthesize ABA triblock copolymers (denoted as PMMAzo12-PEG13-PMMAzo12, PEMAzo14-PEG13-PEMAzo14, and PNMAzo14-PEG13-PNMAzo14) by atom transfer radical polymerization (ATRP). These copolymers were characterized with 1H NMR and GPC, and exhibited controlled molecular weights and narrow molecular weight distributions. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) have shown that these copolymers have mesophases. PMMAzo12-PEG13-PMMAzo12 has a smectic mesophase and a nematic mesophase, while both PEMAzo14-PEG13-PEMAzo14 and PNMAzo14-PEG13-PNMAzo14 have a nematic mesophase. This demonstrates that the LC properties of these copolymers highly depend on the terminal substituent of azobenzene.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

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).

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