Origin of the Difference in Phase Transition Behavior between TwoType of All-Organic Radical Liquid Crystals

We have synthesized two types of all-organic radical liquid crystalline (LC) compounds, trans-2-alkoxyphenyl-5-[4-(4-alkoxybenzenecarbonyloxy)phenyl]-2,5-dimethylpyrrolidine-1-oxy (1) and 4-alkoxyphenyl trans-4-[5-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxy-2-yl]benzoate (2) and have fully characterized their LC properties. Although the only difference in the molecular structure between 1 and 2 is the orientation of a binding group connecting the core portion and one side-chain (-OCO- and -COO- for 1 and 2), the racemic or enantiomerically enriched 2 showed an SmA phase, or SmA* and TGBA* phases, which were not observed for 1, besides N and SmC, or N* and SmC* phases, respectively. Here we discuss the origin of these differences on the basis of their crystal structures determined by X-ray crystallographic analysis.

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Origin of the Difference in Phase Transition Behavior between TwoType of All-Organic Radical Liquid Crystals

Advances in Science and Technology - Smart Optics ◽

10.4028/3-908158-12-5.42 ◽

2008 ◽

pp. 42-45

Author(s):

Yoshiaki Uchida ◽

Rui Tamura ◽

Naohiko Ikuma ◽

Satoshi Shimono ◽

Hiroki Takahashi ◽

...

Keyword(s):

Phase Transition ◽

Liquid Crystals ◽

Organic Radical ◽

Phase Transition Behavior ◽

Transition Behavior ◽

The Difference

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Molecular structure of side-chain liquid crystalline polysiloxane in the smectic C phase from X-ray diffraction and molecular modeling

Polymer ◽

10.1016/j.polymer.2007.06.045 ◽

2007 ◽

Vol 48 (17) ◽

pp. 5161-5173 ◽

Cited By ~ 1

Author(s):

Kuei-Jen Lee ◽

Ging-Ho Hsiue ◽

Jung-Lung Wu ◽

Yi-An Sha

Keyword(s):

Molecular Structure ◽

Molecular Modeling ◽

Liquid Crystalline ◽

Side Chain ◽

X Ray Diffraction ◽

X Ray ◽

Smectic C ◽

Liquid Crystalline Polysiloxane

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Characterization of some mesogenic alkyl 1-thioglycosides

Canadian Journal of Chemistry ◽

10.1139/v02-157 ◽

2002 ◽

Vol 80 (8) ◽

pp. 1162-1165 ◽

Cited By ~ 2

Author(s):

B Henrissat ◽

G K Hamer ◽

M G Taylor ◽

R H Marchessault

Keyword(s):

Phase Transition ◽

Liquid Crystal ◽

Solid State ◽

Solid State Nmr ◽

Liquid Crystalline ◽

Liquid Crystal Phase ◽

X Ray Diffraction ◽

X Ray ◽

Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

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The role of π-bonding on the high temperature structure of the double perovskites Ba2CaUO6and BaSrCaUO6

Dalton Transactions ◽

10.1039/c5dt02663f ◽

2015 ◽

Vol 44 (36) ◽

pp. 16036-16044 ◽

Cited By ~ 1

Author(s):

Emily Reynolds ◽

Gordon J. Thorogood ◽

Maxim Avdeev ◽

Helen E. A. Brand ◽

Qinfen Gu ◽

...

Keyword(s):

Phase Transition ◽

High Temperature ◽

Neutron Diffraction ◽

Temperature Structure ◽

Double Perovskites ◽

Phase Transition Behavior ◽

X Ray ◽

Progressive Loss ◽

Octahedral Tilting

High temperature synchrotron X-ray and neutron diffraction powder diffraction studies of the uranium perovskites Ba2CaUO6and BaSrCaUO6reveal unusual phase transition behavior associated with the progressive loss of cooperative octahedral tilting.

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The Meisenheimer rearrangement in heterocyclic synthesis. II. Synthesis and X-ray crystal structure of a tetrahydro-1H-2,3-benzoxazocine and preparation of a hexahydro-2,3-benzoxazonine

Australian Journal of Chemistry ◽

10.1071/ch9801323 ◽

1980 ◽

Vol 33 (6) ◽

pp. 1323 ◽

Cited By ~ 15

Author(s):

JB Bremner ◽

EJ Browne ◽

PE Davies ◽

CLWAH Raston

Keyword(s):

Molecular Structure ◽

Crystal Structure ◽

Acetic Acid ◽

Crystal And Molecular Structure ◽

Phosphorus Oxychloride ◽

Crystallographic Analysis ◽

Heterocyclic Synthesis ◽

Reaction Conditions ◽

X Ray ◽

Heterocyclic Derivatives

The heterocyclic derivatives, 8,9-dimethoxy-3-methyl-1-phenyl-3,4,5,6- tetrahydro-1H-2,3-benzoxazocine(3a) and 9,10-dimethoxy-3-methyl-1- phenyl-1,3,4,5,6,7-hexahydro-2,3-benzoxazonine (3b),examples of two new ring systems, have been prepared by Meisenheimer rearrangement of the corresponding 2-benzazepine and 2-benzazocine N-oxide derivatives (2a) and (2b). The Bischler-Napieralski-type cyclization reaction was used in the preparation of the tertiary amine precursors of these N-oxides reaction conditions for the cyclization were critical and phosphorus oxychloride in refluxing butanenitrile was found to give the best yields of the seven- or eight-membered cyclic imine intermediates. Reductive cleavage of the benzoxazocine derivative (3a) with zinc in acetic acid followed by N-methylation gave the expected product, [2-{3- (dimethylamino)propyl}-4,5-di-methoxyphenyl]phenylmethanol (12). The crystal and molecular structure of (3a) has been determined by X-ray crystallographic analysis.

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Hydrogen bonding liquid crystalline benzoic acids with alkylthio groups: phase transition behavior and insights into the cybotactic nematic phase

New Journal of Chemistry ◽

10.1039/c7nj00282c ◽

2017 ◽

Vol 41 (14) ◽

pp. 6514-6522 ◽

Cited By ~ 16

Author(s):

Yuki Arakawa ◽

Yukito Sasaki ◽

Kazunobu Igawa ◽

Hideto Tsuji

Keyword(s):

Phase Transition ◽

Hydrogen Bonding ◽

Nematic Phase ◽

Liquid Crystalline ◽

Benzoic Acids ◽

Phase Transition Behavior ◽

Transition Behavior

A novel class of hydrogen bonding liquid crystalline benzoic acids with alkylthio groups was established and their phase transition behavior was investigated in detail.

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X-ray study of bilayered tilted structures in liquid crystalline side chain methacrylic polymers

Liquid Crystals ◽

10.1080/0267829031000091129 ◽

2003 ◽

Vol 30 (5) ◽

pp. 585-589 ◽

Cited By ~ 4

Author(s):

Eduardo A. Soto-Bustamante ◽

Rafael Vergara-Toloza ◽

Danilo Saldaño-Hurtado ◽

Patricio Navarrete-Encina

Keyword(s):

Liquid Crystalline ◽

Side Chain ◽

X Ray

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Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Crystals ◽

10.3390/cryst9090473 ◽

2019 ◽

Vol 9 (9) ◽

pp. 473 ◽

Cited By ~ 2

Author(s):

Malay Kumar Das ◽

Barnali Barman ◽

Banani Das ◽

Věra Hamplová ◽

Alexey Bubnov

Keyword(s):

Molecular Structure ◽

Phase Transition ◽

Liquid Crystalline ◽

Alkyl Chain ◽

Dielectric Strength ◽

Relaxation Frequency ◽

Goldstone Mode ◽

Aromatic Rings ◽

Structural Variations ◽

Polar Order

The tilted ferroelectric SmC* phase of three structurally different series having three aromatic rings in the core structure connected by ester groups with different end alkyl chain lengths, all of which are derived from lactic acid, have been observed by broadband dielectric spectroscopy. Introduction of structural variations within the liquid crystalline compounds has led to the formation of chiral nematic N*, or the paraelectric orthogonal SmA* phase at higher temperatures. The dielectric spectra strongly depend both on the temperature as well as the specific molecular structure of the self-assembling compounds possessing the ferroelectric polar order. The results reveal a strong Goldstone mode in the ferroelectric SmC* phase with ~kHz relaxation frequency. In the SmC* phase, the real and imaginary parts of the complex permittivity increase up to certain temperature near the SmC*-N*/SmA* transition and then decrease with increasing temperature, perhaps due to the disruption of the molecular domains at the onset of the SmA*/N* phase transition. The dielectric strength attains a maximum value in the SmC* phase and then decreases near the SmA*/N* phase transition. The dielectric strength is also influenced by the lengths of the alkyl chain and the nature of the connecting unit of the constituent molecules. The relaxation time and the relaxation frequency are found to vary with the molecular structure of the studied ferroelectric compounds.

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Phase Transition Behavior of Main Chain Nematic Liquid-Crystalline Polymers Based on 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone

MRS Proceedings ◽

10.1557/opl.2012.369 ◽

2012 ◽

Vol 1403 ◽

Author(s):

Christain Melchert ◽

M. Behl ◽

A. Lendlein

Keyword(s):

Phase Transition ◽

Nematic Phase ◽

Liquid Crystalline ◽

Liquid Crystalline Polymers ◽

Phase Transition Behavior ◽

Scanning Calorimetry ◽

Thermal Stabilities ◽

Crystalline Polymers ◽

Transition Behavior ◽

X Ray Scattering

ABSTRACTThe control of phase transition behavior in liquid crystalline polymers could enable potential application in the field of actuators and sensors by enabling a higher actuator performance of liquid crystalline elastomers (LCE). In this context the phase transition behavior of siloxane based liquid crystalline copolymers synthesized from 1,1,3,3-tetramethyldisiloxane, 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-MeHq), and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-tBHq) was explored. The selected monomers provided different thermal stabilities of the nematic phase, while the non-flexible siloxane spacer suppressed a smectic phase. The mesogenic properties were studied by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray scattering (WAXS). With increasing fraction of M-MeHq the nematic phase of the copolymer was stabilized and a tailoring of relatively low TNI was achieved.

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