Nematische Systeme, V

Steinsträßer, Ralf

doi:10.1515/znb-1972-0711

Cited by 58 publications

(5 citation statements)

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“…A comparison of 3 , the first mesogenic benzamidine, to its Schiff base and ester analogues demonstrates the importance of intermolecular hydrogen bonding between the amidinyl groups in the stabilization of lamellar phases. The Schiff base and ester show only nematic phases with T NI of 119 and 91.5 °C, respectively. In contrast, the amidine exhibits three smectic polymorphs with a clearing temperature T SI of 136 °C.…”

Section: Discussionmentioning

confidence: 97%

Synthesis of Liquid Crystalline 4H-Benzo[1,2,4]thiadiazines and Generation of Persistent Radicals

et al. 2007

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Four substituted 4H-benzo[1,2,4]thiadiazines 2 were prepared by condensation of the appropriate anilines and benzonitriles followed by oxidative cyclization. The preparation of three fluorinated derivatives 2b-2d proceeded smoothly, while the synthesis of 2a was problematic, presumably due to the relatively high electron density of the benzene ring. The four-ring derivatives 2c and 2d exhibited liquid crystalline properties (2c: Cr 95 SmA 158 I and 2d: Cr 142 SmA 212 I). 4H-Benzo[1,2,4]thiadiazines 2 were oxidized with AgO to generate the corresponding persistent radicals 1 (g=2.0057). The stability of the radicals followed the order 1b approximately 1d>1c>1a, and the two fluorinated radicals 1b and 1d were isolated as crude solids. The lower stability of 1c is presumably due to the presence of the reactive benzylic CH position, and 1a lacks the stabilizing effect of the three fluorine atoms. ESR spectra for 1 were simulated using DFT-derived hfcc as the starting point.

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Section: Discussionmentioning

confidence: 97%

Synthesis of Liquid Crystalline 4H-Benzo[1,2,4]thiadiazines and Generation of Persistent Radicals

et al. 2007

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“…The melting points and nematic-isotropic transition temperatures Te, were determined with a Reichert Thermopan polarizing microscope and a Mettler FP 52 heating stage. 6 . Compound 6 was prepared by Nagano's method 8 .…”

Section: Methodsmentioning

confidence: 99%

Dielectric Constants and Molecular Structure of Nematic Liquid CrystalsII. Variation of the Bridging Group

Jeu

Lathouwers

1975

Zeitschrift Für Naturforschung A

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“…may be widened if these materials can be used in It is known that in an ideal system the clearing point mixtures with normal liquid crystals that are used for display devices. In the present communication, we report liquid crystalline properties for binary mixtures of a hydrogen-bonded mesogenic complex with normal liquid crystal materials which involve only covalent bonds.We selected a 1 5 1 complex ( 6O BA /8Py) [ 15, 16] consisting of 4-hexyloxybenzoic acid and 4-octylpyridine as a hydrogen-bonded mesogenic complex, and 4-octylphenyl 4-hexyloxybenzoate (OPHOB ) [ 16,18] and 4¾ -heptyl-4-cyanobiphenyl ( 7C B) [19] as normal Figure 1. Structures of the hydrogen-bonded liquid crystal complex and normal liquid crystal materials used in this study.…”

mentioning

confidence: 99%

“…We selected a 1 5 1 complex ( 6O BA /8Py) [ 15, 16] consisting of 4-hexyloxybenzoic acid and 4-octylpyridine as a hydrogen-bonded mesogenic complex, and 4-octylphenyl 4-hexyloxybenzoate (OPHOB ) [ 16,18] and 4¾ -heptyl-4-cyanobiphenyl ( 7C B) [19] as normal Figure 1. Structures of the hydrogen-bonded liquid crystal complex and normal liquid crystal materials used in this study.…”

mentioning

confidence: 99%

“…We selected a 1 5 1 complex ( 6O BA /8Py) [ 15,16] consisting of 4-hexyloxybenzoic acid and 4-octylpyridine as a hydrogen-bonded mesogenic complex, and 4-octylphenyl 4-hexyloxybenzoate (OPHOB ) [ 16,18] and 4¾ -heptyl-4-cyanobiphenyl ( 7C B) [19] as normal Complex 6O BA /8Py is miscible with both OPH OB and interaction exists between 6O BA /8Py and OPH OB. The smectic A phase is observed for mixtures containing less 7C B.…”

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confidence: 99%

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Preliminary communication - Miscibility of a hydrogen-bonded mesogenic complex with normal liquid crystals

Fukumasa¹,

Takeuchi²,

Kato³

1998

Liquid Crystals

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Recently, there has been increasing interest in the use liquid crystals for miscibility study. The molecular strucof hydrogen bonding between di erent molecular species tures of these materials are given in ® gure 1. Complex for building new liquid crystals [1± 3]. A variety of low 6O BA /8Py shows a nematic phase from 50 to 31ß C on molar mass liquid crystals [ 4± 7 ], polymeric liquid cooling; a nematic phase is seen for 4-hexyloxybenzoic crystals [8,9 ], and mesogenic networks [10] have acid ( 6O BA ) from 151 to 95ß C on cooling, while been built through intermolecular hydrogen bonds.4-octylpyridine ( 8Py) is an isotropic liquid at room Furthermore, the applicability of hydrogen-bonded temperature and exhibits no mesomorphic behaviour. liquid crystals for electro-optic devices has been studied Upon cooling, compound OPH OB exhibits isotropic± for both smectogenic and nematogenic complexes nematic, nematic± smectic A, and smectic A± crystal [11± 17]. The induction of chiral smectic C phases and transitions at 59, 39, and 11ß C, respectively; compound ferroelectric properties have also been observed for 7C B displays a nematic phase from 40 to 2ß C. hydrogen-bonded complexes derived from chiral molecu-The binary phase diagram for mixtures of 6O BA /8Py lar components [11± 14 ]. Moreover, room-temperature and OPH OB is shown in ® gure 2. The phase transition nematic phases can be achieved for complexes of benzoic behaviour was observed visually on cooling. Complex acid derivatives and simple 4-alkylpyridines [15± 17], 6O BA /8Py is miscible with OPH OB and no phase and alignment on rubbed surfaces and electro-optic separation is observed. The mixtures of these two nemae ects in a twisted nematic cell have been observed for togenic materials exhibit nematic phases over the entire the room temperature nematics [ 16]. range of composition; the I± N transition temperature The applicability of hydrogen-bonded liquid crystals behaviour is almost linear. may be widened if these materials can be used in It is known that in an ideal system the clearing point mixtures with normal liquid crystals that are used for display devices. In the present communication, we report liquid crystalline properties for binary mixtures of a hydrogen-bonded mesogenic complex with normal liquid crystal materials which involve only covalent bonds.We selected a 1 5 1 complex ( 6O BA /8Py) [ 15, 16] consisting of 4-hexyloxybenzoic acid and 4-octylpyridine as a hydrogen-bonded mesogenic complex, and 4-octylphenyl 4-hexyloxybenzoate (OPHOB ) [ 16,18] and 4¾ -heptyl-4-cyanobiphenyl ( 7C B) [19] as normal Figure 1. Structures of the hydrogen-bonded liquid crystal complex and normal liquid crystal materials used in this study.

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Nematische Systeme, V

Cited by 58 publications

References 2 publications

Synthesis of Liquid Crystalline 4H-Benzo[1,2,4]thiadiazines and Generation of Persistent Radicals

Synthesis of Liquid Crystalline 4H-Benzo[1,2,4]thiadiazines and Generation of Persistent Radicals

Dielectric Constants and Molecular Structure of Nematic Liquid CrystalsII. Variation of the Bridging Group

Preliminary communication - Miscibility of a hydrogen-bonded mesogenic complex with normal liquid crystals

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