Design and synthesis of new ferroelectric liquid crystals.  2.  Liquid crystals containing a nonracemic 2,3-epoxy alcohol unit

Walba, David M.; Vohra, Rohini T.; Clark, Noel A.; Handschy, Mark A.; Xue, Jiuzhi; Parmar, D. S.; Lagerwall, S. T.; Skarp, Kent

doi:10.1021/ja00283a056

Cited by 61 publications

(10 citation statements)

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“…((S,Sj-EPHDBPE) suggest that the phase sequence in thin liquid crystal cells on heating IS C 77"C N* 95'7"C I and on cooling I 95'7"C N* (78 '6"C S~) (57·rC S,) 57"C C which do not agree with previously published data [12]. The compound is commercially available from Aldrich Chemical Company with a purity of 98 per cent, according to the producer.…”

Section: Experimental Polarizing Microscopic Observations On 4-[(ss)-contrasting

confidence: 76%

“…4. Conclusion In contrast to previously published work [12] the phase sequence of (S,sl-EPHDBPE is given by C (5TC SI) (5nO C S~) 78·l o C N* %7°C I. and a helix inversion of this one component material is detected in the cholesteric state, A smectic A phase was not detected by the polarizing microscopic study, and is not supported by DSC measurements, This phase sequence can be exploited to produce well oriented textures for investigations in the S~ phase, The cholesteric helix can easily be unwound by an appropriate electric field, and passing the S~-N· transition, the ferroelectric irreversible S~ state is obtained with a nearly perfect texture.…”

Section: Dierking Et Ajcontrasting

confidence: 72%

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Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells

et al. 1993

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Investigations of 4{{S,s)-2,3 epoxyhexyloxy]-phenyl-4-(decyloxy)-benzoate by polarizing microscopy. the Cano-Grandjean method, optical rotation dispersion and UV-VIS spectroscopy reveal a cholesteric phase with temperature induced reversal of the helical twist. Switching time experiments in the S~ phase show that the intrinsic helix can be unwound reversibly and irreversibly by application of electric fields of different strengths.

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Section: Experimental Polarizing Microscopic Observations On 4-[(ss)-contrasting

confidence: 76%

Section: Dierking Et Ajcontrasting

confidence: 72%

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells

et al. 1993

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“…The enantiomeric purity of (R)-1 and (R)-2 was determined by HPLC to be 79.4 and 84.4% ee, respectively. Elemental analysis, IR, 1 H, and 13 C NMR spectroscopies confirm the expected structure and the high chemical purity for these compounds. The isolated yield of oxiranes with this synthetic route is between 45-65% using a 10% excess of the sodium salts of 4-methoxy-4Ј-hydroxybiphenyl and 4-cyano-4Ј-hydroxybiphenyl.…”

Section: Synthesis Of Oxiranesmentioning

confidence: 53%

“…The IR, 1 H NMR, 13 C NMR spectroscopic data indicated that the final oxirane products were of high chemical purity. The optical purity and yield data on both the first and second series of oxiranes 1-5 are summarized in Table 1.…”

Section: Synthesis Of Oxiranesmentioning

confidence: 98%

“…In particular, optically active liquid crystalline oxiranes derived from 2-n-propyl glycidol form cholesteric or C* phases and show in some cases unusual behavior like an inversion of helical twist sense in cholesteric or in C* phases. 13,14 The aim of the present work is to report the synthesis of glycidic ethers (either racemic or optically active) that contain mesogenic groups. Such oxiranes are precursors for the synthesis of side chain liquid crystalline polyethers.…”

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confidence: 99%

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Synthesis of racemic and optically active glycidic ethers, precursors of liquid crystalline polyethers

Taton

Borgne²,

Chen³

et al. 1998

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TheMitsunobu Reaction

1992

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Alkyl and aryl phosphites and phosphines react with compounds having weak heteroatom–heteroatom bonds, such as SS, OO, etc., and with azo compounds to form reactive phosphonium salts. These phosphonium salts in turn promote “redox” condensation reactions with compounds having active hydrogens. The condensation reaction of alcohols using the redox couple of a triaryl‐ or trialkylphosphine and a dialkyl azodicarboxylate has become known as the Mitsunobu reaction, based on his pioneering work in the late 1960s. The overall reaction is summarized, wherein the alcohol (R 1 OH) and acidic compound (H–Nu) are condensed to form product (R 1 –Nu), while triphenylphosphine is oxidized to triphenylphosphine oxide and the azodicarboxylate is reduced to the hydrazine. Although the typical redox combination is diethyl azodicarboxylate (DEAD) and triphenylphosphine, many other combinations have found selected use. The reaction is generally limited to primary and secondary alcohols, although tertiary alcohols react in a few intramolecular and intermolecular reactions. For secondary alcohols the reaction usually proceeds with clean inversion of stereochemistry. The acidic component of the reaction generally has an aqueous p K a < 15, with intramolecular reactions providing the exceptions. Examples of H–Nu include oxygen nucleophiles such as carboxylic acids and phenols; nitrogen nucleophiles such as imides, hydroxamates, and heterocycles; sulfur nucleophiles such as thiols and thioamides; and carbon nucleophiles such as β‐ketoesters. Major reviews of the Mitsunobu reaction were published in 1981 by Mitsunobu and in 1983 by Castro. The former review concentrated on reactions using DEAD/triphenylphosphine, while the latter review focused on reactions in which halogens replaced the hydroxy group using reagents such as triphenylphosphine/carbon tetrachloride, triphenyl phosphite/iodomethane, and triphenylphosphine/ N ‐halosuccinimide. Reactions involving the DEAD/triphenylphosphine redox system are the principal subject of this chapter, with emphasis on the literature between 1981 and 1988.

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Design and synthesis of new ferroelectric liquid crystals. 2. Liquid crystals containing a nonracemic 2,3-epoxy alcohol unit

Cited by 61 publications

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Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells

Synthesis of racemic and optically active glycidic ethers, precursors of liquid crystalline polyethers

TheMitsunobu Reaction

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Design and synthesis of new ferroelectric liquid crystals. 2. Liquid crystals containing a nonracemic 2,3-epoxy alcohol unit

Cited by 61 publications

References 0 publications

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding Sc∗ phase in thin liquid crystal cells

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding Sc∗ phase in thin liquid crystal cells

Synthesis of racemic and optically active glycidic ethers, precursors of liquid crystalline polyethers

TheMitsunobu Reaction

Contact Info

Product

Resources

About

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells

Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S_c∗ phase in thin liquid crystal cells