Chiral recognition in molecular and macromolecular pairs of liquid crystals of (2R,3S)- and (2S,3S)-2-fluoro-3-methylpentyl 4'-[[11-(vinyloxy)undecanyl]oxy]biphenyl-4-carboxylate diastereomers

Percéc, Virgil; Oda, Hiroji; Rinaldi, P. L.; Hensley, Darlene R.

doi:10.1021/ma00079a003

Cited by 15 publications

(21 citation statements)

References 1 publication

(1 reference statement)

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“…In contrast, the crystalline melting of such systems shows a negative deviation from ideal solution behavior due to 137 141 the different physical properties of diastereomers. 136…”

Section: • • -•mentioning

confidence: 99%

Molecular engineering of side-chain liquid crystalline polymers by living polymerizations

Pugh

Kiste

1997

Progress in Polymer Science

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Living" anionic, cationic, metalloporphyrin and ring-opening metathesis polymer izations have been used to prepare well-defined side-chain liquid crystalline homopolymers, block and graft copolymers and statistical copolymers. This paper analyzes their successes and failures by reviewing the mechanistic aspects and experimental conditions of each type of polymerization, and identifies other classes of mesogenic monomers that could be polymerized in a controlled manner in the future. The emerging structure/property relationships are then identified using well defined SCLCPs in which only one structural feature is varied while all others remain constant. The the:rmal transitions of liquid crystalline polymethacrylates, polynorbomenes and poly(vinyl ether)s reach their limiting values at less than 50 repeat units, which are generally equal to those of the corresponding infinite molecular weight polymers:Increasing spacer length depresses the glass transition of SCLCPs, and consequently often uncovers mesophases that are not observed without a spacer. The crystalline melting of tactic SCLCPs also tends to decrease (with odd-even alternation) with increasing spacer length. Without additional order within the polymer backbone due to high tacticity, mesogenic side-chains generally do not crystallize until the spacer contains at least nine carbon atoms. As the flexibility of the polymer backbone increases, the glass transition temperature decreases, and the side chains are able to crystallize at shorter spacer lengths and form more

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“…In contrast, the crystalline melting of such systems shows a negative deviation from ideal solution behavior due to 137 141 the different physical properties of diastereomers. 136…”

Section: • • -•mentioning

confidence: 99%

Molecular engineering of side-chain liquid crystalline polymers by living polymerizations

Pugh

Kiste

1997

Progress in Polymer Science

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“…As shown in Figure 2, the cyclic olefin protons of these monomers appear at δ ~5.7 and ~6.2 ppm. After ROMP reactions, the original cyclic olefin protons become acyclic olefin 10 protons which move upfield to ~5.2 ppm. These NMR spectra demonstrate that our desired LCPs have been successfully polymerized.…”

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confidence: 99%

“…Besides glass45 transitions, DSC spectra of all four LCPs except PNEM3, exhibit another apparent first order phase transition, which is the LC-toisotropic phase transition. As to PNEM3, since the flexible alkyl spacer linking polymer backbone and mesogens is too short (DSC curves of (A) two side-on SCLCPs: PNSM3, PNSM6 and (B) two end-on SCLCPs: PNEM3, PNEM6 during the first cooling scan and the second heating scan at a rate of 10 ℃/min under nitrogen10 atmosphere.…”

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confidence: 99%

Side chain liquid crystalline polymers with an optically active polynorbornene backbone and achiral mesogenic side groups

Geng

Lin

et al. 2015

Polym. Chem.

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Most of traditional chiral side-chain liquid crystalline polymers (SCLCP) depend on pendant chiral mesogenic units to introduce chirality in their structure, with the polymer backbones being usually achiral. In this work, we asymmetrically synthesize several enantiomerically pure norbornene monomers functionalized with achiral mesogenic units, and further apply ring-opening metathesis polymerization 10 technique to prepare series of side-on and end-on SCLCPs with an optically active polynorbornene main chain and achiral mesogens. Their physical properties are fully characterized by NMR, UV, CD, GPC, TGA, DSC, polarimetry, polarized optical microscopy and small-angle X-ray scattering. The obtained side-on SCLCPs display the tendency of forming nematic, i.e. achiral mesophases, in strong contrast with the chiral nematic (cholesteric) mesophase exhibited by their comparative end-on analogues. The 15 proposed explanation for this phenomenon is that the chiral backbones and the laterally attached mesogens of side-on SCLCPs can concurrently exist in a parallel arrangement so that the mesogenic directors might not be affected by the chirality information, while the mesogenic directors of end-on SCLCPs always tilt to the backbone orientation so that the twisting power of chiral main chains might force the terminally attached mesogens to form helical structures.

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“…Recently, we initiated a systematic series of investigations on chiral molecular recognition by studying the relationship among molecular, macromolecular, and supramolecular structures and the extent of the manifestation of heterochiral recognition 10a–d. The methodology used in our research involves the synthesis of enantiomeric and diastereomeric mesogenic vinyl ethers and of the corresponding homopolymers and copolymers by living cationic polymerization and copolymerization reactions.…”

Section: Introductionmentioning

confidence: 99%

“…The methodology used in our research involves the synthesis of enantiomeric and diastereomeric mesogenic vinyl ethers and of the corresponding homopolymers and copolymers by living cationic polymerization and copolymerization reactions. Living cationic polymerization provides homogeneous polymers and copolymers with well‐controlled molecular weight, composition, and narrow molecular weight distribution 10e–g, 11, 12. Chiral recognition is detected by the study of the phase diagrams of monomers, homopolymers, and copolymers as a function of enantiomeric composition.…”

Section: Introductionmentioning

confidence: 99%

Chiral recognition in molecular and macromolecular pairs of (S)- and (R)-1-cyano-2-methylpropyl-4?- {[4-(8-vinyloxyoctyloxy)benzoyl]oxy}biphenyl-4- carboxylate enantiomers

Percéc

Asandei

Zheng

2000

J. Polym. Sci. A Polym. Chem.

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(S)‐1‐Cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐ 4‐carboxylate [(S)‐11] and (R)‐1‐cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐carboxylate [(R)‐11] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[(S)‐11] and poly[(R)‐11], with well‐defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)‐11 and poly[(S)‐11] are identical to those of (R)‐11 and poly[(R)‐11], respectively. Both (S)‐11 and (R)‐11 exhibit enantiotropic SA, S *C, and SX (unidentified smectic) phases. The corresponding homopolymers exhibit SA and S *C phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second SX phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)‐11/(R)‐11, (S)‐11/poly[(R)‐11], and poly[(S)‐11]/poly[(R)‐11], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the SA and S *C phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the SA and SX phases of the monomers but not in the SA phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S *C phase of the monomers below their crystallization temperature and in the S *C phase of the polymers below their glass‐transition temperature. In the S *C phase of the monomers above the melting temperature and of the polymers above the glass‐transition temperature, nonideal solution behavior was observed. However, in the SA phase the monomer–polymer and polymer–polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631–3655, 2000

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Chiral recognition in molecular and macromolecular pairs of liquid crystals of (2R,3S)- and (2S,3S)-2-fluoro-3-methylpentyl 4'-[[11-(vinyloxy)undecanyl]oxy]biphenyl-4-carboxylate diastereomers

Abstract: M2 12 (1994)

Cited by 15 publications

References 1 publication

Molecular engineering of side-chain liquid crystalline polymers by living polymerizations

Molecular engineering of side-chain liquid crystalline polymers by living polymerizations

Side chain liquid crystalline polymers with an optically active polynorbornene backbone and achiral mesogenic side groups

Chiral recognition in molecular and macromolecular pairs of (S)- and (R)-1-cyano-2-methylpropyl-4?- {[4-(8-vinyloxyoctyloxy)benzoyl]oxy}biphenyl-4- carboxylate enantiomers

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