Helical twisting power of chiral mono- and bis-aminoanthraquinones. Intramolecular and intermolecular chirality transfer in liquid-crystal phases

Kuball, Hans‐Georg; Brüning, H.; Müller, Thomas; Türk, Oliver; Schönhofer, Alfred

doi:10.1039/jm9950502167

Cited by 39 publications

(39 citation statements)

References 52 publications

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“…Values of TD mic S° are large compared with those for ionic surfactants, for which the disrupting influence of ionic head groups on the ordering of water around the monomer is greater. TD mic S° per CH 2 averages roughly 0.7 kJ mol 21 . The main driving force of micellization at 40 °C is the entropy term supported in some cases by an exothermic enthalpy term.…”

Section: Scheme 17mentioning

confidence: 96%

“…The contribution of each methylene group on going from C 8 to C 12 to the enthalpy of micellization, D mic H° (CH 2 ), is approximately 22.4 kJ mol 21 . This pattern is in good agreement with increments reported for other surfactants.…”

Section: Scheme 17mentioning

confidence: 99%

“…By way of comparison cholesteryl laurate has an HTP of 12 mm 21 and cholesteryl cetyloxybenzoate 10 mm 21 . 20 The carbohydrate derivative 2,5-di(p-hexyloxybenzoyl)-dianhydro-D-glucitol has an HTP of 62 mm 21 .…”

Section: Scheme 15mentioning

confidence: 99%

“…20 The carbohydrate derivative 2,5-di(p-hexyloxybenzoyl)-dianhydro-D-glucitol has an HTP of 62 mm 21 . 20 HTP values of up to 115 mm 21 have been reported for mono-and bis-aminoanthraquinone derivatives but these compounds are poorly compatible. 21 It is clear that these sugar derivatives have both high HTP values and good compatibility, characteristics that make these compounds attractive for applications.…”

Section: Scheme 15mentioning

confidence: 99%

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Mesogenic sugars. From aldoses to liquid crystals and surfactants

et al. 2000

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Amphiphilic sugar derivatives, formed by condensation of functionalized aliphatic chains with aldoses, form liquid crystals, in most cases smectic. A puzzling observation was the failure of the S,S-acetals of 6-deoxy sugars, L-rhamnose and D-fucose, to form such phases. A satisfactory model to explain this behavior involves-in most cases-the formation of columns, which are destabilized with the deoxy sugars in which the apolar end methyl groups are pushed together.Despite the abundance of chiral centers in the mono-and disaccharides used the smectic phases themselves in general display no chirality. By appropriate molecular design in which the amphiphilic character was deliberately suppressed it was possible to prepare glucose derivatives that exhibit chiral nematic phases as well as impressive helical twisting powers. Simple condensation chemistry is used to produce such derivatives.The amphiphilic character can be deliberately enhanced, and this is readily achieved in double headed 'gemini' derivatives formed by condensation of glucose or lactose with a long chain diamine followed by reduction followed by acylation of the nitrogen atoms with long chain acyl anhydrides. The thermodynamics of micellization of precursors to these derivatives have been studied. The gemini derivatives themselves display remarkable properties including the formation of giant vesicles and an appreciable capacity for the solubilization of hydrocarbons.

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Section: Scheme 17mentioning

confidence: 96%

Section: Scheme 17mentioning

confidence: 99%

Section: Scheme 15mentioning

confidence: 99%

Section: Scheme 15mentioning

confidence: 99%

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Mesogenic sugars. From aldoses to liquid crystals and surfactants

et al. 2000

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“…The pitch or the HTP are also chirality measurements which give like the ACD "anisotropic chirality information". 16,19 Both chirality measurements, pitch and HTP, on one hand, and CD on the other hand, can be traced back to the absolute configuration of the chiral molecule. Therefore, the question arises whether there is a correlation between both different chirality measurements when as a presupposition the same regions of the molecule are responsible for both effects.…”

Section: Chiral Phases With and Without Suprastructural Chiralitymentioning

confidence: 99%

Chirality and circular dichroism of oriented molecules and anisotropic phases

Kuball

Höfer

2000

Chirality

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The results of the “Chirality measurement” circular dichroism along different viewing directions within molecules and phases—the anisotropy of circular dichroism can give suitable information in order to check helicity rules or to analyze the suprastructural chirality of films of organic materials, respectively. These results of the ACD spectroscopy (the CD of anisotropic phases and oriented molecules) show that in an oriented state different information about “chirality” will be gained from different viewing directions. ACD measurements of α,β‐unsaturated ketosteroids, TADDOLes and binaphthol derivatives were analyzed. The chiral induction of cholesteric phases, the helical twisting power, is introduced as another chirality measurement which may possibly be a new relative method for the determination of the absolute configuration. Chirality 12:278–286, 2000. © 2000 Wiley‐Liss, Inc.

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Helical twisting power and circular dichroism as chirality observations: The intramolecular and intermolecular chirality transfer

Kuball

Brüning

1997

Chirality

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The helical twisting power (HTP) of a chiral guest in a chiral or achiral mesophase as host system is a chirality observation and, therefore, should be a suitable quantity for determination of the absolute configuration. Rules correlating the sign of the HTP and the absolute configuration of the guest are not known or, as sometimes proposed, do not exist at all. The sign and size of the HTP of compounds with one or more chiral centers are determined by the effects of an intramolecular and an intermolecular chirality transfer. The intramolecular chirality transfer is a well known phenomena in the development of sector or helicity rules for circular dichroism spectroscopy. Due to the strong omisotrophy of the intermolecular chirality transfer in a liquid crystal phase the development of rules for the determination of the absolute configuration from the sign of the HTP is called in question. By analysis of the HTP and the circular dichroism (CD) of mono‐ and bis‐aminoanthraquinones we now show that the development of rules in comparison to CD measurements does seem to be possible if some specialities of the anisotropic mesophases are taken into account. Chirality 9:407–423, 1997. © 1997 Wiley‐Liss, Inc.

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Helical twisting power of chiral mono- and bis-aminoanthraquinones. Intramolecular and intermolecular chirality transfer in liquid-crystal phases

Cited by 39 publications

References 52 publications

Mesogenic sugars. From aldoses to liquid crystals and surfactants

Mesogenic sugars. From aldoses to liquid crystals and surfactants

Chirality and circular dichroism of oriented molecules and anisotropic phases

Helical twisting power and circular dichroism as chirality observations: The intramolecular and intermolecular chirality transfer

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