Neue Ansichten �ber die St�rke

Freudenberg, Karl; Schaaf, E.; Dumpert, Gertrud; Ploetz, Theodor

doi:10.1007/bf01489430

Cited by 155 publications

(43 citation statements)

References 5 publications

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“…Making an analogy with the way cyclodextrins (then called Schardinger dextrins) absorbed iodine, Freudenberg et al proposed that in V iodine , amylose formed 6-fold single helices and that the iodine atoms formed a column inside these helices. [17] Using X-ray powder diffraction data, Rundle et al confirmed this hypothesis and proposed that the complex had a hexagonal unit cell containing helices with an external diameter of about 1.3 nm. [18,19] A more detailed structure based on an orthorhombic unit cell was proposed later on by Bluhm and Zugenmaier from X-ray diffraction data of V iodine fibers.…”

Section: Introductionmentioning

confidence: 83%

Helical Conformation in Crystalline Inclusion Complexes of V‐Amylose: A Historical Perspective

Putaux

Nishiyama

Mazeau

et al. 2011

Macromolecular Symposia

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Summary: Amylose forms V-type crystalline inclusion complexes with a large variety of small molecules. Several authors have proposed models for these complexes based on amylose single helices with 6, 7 and 8 glucosyl units per turn. However, so far, only a small number of crystal structures have been solved and several models are still hypothetical. We have recently shown that in the unit cell of such complex with isopropanol, the amylose molecules were organized in 7-fold left-handed helices, with isopropanol and water molecules located as guests both within and between the helices.

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Section: Introductionmentioning

confidence: 83%

Helical Conformation in Crystalline Inclusion Complexes of V‐Amylose: A Historical Perspective

Putaux

Nishiyama

Mazeau

et al. 2011

Macromolecular Symposia

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“…Thus, CE offers significant advantages not only for the separation of analytes but also for the investigation of fine effects in various noncovalent intermolecular interactions. The inclusion complex formation [5,6] and chiral recognition ability [7,8] of CDs are known for a long time.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic study on the opposite migration order of clenbuterol enantiomers in capillary electrophoresis with β-cyclodextrin and single-isomer heptakis(2,3-diacetyl-6-sulfo)-β-cyclodextrin

Chankvetadze¹,

Lomsadze²,

Bergenthal³

et al. 2001

Electrophoresis

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Opposite migration order was observed for the enantiomers of the chiral beta2-adrenergic drug clenbuterol (CL) in capillary electrophoresis (CE) when resolved with native beta-cyclodextrin (beta-CD) and heptakis (2,3-diacetyl-6-sulfo)-beta-CD (HDAS-beta-CD). The possible mechanisms of the affinity reversal of the CL enantiomers depending on the structure of the CD were studied using 1H-nuclear magnetic resonance (1H-NMR) spectrometry and one-dimensional rotating frame nuclear Overhauser and exchange spectrometry (1-D ROESY). Significant differences were observed between the structure of the (+/-)-CL complexes with beta-CD and HDAS-beta-CD.

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“…For example, Zwick hypothesized a structure in which a linear polyiodine chain is included by helical PYA chains going around, 4 according to the structure of the iodine-amylose complex. 8 Inagaki et a/. 9 support this structure with the similarity between the raman spectra of iodine-PYA and iodine-amylose complexes.…”

mentioning

confidence: 52%

Effects of the Degree of Hydration of Water Swollen Poly(vinyl alcohol) Films on Their Iodine Complexation

Oishi

Mlyasaka

1986

Polym J

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ABSTRACT:PYA films with a wide span of hydration (swelling) were soaked at different temperatures in iodine aqueous solutions to make the iodine-PYA complex, with a particular concern for the effects of the degree of hydration (D.H.) on the complex formation. The visible absorption maximum A.m., increased with D.H., while it decreased with temperature. The equilibrium amount of the complex increased with D.H. at a given concentration of iodine below 20°C. However, the effects of D. H. on the amount of complex deteriorated with increasing temperature and at 45°C became reversed to those at low temperature. When the samples soaked at soc were heated in the solution, the amount of complex suddenly began to decrease at 20oC; this corresponded to the sudden stress relaxation of water swollen PV A films. This transition seems to have great effect on the complexation. Poly(vinyl alcohol) (PYA) forms a complex with iodine, changing the color from brown to blue. 1 • 2 The most important application of the complex is use as sheet polarizers with a high quality of dichroism. 3 The polarizer is usually prepared by soaking PYA films in the iodinepotassium iodide solution with boric acid and by subsequent drawing to cause a high degree of uniaxial orientation. The iodine-PYA complexation occurs both in the aqueous solution and swollen gel states of PYA depending on the iodine concentration and temperature. For example, in solution, the amount of increases with increasing concentrations of PYA, iodine and boric acid. 4 The complex disappears during heating and again appears during cooling, resulting in color changes between blue and brown. 2 • 5 • 6 The extension of PYA gels enhances the complexation, 5 • 7 suggesting that the extended conformation of PYA chain segments is favorable for complexation. The strain-induced complexation is reversed on removal of the strain. 7 Many studies have been made also on the structure of the complex. For example, Zwick hypothesized a structure in which a linear polyiodine chain is included by helical PYA chains going around, 4 according to the structure of the iodine-amylose complex. 8 Inagaki et a/. 9 support this structure with the similarity between the raman spectra of iodine-PYA and iodine-amylose complexes. On the other hand: Rundle et a/. 10 proposed another one in which a polyiodine chain lies parallel to an extended part (segment) of a PYA chain. Tebelev 11 supports Rundle's model and further proposes that the iodine chain is surrounded by several extended PYA segments. In spite of these propositions, the structure has not been explicitly determined. We have been interested in 307

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Neue Ansichten �ber die St�rke

Cited by 155 publications

References 5 publications

Helical Conformation in Crystalline Inclusion Complexes of V‐Amylose: A Historical Perspective

Helical Conformation in Crystalline Inclusion Complexes of V‐Amylose: A Historical Perspective

Mechanistic study on the opposite migration order of clenbuterol enantiomers in capillary electrophoresis with β-cyclodextrin and single-isomer heptakis(2,3-diacetyl-6-sulfo)-β-cyclodextrin

Effects of the Degree of Hydration of Water Swollen Poly(vinyl alcohol) Films on Their Iodine Complexation

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