Structure and stability of columnar cyclomaltohexaose (α-cyclodextrin) hydrate

Hunt, Martin A.; Rusa, Cristian C.; Tonelli, Alan E.; Balik, C. M.

doi:10.1016/j.carres.2004.09.012

Cited by 35 publications

(39 citation statements)

References 23 publications

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“…With H 2 O and with small organic molecules, ␣CD forms a variety of crystalline adducts ͑inclusion compounds͒, [8][9][10][11][12][13] and it is likely that these become insoluble in the solutions and precipitate out and/or further transform to other adducts on heating or on cooling. The 1:6 ͑␣CD: H 2 O, molar ratio͒ produces two inclusion compounds of well-defined crystal structures, [8][9][10][11][12] and were these to form, then "freezing on heating" would differ from both crystallization of a pure liquid in the generic, loop-shape Tammann phase diagram, 3 and from reentrant transformations.…”

Section: Discussionmentioning

confidence: 99%

Composition dependence and the nature of endothermic freezing and exothermic melting

Ferrari

Tombari

Salvetti

et al. 2007

The Journal of Chemical Physics

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The heat capacity, C(p), and enthalpy and entropy change of alpha-cyclodextrin, H(2)O, and 4-methylpyridine solutions have been studied during their freezing on heating, isothermal freezing, and the solid's melting on cooling. Freezing occurs in several endothermic steps on heating to 383 K and alpha-cyclodextrin rich solutions freeze in four steps. The melting rate becomes slower with decrease in temperature and its steps merge. Decreasing the amount of alpha-cyclodextrin decreases the C(p) change on freezing. The endothermic freezing phenomenon differs from freezing of a pure liquid and is attributed to formation of a solid inclusion compound and its incongruent way of exothermic melting.

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Section: Discussionmentioning

confidence: 99%

Composition dependence and the nature of endothermic freezing and exothermic melting

Ferrari

Tombari

Salvetti

et al. 2007

The Journal of Chemical Physics

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“…Because HFIP has a relatively low boiling point, it is easily evaporated from the corresponding CD solution under mild conditions. 15 On the other hand, the peak characteristic of the cage-type assembly (2y = 141) 16 in the as-received a-CD almost disappears. Normally channel-type CD assemblies are formed from inclusion complexes between CDs and guest molecules.…”

mentioning

confidence: 99%

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) as a novel and effective solvent to facilely prepare cyclodextrin-assembled materials

et al. 2014

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“…On the other hand, the diffraction pattern of the NFYa-CD KN product exhibits the channel a-CD peak at 2q = 13-with high intensity, but there are no changes either in the characteristic cage peak at 2q = 21.7-or that corresponding to the channel type at 2q = 20-, suggesting an intermediate structure in the KN solid (26). Likewise, the thermal analysis (Fig.…”

Section: X-ray Diffractionmentioning

confidence: 88%

“…The diffraction pattern of the NFYa-CD CE system is equivalent to that of the PM, showing the main peaks of the cage a-CD structure at 2q = 12.1-, 14.3-, and 21.7- (26). On the other hand, the diffraction pattern of the NFYa-CD KN product exhibits the channel a-CD peak at 2q = 13-with high intensity, but there are no changes either in the characteristic cage peak at 2q = 21.7-or that corresponding to the channel type at 2q = 20-, suggesting an intermediate structure in the KN solid (26).…”

Section: X-ray Diffractionmentioning

confidence: 99%

“…Likewise, the X-ray diffraction patterns and the DTA curves of CE and KN products of pure a-CD present the same differences as those obtained from the NFYaCD CE and KN products. Even though the hydrated crystals of natural CDs usually adopt the cage structure, the amount of water in the crystallization process determines the structure of crystals (11,26,27).…”

Section: X-ray Diffractionmentioning

confidence: 99%

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Characterization of Complexes Between Naftifine and Cyclodextrins in Solution and in the Solid State

et al. 2006

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Naftifine (NF) is an antifungal drug poorly soluble in basic aqueous solutions. Complexation with cyclodextrins (CDs) improves the physicochemical characteristics of many drugs. The aim of this work is to characterize the interactions between NF and alpha-CD, beta-CD, hydroxypropylbeta-CD, methylbeta-CD, and gamma-CD. The studies have been developed in pH 12 aqueous solutions at 25 degrees C and in the solid state. The apparent stability constants of the complexes have been determined from phase-solubility diagrams. In the solid state, crystalline and amorphous complexes have been characterized using X-ray diffraction patterns, thermal analysis, and Fourier transform infrared spectroscopy. The solubility of NF improves with all the CDs studied, with the exception of alpha-CD. Different types of diagrams have been found depending on the CD used. The interaction between NF and hydroxypropylbeta-CD is stronger than that with beta-CD due to the specific properties of the substituents. The coevaporation method can be said the best method in preparing the solid complexes, except for NF-alpha-CD; again, there is no evidence of complexation. Furthermore, the presence of different types of CD structures upon complexation (i.e., cage or channel) has been discussed. Dissolution rate studies have been performed, and a positive influence of complexation in the solid state has been observed.

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Structure and stability of columnar cyclomaltohexaose (α-cyclodextrin) hydrate

Cited by 35 publications

References 23 publications

Composition dependence and the nature of endothermic freezing and exothermic melting

Composition dependence and the nature of endothermic freezing and exothermic melting

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) as a novel and effective solvent to facilely prepare cyclodextrin-assembled materials

Characterization of Complexes Between Naftifine and Cyclodextrins in Solution and in the Solid State

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