Crystallization of two forms of a cyclodextrin inclusion complex containing a common organic guest

Caira, Mino R.; Vries, Elise J. C. de; Nassimbeni, Luigi R.

doi:10.1039/b305784b

Cited by 34 publications

(22 citation statements)

References 8 publications

(8 reference statements)

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“…The XRD pattern of 2 is quite different from that of b-CD, and formation of a channeltype array of the CD molecules (Scheme 1) in the solid state is suggested based on the similarity of the XRD pattern to that of a reported b-CD pseudorotaxane of methylparaben. [12] These data agree with the assumption that 2 is a waterinsoluble pseudopolyrotaxane threaded by densely packed b-CD on the polymer.…”

Section: Pthsupporting

confidence: 81%

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β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles

Yamaguchi

Yamamoto

2004

Macromol. Rapid Commun.

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Summary: β‐Cyclodextrin (β‐CD) pseudopolyrotaxanes containing poly(thiophene‐2,5‐diyl), PTh, or poly(3‐methylthiophene‐2,5‐diyl)s, P3MeThs, as an axle were prepared. Structures of the pseudopolyrotaxanes and their inclusion behavior with β‐CD were investigated. The UV‐vis measurements revealed that inclusion of P3MeThs by β‐CD depended on the flexibility of the main chain and their molecular weight.Formation of the inclusion complex of β‐CD and PTh.imageFormation of the inclusion complex of β‐CD and PTh.

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Section: Pthsupporting

confidence: 81%

“…Similar higher reactivity of CDs toward polymers with higher flexibility has been reported. [5,12] After 7 d, the absorbance at 441 nm of 5 started to decrease gradually, suggesting the formation of a water-insoluble pseudopolyrotaxane.…”

Section: P3methmentioning

confidence: 99%

β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles

Yamaguchi

Yamamoto

2004

Macromol. Rapid Commun.

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“…6 However, only a few examples of polymorphism are found in the CD inclusion complexes: b-CD with methyl-4-hydroxybenzoate 7 and barbital. 8 Recently, we have reported the detailed structure of the b-CDbenzoic acid(BA) inclusion complex (form I) by means of single crystal X-ray diffraction. 9 b-CD dimer accommodates two BA molecules forming a 2:2 inclusion complex.…”

mentioning

confidence: 99%

Polymorphism in β-cyclodextrin–benzoic acid inclusion complex: a kinetically controlled crystal growth according to the Ostwald’s rule

Aree

Chaichit

Engkakul

2008

Carbohydrate Research

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“…1 On the other hand, crystal polymorphism, the inverse of isostructurality, 2 was also demonstrated for cyclodextrins in our recent report on the structural characterization of two crystalline forms of the inclusion complex b-cyclodextrin-methyl paraben, isolated at different temperatures. 3 The present report relates to the polymorphism of permethylated b-cyclodextrin [heptakis(2,3,6-tri-O-methyl)-b-cyclodextrin, commonly known as TRIMEB], widely used as a solubilising agent and as host for the encapsulation of organic molecules, 4 including drugs. 5 In 1994, we isolated single crystals of this host as the monohydrate from an aqueous solution of TRIMEB maintained at 50 uC.…”

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confidence: 99%

New crystalline forms of permethylated β-cyclodextrin

et al. 2004

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Two new crystalline forms of permethylated b-cyclodextrin are reported that contain methylglucose residues exclusively in the 4 C 1 conformation, in contrast to the known monohydrate, in which a single methylglucose residue adopts the 1 C 4 conformation.In recent reports, we have focused on two intriguing aspects of the solid-state chemistry of cyclodextrins, namely isostructurality and polymorphism, both of which have practical implications for the continued use of these molecules as drug carriers. Systematic classification of the crystal structures of native and derivatised cyclodextrins, and their inclusion complexes, into isostructural series has proven useful in our laboratory for the definitive identification from X-ray powder diffraction of new inclusion complexes formed by these macrocyclic oligosaccharides. 1 On the other hand, crystal polymorphism, the inverse of isostructurality, 2 was also demonstrated for cyclodextrins in our recent report on the structural characterization of two crystalline forms of the inclusion complex b-cyclodextrin-methyl paraben, isolated at different temperatures. 3 The present report relates to the polymorphism of permethylated b-cyclodextrin [heptakis(2,3,6-tri-O-methyl)-b-cyclodextrin, commonly known as TRIMEB], widely used as a solubilising agent and as host for the encapsulation of organic molecules, 4 including drugs. 5 In 1994, we isolated single crystals of this host as the monohydrate from an aqueous solution of TRIMEB maintained at 50 uC. X-Ray structural analysis revealed that six of the seven methylglucose residues adopt the normal 4 C 1 conformation while the seventh is in the inverted 1 C 4 conformation. 6 A second structure determination of this phase was subsequently reported. 7 To our knowledge, this remains the only known case of ring-inversion in cyclodextrin solid-state chemistry. The resultant, highly distorted conformation of the TRIMEB molecule contrasted strongly with the more regular conformations it adopts in its inclusion complexes.We refer to the above crystal monohydrate as Form 1, in view of our recent isolation of two new crystalline modifications of TRIMEB, namely a trihydrate (Form 2) and an anhydrate (Form 3), which are the subject of this report. These new forms are isostructural with respect to the host molecule, the latter having all seven methylglucose residues in the normal 4 C 1 conformation. Both crystal forms were isolated from failed attempts to obtain inclusion complexes of TRIMEB with drug molecules.{ In all of the experiments performed, the starting host material corresponded to the known monohydrate, Form 1. The trihydrate (Form 2) crystallised from a solution containing TRIMEB and the antihypertensive drug atenolol (4-[2-hydroxy-3-[(1-methylethyl)-amino)propoxy]benzeneacetamide, either in the form of enantiopure (S)-atenolol or as the racemate), in 1 : 1 host-guest molar ratio, as well as from a solution containing TRIMEB and the analgesic drug bucetin (N-(4-ethoxyphenyl)-3-hydroxybutanamide) in 1 : 1 molar ratio. When the cry...

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Crystallization of two forms of a cyclodextrin inclusion complex containing a common organic guest

Abstract: The isolation and structural elucidation by single crystal X-ray diffraction of triclinic and monoclinic modifications of an inclusion complex of beta-cyclodextrin with the same guest, methylparaben, are reported.

Cited by 34 publications

References 8 publications

β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles

β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles

Polymorphism in β-cyclodextrin–benzoic acid inclusion complex: a kinetically controlled crystal growth according to the Ostwald’s rule

New crystalline forms of permethylated β-cyclodextrin

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