Unusual<sup>1</sup>C<sub>4</sub>conformation of a methylglucose residue in crystalline permethyl-β-cyclodextrin monohydrate

Caira, Mino R.; Griffith, Vivienne J.; Nassimbeni, Luigi R.; Oudtshoorn, Bosch van

doi:10.1039/p29940002071

Cited by 70 publications

(69 citation statements)

References 8 publications

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“…Correlation of O4(n)‚‚‚O4(n-1) distance with torsion angle index in R-cyclodextrin complexes with parasubstituted benzenes (O, brick-type cage motif); complexes with herringsbone cage motif (b) and with channel-type motif (4). Torsion angle index defined as: 19,20 …”

Section: Two Types Of Crystal Structures: Channels and Cagesmentioning

confidence: 99%

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

et al. 1998

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Section: Two Types Of Crystal Structures: Channels and Cagesmentioning

confidence: 99%

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

et al. 1998

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“…In fact, deviations from the preferred pyranose ring conformation have been observed for non-reducing end pyranose rings in single-molecule atomic force microscopic studies of dextran [52], MD simulations of cellulose [53] and X-ray crystallographic studies of b-cyclodextrin [54], abrin [55] and neuraminidase± sialic acid complex [56].…”

Section: Pyranose Ring Conformationmentioning

confidence: 99%

“…A soft potential was used for calculating the van der Waals interactions between united atoms separated by three bonds. The dielectric constant was set to its default value (54). No explicit term was used for hydrogen bonding interactions.…”

Section: Software and Force ®Eldmentioning

confidence: 99%

Comparative analysis of ganglioside conformations by MD simulations: implications for specific recognition by proteins

Vasudevan

Balaji

2002

Journal of Molecular Structure: THEOCHEM

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“…6 This collapsed overall conformation was attributed mainly to the tendency for the molecule to minimise the hydrophobic cavity size in the absence of a guest molecule. The extent of ellipticity is measured by the seven 'radial' distances O4Gn … Cg, where Cg is the centre of gravity of the seven O4Gn atoms.…”

mentioning

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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Unusual¹C₄conformation of a methylglucose residue in crystalline permethyl-β-cyclodextrin monohydrate

Cited by 70 publications

References 8 publications

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

Comparative analysis of ganglioside conformations by MD simulations: implications for specific recognition by proteins

New crystalline forms of permethylated β-cyclodextrin

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Unusual1C4conformation of a methylglucose residue in crystalline permethyl-β-cyclodextrin monohydrate

Cited by 70 publications

References 8 publications

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

Structures of the Common Cyclodextrins and Their Larger AnaloguesBeyond the Doughnut

Comparative analysis of ganglioside conformations by MD simulations: implications for specific recognition by proteins

New crystalline forms of permethylated β-cyclodextrin

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Product

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Unusual¹C₄conformation of a methylglucose residue in crystalline permethyl-β-cyclodextrin monohydrate