Crystal and molecular structure of a 2,6-tetradeca-O-methyl-β-cyclodextrin–adamantanol 1 : 1 inclusion complex

Czugler, Mátyás; Eckle, Emil; Stezowski, John J.

doi:10.1039/c39810001291

Cited by 53 publications

(23 citation statements)

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“…13-CD molecules present only slight differences with respect to uncomplexed hydrated or methylated CDs or CDs monosubstituted with bulky groups (26)(27)(28)(29)(30). All glucosidic units are in the 4C1 chair conformation (endocyclic torsion angles all show gauche conformation), and they are related by an approximate sevenfold axis.…”

Section: Resultsmentioning

confidence: 99%

Conformation for a beta-cyclodextrin monosubstituted with a cyclic dipeptide.

Blasio

Pavone

Nastri

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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The structural characterization of a (3-cyclodextrin monosubstituted with the peptide cyclo(L-HiS-L-Leu) is reported. This work provides an x-ray example of a covalently bound group that folds In such a way that the terminal apolar side chain is retained in the hydrophobic interior of the cone-shaped cyclodextrin cavity. 6-Deoxy-6-cycldo(L-histldyl-Lleucyl)-ig-cydodextrin crystallizes in the space group P 1 with cell dimensions a = 14.728 (8) Cyclodextrins (CDs) represent an interesting class of cyclic oligosaccharides constituted by 6-12 D-glucopyranosyl units, linked by a(1-4)-glycosidic bonds (1, 2). Among the known CDs, 1-CD (or cycloheptaamylose) is one of the most widely investigated so far. Crystallographic studies (3-5) have established that CDs are truncated cone-shaped cyclic molecules with glucose units in the 4C1 chair conformation. Because of the presence of the cavity and of primary hydroxyl groups, these cycloamyloses have been used for building molecular models with peculiar properties (6, 7). Furthermore, it has been shown that cyclo(L-histidyl-L-prolyl), a dipeptide with hormonal and neurotropic activity (8-13), inhibits the (Fe+ ascorbic acid)-induced peroxidation of skeletal muscle sarcoplasmic reticulum membrane lipids (14). Bavykina et al. (15) recently published the synthesis of diketopiperazines (DKPs) related to cyclo(L-histidyl-L-prolyl) and attributed the biological behavior ofthis molecule to the antioxidant activity ofthe cyclodipeptide. This suggests that DKP derivatives may be used as antiinflammatory agents (16)(17)(18)(19). In this context, we report here an example of structural characterization by x-ray diffraction analysis of a 13-CD monosubstituted with a potentially bioactive cyclic dipeptide-namely, 6-deoxy-6-cyclo(Lhistidyl-L-leucyl)-1-CD (cHL-,1CD) (Fig.

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Section: Resultsmentioning

confidence: 99%

Conformation for a beta-cyclodextrin monosubstituted with a cyclic dipeptide.

Blasio

Pavone

Nastri

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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“…DM-b-CD is a b-CD derivative in which the hydroxy groups at positions 2 and 6 in each glucose unit are methylated. It has the same cavity diameter as b-CD, but a larger cavity size since the orientation of the 6-O-methyl substituents extends the height of the hydrophobic torus [22]. Compared with b-CD, DMb-CD shows the stronger binding with each of the two ions.…”

Section: Binding Constantsmentioning

confidence: 98%

Comparison of binding of tetraphenylborate and tetraphenylphosphonium ions to cyclodextrins studied by capillary electrophoresis

Nhujak

Goodall

2001

Electrophoresis

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Binding constants for tetraphenylborate and tetraphenylphosphonium ions (Ph4B- and Ph4P+) to cyclodextrins (CDs) to give 1:1 host-guest complexes have been measured using capillary electrophoresis. Mobilities of the ions as a function of gamma-CD concentration give binding constants, K, of 1.08 x 10(5) M-1 for Ph4B- and 0.6 x 10(1) M-1 for Ph4P+. This dramatic difference of four orders of magnitude in binding constants is not seen with beta-CD (K = 7.7 x 10(1) M-1 for Ph4B- and 3.7 x 10(1) M-1 for Ph4P+) or dimethyl (DM)-beta-CD (K = 46 x 10(1) M-1 for Ph4B-1 and 7.7 x 10(1) M-1 for Ph4P+). The crystal and hydrodynamic radii of the ions, the latter calculated from their absolute mobilities, indicate that Ph4B- is smaller than the gamma-CD cavity, whereas Ph4P+ is approximately the gamma-CD cavity size. Results suggest that Ph4B- fits exactly into a gamma-CD cavity, with hydrophobic contacts involving several of the phenyl rings, whereas Ph4P+ is too large to enable these multiple contacts to be made. When only a single phenyl ring can fit into the CD cavity, binding strengths are in the order DM-beta-CD > beta-CD > gamma-CD and Ph4B- > Ph4P+. Measurement of electrophoretic mobilities of the complexes shows that their hydrodynamic radii are in the order gamma-CD < beta-CD approximately DM-beta-CD for Ph4B- and gamma-CD > beta-CD approximately DM-beta-CD for Ph4P+.

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“…For example, by methylation, the depth of the cavity is extended from 780 pm to ~ 1100 pm and the hydrophilic nature of both ends of the cyclodextrin cavity is changed due to the methyl groups attached to the O-2, O-3, or O-6 of the cyclodextrin. Thus, the cavity can fully accommodate adamantanol and naphthalene derivatives [19,20].…”

Section: Dimensionsmentioning

confidence: 99%