Inclusion modes

The inclusion modes of flurbiprofen with beta cyclodextrin and with heptakis(2,3,6-tri-0-methyl)-beta cyclodextrin have been studied by Imai and coworkers. They showed that, although the Cotton effects in the circular dichroic spectra induced by beta cyclodextrin in / (-) and 5(+) flurbiprofen are identical, those induced by heptakis(2,3,6-tri-0-methyl)-beta cyclodextrin differ from each other and from those induced by beta cyclodextrin. C.p.-m.a.s. C-n.m.r. experiments showed that the cyclodextrin ring is probably more distorted in the flurbiprofen inclusion complex with methylated beta cyclodextrin than in that with beta cyclodextrin. 

The guest molecules having a benzene ring are included by a-cyclo-dextrin at the very similar position (depth) of the cavity, independent of the different inclusion mode for para- and meta-substituted benzene, e.g., as seen in Fig. 6. 

Typical Inclusion Modes of Benzene Derivatives by Cyclodextrins... 

Values for two different inclusion modes in the single crystal. 

To confirm the inclusion mode for a sec. amine, the 1 1 piperidine 4 (n = 1) complex was isolated and its molecular structure was determined by X-ray analysis (Fig. 10) [22], The chromophore is planar (except the o-nitro group) within 0.1 A, to which the cyclic polyether ring extends perpendicularly. The protonated piperidine having a chair form structure is placed on the crown ring and stabilized by very short N+ —H—O- (2.65 A) and N+ —H—O (2.93 A) hydrogen bonds, and two N + —O ion-dipole interactions (3.17 and 3.16 A). The remaining ether oxygen, 0(2), seems to be ineffective on the complexation. 

Inclusion complexation of prednisolone with three Cyclodextrins, a (3 and 7-homologues, in aqueous solution and in solid phase was examined using UV absorption, CD, C 13 NMR, C 13-CP/MAS-NMR, X-ray diffractometry and thermal analysis. The spectroscopic data suggested the different inclusion mode of prednisolone within the three cyclodextrin cavities. X-ray diffraction patterns of the complexes differed significantly from those of the physical mixtures (14). 

Fig. 14.1. Proposed inclusion modes of prostaglandin E] with three native CyDs [23],...

Fig. 14.10. Proposed inclusion modes of metoprolol (Met) with three native CyDs [23] (A) a-CyD complex with the methoxyethyl-benzene moiety of Met inserted from the seconda7 hydroxyl side of a-CyD (B) jS-CyD complex with the methoxyethylbenzene moiety...

X-ray diffractometry and thermal analysis, using an antiinflammatory drug flurbiprofen(FP) as a guest molecule. The spectral data suggest that the inclusion mode of FP—TM-3 CyD is somewhat different from those of FP—3"CyD and FP—DM-3-CyD, The solid complexes of FP with 3 ... 

The C-NMR technique was employed to gain insight into the inclusion modes of FP—3 GyD complexes in aqueous solution. The effects of FP on C-chemical shifts of three 3 CyDs are summarized in Table III. The values in Table III and IV were calculated using eq. (1) (13) along with the stability constants of inclusion complexes. 

Furthermore, C-NMR spectroscopy can also be used to gain insight into the inclusion modes of inclusion complexes in aqueous solution. The cyclodextrin-induced change in the chemical shift results predominantly from the electrical environment effect of the cyclodextrin cavity [59]. 

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