4- Nitrophenol, cyclodextrin inclusion

GEOMETRY OF a-CYCLODEXTRIN INCLUSION COMPLEX WITH m-NITROPHENOL DEDUCED FROM QUMTUM CHEMICAL ANALYSIS OF CARBON-13 CHEMICAL SHIFTS... 

Chujo - The geometry of the alpha cyclodextrin inclusion complex with m-nitrophenol deduced from quantum chemical analysis and i C chemical shifts Ishlzakl, H. - See Sakuraba, H. et al. 

The importance of the proximity effect in cyclodextrin catalysis has been discussed on the basis of the structural data. Harata et al. 31,35> have determined the crystal structures of a-cyclodextrin complexes with m- and p-nitrophenols by the X-ray method. Upon the assumption that m- and p-nitrophenyl acetates form inclusion complexes in the same manner as the corresponding nitrophenols, they estimated the distances between the carbonyl carbon atoms of the acetates and the adjacent second-... 

This review will illustrate examples of computer projected models of inclusion complexes of structural isomers (ortho, meta, para nitrophenol), enantiomers (d- and 1- propranolol) and diastereomers [cis and trans. l(p-B-dimethylaminoethoxy-phenyl-butene), tamoxifen] in either a- or B-cyclodextrin. The use of these computer projections of the crystal structures of these complexes allows for the demonstration and prediction of the chromatographic behavior of these agents on immobilized cyclodextrin. 

Figure 2. Computer imaging of crystal structures of the inclusion complexes of para (A), meta (B) and ortho (C) nitrophenol with a-cyclodextrin. The complex is shown with van der Waal s radii, and the front section of the complex cut away in order to expose the nitrophenol molecule.

For example, the time-averaged conformation of the inclusion complex between a-cyclodextrin and w-nitrophenol was determined by this method as shown in Fig. 

This paper describes the elution behavior of benzene, ortho-, meta-, and para-nitrophenol, naphthalene, and biphenyl in aqueous and methanolic cyclodextrin mobile phases. The inclusion complex formation constants of these selected compounds in e-CD mobile phases containing 0%, 10%, and 20% methanol are reported. The formation constants obtained using a CN column/CD mobile phase were determined and used to predict the elution behavior of the test compounds on C-18 columns. Also, the elution behavior of solutes on C-18, e-CD, and Y-CD stationary phases are compared. 

ABSTRACT. The geometries of inclusion complexes of a-cyclodextrin(a-CD) with guests, benzoic acid, p-hydroxy benzoic acid, and p-nitrophenol in aqueous solution have been determined by comparing the complexation induced C-13 shifts of guest molecules with quantum chemical predictions. In the calculations, the non-polar environmental effect produced by the a-CD cavity on the C-13 shifts of included guest molecule has been formulated by the so-called solvent effect theory. The geometries of the complexes predicted theoretically were consistent with those... 

Figure 2. Solid state CP/MAS 25 MHz CNMR spectra of (A) a-cyclodextrin-p-nitrophenol inclusion complex I and, (B) p-nitrophenol, recrystallized from water.

High resolution carbon-13 NMR spectroscopy is one of the most useful methods in the analysis of the structure and molecular dynamics of cyclodextrin inelusion-complexes both in aqueous solution[1,2] and in the solid state[3]. Earlier cariDon-13 NMR studies of a-CD inclusion complexes with benzoic acid, p-nitrophenol, and p-nitrophenolate in aqueous solution have shown that the included lead(head see Fig.lA) carbons show high-field shifts compared to low-field shifts of corresponding para(tail Fig.lA) carbons[4,5]. Similar distinctive patterns of carbon-13 displacement s have been also observed for p-hydroxybenzoic acid and it has been concluded that the carboxyl group of p-hydroxybenzoic acid is directed into the a-CD cavity [4]. A variety of substituted benzenes are known to show quite similar carbon-13 high (head) and low (tail) field shifts, irrespective of the kinds of substituents if their size are matched to the a-CD cavity [4,5]. These characteristic carbon-13 displacements induced by complexation with a-CD... 

Other workers describe how addition of carbon disulfide to hepta-6-amino-6-deoxy-p-cyclodextrin in the presence of ammonia gas affords a mixture of partially substimted dithiocarbamate derivatives. When bound to a silver electrode, they are capable of discriminating between the three positional isomers of the nitrobenzoate ion and nitrophenol (as detected by cyclic voltammetry) an effect that is attributed to the different orientations of the nitro group with respect to the silver surface after inclusion in the cyclodexttin cavity (1835). 

Tojima, T., Katasura, H., Nishiki, M., Nishi, N., Tokura, S., and Sakairi, N. 1999. Chitosan beads with a-cyclodextrin Preparation and inclusion property to nitrophenolates. Carbohydr. Polym. 40 17-22. 

---