Cyclodextrin solute inclusion complexation

The cyclodextrin-solute inclusion complexation is a reversible reaction with an equilibrium constant similar... 

Azobenzene amphiphiles can be isolated from each other and equipped with sufficient free volume for reversible photoisomerization by inclusion into amphiphilic P-cyclodextrin. The inclusion complex can be transferred to give LBK films in which the azobenzene moieties photoisomerize as they would in solution (see Figure 6.11). ... 

In addition, Harada et al. have recently found that /1-cyclodextrin and y-cyclodextrin formed inclusion complexes with poly(dimethylsiloxane) (PDMS), a typical inorganic polymer in aqueous solution [111, 112]. The au-... 

Simultaneously with the Harada s report on the first polyrotaxane, Wenz reported the preparation of polyrotaxanes from polyamines and a-cyclodex-trin in an aqueous solution [108]. a-Cyclodextrin forms inclusion complexes with poly(iminoundecamethylene) and poly(iminotrimethylene-iminode-camethylene) (Scheme 17). The rates of the inclusion of poly(iminounde-camethylene) by a-cyclodextrin are slow on the H NMR time scale in D20 at pH<6. The inclusion formation between poly(iminotrimethylene-imin-odecamethylene) and a-cyclo dextrin took 170 h to reach equilibrium. Wenz... 

Yui et al. found that a-cyclodextrin formed inclusion complexes with poly(e-lysine) in aqueous solution [151]. The inclusion complexation is controllable by changing several parameters, such as the molar composition between poly(e-lysine) and a-cyclodextrin, the pH and the ionic strength of aqueous media [152]. Yui s group is actively developing new polyrotaxane drugs utilizing multi-valent interactions [153-155]. 

Yan and Dong found that -cyclodextrin forms inclusion complexes with linear alka-nethiols in bulk medium and thereby effects solubilization of alkanethiols in the aqueous solution of -cyclodextrin. Such complexes self-assemble on the gold surface to give stable monolayers . 4,4 -Bipyridinium (viologen) containing thiols also form inclusion complexes with cyclodextrins in bulk solution which can be used to prepare self-assembled... 

It has been shown that amylose forms inclusion complexes with iodine and many kinds of organic compounds in aqueous solution. Thus, the most probable model for the interaction of aunylose with TNS is an inclusion complex. Since cyclodextrins form inclusion complexes with TNS and enhance TNS fluorescence in aqueous solution ( ), it is interesting to compare fluorescence decay parameters for TNS-atmylose system with those for TNS-cyclodextrin systems. The values of lifetimes for amylose are the same as those for Y-cyclodextrin. However, the relative content of the long lifetime for amylose is much smaller than that for Y-cyclodextrin.Y -Cyclodextrin is expected to form both 1 1... 

Fluorescence Spectroscopy Fluorescence spectroscopy comes into play when fluorescent molecules in aqueous solution are included in cyclodextrins. The inclusion complex formation generally leads to the change of excitation and emission wavelength of the drug [56]. 

Several intermolecular interactions have been proposed and discussed as being responsible for the formation of cyclodextrin inclusion complexes in an aqueous solution 6-10). They are... 

Water plays a crucial role in the inclusion process. Although cyclodextrin does form inclusion complexes in such nonaqueous solvents as dimethyl sulfoxide, the binding is very weak compared with that in water 13 Recently, it has been shown that the thermodynamic stabilities of some inclusion complexes in aqueous solutions decrease markedly with the addition of dimethyl sulfoxide to the solutions 14,15>. Kinetic parameters determined for inclusion reactions also revealed that the rate-determining step of the reactions is the breakdown of the water structure around a substrate molecule and/or within the cyclodextrin cavity 16,17). 

Lopez-Nicolas JM, Bru R, Sanchez-Ferrer A and Garcia-Carmona F. 1995. Use of soluble lipids for biochemical processes linoleic acid cyclodextrin inclusion complexes in aqueous solutions. Biochem J 308 151-154. 

Complexes of metal cations with carbohydrates in solution, 47, 1 -43 Courtois, Jean Emile, obituary of, 49,11 -18 Cyclomalto-oligosaccharides(cyclodextrins), inclusion complexes of, 46, 205-249 addendum to, 46, 333-335... 

An important advantage of the inclusion complexes of the cyclodextrins over those of other host compounds, particularly in regard to their use as models of enzyme-substrate complexes, is their ability to be formed in aqueous solution. In the case of clathrates, gas hydrates, and the inclusion complexes of such hosts as urea and deoxycholic acid, the cavity in which the guest molecule is situated is formed by the crystal lattice of the host. Thus, these inclusion complexes disintegrate when the crystal is dissolved. The cavity of the cyclodextrins, however, is a property of the size and shape of the molecule and hence it persists in solution. In fact, there is evidence that suggests that the ability of the cyclodextrins to form inclusion complexes is dependent on the presence of water. Once an inclusion complex has formed in solution, it can be crystallized however, in the solid state, additional cavities appear in the lattice, as in the case of the hosts previously mentioned, which enable the inclusion of further guest molecules. ... 

The majority of reported studies of formation of cyclodextrin inclusion complexes in solution have been mainly concerned with determination of the stability constants by using equilibrium spectroscopic techniques, and the measurement of the enthalpy and entropy changes characterizing the complexation reaction. The aim of much of this work has been to determine the driving force of complex-formation. Despite the amount of research in this area, however, no general agreement has been reached, and... 

The cyclodextrins are not the only molecules capable of forming inclusion complexes ( Einschlussverbindungen ). In contrast to the inclusion complexes of many other host molecules, however, those of the cyclodextrins are able to form in solution as well as in the solid state, a fact which was first recognized by Cramer, " after he had observed that... 

In a study of the formation of an inclusion complex between beta cyclodextrin and indole, the stability constant in aqueous solution was found, on the addition of formamide, to decrease, accompanied by a... 

Decene was hydrocarboxylated with a [PdClaj/TPPTS catalyst in acidic aqueous solutions (pH adjusted to 1.8) in the presence of various chemically modified cyclodextrins (Scheme 10.11) [18]. As in most cases, the best results were obtained with DiOMe-P-CD. In an interesting series of reactions 1-decene was hydrocarboxylated in 50 50 mixtures with other compounds. Although all additives decreased somewhat the rate of 1-decene hydroformylation, the order of this inhibitory effect was 1,3,5-trimethylbenzene < cumene < undecanoic acid, which corresponds to the order of the increasing stability of the inclusion complexes of additives with p-CD, at least for 1,3,5-trimethylbenzene (60 M ) and cumene (1200 M ). These results clearly show the possible effect of competition of the various components in the reaction mixture for the cyclodextrin. 

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