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A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS) with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

Photoinduced electron transfer was observed in the supramolecular complexes of p-nitrobenzoyl-beta-cyclodextrin (NBCD) with a number of naphthalene derivatives, which were stabilized clearly via hydrophobic interactions in aqueous solution. Both steady-state and time-resolved fluorescence measurements were conducted, which revealed that there were two routes of electron transfer, i.e., electron transfer between the free donor and free acceptor in solution and electron transfer between the donor and acceptor bound in a supramolecular assembly. The evidence collected demonstrates that the latter route was very efficient. As a result, the rate and quantum yield of the fluorescence quenching in the present supramolecular system were appreciably large.

A series of hydroxypropyl-beta-cyclodextrins was prepared by a method that leads to a preferential substitution on the secondary hydroxyls, mainly O-2, of beta-cyclodextrin with (S)-2-hydroxypropyl groups. The series consisted of mixtures of compounds with average degrees of substitution of 8, 3, and 1.6 and of a specially isolated monosubstituted compound; thus, the number of components progressively decreased in this series. The crystallinity in the series increased progressively, the first member being fully amorphous and the last one fully crystalline. All members of the series formed clear aqueous solutions at concentrations of greater than 50.0, 2.0, 0.6, and 0.3%, respectively. Therefore, pharmaceutically useful hydroxypropylcyclodextrin preparations are those containing a large number of chemically individual compounds--a feature resulting in an amorphous state and high water solubility.

Branched cyclomalto-oligosaccharides (cyclodextrins) were synthesised from cyclomalto-oligosaccharides and maltose or maltotriose through the reverse action of Pseudomonas isoamylase. The reaction rate was greater with maltotriose than with maltose, and with increasing size of the cyclomalto-oligosaccharide (cG6 less than cG7 less than cG8). Maltotriose is effective as both a side-chain donor and acceptor, and three isomers of 6-O-alpha-maltotriosylmaltotriose (branched G6) were formed through mutual condensation, but maltose was effective only as a side-chain donor. Each branched cyclomalto-oligosaccharide and G6 was purified by liquid chromatography, and their structures were determined by chemical, enzymic, and 13C-n.m.r. spectroscopic analyses.

The synthesis is described of a derivative of cyclomaltoheptaose (beta-cyclodextrin) to which the tripeptide Ser-His-Asp, the catalytic triad found in chymotrypsin, has been coupled. The derivative enhanced the rates of hydrolysis of activated esters, as measured by the release of p-nitrophenol, and the formation of amine bonds.

Hydrolysis of 6-deoxyamylose and mono-6-deoxy-6-fluorocyclomaltoheptaose by porcine-pancreatic alpha amylase produces low-molecular-weight modified products, which have been analyzed by chemical and chromatographic techniques. Results for both substrates show that modified D-glucose and two isomers of modified maltoses are produced in the enzyme reaction. In addition, the formation of maltoses modified in the nonreducing residue is more favored than the formation of maltoses modified in the reducing residue. These results indicate that productive binding of 6-fluoro- and 6-deoxy-D-glucose residues is permitted at subsites 1 through 4 of the amylase-active site but that binding of these modified residues may be less favorable at subsite 3, the subsite at which catalytic attack occurs.