Yoshinori Kawaguchi

Macromolecular recognition: new cyclodextrin polyrotaxanes and molecular tubes

It was found that cyclodextrins (CDs, α-, β- and γ-CD) formed inclusion complexes not only with hydrophilic polymers, such as poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG) and poly (methyl vinyl ether) (PMVE), but also with hydrophobic polymers, such as oligoethylene, polypropylene, polyisobutylene and polyesters. α-CD formed complexes with oligoethylene, although β- and γ-CD did not under the same conditions. γ-CD formed complexes with polyisobutylene in high yield, although α-CD did not. There is a good correlation between the sizes of cavities of cyclodextrins and the cross-sectional areas of the polymers. The polymer complexes are crystalline and polyrotaxane-type inclusion complexes. It was also found that cationic polymers such as viologen polymers and polyionenes form complexes with cyclodextrins to give soluble complexes in water. New polyrotaxanes in which many CDs are threaded on to polymer chains have been prepared by capping both polymer ends by large stoppers. Copyright

Complex Formation Between Poly(dimethylsilane) and Cyclodextrins

Poly(dimethylsilane)s form inclusion complexes with cyclodextrins in high selectivity to give crystalline compounds. β-Cyclodextrin forms complexes with poly(dimethylsilane)s of low molecular weight only, γ-cyclodextrin with poly(dimethylsilane)s of high molecular weight in high yield, and α-cyclodextrin does not form complexes with poly(dimethylsilane) at all. Complexes were isolated and characterized by spectroscopic methods and X-ray diffraction.

Supramolecular Polymers Formed by Modified Cyclodextrins

Abstract6-Hydrocinnamoyl α-cyclodextrin(6-HyCiO-α-CD), 6-hydrocinnamoyl β-cyclodextrin(6-HyCiO-β-CD), 6-cinnamoyl α-cyclodextrin(6-CiO-α-CD), and 6-cinnamoyl β-cyclodextrin (6-HyCiO-β-CD) have been prepared.6-HyCiO-β-CD formed an intramolecular complex in an aqueous solution. 6-HyCiO-α-CD formed weak intermolecular complexes.6-CiO-α-CD formed intermolecular complexes to give supramolecular oligomers. 6-CiO-β-CD formed insoluble supramolecular complexes in the solid state. The structures of these complexes are discussed.

Complex formation of cyclodextrins with poly(propylene glycol) derivatives

The complex formation between cyclodextrins (CDs) and poly(propylene glycol) (PPG) derivatives is described. β-CD and γ-CD formed complexes with PPG derivatives such as 1-naphthyl (1NA), 2-naphthyl (2NA), 3,5-dinitrobenzoyl, and 2,4-dinitrophenyl PPG. α-CD did not form complexes with these PPG derivatives. Although γ-CD gave complexes with 9-anthryl PPG (PPG9An), β-CD did not efficiently form complexes with PPG9An. β-CD did not form complexes with trityl PPG, demonstrating that trityl groups were too bulky to thread a (3-CD cavity. The emission spectra of the complexes showed that β-CD bound a single 2NA moiety in its cavity and that γ-CD included two 2NA moieties. In contrast, γ-CD bound a single 1NA moiety in the cavity. X-ray diffraction studies and 1 H NMR analysis showed that the CD molecules were stacked along a PPG chain to form a channel structure. The inclusion modes are discussed.