The Stability of Cyclodextrin Complexes in Solution.

Fluorescence and phosphorescence from higher excited states of organic molecules.

Ultrafast guest dynamics in cyclodextrin nanocavities.

Cyclodextrins (CyDs) are cyclic oligosaccharides, containing a minimum of six D-(+)-glycopyranose units attached by α-1, 4-linkages produced by the action of the cyclodextrin-trans-glycosidase enzyme on a medium containing starch. CyDs are somewhat cone-shaped. The outside of CyDs is hydrophilic and the inside of the cavity is hydrophobic in character. If a molecule fits entirely or at least partially into the cavity, an inclusion complex may be formed. In general, hydrophobic molecules, rather than hydrophilic ones, have a higher affinity to the CyD cavity in aqueous solutions. The CyD complexes thus formed are stabilized by various intermolecular forces, such as hydrophobic interaction, van der Waals forces, hydrogen bonding, release of high energy water molecules in complex formation and release of strain energy in the macromolecular CyD ring. Orally administered CyDs have shown to be harmless, because insignificant amounts are absorbed.Parenterally administered natural CyDs may cause severe ne...

Cyclodextrins in the Pharmaceutical Field

Cyclodextrine werden gerne als Bausteine eingesetzt, da sie sich gezielt sowohl kovalent, als auch nichtkovalent verknupfen lassen. So wurden an ein β-Cyclodextrinmolekul regioselektiv ein, zwei, drei, sieben, vierzehn, achtzehn oder zwanzig Substituenten kovalent gebunden. Cyclodextrine sind zudem organische Wirtmolekule. In ihrem Innenraum finden ein oder zwei Gastmolekule Platz. Umgekehrt konnen ein, zwei oder viele (hundert und mehr) Cyclodextrinmolekule auf ein passendes Gastmolekul aufgefadelt werden. Solche supramolekularen Strukturen entstehen meist in Losung, so das sie durch hochauflosende spektroskopische Methoden charakterisiert werden konnen. Sie lassen sich weiter in sonst sehr schwer zugangliche molekulare Architekturen wie Catenane, Rotaxane, Polyrotaxane und Rohren effizient umwandeln. Cyclodextrine konnen auch recht interessante Funktionen ausuben. So wird ihre Fahigkeit zur molekularen Erkennung zur chromatographischen Trennung von komplexen Stoffgemischen, insbesondere von Racematen, genutzt. Auch konnen Cyclodextrine oder deren Derivate bemerkenswerte katalytische Aktivitaten aufweisen. Schlieslich kann man mit Cyclodextrinen die Verfugbarkeit von Wirkstoffen gunstig beeinflussen, was sicherlich in nachster Zeit zu vielen Anwendungen fuhren wird.

Cyclodextrine als Bausteine supramolekularer Strukturen und Funktionseinheiten

The photoelectron spectra of xanthone, thioxanthone, and acridone

Anomalous fluorescence spectra of benz[a]azulene derivatives

Electronic spectra of carbazole, dibenzofuran and dibenzothiophene

The magnetic circular dichroism (MCD) and electronic absorption spectra of tropothione have been measured. The circular-dichroism (CD) spectrum of the β-cyclodextrin complex with tropothione is also reported. The absorption bands of tropothione are assigned.

Magnetic Circular Dichroism and Electronic Spectra of Tropothione

The assignment of the absorption spectra of benz[b]anthracene (1) is reported by measuring the induced circular dichroism spectra of the β-cyclodextrin complex with1. It is concluded from the signs of the induced circular dichroism bands that the first absorption band (20.4–30.9×103 cm−1) has the transition dipole moment perpendicular to the long axis and the second absorption band (30.9–37.2×102 cm−1) has the transition dipole moment parallel to the long axis of1. Our assignments are in complete agreement with earlier assignments. The induced circular dichroism spectra exhibit Cotton splittings at 19.1×103 and 42.8×103 cm−1. It can be concluded from Cotton splittings of the induced circular dichroism spectra that the association of two 1:1 inclusion complexes forms a ground-state dimer.

H. Yamaguchi

Papers

The photoelectron spectra of xanthone, thioxanthone, and acridone

Anomalous fluorescence spectra of benz[a]azulene derivatives

Electronic spectra of carbazole, dibenzofuran and dibenzothiophene

Magnetic Circular Dichroism and Electronic Spectra of Tropothione

Induced circular dichroiism spectra of benz[ b ]anthracene included in β -cyclodextrin