Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

We report the noncovalent linkage of terminally substituted oligo(dimethylsiloxanes) bearing α-cyclodextrins (α-CD) as host end groups for the cyclopentadienyl rings of ferrocene. This double complexation of unsubstituted ferrocene leads to a supramolecuar formation of the siloxane strands. Structural characterization was performed by the use of 1H NMR and IR spectroscopy and by mass spectrometry. Electron microscopy studies and dynamic light scattering measurements show a significant decrease of the derivative size after the complexation with ferrocene. In addition, further evidence for the successful complexation of the end groups was verified by the shifts of the protons in the 1H NMR spectra and in the correlation signals of the 2D ROESY NMR spectra.

Analysis of Inclusion Complexes of Clotrimazole and Differently Substituted α, β and γ Cyclodextrins by NMR Spectroscopy

Clotrimazole, a widely used imidazole-type antifungal agent and its cyclodextrin complexes were studied. Stoichiometries, structures and stability constants of the inclusion complexes with fourteen different cyclodextrin derivatives were characterized using NMR spectroscopy as primary technique. The cyclodextrin complexes were found to be of high stability (logK ] 2). 2D ROESY NMR spectra revealed the formation of isomeric complexes with every cyclodextrin studied. The highest stability constant was observed with sulfobutylated β-CD, and interestingly enough the heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin showed the lowest stability.