Excimer Formation and Induced-Fit Type of Complexation of β-Cyclodextrin Capped by Two Naphthyl Moieties

Publisher Website
Google Scholar
Abstract
Host–guest complexation of β-Cyclodextrin bearing two naphthyl moieties (1) has been studied by circular dichroism and fluorescence spectroscopic methods. The circular dichroism spectrum exhibits a positive band around 225 nm while the fluorescence spectrum exhibits a predominant monomer peak with a shoulder of excimer emission. These data suggest that 1 can take two forms, one of two naphthyl moieties being included in the cavity of the predominant form (A) while both naphthyl moieties being located outside of the cavity in another form (B). With increasing concentration of guests, the dichroism intensity diminishes but the excimer intensity increases. This result indicates that 1 moves the included naphthyl moiety outward from the interior of the cavity during guest binding and then the two naphthyl moieties act as hydrophobic caps. The binding of 1 was stronger for cyclohexanol and 1-adamantanecarboxylic acid but weaker for cyclododecanol than that of the corresponding γ-cyclodextrin derivative in correspondence with size-fitting between the guests and hosts.

This publication has 15 references indexed in Scilit: