OEGylated Cyclodextrins Responsive to Temperature, Redox, and Metal Ions.

The present work provides a versatile access for "smart" cyclodextrins (CDs) that are responsive to temperature, redox, and metal ions. These CDs are modified with oligoethylene glycols through thiol-ene click chemistry, which are inherently thermoresponsive in aqueous solutions. At the same time, their thermoresponsiveness is tunable through oxidation or metal ion chelation of thioether moieties. Significantly, these stimuli-responsive CDs retained strong inclusion abilities to guest dyes, and the inclusion complexation can be tuned by thermally induced phase transitions, oxidation, as well as metal chelation. The stimuli-responsive complexation with dyes allows to fabricate colorimetric/fluorescent sensors for temperature or for soft metal ions, such as Ag+ and Hg2+. With multiple responsiveness integrated in one material, these monodisperse CDs have formed a new class of stimuli-responsive macrocycles, which can reversibly encapsulate and release guest species through multiple switches.