Chemosensors for Water Contaminants Based on Chromophore-Appended Cyclodextrins

Abstract

The development of new chemical sensing methods for the recognition of molecules or ions in water is an important theme in many fields including environmental, biological, and clinical applications and simple methods for detecting organic molecules in water is desired. Chemosensors have been attracting considerable attention among the variety of methods for detecting chemical species. Many kinds of chromophore-appended cyclodextrins have been reported for chemosensors. Here, we review the molecule-sensing abilities of chromophore-appended cyclodextrins as chemosensors. First, turn-off fluorescent chemosensors using chromophore-appended cyclodextrins are discussed. The fluorescence intensities of turn-off fluorescent cyclodextrin chemosensors always decrease upon analyte addition, and the analyte-induced variation of the fluorescence intensities of the turn-off fluorescent cyclodextrin chemosensors depend on a analyte. The sensitivities of the turn-off cyclodextrin chemosensors roughly only depend on the binding affinity for a analyte. Next, dye-appended cyclodextrins are discussed as color-change chemosensors, which are effective for detection by the naked eye. Then, turn-on fluorescent chemosensors using chromophore-appended cyclodextrins are discussed. The fluorescence intensities of turn-on fluorescent cyclodextrin chemosensors increase upon addition of special analytes, which have a comparatively spherical shape. The turn-on fluorescent β-cyclodextrin chemosensor is not sensitive to bile acids, which are strongly bound by β-cyclodextrin. The shape and size of analytes have a greater influence on the fluorescence intensity than the binding affinity. Finally, chromophore-appended cyclodextrins for detection of anion or cation species are discussed.