Creation of 3,4-bis-triazolocoumarin-sugar conjugates via flourogenic dual click chemistry and their quenching specificity with silver(I) in aqueous media

Fluorogenic click chemistry has recently emerged as an ingenious and powerful tool toward numerous biochemical purposes. We describe herein the use of dual click chemistry toward the fluorescence restoration of a fluorogenic coumarin on epimeric dipropargyl sugar scaffolds and their practical utility in selective metal ion detection. The dual click reactions were smoothly proceeded under microwave irradiation between silylated 3,4-di-O-propynyl gluco- or galactoside and 3-azidocoumarin, forming fluorescently reactivated bis-triazolocoumarins on sugar templates. Subsequent desilylation resulted in the OH-glycosides with desired water solubility. The following photochemical study disclosed that their fluorescence could be uniquely quenched by silver(I) in aqueous media with very minor responses to the addition of other metal ions. This research would presumably prompt the efficient creation of water soluble and potentially low toxic chemosensors via the fluorogenic dual click chemistry in using the universally existent sugars as the central scaffold.