Fluorescent benzofurazan derivatized triazole linked mono and di-glucopyranosyl conjugates: Selective sensing of fluoride ion and coordination features by DFT computation

Abstract

Novel benzofurazan derivatized triazole linked mono and di-glucopyranosyl conjugates (L1, and L2) have been synthesized by Cu+1 catalyzed alkyne-azide 1,3 dipolar cycloaddition reaction. All the precursors and the molecules (L1, and L2) were isolated and characterized by 1H &13C NMR, and ESI-MS. The glycoconjugates have been studied with fourteen different anions for their selective recognition in solution. Among the anions studied L1 exhibited selective fluorescent sensing properties upon binding with F− by showing a 151 ± 8 fold decrease in the emission intensity at 518 nm. The minimum detection limit for F− in acetonitrile was found to be 124 ± 5 ppb. A hypsochromic shift (∼60 nm) of the 450 nm band of L1 was observed upon the interaction with F− through the formation of hydrogen bonding of –NH moiety. The coordination features of [L1+F−] complex were established by Density Functional Theory (DFT) computational studies. The outcome of the study of new glycoconjugates based recognition promotes the emerging of new biological sensor diagnostic tools in the future.