Triazole linked picolylimine conjugate of calix[6]arene as a sequential sensor for La³⁺ followed by F^–

Abstract

A new 1,3,5-tris-triazole linked picolylimine conjugate of calix[6]arene (L) has been shown to be selective toward La³⁺ by turn on fluorescence with ∼70-fold enhancement and emits blue, with a minimal detection limit of 65 ± 5 ppb (490 nM). The species of recognition has been modeled computationally to have a monocapped twisted square antiprism with a N₆O₃ binding core about La³⁺. The in situ complex of L with La³⁺ recognizes F^– via fluorescence quenching. The reversible response of sensing La³⁺ and F^– sequentially by L has been demonstrated.