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 (<b>L</b>) has been shown to be selective toward La³⁺ by <i>turn on</i> 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 <i>in situ</i> complex of <b>L</b> with La³⁺ recognizes F^– via fluorescence quenching. The reversible response of sensing La³⁺ and F^– sequentially by <b>L</b> has been demonstrated