A highly selective fluorescent chemosensor for Ag + based on calix[4]arene with lower-rim proximal triazolylpyrenes

Ligand 3, a calix[4]arene with lower-rim proximal triazolylpyrenes, is a ratiometric fluorescent chemosensor for Ag ⁺ with higher sensitivity compared to ligand 5, a calix[4]arene with lower-rim distal triazolylpyrenes, and the conventional fluoroionophore with non-conjugated triazole and pyrene. In a polar protic solvent, the binding ratios for 3·Ag ⁺ was determined to be 1:1 and the association constant was found to be 7.0 × 10 ³ M ^-1. The detection of Ag ⁺ by ligand 3 even works in aqueous methanol solution.