A coumarin-based colorimetric and fluorescent probe for the highly selective detection of Au3+ ions

We develop a novel coumarin-alkyne derivative (NC7-AL), which can specifically react with Au³⁺ and give a colorimetric and fluorescent “turn-on” response toward Au³⁺. Notably, other alkynophilic metal species such as Au⁺, Ag⁺, Pd²⁺, Ni²⁺, Cu²⁺, and Hg²⁺ do not produce an interfering signal. A good linear relationship between emission intensity at 420 nm and Au³⁺ concentration from 0 to 2 equivalent is observed, and the detection limit (3σ/k) is estimated to be ca. 3.58 nmol/L. Harnessing the Au³⁺-induced color change from light yellow to colorless, we find that NC7-AL-based modified TLC plate can be used for convenient naked-eye detection of Au³⁺.