Naphthalene Ring-Fused 2-Aminotryptanthrin as a Fluorescent Chemosensor for Al³⁺

Abstract

Naphthalene ring-fused 2-aminotryptanthrin (Naph-T2NH₂) was synthesized as a fluorescent chemosensor for Al³⁺. We investigated the metal-ion recognition of Naph-T2NH₂ through individual addition of Mg²⁺, Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, and Pb²⁺ in an acetonitrile solution. When Mg²⁺, Ca²⁺, Ba²⁺, Co²⁺, Ag⁺, Zn²⁺, and Cd²⁺ were individually added to the solution, the shape and intensity of the fluorescence spectra did not change. Conversely, when Fe²⁺, Fe³⁺, Ni²⁺, Cu²⁺, Hg²⁺, and Pb²⁺ were individually added to the solution, the fluorescence at 604 nm was quenched. However, the fluorescence at 494 nm increased significantly upon addition of Al³⁺. Thus, Naph-T2NH₂ is well suited for use as a fluorescent chemosensor for Al³⁺.