Fluorescent detection of Zn²⁺ and Cu²⁺ by a phenanthrene-based multifunctional chemosensor that acts as a basic pH indicator

A novel phenanthrene-based sensor 1 was synthesized for the recognition of Zn²⁺, Cu²⁺ and basic pH range by a integration of phenanthrene-9,10-dione and 3-methoxysalicylaldehyde. Sensor 1 could detect Zn²⁺ by fluorescent color change and Cu²⁺ by fluorescence quenching, and their detection limits were 0.43 μM and 0.18 μM, respectively. Moreover, 1 also acted as a basic pH indicator by fluorescence quenching. The sensing behaviors and mechanisms of 1 toward Zn²⁺ and Cu²⁺ were proposed by photophysical studies and theoretical calculations.