A new acridine derivative as a highly selective fluoroionophore for Cu2+ in 100% aqueous solution

A new acridine fluoroionophore containing two iminodiacetic acid ligands, Acridinyl Tetra Acid (ATA), was synthesized. The fluorescence sensing behavior of ATA toward metal ions was investigated in buffered aqueous media. The presence of Cu2+ resulted in significant quenching of the fluorescence emission from ATA, while other metal ions posed little interferences, if any. The fluorescence response was concentration-dependent and can be well described by the modified Stern–Volmer equation. A good linear relationship (R2=0.9952) was observed up to 3.0×10−6 mol L−1 Cu2+ ions. The detection limit, calculated following the 3σ IUPAC criteria, was 1.24×10−7 mol L−1. The presence of Cu2+ induces the formation of a 1:1 ligand/metal complex at neutral pH.