Solvent-directed multiple correspondence fluorescent probe for highly selective and sensitive detection of Cu²⁺ and...

A solvent-directed, new Schiff base multiple correspondence fluorescent probe, (E)-2-(2-hydroxybenzylidene) hydrazine-1-carboxamid (L), was synthesized for selective sensing of Cu²⁺ and Mg²⁺ ions. L showed excellent selectivity and high sensitivity toward Cu²⁺ in "turn off" mode with a detection limit of 40.5 nM in 10 mM, pH = 7.0 PBS buffer. Contrary to that, when acetonitrile was used as the solvent, L exhibited highly selective and sensitive fluorescence sensing ability for Mg²⁺ in "turn on" mode with a detection limit of 9.5 nM. L can coordinate to Cu²⁺ and Mg²⁺ in a 1:1 molar ratio, respectively, evidenced by Job's plot analysis. Their binding modes were investigated by NMR, IR and XPS spectroscopies. Moreover, the satisfied results were obtained when L was used to detect Cu²⁺ and Mg²⁺ in real water samples.