Europium(iii) β-diketone complex as portable luminescent chemosensor for naked eye Cu2+ detection and recyclable on–off–on vapor response

Abstract

A novel Eu³⁺ complex coordinated by polymers with β-diketone pendant groups (Eu³⁺–PDKMA) has been synthesized for Cu²⁺ cation and acid–base vapor detections. Its sensitive and selective response to Cu²⁺ is confirmed by fluorescence quenching of characteristic emission of Eu³⁺ at 612 nm wavelength. The fluorescence intensity of Eu³⁺–PDKMA obeys linear relationship at the presence of Cu²⁺ with the concentration in the order of 10⁻⁷ mol L⁻¹. The detection limit of Cu²⁺ is as low as 2.0 × 10⁻⁸ mol L⁻¹ at natural pH, which makes Eu³⁺–PDKMA an excellent luminescent sensor. Portable strips containing Eu³⁺–PDKMA can be easily prepared to detect Cu²⁺ in aqueous solution. Moreover, the same strips can also be used to recognize and sense acidic and basic environments by naked eye. The red emission can be switched “off” and “on” when the strips contact acid and base vapors, respectively. The produced strips exhibit relatively fast response time less than 10 s, and good reusability over 10 times. The Eu³⁺–PDKMA materials are promising in biological and environmental applications.