A highly selective fluorescence and absorption sensor for rapid recognition and detection of Cu 2+ ions in aqueous solution and film.

A fluorescence and absorption chemosensor (SAAT) based on 5-(hydroxymethyl)-salicylaldehyde (SA) and o-aminothiophenol (AT) was designed and synthesized. SAAT in DMSO-HEPES (20.0 mM, v/v, 1:99, pH = 7.0) solution shows a highly selective and sensitive absorption and an 'on-off' fluorescence response to Cu 2+ ions in aqueous solutions over all other competitive metal ions including Na + , Ag + , Ba 2+ , Ca 2+ , Cd 2+ , Mg 2+ , Zn 2+ , Cr 3+ , Al 3+ , Hg 2+ , K + , Mn 2+ , Ni 2+ , Sr 2+ , Tb 3+ and Co 2+ . SAAT exhibits ratiometric absorption sensing ability for Cu 2+ ions. Importantly, SAAT also can sense Cu 2+ ions using fluorescence quenching, the fluorescence intensity of SAAT showed a good linear relationship with Cu 2+ concentration, and the detection limit of Cu 2+ was 0.34 μM. The results of Job's plot, Benesi-Hildebrand plot, mass spectra, and density functional theory calculations confirmed that the selective absorption and fluorescence response were attributed to the formation of a 1:1 complex between SAAT and Cu 2+ . SAAT in test film could identify Cu 2+ in water samples using the intuitive fluorescence colour change under a UV lamp. SAAT has great application value as a selective and sensitive chemosensor to discriminate and detect Cu 2+ ions.