A highly selective fluorescence and absorption sensor for rapid recognition and detection of Cu 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 ions in aqueous solutions over all other competitive metal ions including Na , Ag , Ba , Ca , Cd , Mg , Zn , Cr , Al , Hg , K , Mn , Ni , Sr , Tb and Co . SAAT exhibits ratiometric absorption sensing ability for Cu ions. Importantly, SAAT also can sense Cu ions using fluorescence quenching, the fluorescence intensity of SAAT showed a good linear relationship with Cu concentration, and the detection limit of Cu 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 . SAAT in test film could identify Cu 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 ions.