The well-known 8-aminoquinoline framework offers an ideal model for the development of fluorescence-enhanced chemosensors through simple and convenient syntheses. Herein, a novel and simple molecule chemosensor, 5-diethylamino-2-(quinolin-8-yliminomethyl)-phenol (HL), has been designed by combining an 8-aminoquinoline moiety and a 4-(diethylamino)salicylaldehyde in a single molecule to prove the selectivity and sensitivity for Mg²⁺, Zn²⁺, and Co²⁺ in a dual-channel mode (fluorescence emission and UV/Vis). When binding Mg²⁺, HL not only showed an obvious fluorescence enhancement but also enabled the Mg²⁺ detection range over 1.68 ppb. Meanwhile, in mixed solvent media, HL displayed selectivity for Zn²⁺ over other cations by the emission spectrum. It was worth noting that HL could be a colorimetric sensor for Co²⁺ in a semi-aqueous solution by monitoring the absorption spectral behavior and be a colorimetric reagent for sensing and staining of Co²⁺ in the cells. The results indicate that HL can be applied in multianalyte detection.

A luminescent probe based on a europium complex is developed, which effectively distinguishes adenosine-5′-triphosphate (ATP) from adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in pure water at pH 6.8. With a longer lifetime (in ms range), the probe is prospectively applied to biological systems to monitor ATP levels by completely removing the background fluorescence of other molecules.