Zinc sensor molecules containing quinoline have been synthesized, which show fluorescence in the presence of Zn2+. The nitrogen in quinoline is critical to fluorescence and fluorescence enhancement is promoted by deprotonating the sensor's amide. One of the sensors is highly selective for Zn2+ over Cd2+ and other cations such as Hg2+, Fe2+, Mn2+ and Ca2+. This selectivity can be attributed to the increased absorption of the sensor in the presence of Zn 2+ and the strong binding of Zn2+. Structural studies, including X-ray and NMR, show the ability of dipicolylamine (DPA) to bind in facial and meridional manners to Zn2+. Crystal structures of different compounds show Zn2+ coordinating to three, four, and five nitrogens from the compounds. They also indicate that the selectivity of DPA containing compounds towards Zn2+ may originate from Zn2+ being stable in different coordination environments.
- Fluorescence enhancement
- Zinc sensor