Used as a fluorescent sensor for metal ions, particularly Fe³⁺ and Cu²⁺, in biological and environmental sensing due to its strong emission changes in response to coordination with these ions. The bis(pyridin-2-ylmethyl)amino ethylamino side chain provides selective chelation, while its spirocyclic structure enables fluorescence modulation upon metal binding, resulting in a visible color and fluorescence shift analogous to pH-induced ring-opening. Commonly applied in biochemical research to monitor metal-dependent enzyme activity and in biosensors for detecting heavy metal levels in biological samples such as blood or cells. High selectivity, photostability, and compatibility with aqueous systems make it suitable for live-cell imaging and real-time monitoring in complex matrices.