Fluorescence spectroscopy is the most powerful research tool for visualizing the structure and dynamics of living systems at the molecular level. 1-4 During the last two decades, extensive efforts have been exerted to develop fluorescent probes for biologically relevant ions and molecules. 5-7 Effective intracellular probes for alkali and alkali earth metal ions are commercially available at present. 8 However, there is still a need for probes with an ...
