Fig. 1. Simplified synthetic scheme for the preparation of Mg-sensitive BODIPY fluorophores based on the 4-oxo-4H-quinolizine-3-carboxylic acid chelating scaffold. Below are represented the chemical structures of BODIPY fluorophores 2, 3 and 4 and their corresponding activation modes upon Mg2+ recognition. Fluorescence quantum yields were determined relative to fluorescein in basic ethanol.
