BODIPY 630/650X succinimide ester (SE) is an amine-reactive fluorescent probe that contains an integrated aminohexanoyl linker (X). It displays excitation/emission maxima of 630/650 nm, respectively. BODIPY 630/650X SE has been used, linked to adenosine A1 receptor ligands, as a fluorescent probe to quantify ligand-receptor binding using fluorescence correlation spectroscopy.