Synthesis and fluorescence properties of stable nitroxide free radicals (10a, 11a, 12a, 14a, 20a, 21a) and their amine (10b, 11b, 12b, 14b, 20b, 21b) precursors covalently linked to dansyl or 3- and 4-aminophthalimide are reported. The best intramolecular quenching is achieved when the fluorophore and the nitroxide are in the closest possible position