Polyaromatic profluorescent nitroxide probes with enhanced photostability

Novel profluorescent mono- and bis-​isoindoline nitroxides linked to naphthalimide and perylene diimide structural cores are described. These nitroxide-​fluorophore probes display strongly suppressed fluorescence in comparison to their corresponding non-​radical diamagnetic methoxyamine derivs. The perylene-​based probe possessing two isoindoline systems tethered through ethynyl linkages was shown to be the most photostable in soln., demonstrating significantly enhanced longevity over the 9,​10-​bis(phenylethynyl)​anthracene fluorophore used in previous profluorescent nitroxide probes.