Copley, G.; Gillmore, J. G.; Crisman, J.; Kodis, G.; Gray, C. L.; Cherry, B. R.; Sherman, B. D.; Liddell, P. A.; Paquette, M. M.; Kelbauskas, L.; Frank, N. L.; Moore, A. L.; Moore, T. A.; Gust, D. Modulating short wavelength fluorescence with long wavelength light J. Am. Chem. Soc. 2014 136, 34, 11994-12003 (AUG 27 2014). DOI: 10.1021/ja504879p
The fluorescence of a fluorophore is modulated with long wavelength visible irradiation in a spirooxazine-photochromic dyad. This unusual fluorescence behavior is the result of quenching of fluorophore fluorescence by the thermally stable, open, zwitterionic form of an azahomoadamantyl-spirooxazine, whereas the photogenerated closed, spirocyclic form has no effect on the fluorophore excited state. Because the merocyanine-spirooxazine is an unusual reverse photochrome with a thermally stable PMC form, this phenomenon does not require irradiation of the molecules with potentially damaging ultraviolet light, and rapid modulation of fluorescence is possible. Molecules demonstrating these properties may be useful in fluorescent probes, as their use can discriminate between probe fluorescence and various types of adventitious "autofluorescence" from other molecules in the system being studied.