title: Modulating short wavelength fluorescence with long wavelength light.
abstract: Two molecules in which the intensity of shorter-wavelength fluorescence from a strong fluorophore is modulated by longer-wavelength irradiation of an attached merocyanine-spirooxazine reverse photochromic moiety have been synthesized and studied. This unusual fluorescence behavior is the result of quenching of fluorophore fluorescence by the thermally stable, open, zwitterionic form of the spirooxazine, whereas the photogenerated closed, spirocyclic form has no effect on the fluorophore excited state. The population ratio of the closed and open forms of the spirooxazine is controlled by the intensity of the longer-wavelength modulated light. Both square wave and sine wave modulation were investigated. Because the merocyanine-spirooxazine is an unusual reverse photochrome with a thermally stable long-wavelength absorbing form and a short-wavelength absorbing photogenerated isomer with a very short lifetime, 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.
authors: Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85287, United States.
authors: Graeme
authors: G
authors: Copley
authors: Jason G
authors: JG
authors: Gillmore
authors: Jeffrey
authors: J
authors: Crisman
authors: Gerdenis
authors: G
authors: Kodis
authors: Christopher L
authors: CL
authors: Gray
authors: Brian R
authors: BR
authors: Cherry
authors: Benjamin D
authors: BD
authors: Sherman
authors: Paul A
authors: PA
authors: Liddell
authors: Michelle M
authors: MM
authors: Paquette
authors: Laimonas
authors: L
authors: Kelbauskas
authors: Natia L
authors: NL
authors: Frank
authors: Ana L
authors: AL
authors: Moore
authors: Thomas A
authors: TA
authors: Moore
authors: Devens
authors: D
authors: Gust
mesh_terms: D065638:Absorption, Radiation; D001578:Benzopyrans / Q000737:chemistry*; D055664:Electrochemical Techniques; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D015394:Molecular Structure; D010078:Oxazines / Q000737:chemistry*; D055668:Photochemical Processes; D013141:Spiro Compounds / Q000737:chemistry*
chemical_list: D001578:Benzopyrans; D005456:Fluorescent Dyes; D007211:Indoles; D010078:Oxazines; D013141:Spiro Compounds; C548873:merocyanine