Quantum Yield of Photosensitized Singlet Oxygen (a1.DELTA.g) Production in Solid Polystyrene

Scurlock, Rodger D.; Mártire, Daniel O.; Ogilby, Peter R.; Taylor, Vicki L.; Clough, R.L.

doi:10.1021/ma00095a020

Cited by 41 publications

(51 citation statements)

References 9 publications

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“…Quantum yields of O 2 (a 1 Δ g ) production, φ Δ , were obtained in the standard way by comparing the intensity of the fluorescein-sensitized O 2 (a 1 Δ g ) phosphorescence signal to the corresponding signal from O 2 (a 1 Δ g ) produced by a reference sensitizer, using data obtained over a range of incident laser powers [ 40 ]. For our present experiments, the reference used was phenalen-1-one-2-sulfonic acid (PNS) [ 41 ].…”

Section: Resultsmentioning

confidence: 99%

Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination

McLoughlin

Kotroni

Bregnhøj

et al. 2020

Sensors

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Fluorescein, and derivatives of fluorescein, are often used as fluorescent probes and sensors. In systems where pH is a variable, protonation/deprotonation of the molecule can influence the pertinent photophysics. Fluorination of the xanthene moiety can alter the molecule’s pKa such as to render a probe whose photophysics remains invariant over a wide pH range. Di-fluorination is often sufficient to accomplish this goal, as has been demonstrated with compounds such as Oregon Green in which the xanthene moiety is symmetrically difluorinated. In this work, we synthesized a non-symmetrical difluorinated analog of Oregon Green which we call Athens Green. We ascertained that the photophysics and photochemistry of Athens Green, including the oxygen-dependent photophysics that results in the sensitized production of singlet oxygen, O2(a1Δg), can differ appreciably from the photophysics of Oregon Green. Our data indicate that Athens Green will be a more benign fluorescent probe in systems that involve the production and removal of O2(a1Δg). These results expand the available options in the toolbox of fluorescein-based fluorophores.

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Section: Resultsmentioning

confidence: 99%

Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination

McLoughlin

Kotroni

Bregnhøj

et al. 2020

Sensors

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“…When compared with O 2 (a 1 Δ g ) data recorded from photosensitized experiments in bulk D 2 O solutions, the present observation reflects the relatively slow process of oxygen diffusion through the protein to quench the O 2 (a 1 Δ g ) precursor, the FMN triplet state. To undertake a proper kinetic analysis of this O 2 (a 1 Δ g ) signal and obtain the correct O 2 (a 1 Δ g ) lifetime, τ Δ , used to normalize the integrated phosphorescence intensity for the ϕ Δ determination , we independently quantified the rate constant for deactivation of the protein‐encased FMN triplet state, k T ~ (31 μs) −1 , in a time‐resolved triplet absorption experiment at 650 nm under air‐saturated conditions. This rate constant was then used in a fitting routine to obtain τ Δ from data such as those shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Oxygen‐Dependent Photochemistry and Photophysics of “MiniSOG,” a Protein‐Encased Flavin

Pimenta

Jensen

Breitenbach

et al. 2013

Photochem & Photobiology

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Selected photochemical and photophysical parameters of flavin mononucleotide (FMN) have been examined under conditions in which FMN is (1) solvated in a buffered aqueous solution, and (2) encased in a protein likewise solvated in a buffered aqueous solution. The latter was achieved using the so-called "mini Singlet Oxygen Generator" (miniSOG), an FMN-containing flavoprotein engineered from Arabidopsis thaliana phototropin 2. Although FMN is a reasonably good singlet oxygen photosensitizer in bulk water (ϕΔ = 0.65 ± 0.04), enclosing FMN in this protein facilitates photoinitiated electron-transfer reactions (Type-I chemistry) at the expense of photosensitized singlet oxygen production (Type-II chemistry) and results in a comparatively poor yield of singlet oxygen (ϕΔ = 0.030 ± 0.002). This observation on the effect of the local environment surrounding FMN is supported by a host of spectroscopic and chemical trapping experiments. The results of this study not only elucidate the behavior of miniSOG but also provide useful information for the further development of well-characterized chromophores suitable for use as intracellular sensitizers in mechanistic studies of reactive oxygen species.

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“…This is arguably expected given the position of the LSPRs in our sample. In any event, even if there was an effect on Φ Δ , because the inherent singlet oxygen yield for TPP is already high (Φ Δ = 0.7) [57], a metalenhanced increase in the production efficiency of singlet oxygen would not be able to account for the observed data. Moreover, we have also ascertained that the metal discs have no effect on the singlet oxygen lifetime, τ Δ .…”

Section: Enhancement Of Singlet Oxygen Phosphorescencementioning

confidence: 94%

Metal nanoparticle-enhanced radiative transitions: Giving singlet oxygen emission a boost

Toftegaard

Arnbjerg

Cong

et al. 2011

Pure and Applied Chemistry

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The fabrication and use of metal nanoparticles to influence electronic transitions in a given molecule is of growing interest; there is much to be gained by developing and exploiting methods to enhance weak optical signals. Singlet molecular oxygen, O 2 (a 1 Δ g ), which is an important intermediate in many oxidation reactions, particularly in biological systems, is ideally monitored by the 1275-nm O 2 (a 1 Δ g ) → O 2 (X 3 Σ g -) phosphorescent transition. Unfortunately, the latter is highly forbidden and, as such, often presents a severe limitation in the application of this optical probe. In this paper, we describe how this weak phosphorescent transition can be enhanced by using localized surface plasmons (LSPs) from specially engineered gold nanostructures. In an attempt to elucidate the mechanism of this process, data were recorded from samples in which we decoupled the component of the plasmon resonance that absorbs incident light from the component that scatters incident light. We find that the latter appears to be the feature of significance in the process through which singlet oxygen phosphorescence is enhanced. In this work, we also illustrate how the singlet oxygen system provides an ideal model for a general study of metal-enhanced radiative rate constants.

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Quantum Yield of Photosensitized Singlet Oxygen (a1.DELTA.g) Production in Solid Polystyrene

Cited by 41 publications

References 9 publications

Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination

Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination

Oxygen‐Dependent Photochemistry and Photophysics of “MiniSOG,” a Protein‐Encased Flavin

Metal nanoparticle-enhanced radiative transitions: Giving singlet oxygen emission a boost

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