Factors governing the efficiency of singlet oxygen production during oxygen quenching of singlet and triplet states of anthracene derivatives in cyclohexane solution

Wilkinson, Frank; McGarvey, David J.; Olea, Andrés F.

doi:10.1021/ja00078a062

Cited by 88 publications

(134 citation statements)

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“…Later Wilkinson and Garner found that charge‐transfer (CT) interactions between T 1 excited sensitizer and O 2 lead to a strong increase of k T Q in the region of high values of E T (15). Further investigations of the same group demonstrated that for sensitizers of high and almost constant triplet energy values of k T Q increase and those of SΔ decrease with decreasing sensitizer oxidation potential E ox , indicating the competition of a CT and a non‐CT pathway in the quenching of triplet states by O 2 (16–24). Interestingly, both pathways contribute to the formation of O 2 (1Δ g ).…”

Section: Discussionmentioning

confidence: 97%

Photosensitized Generation of Singlet Oxygen

Schmidt

2007

Photochemistry and Photobiology

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This work gives an overview of what is currently known about the mechanisms of the photosensitized production of singlet oxygen. Quenching of ππ* excited triplet states by O2 proceeds via internal conversion of excited encounter complexes and exciplexes of sensitizer and O2. Both deactivation channels lead with different efficiencies to singlet oxygen generation. The balance between the deactivation channels depends on the triplet‐state energy and oxidation potential of the sensitizer, and on the solvent polarity. A model has been developed that reproduces rate constants and efficiencies of the competing processes quantitatively. Sensitization by excited singlet states is much more complex and hence only qualitative rules could be elaborated, despite serious efforts of many groups. However, the most important deactivation paths of fluorescence quenching by O2 are again directed by excess energies and charge‐transfer interactions similar to triplet‐state quenching by O2. Finally, two recent developments in photo‐sensitization of singlet oxygen are reviewed: Two‐photon sensitizers with particular application potential for photodynamic therapy and fluorescence imaging of biological samples and singlet oxygen sensitization by nanocrystalline porous silicon, a material with very different photophysics compared to molecular sensitizers.

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Section: Discussionmentioning

confidence: 97%

Photosensitized Generation of Singlet Oxygen

Schmidt

2007

Photochemistry and Photobiology

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“…118,135 Previous work had shown that certain organic fluorophores were quenched by covalent attachment to anthracene. 141,142 Quenching was alleviated upon reaction of the anthracene with 1 O 2 to form an endoperoxide. 141–144 By appending anthracene to the pyridine of the sensitizing polyacid chelate, the resulting Ln(III) complex responds with an increase in luminescence intensity in the presence of 1 O 2 .…”

Section: Lanthanide Probes For Optical Imagingmentioning

confidence: 99%

Lanthanide Probes for Bioresponsive Imaging

2013

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“…After laser excitation, singlet excited states of anthracene ( 1 A*) are generated (eq 1), which can be quenched by molecular oxygen (triplet oxygen, 3 O 2 ), k S∆ O 2 ) 2.5 × 10 10 M -1 s -1 (eq 3). 28 The triplet state of anthracene is generated by intersystem crossing (eq 2). The triplet anthracene ( 3 A*) can be quenched either by O-TEMPO (eq 5) (leading to emissive nitroxide CIDEP) or by molecular oxygen (triplet oxygen, 3 37 singlet oxygen is generated efficiently by the quenching of 3 A* with 3 O 2 .…”

Section: Chartmentioning

confidence: 99%

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

et al. 2005

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An absorptive chemically induced dynamic electron polarization (CIDEP) was generated by the quenching of singlet oxygen by nitroxide radicals (TEMPO derivatives). The spin polarization decay time of the nitroxide (measured by time-resolved EPR) correlates with the lifetime of singlet oxygen (measured by singlet oxygen phosphorescence spectroscopy). In addition, a deuterium isotope effect on the spin polarization decay time was observed, a signature of singlet oxygen involvement. With use of isotope labeled nitroxides ( 15 N, 14 N), the relative spin polarization efficiencies of TEMPO, 4-oxo-TEMPO, and 4-hydroxy-TEMPO by singlet oxygen were determined. The relative spin polarization efficiencies (per quenching event) decrease in the order 4-hydroxy-TEMPO > TEMPO > 4-oxo-TEMPO, whereas an opposite trend was observed for the total quenching rate constants of singlet oxygen by the nitroxides where the order is 4-hydroxy-TEMPO < TEMPO < 4-oxo-TEMPO.

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Factors governing the efficiency of singlet oxygen production during oxygen quenching of singlet and triplet states of anthracene derivatives in cyclohexane solution

Cited by 88 publications

References 0 publications

Photosensitized Generation of Singlet Oxygen

Photosensitized Generation of Singlet Oxygen

Lanthanide Probes for Bioresponsive Imaging

Chemically Induced Dynamic Electron Polarization Generated through the Interaction between Singlet Molecular Oxygen and Nitroxide Radicals

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