Intramolecular Transfer of Singlet Oxygen

Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in-vitro. Recent developments allow for the estimation of some of these photochemical parameters in-vivo. This review will cover the currently available in-vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.

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“…naphthalene, anthracene (Wasserman and Larsen, 1972; Fudickar and Linker, 2014; Klaper and Linker, 2015). …”

Section: Figure A1mentioning

confidence: 99%

On thein vivophotochemical rate parameters for PDT reactive oxygen species modeling

Kim¹,

Ghogare²,

Greer³

et al. 2017

Phys. Med. Biol.

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“…Additional methyl groups in other positions of the naphthalene further increase their stability. Very recently, we described the influence of esters and amides in the 2‐position of naphthalenes on the kinetics of the reversible reaction with 1 O 2 and applied such compounds for an intramolecular transfer of singlet oxygen for the first time …”

Section: Introductionmentioning

confidence: 99%

Photooxygenation of oxygen‐substituted naphthalenes

Bauch

Krtitschka

Linker

2017

J of Physical Organic Chem

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The reaction of oxygen‐substituted naphthalenes with singlet oxygen (1O2) has been investigated, and labile endoperoxides have been isolated and characterized at –78°C for the first time. Low‐temperature kinetics by UV spectroscopy revealed that alkoxy and silyloxy substituents remarkably increase the rate of photooxygenations compared to 1,4‐dimethylnaphthalene, whereas acyloxy‐substituted acenes are inert towards 1O2. The reactivities nicely correlate with HOMO energies and free activation energies, which we determined by density functional theory calculations. The lability of the isolated endoperoxides is due to their very fast back reaction to the corresponding naphthalenes even at –20°C under release of 1O2, making them to superior sources of this reactive species under very mild conditions. Finally, a carbohydrate‐substituted naphthalene has been synthesized, which reacts reversibly with 1O2 and might be applied for enantioselective oxidations in future work.

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“…Thus, we found a strong influence of substituents R and the solvent on the kinetics of the photooxygenations, giving evidence for polar zwitterionic intermediates in favor of a concerted cycloaddition (Scheme ) . More recently, we became interested in an intramolecular transfer of 1 O 2 from an EPO to an acceptor . For this purpose, we had to cleave the endoperoxide and had to understand the mechanism of such reactions.…”

Section: Introductionmentioning

confidence: 99%

Intermediates in the cleavage of endoperoxides

Bauch

Klaper

Linker

2016

J of Physical Organic Chem

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The decomposition of anthracene endoperoxides has been investigated under various conditions. Thermolyses proceed via radical intermediates and afford anthracenes and rearrangement products, depending on the substitution pattern. Interestingly, not only the O–O but also the C–O bond can be cleaved homolytically. Under basic conditions fragmentations take place, affording anthraquinone, and reactive oxygen species. This mechanism explains the often observed decomposition of endoperoxides during work‐up. Finally, an acid‐catalyzed cleavage has been observed under release of hydrogen peroxide. The results should be interesting for the mechanistic understanding of peroxide decomposition and the endoperoxides might serve as mild sources of reactive oxygen species for future applications. Copyright © 2016 John Wiley & Sons, Ltd.

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Intramolecular Transfer of Singlet Oxygen

Cited by 65 publications

References 65 publications

On thein vivophotochemical rate parameters for PDT reactive oxygen species modeling

On thein vivophotochemical rate parameters for PDT reactive oxygen species modeling

Photooxygenation of oxygen‐substituted naphthalenes

Intermediates in the cleavage of endoperoxides

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