TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Release of Singlet Oxygen from Organic Peroxides under Mild Conditions JF - ChemPhotoChem N2 - Singlet oxygen can be released in the dark in nearly quantitative yield from endoperoxides of naphthalenes, anthracenes and pyridones as an alternative to its generation by photosensitization. Recently, new donor systems have been designed which operate at very low temperatures but which are prepared from their parent forms at acceptable rates. Enhancement of the reactivity of donors is conveniently achieved by the design of the substitution pattern or through the use of plasmonic heating of nanoparticle-bound donors. The most important aim of these donor molecules is to transfer singlet oxygen in a controlled and directed manner to a target. Low temperatures and the linking between donors and acceptors reduce the random walk of oxygen and may force an attack at the desired position. By using chiral donor systems, new stereocenters might be introduced into prochiral acceptors. KW - donor-acceptor systems KW - oxygenation KW - peroxides KW - polycycles KW - retro reactions Y1 - 2018 U6 - https://doi.org/10.1002/cptc.201700235 SN - 2367-0932 VL - 2 IS - 7 SP - 548 EP - 558 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bauch, Marcel A1 - Klaper, Matthias A1 - Linker, Torsten T1 - Intermediates in the cleavage of endoperoxides JF - Journal of physical organic chemistry N2 - 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 (C) 2016 John Wiley & Sons, Ltd. KW - peroxides KW - radicals KW - reaction mechanism KW - reactive intermediates Y1 - 2017 U6 - https://doi.org/10.1002/poc.3607 SN - 0894-3230 SN - 1099-1395 VL - 30 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Klaper, Matthias A1 - Linker, Torsten T1 - New Singlet Oxygen Donors Based on Naphthalenes: Synthesis, Physical Chemical Data, and Improved Stability JF - Chemistry - a European journal N2 - Singlet oxygen donors are of current interest for medical applications, but suffer from a short half-life leading to low singlet oxygen yields and problems with storage. We have synthesized more than 25new singlet oxygen donors based on differently substituted naphthalenes in only a few steps. The influence of functional groups on the reaction rate of the photooxygenations, thermolysis, half-life, and singlet oxygen yield has been thoroughly studied. We determined various thermodynamic data and compared them with density functional calculations. Interestingly, remarkable stabilities of functional groups during the photooxygenations and stabilizing effects for some endoperoxides during the thermolysis have been found. Furthermore, we give evidence for a partly concerted and partly stepwise thermolysis mechanism leading to singlet and triplet oxygen, respectively. Our results might be interesting for dark oxygenations and future applications in medicine. KW - density functional calculations KW - oxygenation KW - peroxides KW - photodynamic therapy KW - singlet oxygen Y1 - 2015 U6 - https://doi.org/10.1002/chem.201500146 SN - 0947-6539 SN - 1521-3765 VL - 21 IS - 23 SP - 8569 EP - 8577 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Reversible Photooxygenation of Alkynylanthracenes chemical generation of singlet oxygen under very mild conditions JF - Chemistry - a European journal KW - anthracenes KW - oxidation KW - peroxides KW - reversibility KW - singlet oxygen Y1 - 2011 U6 - https://doi.org/10.1002/chem.201102230 SN - 0947-6539 VL - 17 IS - 49 SP - 13661 EP - 13664 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Klaper, Matthias A1 - Linker, Torsten T1 - Evidence for an oxygen anthracene sandwich complex JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition KW - arenes KW - peroxides KW - sandwich complexes KW - singlet oxygen KW - interactions Y1 - 2013 U6 - https://doi.org/10.1002/anie.201304768 SN - 1433-7851 SN - 1521-3773 VL - 52 IS - 45 SP - 11896 EP - 11899 PB - Wiley-VCH CY - Weinheim ER -