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 - Wessig, Pablo A1 - Linker, Torsten T1 - Base catalysed decomposition of anthracene endoperoxide JF - Chemical communications N2 - Catalytic amounts of a weak base are sufficient to induce the decomposition of anthracene endoperoxides to anthraquinone. The mechanism has been elucidated by isolation of intermediates in combination with DFT calculations. The whole process is suitable for the convenient generation of hydrogen peroxide under very mild conditions. Y1 - 2016 U6 - https://doi.org/10.1039/c5cc08606j SN - 1359-7345 SN - 1364-548X VL - 52 SP - 1210 EP - 1213 PB - Royal Society of Chemistry CY - Cambridge 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 - Klaper, Matthias A1 - Linker, Torsten T1 - Intramolecular Transfer of Singlet Oxygen JF - Journal of the American Chemical Society N2 - The intramolecular transfer of energy (FRET) and electrons (Dexter) are of great interest for the scientific community and are well-understood. In contrast, the intramolecular transfer of singlet oxygen (O-1(2)), a reactive and short-lived oxygen species, has until now been unknown. This process would be very interesting because O-1(2) plays an important role in photodynamic therapy (PDT). Herein, we present the first successful intramolecular transfer of O-1(2) from a donor to acceptor. Also, we found a dependence of conformation and temperature comparable with those of FRET. We provide several pieces of evidence for the intramolecular character of this transfer, including competition experiments. Our studies should be interesting not only from the theoretical and mechanistic point of view but also for the design of new O-1(2) donors and applications in PDT. Y1 - 2015 U6 - https://doi.org/10.1021/jacs.5b07848 SN - 0002-7863 VL - 137 IS - 43 SP - 13744 EP - 13747 PB - American Chemical Society CY - Washington 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 -