Photoinduced Reactivity in a Dispiro-1,2,4-trioxolane: Adamantane Ring Expansion and First Direct Observation of the Long-Lived Triplet Diradical Intermediates
JOURNAL OF PHYSICAL CHEMISTRY A, cilt.124, sa.21, ss.4202-4210, 2020 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 124 Sayı: 21
- Basım Tarihi: 2020
- Doi Numarası: 10.1021/acs.jpca.0c01974
- Dergi Adı: JOURNAL OF PHYSICAL CHEMISTRY A
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Applied Science & Technology Source, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), Artic & Antarctic Regions, Chemical Abstracts Core, Chimica, Compendex, Computer & Applied Sciences, EMBASE, INSPEC, MEDLINE
- Sayfa Sayıları: ss.4202-4210
- İstanbul Kültür Üniversitesi Adresli: Evet
Özet
Dispiro-1,2,4-trioxolane, 1, an ozonide with efficient and broad antiparasitic activity, was synthesized and investigated using matrix isolation FTIR and EPR spectroscopies together with both B3LYP/6-311++G(3df, 3dp) and M06- 2X/6-311++G-(3df,3dp) theoretical methods. Irradiations (lambda >= 290 nm) of the matrix isolated 1 (Ar or N-2) afforded exclusively 4-oxahomoadamantan-5-one, 4, and 1,4-cyclohexanedione, 5. These results suggested that the reaction proceeded via a dioxygen-centered diradical intermediate, formed upon homolytic cleavage of the labile peroxide bond, which regioselectively isomerized to form the more stable (secondary carbon-centered)/oxygen-centered diradical. In situ EPR measurements during the photolysis of 1 deposited in a MeTHF-matrix led to the detection of signals corresponding to two triplet species, one of which was short-lived while the other proved to be persistent at 10 K. These observations strongly support the proposed mechanism for the photogeneration of 4 and 5, which involves intramolecular rearrangement of the intermediate diradical species 2 to afford the triplet diradical 3.