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Photoinduced reactivity in a Dispiro-1,2,4-trioxolane: Adamantane ring expansion and first direct observation of the long-lived triplet diradical intermediates

2020-05Journal article Restricted access
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dc.contributor.authorM Brás, Elisa
dc.contributor.authorCabral, Lília
dc.contributor.authorAmado, Patrícia
dc.contributor.authorAbe, Manabu
dc.contributor.authorFausto, Rui
dc.contributor.authorCristiano, Maria De Lurdes
dc.date.accessioned2021-06-24T11:35:34Z
dc.date.available2021-06-24T11:35:34Z
dc.date.issued2020-05
dc.description.abstractDispiro-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.
dc.description.sponsorshipPortuguese Science Foundation (FCT)Portuguese Foundation for Science and Technology [UID/QUI/0313/2019, UID/MULTI/04326/2019]
dc.description.sponsorshipCOMPETE-EU
dc.description.sponsorshipFCTPortuguese Foundation for Science and TechnologyEuropean Commission [CCMAR/BI/0013/2017, PTDC/MAR-BIO/4132/2014, SFRH/BD/136246/2018, SFRH/BD/130407/2017]
dc.description.sponsorshipCCMar [PTDC/MAR-BIO/4132/2014]
dc.description.versioninfo:eu-repo/semantics/publishedVersion
dc.identifier.doi10.1021/acs.jpca.0c01974
dc.identifier.issn1089-5639
dc.identifier.urihttp://hdl.handle.net/10400.1/16476
dc.language.isoeng
dc.peerreviewedyes
dc.publisherAmerican Chemical Society
dc.subject.otherChemistry
dc.titlePhotoinduced reactivity in a Dispiro-1,2,4-trioxolane: Adamantane ring expansion and first direct observation of the long-lived triplet diradical intermediates
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage4210
oaire.citation.issue21
oaire.citation.startPage4202
oaire.citation.titleJournal of Physical Chemistry A
oaire.citation.volume124
person.familyNameM Brás
person.familyNameCabral
person.familyNameMenalha Amado
person.familyNameCristiano
person.givenNameElisa
person.givenNameLília
person.givenNamePatrícia Sofia
person.givenNameMaria de Lurdes
person.identifier.ciencia-id7418-39EA-1089
person.identifier.ciencia-id3510-24A8-36B6
person.identifier.ciencia-id8617-A360-B70A
person.identifier.ciencia-idE411-6006-5A01
person.identifier.orcid0000-0003-1365-3628
person.identifier.orcid0000-0001-9362-8128
person.identifier.orcid0000-0002-7307-9210
person.identifier.orcid0000-0002-9447-2855
person.identifier.ridM-4279-2013
person.identifier.ridG-2345-2012
person.identifier.scopus-author-id57194523796
person.identifier.scopus-author-id9238724800
rcaap.rightsrestrictedAccess
rcaap.typearticle
relation.isAuthorOfPublication5d27e554-7e21-476a-9129-9f651058b7dc
relation.isAuthorOfPublication175a6aa3-9993-480b-9663-ed083a17eedf
relation.isAuthorOfPublication5b28f1eb-1d56-4094-8242-2d1163618e5f
relation.isAuthorOfPublicationb16751a6-748e-44b0-9c59-058cbd5b2cc3
relation.isAuthorOfPublication.latestForDiscovery5d27e554-7e21-476a-9129-9f651058b7dc

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