Direct Observation of Photoinduced Ultrafast Generation of Singlet and Triplet Quinone Methides in Aqueous Solutions and Insight into the Roles of Acidic and Basic Sites in Quinone Methide Formation.
Femtosecond time-resolved transient absorption spectroscopy experiments and density functional theory computations were done for a mechanistic investigation of 3- (1-phenylvinyl)phenol (1) and 3-hydroxybenzophenone (2) in selected solvents. Both compounds went through an intersystem crossing (ISC) t...
| Publicado en: | Journal of the American Chemical Society Vol. 139; no. 50; pp. 18349 - 18358 |
|---|---|
| Autores principales: | , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
12/20/2017
|
| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=127093258&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 127093258 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 12/20/2017 vid: 139 iid: 50 pid: 997 pub: American Chemical Society artinfo: ui: 127093258 10.1021/jacs.7b10387 ppf: 18349 ppct: 9 formats: tig: atl: Direct Observation of Photoinduced Ultrafast Generation of Singlet and Triplet Quinone Methides in Aqueous Solutions and Insight into the Roles of Acidic and Basic Sites in Quinone Methide Formation. aug: au: Jiani Ma Xiting Zhang Basarić, Nikola Phillips, David Lee affil: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, P. R. China Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia su: Quinone methides Femtochemistry Cancer phototherapy Density functional theory Acetonitrile sug: subj: Quinone methides Femtochemistry Cancer phototherapy Density functional theory Acetonitrile ab: Femtosecond time-resolved transient absorption spectroscopy experiments and density functional theory computations were done for a mechanistic investigation of 3- (1-phenylvinyl)phenol (1) and 3-hydroxybenzophenone (2) in selected solvents. Both compounds went through an intersystem crossing (ISC) to form the triplet excited states Tππ* and TnÏ€* in acetonitrile but behave differently in neutral aqueous solutions, in which a triplet excited state proton transfer (ESPT) induced by the ISC process is also proposed for 2 but a singlet ESPT without ISC is proposed for 1, leading to the production of the triplet quinone methide (QM) and the singlet excited QM species respectively in these two systems. The triplet QM then underwent an ISC process to form an unstable ground state intermediate which soon returned to its starting material 2. However, the singlet excited state QM went through an internal conversion process to the ground state QM followed by the formation of its final product in an irreversible manner. These differences are thought to be derived from the slow vinyl C−C rotation and the moderate basicity of the vinyl C atom in 1 as compared with the fast C−O rotation and the greater basicity of the carbonyl O atom of 2 after photoexcitation. This can account for the experimental results in the literature that the aromatic vinyl compounds undergo efficient singlet excited state photochemical reactions while the aromatic carbonyl compounds prefer triplet photochemical reactions under aqueous conditions. These results have fundamental and significant implications for understanding of the ESPT reactivity in general, as well as for the design of molecules for efficient QM formation in aqueous media with potential applications in cancer phototherapy. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2017 holdings: @attributes: islocal: N |
|---|