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Pregled bibliografske jedinice broj: 912286

Časopis

Autori: Ma, Jiani; Zhang, Xiting; Basarić, Nikola; Phillips, David Lee
Naslov: 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
Izvornik: Journal of the American Chemical Society (0002-7863) 139 (2017), 2017; 18349-18357
Vrsta rada: članak
Ključne riječi: ESPT ; Quinone methide ; Ultrafast transient absorption ; DFT calculations
Sažetak:
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 Tnπ* 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.
Projekt / tema: HRZZ-IP-2014-09-6312
Izvorni jezik: ENG
Rad je indeksiran u
bazama podataka:
Current Contents Connect (CCC)
MEDLINE
Scopus
SCI-EXP, SSCI i/ili A&HCI
Science Citation Index Expanded (SCI-EXP) (sastavni dio Web of Science Core Collectiona)
Kategorija: Znanstveni
Znanstvena područja:
Kemija
URL Internet adrese: http://pubs.acs.org/doi/abs/10.1021/jacs.7b10387
Broj citata:
Altmetric:
DOI: 10.1021/jacs.7b10387
URL cjelovitog teksta:
Google Scholar: 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
Upisao u CROSBI: Enidija Lukša (Enidija.Luksa@irb.hr), 13. Pro. 2017. u 10:40 sati



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