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- Publisher Website: 10.1021/ja304441n
- Scopus: eid_2-s2.0-84961983490
- PMID: 22909212
- WOS: WOS:000308574800044
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Article: How and When Does an Unusual and Efficient Photoredox Reaction of 2-(1-Hydroxyethyl) 9,10-Anthraquinone Occur? A Combined Time-Resolved Spectroscopic and DFT Study
Title | How and When Does an Unusual and Efficient Photoredox Reaction of 2-(1-Hydroxyethyl) 9,10-Anthraquinone Occur? A Combined Time-Resolved Spectroscopic and DFT Study |
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Authors | |
Issue Date | 2012 |
Publisher | American Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html |
Citation | Journal of the American Chemical Society, 2012, v. 134 n. 36, p. 14858-14868 How to Cite? |
Abstract | The photophysics and photochemical reactions of 2-(1-hydroxyethyl) 9,10-anthroquinone (2-HEAQ) were studied using femtosecond transient absorption (fs-TA), nanosecond transient absorption (ns-TA), and nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopy techniques and density functional theory (DFT) calculations. In acetonitrile, 2-HEAQ underwent efficient intersystem crossing to the triplet excited state ((2-HEAQ)(3)). A typical photoreduction reaction for aromatic ketones took place via production of a ketyl radical intermediate for 2-HEAQ in isopropanol. In water-containing solutions with pH values between 2 and 10, an unusual photoredox reaction reported by Wan and co-workers was detected and characterized. Observation of the protonated species in neutral and acidic aqueous solutions by fs-TA spectra indicated the carbonyl oxygen of (2-HEAQ)(3) was protonated initially and acted as a precursor of the photoredox reaction. The preference of the photoredox reaction to occur under moderate acidic conditions compared to neutral condition observed using ns-TR(3) spectroscopy was consistent with results from DFT calculations, which suggested protonation of the carbonyl group was the rate-determining step. Under stronger acidic conditions (pH 0), although the protonated (2-HEAQ)(3) was formed, the predominant reaction was the photohydration reaction instead of the photoredox reaction. In stronger basic solutions (pH 12), (2-HEAQ)(3) decayed with no obvious photochemical reactions detected by time-resolved spectroscopic experiments. Reaction mechanisms and key reactive intermediates for the unusual photoredox reaction were elucidated from time-resolved spectroscopy and DFT results. A brief discussion is given of when photoredox reactions may likely take place in the photochemistry of aromatic carbonyl-containing compounds and possible implications for using BP and AQ scaffolds for phototrigger compounds. |
Persistent Identifier | http://hdl.handle.net/10722/188227 |
ISSN | 2023 Impact Factor: 14.4 2023 SCImago Journal Rankings: 5.489 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Ma, J | - |
dc.contributor.author | Su, T | - |
dc.contributor.author | Li, MD | - |
dc.contributor.author | Du, W | - |
dc.contributor.author | Huang, J | - |
dc.contributor.author | Guan, X | - |
dc.contributor.author | Phillips, DL | - |
dc.date.accessioned | 2013-08-23T03:13:15Z | - |
dc.date.available | 2013-08-23T03:13:15Z | - |
dc.date.issued | 2012 | - |
dc.identifier.citation | Journal of the American Chemical Society, 2012, v. 134 n. 36, p. 14858-14868 | - |
dc.identifier.issn | 0002-7863 | - |
dc.identifier.uri | http://hdl.handle.net/10722/188227 | - |
dc.description.abstract | The photophysics and photochemical reactions of 2-(1-hydroxyethyl) 9,10-anthroquinone (2-HEAQ) were studied using femtosecond transient absorption (fs-TA), nanosecond transient absorption (ns-TA), and nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopy techniques and density functional theory (DFT) calculations. In acetonitrile, 2-HEAQ underwent efficient intersystem crossing to the triplet excited state ((2-HEAQ)(3)). A typical photoreduction reaction for aromatic ketones took place via production of a ketyl radical intermediate for 2-HEAQ in isopropanol. In water-containing solutions with pH values between 2 and 10, an unusual photoredox reaction reported by Wan and co-workers was detected and characterized. Observation of the protonated species in neutral and acidic aqueous solutions by fs-TA spectra indicated the carbonyl oxygen of (2-HEAQ)(3) was protonated initially and acted as a precursor of the photoredox reaction. The preference of the photoredox reaction to occur under moderate acidic conditions compared to neutral condition observed using ns-TR(3) spectroscopy was consistent with results from DFT calculations, which suggested protonation of the carbonyl group was the rate-determining step. Under stronger acidic conditions (pH 0), although the protonated (2-HEAQ)(3) was formed, the predominant reaction was the photohydration reaction instead of the photoredox reaction. In stronger basic solutions (pH 12), (2-HEAQ)(3) decayed with no obvious photochemical reactions detected by time-resolved spectroscopic experiments. Reaction mechanisms and key reactive intermediates for the unusual photoredox reaction were elucidated from time-resolved spectroscopy and DFT results. A brief discussion is given of when photoredox reactions may likely take place in the photochemistry of aromatic carbonyl-containing compounds and possible implications for using BP and AQ scaffolds for phototrigger compounds. | - |
dc.language | eng | - |
dc.publisher | American Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html | - |
dc.relation.ispartof | Journal of the American Chemical Society | - |
dc.subject.mesh | Anthraquinones - chemical synthesis - chemistry | - |
dc.subject.mesh | Molecular Structure | - |
dc.subject.mesh | Oxidation-Reduction | - |
dc.subject.mesh | Photochemical Processes | - |
dc.subject.mesh | Quantum Theory | - |
dc.title | How and When Does an Unusual and Efficient Photoredox Reaction of 2-(1-Hydroxyethyl) 9,10-Anthraquinone Occur? A Combined Time-Resolved Spectroscopic and DFT Study | en_US |
dc.type | Article | en_US |
dc.identifier.email | Phillips, DL: phillips@hku.hk | - |
dc.identifier.doi | 10.1021/ja304441n | - |
dc.identifier.pmid | 22909212 | - |
dc.identifier.scopus | eid_2-s2.0-84961983490 | - |
dc.identifier.hkuros | 220087 | - |
dc.identifier.volume | 134 | - |
dc.identifier.issue | 36 | - |
dc.identifier.spage | 14858 | - |
dc.identifier.epage | 14868 | - |
dc.identifier.isi | WOS:000308574800044 | - |
dc.publisher.place | United States | - |
dc.identifier.issnl | 0002-7863 | - |