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Article: Time-resolved resonance Raman and density functional theory study of the photochemistry of 4-benzoylpyridine in acetonitrile and 2-propanol

TitleTime-resolved resonance Raman and density functional theory study of the photochemistry of 4-benzoylpyridine in acetonitrile and 2-propanol
Authors
Keywords4-benzoylpyridine
Hydrogen abstraction
Ketyl radical
Resonance Raman spectroscopy
Time-resolved spectroscopy
Issue Date2008
PublisherJohn Wiley & Sons Ltd. The Journal's web site is located at http://www3.interscience.wiley.com/cgi-bin/jhome/3420
Citation
Journal Of Raman Spectroscopy, 2008, v. 39 n. 4, p. 503-514 How to Cite?
AbstractA nanosecond time-resolved resonance Raman (ns-TR 3) spectroscopic investigation of the intermolecular hydrogen-abstraction reaction of the triplet state of 4-benzoylpyridine (4-BPy) in 2-propanol solvent is reported. The TR 3 results reveal a rapid hydrogen abstraction (<10 ns) by the 4-BPy triplet state (nπ*) with the 2-propanol solvent, leading to formation of a 4-BPy ketyl radical and an associated dimethyl ketyl radical partner from the solvent. The recombination of these two radical species occurs with a time constant about 200 ns to produce a para-N-LAT (light absorbing transient). The structure, major spectral features, and identification of the ketyl radical and the para-N-LAT coupling complex have been determined and confirmed by comparison of the TR 3 results with results from density functional theory (DFT) calculations. A reaction pathway for the photolysis of 4-BPy in 2-propanol deduced from the TR 3 results is also presented. The electron-withdrawing effect of the heterocyclic nitrogen for 4-BPy on the triplet state makes it have a significantly higher chemical reactivity for the hydrogen abstraction with 2-propanol compared to the previously reported corresponding benzophenone triplet reaction under similar reaction conditions. In addition, the 4-BPy ketyl radical reacts with the dimethyl ketyl radical to attach at the para-N atom position of the pyridine ring to form a cross-coupling product such as 2-[4-(hydroxy-phenyl-methylene)- 4h-pyridin-1-yl]-propan-2-ol instead of attacking at the para-C atom position as was observed for the corresponding benzophenone reaction reported in an earlier study. Copyright © 2008 John Wiley & Sons, Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/132170
ISSN
2015 Impact Factor: 2.395
2015 SCImago Journal Rankings: 1.075
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorDu, Yen_HK
dc.contributor.authorXue, Jen_HK
dc.contributor.authorMa, Cen_HK
dc.contributor.authorKwok, WMen_HK
dc.contributor.authorPhillips, DLen_HK
dc.date.accessioned2011-03-21T08:58:22Z-
dc.date.available2011-03-21T08:58:22Z-
dc.date.issued2008en_HK
dc.identifier.citationJournal Of Raman Spectroscopy, 2008, v. 39 n. 4, p. 503-514en_HK
dc.identifier.issn0377-0486en_HK
dc.identifier.urihttp://hdl.handle.net/10722/132170-
dc.description.abstractA nanosecond time-resolved resonance Raman (ns-TR 3) spectroscopic investigation of the intermolecular hydrogen-abstraction reaction of the triplet state of 4-benzoylpyridine (4-BPy) in 2-propanol solvent is reported. The TR 3 results reveal a rapid hydrogen abstraction (<10 ns) by the 4-BPy triplet state (nπ*) with the 2-propanol solvent, leading to formation of a 4-BPy ketyl radical and an associated dimethyl ketyl radical partner from the solvent. The recombination of these two radical species occurs with a time constant about 200 ns to produce a para-N-LAT (light absorbing transient). The structure, major spectral features, and identification of the ketyl radical and the para-N-LAT coupling complex have been determined and confirmed by comparison of the TR 3 results with results from density functional theory (DFT) calculations. A reaction pathway for the photolysis of 4-BPy in 2-propanol deduced from the TR 3 results is also presented. The electron-withdrawing effect of the heterocyclic nitrogen for 4-BPy on the triplet state makes it have a significantly higher chemical reactivity for the hydrogen abstraction with 2-propanol compared to the previously reported corresponding benzophenone triplet reaction under similar reaction conditions. In addition, the 4-BPy ketyl radical reacts with the dimethyl ketyl radical to attach at the para-N atom position of the pyridine ring to form a cross-coupling product such as 2-[4-(hydroxy-phenyl-methylene)- 4h-pyridin-1-yl]-propan-2-ol instead of attacking at the para-C atom position as was observed for the corresponding benzophenone reaction reported in an earlier study. Copyright © 2008 John Wiley & Sons, Ltd.en_HK
dc.languageengen_US
dc.publisherJohn Wiley & Sons Ltd. The Journal's web site is located at http://www3.interscience.wiley.com/cgi-bin/jhome/3420en_HK
dc.relation.ispartofJournal of Raman Spectroscopyen_HK
dc.rightsJournal of Raman Spectroscopy. Copyright © John Wiley & Sons Ltd.-
dc.subject4-benzoylpyridineen_HK
dc.subjectHydrogen abstractionen_HK
dc.subjectKetyl radicalen_HK
dc.subjectResonance Raman spectroscopyen_HK
dc.subjectTime-resolved spectroscopyen_HK
dc.titleTime-resolved resonance Raman and density functional theory study of the photochemistry of 4-benzoylpyridine in acetonitrile and 2-propanolen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0377-0486&volume=39&issue=4&spage=503&epage=514&date=2008&atitle=Time-resolved+resonance+Raman+and+density+functional+theory+study+of+the+photochemistry+of+4-benzoylpyridine+in+acetonitrile+and+2-propanol-
dc.identifier.emailMa, C:macs@hkucc.hku.hken_HK
dc.identifier.emailPhillips, DL:phillips@hku.hken_HK
dc.identifier.authorityMa, C=rp00758en_HK
dc.identifier.authorityPhillips, DL=rp00770en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1002/jrs.1869en_HK
dc.identifier.scopuseid_2-s2.0-51549104971en_HK
dc.identifier.hkuros177067en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-51549104971&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume39en_HK
dc.identifier.issue4en_HK
dc.identifier.spage503en_HK
dc.identifier.epage514en_HK
dc.identifier.isiWOS:000255206600011-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridDu, Y=35310175500en_HK
dc.identifier.scopusauthoridXue, J=23007272500en_HK
dc.identifier.scopusauthoridMa, C=7402924979en_HK
dc.identifier.scopusauthoridKwok, WM=7103129332en_HK
dc.identifier.scopusauthoridPhillips, DL=7404519365en_HK

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