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Article: Time-resolved resonance raman study of the effect of ph on the photoreactions of 3-benzoylpyridine in aqueous solution

TitleTime-resolved resonance raman study of the effect of ph on the photoreactions of 3-benzoylpyridine in aqueous solution
Authors
Issue Date2009
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpca
Citation
Journal Of Physical Chemistry A, 2009, v. 113 n. 44, p. 12215-12224 How to Cite?
AbstractA nanosecond time-resolved resonance Raman investigation of the photoreactions of 3-benzoylpyridine (3-BPy) in different pH aqueous solutions is reported. In neutral, basic, and pH = 5 aqueous solution conditions, the photoreduction reaction from the triplet 3-BPy species is observed to produce the corresponding 3-phenyl pyridyl ketyl radical that was also observed in a 2-propanol solvent. Under moderate acidic conditions (at pH = 3 for example), most of the 3-BPy triplet state species goes through two protonation steps at the nitrogen atom and the carbonyl oxygen atom after UV laser photolysis and then forms a short-lived hydration intermediate via a hydration reaction at the ortho position in the benzene ring. This new species is tentatively assigned to the o- 3[3-BPyH +· 2O] hydration species. In acidic aqueous solutions with a pH < 1, the protonated triplet states of 3-BPy cations at the nitrogen atom are generated from photoexcitation of the protonated ground state and are subsequently further protonated at the carbonyl oxygen atom to form a 3-BPy-dication triplet state. This dication intermediate reacts with water molecules at the ortho position of the benzene ring to produce the o- 3[3-BPyH +·H 2O] hydration species. The mechanisms of photoreduction observed for 3-BPy in different pH aqueous solutions were investigated using density functional theory calculations, and these results were used to help assign the intermediates observed in the experiments. The structures and properties of these species are briefly discussed, and an overall photoreaction mechanism is proposed based on the results from the time-resolved resonance Raman experiments and the density functional theory calculations. © 2009 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/168411
ISSN
2015 Impact Factor: 2.883
2015 SCImago Journal Rankings: 1.231
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLi, MDen_US
dc.contributor.authorDu, Yen_US
dc.contributor.authorYeung, CSen_US
dc.contributor.authorPhillips, DLen_US
dc.date.accessioned2012-10-08T03:18:36Z-
dc.date.available2012-10-08T03:18:36Z-
dc.date.issued2009en_US
dc.identifier.citationJournal Of Physical Chemistry A, 2009, v. 113 n. 44, p. 12215-12224en_US
dc.identifier.issn1089-5639en_US
dc.identifier.urihttp://hdl.handle.net/10722/168411-
dc.description.abstractA nanosecond time-resolved resonance Raman investigation of the photoreactions of 3-benzoylpyridine (3-BPy) in different pH aqueous solutions is reported. In neutral, basic, and pH = 5 aqueous solution conditions, the photoreduction reaction from the triplet 3-BPy species is observed to produce the corresponding 3-phenyl pyridyl ketyl radical that was also observed in a 2-propanol solvent. Under moderate acidic conditions (at pH = 3 for example), most of the 3-BPy triplet state species goes through two protonation steps at the nitrogen atom and the carbonyl oxygen atom after UV laser photolysis and then forms a short-lived hydration intermediate via a hydration reaction at the ortho position in the benzene ring. This new species is tentatively assigned to the o- 3[3-BPyH +· 2O] hydration species. In acidic aqueous solutions with a pH < 1, the protonated triplet states of 3-BPy cations at the nitrogen atom are generated from photoexcitation of the protonated ground state and are subsequently further protonated at the carbonyl oxygen atom to form a 3-BPy-dication triplet state. This dication intermediate reacts with water molecules at the ortho position of the benzene ring to produce the o- 3[3-BPyH +·H 2O] hydration species. The mechanisms of photoreduction observed for 3-BPy in different pH aqueous solutions were investigated using density functional theory calculations, and these results were used to help assign the intermediates observed in the experiments. The structures and properties of these species are briefly discussed, and an overall photoreaction mechanism is proposed based on the results from the time-resolved resonance Raman experiments and the density functional theory calculations. © 2009 American Chemical Society.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpcaen_US
dc.relation.ispartofJournal of Physical Chemistry Aen_US
dc.titleTime-resolved resonance raman study of the effect of ph on the photoreactions of 3-benzoylpyridine in aqueous solutionen_US
dc.typeArticleen_US
dc.identifier.emailPhillips, DL:phillips@hku.hken_US
dc.identifier.authorityPhillips, DL=rp00770en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/jp905984wen_US
dc.identifier.pmid19824666-
dc.identifier.scopuseid_2-s2.0-70350539664en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-70350539664&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume113en_US
dc.identifier.issue44en_US
dc.identifier.spage12215en_US
dc.identifier.epage12224en_US
dc.identifier.isiWOS:000271105800022-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridLi, MD=7405265795en_US
dc.identifier.scopusauthoridDu, Y=35310175500en_US
dc.identifier.scopusauthoridYeung, CS=35173915800en_US
dc.identifier.scopusauthoridPhillips, DL=7404519365en_US

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