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Article: Time-resolved resonance Raman and density functional theory study of the deprotonation reaction of the triplet state of p-hydroxyacetophenone in water solution

TitleTime-resolved resonance Raman and density functional theory study of the deprotonation reaction of the triplet state of p-hydroxyacetophenone in water solution
Authors
Issue Date2005
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/joc
Citation
Journal Of Organic Chemistry, 2005, v. 70 n. 22, p. 8661-8675 How to Cite?
AbstractPicosecond and nanosecond time-resolved resonance Raman (TR3) spectroscopy was employed to investigate the deprotonation/ionization reaction of p-hydroxyacetophenone (HA) after ultraviolet photolysis in water solution. The TR3 spectra in conjunction with density functional theory (DFT) calculations were used to characterize the structure and dynamics of the excited-state HA deprotonation to form HA anions in near neutral water solvent. DFT calculations based on a solute-solvent intermolecular H-bonded complex model containing up to three water molecules were used to evaluate the H-bond interactions and their influence on the deprotonation reaction and the structures of the intermediates. The deprotonation reaction was found to occur on the triplet manifold with a planar H-bonded HA triplet complex as the precursor species. The HA triplet species is generated within several picoseconds and then decays with a ∼10 ns time constant to produce the HA triplet anion species after 267 nm photolysis of HA in water solution. The triplet anion species was observed to decay with a time constant of about 90 ns into the ground-state anion species that was found to have a lifetime of about 200 ns. The DFT calculations on the H-bonded complexes of the anion triplet and ground-states species suggest that these anion species are H-bonded complexes with planar quinonoidal structures containing two water molecules H-bonded, respectively, with oxygen lone pairs of the carbonyl and deprotonated hydroxyl moieties. A deactivation scheme of the photoexcited HA in regard to the deprotonation reaction in neutral water solutions was proposed. With the above dynamic and structural information available, we briefly discuss the possible implications of the model HA photochemistry in water solutions for the photodeprotection reactions of related p-HP phototrigger compounds in aqueous solutions. © 2005 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/167964
ISSN
2015 Impact Factor: 4.785
2015 SCImago Journal Rankings: 2.095
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZuo, Pen_US
dc.contributor.authorMa, Cen_US
dc.contributor.authorKwok, WMen_US
dc.contributor.authorChan, WSen_US
dc.contributor.authorPhillips, DLen_US
dc.date.accessioned2012-10-08T03:13:29Z-
dc.date.available2012-10-08T03:13:29Z-
dc.date.issued2005en_US
dc.identifier.citationJournal Of Organic Chemistry, 2005, v. 70 n. 22, p. 8661-8675en_US
dc.identifier.issn0022-3263en_US
dc.identifier.urihttp://hdl.handle.net/10722/167964-
dc.description.abstractPicosecond and nanosecond time-resolved resonance Raman (TR3) spectroscopy was employed to investigate the deprotonation/ionization reaction of p-hydroxyacetophenone (HA) after ultraviolet photolysis in water solution. The TR3 spectra in conjunction with density functional theory (DFT) calculations were used to characterize the structure and dynamics of the excited-state HA deprotonation to form HA anions in near neutral water solvent. DFT calculations based on a solute-solvent intermolecular H-bonded complex model containing up to three water molecules were used to evaluate the H-bond interactions and their influence on the deprotonation reaction and the structures of the intermediates. The deprotonation reaction was found to occur on the triplet manifold with a planar H-bonded HA triplet complex as the precursor species. The HA triplet species is generated within several picoseconds and then decays with a ∼10 ns time constant to produce the HA triplet anion species after 267 nm photolysis of HA in water solution. The triplet anion species was observed to decay with a time constant of about 90 ns into the ground-state anion species that was found to have a lifetime of about 200 ns. The DFT calculations on the H-bonded complexes of the anion triplet and ground-states species suggest that these anion species are H-bonded complexes with planar quinonoidal structures containing two water molecules H-bonded, respectively, with oxygen lone pairs of the carbonyl and deprotonated hydroxyl moieties. A deactivation scheme of the photoexcited HA in regard to the deprotonation reaction in neutral water solutions was proposed. With the above dynamic and structural information available, we briefly discuss the possible implications of the model HA photochemistry in water solutions for the photodeprotection reactions of related p-HP phototrigger compounds in aqueous solutions. © 2005 American Chemical Society.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jocen_US
dc.relation.ispartofJournal of Organic Chemistryen_US
dc.subject.meshAcetophenones - Chemistryen_US
dc.subject.meshAnions - Chemistryen_US
dc.subject.meshKineticsen_US
dc.subject.meshModels, Chemicalen_US
dc.subject.meshMolecular Conformationen_US
dc.subject.meshProtonsen_US
dc.subject.meshSolutionsen_US
dc.subject.meshSpectrum Analysis, Ramanen_US
dc.subject.meshTime Factorsen_US
dc.subject.meshVibrationen_US
dc.subject.meshWateren_US
dc.titleTime-resolved resonance Raman and density functional theory study of the deprotonation reaction of the triplet state of p-hydroxyacetophenone in water solutionen_US
dc.typeArticleen_US
dc.identifier.emailMa, C:macs@hkucc.hku.hken_US
dc.identifier.emailPhillips, DL:phillips@hku.hken_US
dc.identifier.authorityMa, C=rp00758en_US
dc.identifier.authorityPhillips, DL=rp00770en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/jo050761qen_US
dc.identifier.pmid16238294-
dc.identifier.scopuseid_2-s2.0-27444443332en_US
dc.identifier.hkuros117009-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-27444443332&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume70en_US
dc.identifier.issue22en_US
dc.identifier.spage8661en_US
dc.identifier.epage8675en_US
dc.identifier.isiWOS:000232909300002-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridZuo, P=35068878800en_US
dc.identifier.scopusauthoridMa, C=7402924979en_US
dc.identifier.scopusauthoridKwok, WM=7103129332en_US
dc.identifier.scopusauthoridChan, WS=35067933100en_US
dc.identifier.scopusauthoridPhillips, DL=7404519365en_US

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