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Article: Time-resolved resonance raman study of the triplet states of p-hydroxyacetophenone and the p-hydroxyphenacyl diethyl phosphate phototrigger compound

TitleTime-resolved resonance raman study of the triplet states of p-hydroxyacetophenone and the p-hydroxyphenacyl diethyl phosphate phototrigger compound
Authors
Issue Date2004
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/joc
Citation
Journal Of Organic Chemistry, 2004, v. 69 n. 20, p. 6641-6657 How to Cite?
AbstractPico- and nanosecond time-resolved resonance Raman (TR 3) spectroscopy have been utilized to study the dynamics and structure of p-hydroxyacetophenone (HA) and the p-hydroxyphenacyl-caged photo trigger compound p-hydroxyphenacyl diethyl phosphate (HPDP) in acetonitrile solution. Transient intermediates were detected and attributed to the triplet states of HA and HPDP. Nanosecond-TR 3 measurements were done for two isotopically substituted HA molecules to help better assign the triplet state carbonyl C=O stretching and the ring related vibrational modes. The dynamics of formation and the spectral characteristics for the triplet states were found to be similar for the HA and HPDP. The temporal evolution at very early picosecond time scale indicates there is rapid intersystem crossing (ISC) conversion and subsequent relaxation of the excess energy of the initially produced energetic triplet state. B3LYP/6-311G** density functional theory (DFT) calculations were done to determine the structures and vibrational frequencies for both the triplet and ground states of HA and HPDP. The calculated spectra reproduce the experimental spectra and the observed isotopic shifts reasonably well and were used to make tentative assignments to all the experimentally observed features. The triplet states were found to have extensive conjugated ππ* nature with a single-bond-like carbonyl CO bond. We briefly compare the triplet structure and formation dynamics of HA and HPDP as well as the conformational changes upon going from the ground state to the triplet state. We discuss our present results in relation to the initial pathway for the p-hydroxyphenacyl photodeprotection process. We also compare and discuss the properties of the HA ππ* triplet state relative to the published results of other aromatic carbonyl compounds.
Persistent Identifierhttp://hdl.handle.net/10722/69183
ISSN
2015 Impact Factor: 4.785
2015 SCImago Journal Rankings: 2.095
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorMa, Cen_HK
dc.contributor.authorZuo, Pen_HK
dc.contributor.authorWai, MKen_HK
dc.contributor.authorWing, SCen_HK
dc.contributor.authorKan, JTWen_HK
dc.contributor.authorToy, PHen_HK
dc.contributor.authorPhillips, DLen_HK
dc.date.accessioned2010-09-06T06:11:20Z-
dc.date.available2010-09-06T06:11:20Z-
dc.date.issued2004en_HK
dc.identifier.citationJournal Of Organic Chemistry, 2004, v. 69 n. 20, p. 6641-6657en_HK
dc.identifier.issn0022-3263en_HK
dc.identifier.urihttp://hdl.handle.net/10722/69183-
dc.description.abstractPico- and nanosecond time-resolved resonance Raman (TR 3) spectroscopy have been utilized to study the dynamics and structure of p-hydroxyacetophenone (HA) and the p-hydroxyphenacyl-caged photo trigger compound p-hydroxyphenacyl diethyl phosphate (HPDP) in acetonitrile solution. Transient intermediates were detected and attributed to the triplet states of HA and HPDP. Nanosecond-TR 3 measurements were done for two isotopically substituted HA molecules to help better assign the triplet state carbonyl C=O stretching and the ring related vibrational modes. The dynamics of formation and the spectral characteristics for the triplet states were found to be similar for the HA and HPDP. The temporal evolution at very early picosecond time scale indicates there is rapid intersystem crossing (ISC) conversion and subsequent relaxation of the excess energy of the initially produced energetic triplet state. B3LYP/6-311G** density functional theory (DFT) calculations were done to determine the structures and vibrational frequencies for both the triplet and ground states of HA and HPDP. The calculated spectra reproduce the experimental spectra and the observed isotopic shifts reasonably well and were used to make tentative assignments to all the experimentally observed features. The triplet states were found to have extensive conjugated ππ* nature with a single-bond-like carbonyl CO bond. We briefly compare the triplet structure and formation dynamics of HA and HPDP as well as the conformational changes upon going from the ground state to the triplet state. We discuss our present results in relation to the initial pathway for the p-hydroxyphenacyl photodeprotection process. We also compare and discuss the properties of the HA ππ* triplet state relative to the published results of other aromatic carbonyl compounds.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jocen_HK
dc.relation.ispartofJournal of Organic Chemistryen_HK
dc.titleTime-resolved resonance raman study of the triplet states of p-hydroxyacetophenone and the p-hydroxyphenacyl diethyl phosphate phototrigger compounden_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0022-3263&volume=69&issue=20&spage=6641&epage=6657&date=2004&atitle=Time-resolved+resonance+Raman+study+of+the+triplet+states+of+p-hydroxyacetophenone+and+the+p-hydroxyphenacyl+diethyl+phosphate+phototrigger+compounden_HK
dc.identifier.emailMa, C:macs@hkucc.hku.hken_HK
dc.identifier.emailToy, PH:phtoy@hkucc.hku.hken_HK
dc.identifier.emailPhillips, DL:phillips@hku.hken_HK
dc.identifier.authorityMa, C=rp00758en_HK
dc.identifier.authorityToy, PH=rp00791en_HK
dc.identifier.authorityPhillips, DL=rp00770en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/jo049331aen_HK
dc.identifier.scopuseid_2-s2.0-4644263204en_HK
dc.identifier.hkuros98493en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-4644263204&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume69en_HK
dc.identifier.issue20en_HK
dc.identifier.spage6641en_HK
dc.identifier.epage6657en_HK
dc.identifier.isiWOS:000224143000015-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridMa, C=7402924979en_HK
dc.identifier.scopusauthoridZuo, P=35068878800en_HK
dc.identifier.scopusauthoridWai, MK=8761955300en_HK
dc.identifier.scopusauthoridWing, SC=8761955400en_HK
dc.identifier.scopusauthoridKan, JTW=8753189200en_HK
dc.identifier.scopusauthoridToy, PH=7006579247en_HK
dc.identifier.scopusauthoridPhillips, DL=7404519365en_HK

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