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Article: Ultrafast time-resolved transient absorption and resonance Raman spectroscopy study of the photodeprotection and rearrangement reactions of p-hydroxyphenacyl caged phosphates

TitleUltrafast time-resolved transient absorption and resonance Raman spectroscopy study of the photodeprotection and rearrangement reactions of p-hydroxyphenacyl caged phosphates
Authors
Issue Date2006
PublisherAmerican 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, 2006, v. 128 n. 8, p. 2558-2570 How to Cite?
AbstractThe kinetics and mechanism of the photodeprotection and rearrangement reactions for the pHP phototrigger compounds p-hydroxyphenacyl diethyl phosphate (HPDP) and diphenyl phosphate (HPPP) were studied using transient absorption (TA) and picosecond time-resolved resonance Raman (ps-TR 3) spectroscopy. TA spectroscopy was employed to detect the dynamics of the triplet precursor decay as well as to investigate the influence of the solvent and leaving group on the triplet quenching process. Ps-TR 3 spectroscopy was used to directly monitor the formation dynamics for the photosolvolytic rearrangement product and its solvent and leaving group dependence. The TA and TR 3 spectroscopy experiments were also used to characterize the structural and electronic properties of the triplet precursor to the HPDP and HPPP deprotection reactions. The solvent effect observed in conjunction with the leaving group dependence of the triplet decay dynamics are consistent with a concerted solvent assisted triplet cleavage through a heterolytic mechanism for the HPDP and HPPP photodeprotection process. Correlation of the dynamics between the deprotection and rearrangement processes reveals there is a consecutive mechanism and the involvement of an intermediate between the two reaction steps. The reaction rate of the deprotection and rearrangement steps and the influence of the solvent and leaving group were determined and evaluated based on kinetic modeling of the dynamical data obtained experimentally for HPDP and HPPP in H 2O/MeCN mixed solvents with varying water concentration in the solvent system. A solvation complex with a contact ion pair character was proposed to be the intermediate involved in the deprotection and rearrangement pathway. The results here combined with our previous study on the photophysical events occurring on the early picosecond time scale (Ma; et al. J. Am. Chem. Soc. 2005, 127, 1463-1472) provide a real time overall mechanistic description for the photodeprotection and rearrangement reactions of pHP caged phosphate phototrigger compounds. © 2006 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/69928
ISSN
2015 Impact Factor: 13.038
2015 SCImago Journal Rankings: 7.123
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorMa, Cen_HK
dc.contributor.authorKwok, WMen_HK
dc.contributor.authorChan, WSen_HK
dc.contributor.authorDu, Yen_HK
dc.contributor.authorKan, JTWen_HK
dc.contributor.authorToy, PHen_HK
dc.contributor.authorPhillips, DLen_HK
dc.date.accessioned2010-09-06T06:18:07Z-
dc.date.available2010-09-06T06:18:07Z-
dc.date.issued2006en_HK
dc.identifier.citationJournal Of The American Chemical Society, 2006, v. 128 n. 8, p. 2558-2570en_HK
dc.identifier.issn0002-7863en_HK
dc.identifier.urihttp://hdl.handle.net/10722/69928-
dc.description.abstractThe kinetics and mechanism of the photodeprotection and rearrangement reactions for the pHP phototrigger compounds p-hydroxyphenacyl diethyl phosphate (HPDP) and diphenyl phosphate (HPPP) were studied using transient absorption (TA) and picosecond time-resolved resonance Raman (ps-TR 3) spectroscopy. TA spectroscopy was employed to detect the dynamics of the triplet precursor decay as well as to investigate the influence of the solvent and leaving group on the triplet quenching process. Ps-TR 3 spectroscopy was used to directly monitor the formation dynamics for the photosolvolytic rearrangement product and its solvent and leaving group dependence. The TA and TR 3 spectroscopy experiments were also used to characterize the structural and electronic properties of the triplet precursor to the HPDP and HPPP deprotection reactions. The solvent effect observed in conjunction with the leaving group dependence of the triplet decay dynamics are consistent with a concerted solvent assisted triplet cleavage through a heterolytic mechanism for the HPDP and HPPP photodeprotection process. Correlation of the dynamics between the deprotection and rearrangement processes reveals there is a consecutive mechanism and the involvement of an intermediate between the two reaction steps. The reaction rate of the deprotection and rearrangement steps and the influence of the solvent and leaving group were determined and evaluated based on kinetic modeling of the dynamical data obtained experimentally for HPDP and HPPP in H 2O/MeCN mixed solvents with varying water concentration in the solvent system. A solvation complex with a contact ion pair character was proposed to be the intermediate involved in the deprotection and rearrangement pathway. The results here combined with our previous study on the photophysical events occurring on the early picosecond time scale (Ma; et al. J. Am. Chem. Soc. 2005, 127, 1463-1472) provide a real time overall mechanistic description for the photodeprotection and rearrangement reactions of pHP caged phosphate phototrigger compounds. © 2006 American Chemical Society.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.htmlen_HK
dc.relation.ispartofJournal of the American Chemical Societyen_HK
dc.titleUltrafast time-resolved transient absorption and resonance Raman spectroscopy study of the photodeprotection and rearrangement reactions of p-hydroxyphenacyl caged phosphatesen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0002-7863&volume=128&spage=2558&epage=2570&date=2006&atitle=Ultrafast+time-resolved+transient+absorption+and+resonance+Raman+spectroscopy+study+of+the+photodeprotection+and+rearrangement+reactions+of+p-hydroxyphenacyl+caged+phosphates+en_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/ja0532032en_HK
dc.identifier.pmid16492039-
dc.identifier.scopuseid_2-s2.0-33644650434en_HK
dc.identifier.hkuros117605en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-33644650434&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume128en_HK
dc.identifier.issue8en_HK
dc.identifier.spage2558en_HK
dc.identifier.epage2570en_HK
dc.identifier.eissn1520-5126-
dc.identifier.isiWOS:000235787200028-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridMa, C=7402924979en_HK
dc.identifier.scopusauthoridKwok, WM=7103129332en_HK
dc.identifier.scopusauthoridChan, WS=35067933100en_HK
dc.identifier.scopusauthoridDu, Y=35310175500en_HK
dc.identifier.scopusauthoridKan, JTW=8753189200en_HK
dc.identifier.scopusauthoridToy, PH=7006579247en_HK
dc.identifier.scopusauthoridPhillips, DL=7404519365en_HK

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