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Article: Photophysics and photodeprotection reactions of p-methoxyphenacyl phototriggers: An ultrafast and nanosecond time-resolved spectroscopic and density functional theory study

TitlePhotophysics and photodeprotection reactions of p-methoxyphenacyl phototriggers: An ultrafast and nanosecond time-resolved spectroscopic and density functional theory study
Authors
Issue Date2010
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/joc
Citation
Journal Of Organic Chemistry, 2010, v. 75 n. 17, p. 5837-5851 How to Cite?
AbstractTime-resolved spectroscopic experiments were performed to investigate the kinetics and mechanisms of the photodeprotection reactions for p-methoxyphenacyl (pMP) compounds, p-methoxyphenacyl diethyl phosphate (MPEP) and diphenyl phosphate (MPPP). The experimental results reveal that compared to the previous reports for the counterpart p-hydroxyphenacyl (pHP) phosphates, the 3nπ/ππ* mixed character triplet of pMP acts as a reactive precursor that leads to the subsequent solvent and leaving group dependent chemical reactions and further affects the formation of photoproducts. The MPPP triplet in H 2O/CH 3CN and in fluorinated alcohols shows a rapid heterolytic cleavage (τ ≈ 5.4 ns) that results in deprotection and formation of a solvolytic rearrangement product, whereas the MPPP triplet in CH 3CN and the MPEP triplet in CH 3CN and H 2O/CH 3CN and fluorinated alcohols decay on a much longer time scale (τ ≈ 100 ns) with little observation of the rearrangement product. The density functional theory (DFT) calculations reveal a substantial solvation effect that is connected with the methoxy versus hydroxyl substitution in accounting for the different deprotection reactivity of pMP and pHP compounds. The results reported here provide new insight in elucidating the solvent and leaving group dependent dual reactivity of pMP compounds on the formation of the rearrangement versus reductive photoproduct. © 2010 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/138996
ISSN
2015 Impact Factor: 4.785
2015 SCImago Journal Rankings: 2.095
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council of Hong KongHKU 1/01C
HKU 7039/07P
PolyU/7029/07p
PolyU/5007/08p
Croucher Foundation
University of Hong Kong
Funding Information:

The research was supported by grants from the Research Grants Council of Hong Kong (HKU 1/01C and HKU 7039/07P) to D.L.P. and (PolyU/7029/07p and PolyU/5007/08p) to W.M.K. D.L.P. thanks the Croucher Foundation for the Award of a Senior Research Fellowship and the University of Hong Kong for the Outstanding Researcher Award.

References
Grants

 

DC FieldValueLanguage
dc.contributor.authorAn, HYen_HK
dc.contributor.authorKwok, WMen_HK
dc.contributor.authorMa, Cen_HK
dc.contributor.authorGuan, Xen_HK
dc.contributor.authorKan, JTWen_HK
dc.contributor.authorToy, PHen_HK
dc.contributor.authorPhillips, DLen_HK
dc.date.accessioned2011-09-23T05:43:51Z-
dc.date.available2011-09-23T05:43:51Z-
dc.date.issued2010en_HK
dc.identifier.citationJournal Of Organic Chemistry, 2010, v. 75 n. 17, p. 5837-5851en_HK
dc.identifier.issn0022-3263en_HK
dc.identifier.urihttp://hdl.handle.net/10722/138996-
dc.description.abstractTime-resolved spectroscopic experiments were performed to investigate the kinetics and mechanisms of the photodeprotection reactions for p-methoxyphenacyl (pMP) compounds, p-methoxyphenacyl diethyl phosphate (MPEP) and diphenyl phosphate (MPPP). The experimental results reveal that compared to the previous reports for the counterpart p-hydroxyphenacyl (pHP) phosphates, the 3nπ/ππ* mixed character triplet of pMP acts as a reactive precursor that leads to the subsequent solvent and leaving group dependent chemical reactions and further affects the formation of photoproducts. The MPPP triplet in H 2O/CH 3CN and in fluorinated alcohols shows a rapid heterolytic cleavage (τ ≈ 5.4 ns) that results in deprotection and formation of a solvolytic rearrangement product, whereas the MPPP triplet in CH 3CN and the MPEP triplet in CH 3CN and H 2O/CH 3CN and fluorinated alcohols decay on a much longer time scale (τ ≈ 100 ns) with little observation of the rearrangement product. The density functional theory (DFT) calculations reveal a substantial solvation effect that is connected with the methoxy versus hydroxyl substitution in accounting for the different deprotection reactivity of pMP and pHP compounds. The results reported here provide new insight in elucidating the solvent and leaving group dependent dual reactivity of pMP compounds on the formation of the rearrangement versus reductive photoproduct. © 2010 American Chemical Society.en_HK
dc.languageengen_US
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.subject.meshAldehydes - chemical synthesis - chemistry-
dc.subject.meshComputer Simulation-
dc.subject.meshEsters - chemical synthesis - chemistry-
dc.subject.meshQuantum Theory-
dc.subject.meshSpectrometry, Fluorescence-
dc.titlePhotophysics and photodeprotection reactions of p-methoxyphenacyl phototriggers: An ultrafast and nanosecond time-resolved spectroscopic and density functional theory studyen_HK
dc.typeArticleen_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/jo100848ben_HK
dc.identifier.pmid20684501-
dc.identifier.scopuseid_2-s2.0-77956166549en_HK
dc.identifier.hkuros195707en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77956166549&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume75en_HK
dc.identifier.issue17en_HK
dc.identifier.spage5837en_HK
dc.identifier.epage5851en_HK
dc.identifier.isiWOS:000281180100006-
dc.publisher.placeUnited Statesen_HK
dc.relation.projectUltrafast laser facility for investigations of novel electronic excited states and intermediates in inorganic photochemistry, semiconductor materials and nanomaterials-
dc.identifier.scopusauthoridAn, HY=54411879800en_HK
dc.identifier.scopusauthoridKwok, WM=7103129332en_HK
dc.identifier.scopusauthoridMa, C=7402924979en_HK
dc.identifier.scopusauthoridGuan, X=8313149700en_HK
dc.identifier.scopusauthoridKan, JTW=8753189200en_HK
dc.identifier.scopusauthoridToy, PH=7006579247en_HK
dc.identifier.scopusauthoridPhillips, DL=7404519365en_HK

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