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Article: Resonance raman characterization of different forms of ground-state 8-bromo-7-hydroxyquinoline caged acetate in aqueous solutions

TitleResonance raman characterization of different forms of ground-state 8-bromo-7-hydroxyquinoline caged acetate in aqueous solutions
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. 12, p. 2831-2837 How to Cite?
AbstractThe 8-bromo-7-hydroxyquinolinyl group (BHQ) is a derivative of 7-hydroxyquinoline (7-HQ) and BHQ molecules coexisting as different forms in aqueous solution. Absorption and resonance Raman spectroscopic methods were used to examine 8-bromo-7-hydroxyquinoline protected acetate (BHQ-OAc) in acetonitrile (MeCN), H 20/MeCN (60:40, v/v, pH 6-7), and NaOH-H 20/MeCN (60:40, v/v, pH 11-12) to obtain a better characterization of the forms of the ground-state species of BHQ-OAc in aqueous solutions and to examine their properties. The absorption spectra of BHQ-OAc in water show no absorption bands of the tautomeric species unlike the strong band at about 400 nm observed for the tautomeric form in 7-HQ aqueous solution. The resonance Raman spectra in conjunction with Raman spectra predicted from density functional theory (DFT) calculations reveal the observation of a double Raman band system characteristic of the neutral form (the nominal C=C ring stretching, C-N stretching, and O-H bending modes at 1564 and 1607 cm -1) and a single Raman band diagnostic of the enol-deprotonated anionic form (the nominal C=C ring, C-N, and C-O - stretching modes in the 1593 cm -1 region). These results suggest that the neutral form of BHQ-OAc is the major species in neutral aqueous solution. There is a modest increase in the amount of the anionic form and a big decrease in the amount of the tautomeric form of the molecules for BHQ-OAc compared to 7-HQ in neutral aqueous solution. The presence of the 8-bromo group and/or competitive hydrogen bonding that hinder the formation and transfer process of a BHQ-OAc-water cyclic complex may be responsible for this large substituent effect. © 2009 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/58415
ISSN
2015 Impact Factor: 2.883
2015 SCImago Journal Rankings: 1.231
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorAn, HYen_HK
dc.contributor.authorChensheng, Men_HK
dc.contributor.authorNganga, JLen_HK
dc.contributor.authorZhu, Yen_HK
dc.contributor.authorDore, TMen_HK
dc.contributor.authorPhillips, DLen_HK
dc.date.accessioned2010-05-31T03:29:54Z-
dc.date.available2010-05-31T03:29:54Z-
dc.date.issued2009en_HK
dc.identifier.citationJournal Of Physical Chemistry A, 2009, v. 113 n. 12, p. 2831-2837en_HK
dc.identifier.issn1089-5639en_HK
dc.identifier.urihttp://hdl.handle.net/10722/58415-
dc.description.abstractThe 8-bromo-7-hydroxyquinolinyl group (BHQ) is a derivative of 7-hydroxyquinoline (7-HQ) and BHQ molecules coexisting as different forms in aqueous solution. Absorption and resonance Raman spectroscopic methods were used to examine 8-bromo-7-hydroxyquinoline protected acetate (BHQ-OAc) in acetonitrile (MeCN), H 20/MeCN (60:40, v/v, pH 6-7), and NaOH-H 20/MeCN (60:40, v/v, pH 11-12) to obtain a better characterization of the forms of the ground-state species of BHQ-OAc in aqueous solutions and to examine their properties. The absorption spectra of BHQ-OAc in water show no absorption bands of the tautomeric species unlike the strong band at about 400 nm observed for the tautomeric form in 7-HQ aqueous solution. The resonance Raman spectra in conjunction with Raman spectra predicted from density functional theory (DFT) calculations reveal the observation of a double Raman band system characteristic of the neutral form (the nominal C=C ring stretching, C-N stretching, and O-H bending modes at 1564 and 1607 cm -1) and a single Raman band diagnostic of the enol-deprotonated anionic form (the nominal C=C ring, C-N, and C-O - stretching modes in the 1593 cm -1 region). These results suggest that the neutral form of BHQ-OAc is the major species in neutral aqueous solution. There is a modest increase in the amount of the anionic form and a big decrease in the amount of the tautomeric form of the molecules for BHQ-OAc compared to 7-HQ in neutral aqueous solution. The presence of the 8-bromo group and/or competitive hydrogen bonding that hinder the formation and transfer process of a BHQ-OAc-water cyclic complex may be responsible for this large substituent effect. © 2009 American Chemical Society.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpcaen_HK
dc.relation.ispartofJournal of Physical Chemistry Aen_HK
dc.titleResonance raman characterization of different forms of ground-state 8-bromo-7-hydroxyquinoline caged acetate in aqueous solutionsen_HK
dc.typeArticleen_HK
dc.identifier.emailChensheng, M:macs@hkucc.hku.hken_HK
dc.identifier.emailPhillips, DL:phillips@hku.hken_HK
dc.identifier.authorityChensheng, M=rp00758en_HK
dc.identifier.authorityPhillips, DL=rp00770en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/jp809586hen_HK
dc.identifier.pmid19296708en_HK
dc.identifier.scopuseid_2-s2.0-63849219908en_HK
dc.identifier.hkuros160814en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-63849219908&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume113en_HK
dc.identifier.issue12en_HK
dc.identifier.spage2831en_HK
dc.identifier.epage2837en_HK
dc.identifier.isiWOS:000264348800022-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridAn, HY=54411879800en_HK
dc.identifier.scopusauthoridChensheng, M=7402924979en_HK
dc.identifier.scopusauthoridNganga, JL=26429870200en_HK
dc.identifier.scopusauthoridZhu, Y=36560602200en_HK
dc.identifier.scopusauthoridDore, TM=6603830858en_HK
dc.identifier.scopusauthoridPhillips, DL=7404519365en_HK

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