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Influence of Negatively Charged Interfaces on the Ground and Excited State Properties of Methylene Blue ¶

2007; Wiley; Volume: 77; Issue: 5 Linguagem: Inglês

10.1562/0031-8655(2003)0770459ioncio2.0.co2

1751-1097

Divinomar Severino, Helena C. Junqueira, Marcos Gugliotti, Dino Santesso Gabrielli, Maurı́cio S. Baptista,

Porphyrin and Phthalocyanine Chemistry

Photochemistry and PhotobiologyVolume 77, Issue 5 p. 459-468 Influence of Negatively Charged Interfaces on the Ground and Excited State Properties of Methylene Blue ¶ Divinomar Severino, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorHelena C. Junqueira, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorMarcos Gugliotti, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorDino S. Gabrielli, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorMauricio S. Baptista, Corresponding Author Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil *To whom correspondence should be addressed at: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, São Paulo, SP 05508-900, Brazil. Fax: 551-3815-5579; baptista@iq.usp.brSearch for more papers by this author Divinomar Severino, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorHelena C. Junqueira, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorMarcos Gugliotti, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorDino S. Gabrielli, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, BrazilSearch for more papers by this authorMauricio S. Baptista, Corresponding Author Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil *To whom correspondence should be addressed at: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, São Paulo, SP 05508-900, Brazil. Fax: 551-3815-5579; baptista@iq.usp.brSearch for more papers by this author First published: 01 May 2007 https://doi.org/10.1562/0031-8655(2003)0770459IONCIO2.0.CO2Citations: 12 ¶ Posted on the website on 20 March 2003. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat ABSTRACT Properties of the ground and excited states of methylene blue (MB) were studied in negatively charged vesicles, normal and reverse micelles and sodium chloride solutions. All these systems induce dimer formation as attested by the appearance of the dimer band in the absorption spectra (λD∼ 600 nm). In reverse micelles the dimerization constant (KD) corrected for the aqueous pseudophase volume fraction is two–three orders of magnitude smaller than KD of MB in water, and it does not change when W0 is increased from 0.5 to 10. Differences in the fluorescence intensity as a function of dimer–monomer ratio as well as in the resonance light scattering spectra indicate that distinct types of dimers are induced in sodium dodecyl sulfate (SDS) micelles and aerosol-OT (sodium dioctyl sulfoxinate, AOT) reversed micelles. The properties of the photoinduced transient species of MB in these systems were studied by time-resolved near infrared (NIR) emission (efficiency of singlet oxygen generation), by laser flash photolysis (transient spectra, yield and decay rate of triplets) and by thermal lensing (amount of heat deposited in the medium). The competition between electron transfer (dye*–dye) and energy transfer (dye*–O2) reactions was accessed as a function of the dimer–monomer ratio. The lower yield of electron transfer observed for dimers in AOT reverse micelles and intact vesicles compared with SDS micelles and frozen vesicles at similar dimer–monomer ratios is related with the different types of aggregates induced by each interface. Citing Literature Volume77, Issue5May 2003Pages 459-468 RelatedInformation