Int. J. Mol. Sci. 2012, 13(1), 596-611; doi:10.3390/ijms13010596
Article

Surface Photochemistry: 3,3'-Dialkylthia and Selenocarbocyanine Dyes Adsorbed onto Microcrystalline Cellulose

1,* email, 1email, 1email, 1,2email, 1email, 1,2email, 3email, 4email and 4email
Received: 12 December 2011; in revised form: 29 December 2011 / Accepted: 29 December 2011 / Published: 9 January 2012
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this work, thia and selenocarbocyanines with n-alkyl chains of different length, namely with methyl, ethyl, propyl, hexyl and decyl substituents, were studied in homogeneous and heterogeneous media for comparison purposes. For both carbocyanine dyes adsorbed onto microcrystalline cellulose, a remarkable increase in the fluorescence quantum yields and lifetimes were detected, when compared with solution. Contrary to the solution behaviour, where the increase in the n-alkyl chains length increases to a certain extent the fluorescence emission FF and τF, on powdered solid samples a decrease of FF and τF was observed. The use of an integrating sphere enabled us to obtain absolute FF’s for all the powdered samples. The main difference for liquid homogeneous samples is that the increase of the alkyl chain strongly decreases the FF values, both for thiacarbocyanines and selenocarbocyanines. A lifetime distribution analysis for the fluorescence of these dyes adsorbed onto microcrystalline cellulose, evidenced location on the ordered and crystalline part of the substrate, as well as on the more disordered region where the lifetime is smaller. The increase of the n-alkyl chains length decreases the photoisomer emission for the dyes adsorbed onto microcrystalline cellulose, as detected for high fluences of the laser excitation, for most samples.
Keywords: surfaces and nanocavities; thia and selenocarbocyanine dyes; lifetime distribution analysis; absolute quantum yields of fluorescence emission; singlet oxygen formation quantum yield
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MDPI and ACS Style

Vieira Ferreira, L.F.; Ferreira, D.P.; Duarte, P.; Oliveira, A.S.; Torres, E.; Ferreira Machado, I.; Almeida, P.; Reis, L.V.; Santos, P.F. Surface Photochemistry: 3,3'-Dialkylthia and Selenocarbocyanine Dyes Adsorbed onto Microcrystalline Cellulose. Int. J. Mol. Sci. 2012, 13, 596-611.

AMA Style

Vieira Ferreira LF, Ferreira DP, Duarte P, Oliveira AS, Torres E, Ferreira Machado I, Almeida P, Reis LV, Santos PF. Surface Photochemistry: 3,3'-Dialkylthia and Selenocarbocyanine Dyes Adsorbed onto Microcrystalline Cellulose. International Journal of Molecular Sciences. 2012; 13(1):596-611.

Chicago/Turabian Style

Vieira Ferreira, Luís F.; Ferreira, Diana P.; Duarte, Paulo; Oliveira, A. S.; Torres, E.; Ferreira Machado, I.; Almeida, P.; Reis, Lucinda V.; Santos, Paulo F. 2012. "Surface Photochemistry: 3,3'-Dialkylthia and Selenocarbocyanine Dyes Adsorbed onto Microcrystalline Cellulose." Int. J. Mol. Sci. 13, no. 1: 596-611.

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