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A Comparative Study on the Photophysics and Photochemistry of Xanthene Dyes in the Presence of Polyamidoamine (PAMAM) Dendrimers
Author(s) -
Arbeloa Ernesto Maximiliano,
Previtali Carlos Mario,
Bertolotti Sonia Graciela
Publication year - 2018
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201701295
Subject(s) - xanthene , photochemistry , flash photolysis , chemistry , dendrimer , bathochromic shift , rose bengal , quenching (fluorescence) , cyanine , eosin y , absorption spectroscopy , absorption (acoustics) , photoinduced electron transfer , fluorescence , electron transfer , triplet state , reaction rate constant , molecule , organic chemistry , materials science , kinetics , photocatalysis , physics , quantum mechanics , composite material , catalysis
The photophysical and photochemical properties of the xanthene dyes Eosin Y, Erythrosin B, and Rose Bengal are evaluated in the presence of amino‐terminated polyamidoamine (PAMAM) dendrimers of relatively high generation (G3–G5) in alkaline aqueous solution. UV/Vis absorption and fluorescence spectra of the dyes show bathochromic shifts, which correlate with the size of the dendrimer. Binding constants ( K bind ) are calculated from absorption data. The resulting high K bind values indicate strong interactions between both molecules. Triplet–triplet absorption spectra of the dyes are recorded by laser flash photolysis, and a decrease in the triplet lifetimes is observed in the presence of dendrimers. At the same time, an increase in the absorption of the semireduced form of the dyes is observed. Rate constants for triplet quenching ( 3 k q ) and radical quantum yields ( Φ R ) are obtained. The results are explained by a very efficient electron‐transfer process from PAMAM to xanthene dyes for all of the dye/dendrimer couples that are evaluated.