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The excited states interaction of safranine-O with PAMAM and DAB dendrimers in methanol

Paper ID Volume ID Publish Year Pages File Format Full-Text
28386 44072 2009 6 PDF Available
Title
The excited states interaction of safranine-O with PAMAM and DAB dendrimers in methanol
Abstract

The quenching of the excited singlet and triplet states of the synthetic dye safranine-O by low generation PAMAM and DAB dendrimers was investigated in methanol. The rate constants for the quenching of the excited singlet state depend on the number of primary amino groups in the dendrimer. The first-order rate constant for the decay of the triplet state presents a downward curvature as a function of the quencher concentration. This behavior was interpreted in terms of the reversible formation of an intermediate complex in the excited state. From a kinetic analysis of the quenching mechanism the equilibrium constant Kexc could be extracted. The values of Kexc may be related to the proton affinity of the quencher. The results were interpreted in terms of a reversible proton transfer quenching. This was further confirmed by the transient absorption spectra obtained by laser flash photolysis. The transient absorption immediately after the triplet state quenching could be assigned to the unprotonated form of the dye. At later times the spectrum matches the semireduced form of the dye. The overall process corresponds to a one-electron reduction of the dye mediated by the deprotonated triplet state.

Keywords
Triplet quenching; Safranine; Dendrimers; PAMAM; DAB
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The excited states interaction of safranine-O with PAMAM and DAB dendrimers in methanol
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 201, Issue 1, 1 January 2009, Pages 69–74
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us