Photochemical behaviour of a new 1,2,3,4-tetrahydroxanthylium fluorescent dye with "rhodamine-like" structure in liquid media and adsorbed onto a TiO sub(2) photo-responsive substrate

A new "rhodamine-like" fluorescent NIR dye based on the 9-(2'-carboxyphenyl)-6-(N,N-diethylamino)-1,2,3,4-tetrahydro xanthylium system was synthesized. Its spectral-luminescent properties were investigated both in solution and adsorbed onto a TiO sub(2) photoactive solid substrate. Re...

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Bibliographic Details
Published in:Dyes and pigments 2016-05, Vol.128, p.279-288
Main Authors: Conceicaoa, D S, Ferreiraa, D P, Prostotab, Y, Santosb, P F, Ferreiraa, LFVieira
Format: Article
Language:English
Subjects:
Cations
Conduction band
Dyes
Fluorescence
Liquids
Semiconductors
Substrates
Titanium dioxide
Online Access:Get full text
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Summary:A new "rhodamine-like" fluorescent NIR dye based on the 9-(2'-carboxyphenyl)-6-(N,N-diethylamino)-1,2,3,4-tetrahydro xanthylium system was synthesized. Its spectral-luminescent properties were investigated both in solution and adsorbed onto a TiO sub(2) photoactive solid substrate. Regarding liquid samples, the highest fluorescent quantum yield and fluorescence lifetime were obtained in dichloromethane (oe sub(F) = 0.28, tau sub(F) = 2.67 ns) while in ethanol and acetonitrile we observed the largest Stokes Shift, indicating a twisted intramolecular charge transfer mechanism. Additionally, the behaviour of the dye adsorbed onto TiO sub(2) revealed some interesting features regarding the formation of the radical derived from the dye cation, following the electron injection in the conduction band of the semiconductor. Laser flash photolysis and ground state diffuse reflectance were used to evaluate and discriminate the mechanism of photoexcitation presented, as well as to characterize the photostability of the molecule. In this case, two different scenarios could be recognized: the self-photosensitization pathway and the photocatalytic mechanism.
ISSN:0143-7208
DOI:10.1016/j.dyepig.2016.01.030