A fresh look into the time-resolved fluorescence of 8-hydroxy-1,3,6-pyrenetrisulfonate with the use of the fluorescence up-conversion technique

Ron Simkovitch, Georgi Gary Rozenman, Dan Huppert*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Steady-state and time-resolved fluorescence techniques were used to study the excited-state-proton-transfer (ESPT) process of 8-hydroxy-1,3,6-pyrenetrisulfonate (HPTS) in H2O and D2O. In this contribution we use the fluorescence up-conversion technique with a time resolution of ∼100 fs to monitor the short-time components of HPTS ROH (protonated) and RO (deprotonated) signals. The ESPT rate constant, kPT, for HPTS in H2O and D2O is rather small 1010s−1 and 3.3 × 109s−1, respectively. In the time-resolved fluorescence signal of the deprotonated form we find a rise-component of 2.5 ps which we assign to slow charge rearrangement as was already suggested by Spry and Fayer [Spry, D. B.; Fayer, M. D. Charge Redistribution and Photoacidity: Neutral Versus Cationic Photoacids. J. Chem. Phys. 2008, 128, 084508-1–084508-9]. Already in the time-window of 0.2–1.2 ns, the proton geminate recombination (GR) fluorescence tail of the ROH form decays as t−α where α ≈ 3/2, as predicted by the diffusion-assisted GR model, but for much longer times (t > 5 ns). We also found that the rotation-relaxation time of the ROH form is about τor = 80 ps in H2O, shorter than previously reported, whereas in methanol solution, with much lower viscosity, it is much larger – τor = 190 ps. We explain this large difference of τor by counter-ion association on all the three sulfonate groups of HPTS.

Original languageEnglish
Pages (from-to)15-27
Number of pages13
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume344
DOIs
StatePublished - 1 Jul 2017

Funding

FundersFunder number
Israel Science Foundation914/12
Tel Aviv University
Universidad de Castilla-La Mancha

    Keywords

    • Excited state proton transfer
    • Fluorescence up-conversion
    • Geminate recombination
    • Photoacid
    • Time-resolved fluorescence

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