Temperature and viscosity dependence of the nonradiative decay rates of auramine-O and thioflavin-T in glass-forming solvents

Yuval Erez, Nadav Amdursky, Rinat Gepshtein, Dan Huppert*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Both auramine-O (AuO) and thioflavin-T (ThT) behave as fluorescent molecular rotors, meaning that their (non)radiative properties are markedly affected by the intramolecular rotation of the molecule. In this article, steady-state and time-resolved fluorescence of AuO and ThT were measured in three alcohols, 1-propanol, 1-butanol, and 1-pentanol, over a wide range of temperatures (86-260 K). These solvents are glass-forming liquids, and their viscosity and dielectric relaxation time increase by more than 10 orders of magnitude as the temperature is lowered from room temperature to ∼100 K. Accordingly, the fluorescence nonradiative rates constants of AuO and ThT in these solvents decrease by about 3 orders of magnitude at the latter temperature range. We found very good correspondence between the temperature dependence of the nonradiative rate constant, knr, of both molecules and the dielectric relaxation rate of the solvents. The knr values of AuO are twice those of ThT along the whole temperature range. The temperature dependence of knr is consistent with the nonradiative model suggested by Glasbeek and co-workers.(1)

Original languageEnglish
Pages (from-to)12056-12064
Number of pages9
JournalJournal of Physical Chemistry A
Volume116
Issue number49
DOIs
StatePublished - 13 Dec 2012

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