Background-Free Fluorescence-Decay-Time Sensing and Imaging of pH with Highly Photostable Diazaoxotriangulenium Dyes

Irene Dalfen, Ruslan I. Dmitriev, Gerhard Holst, Ingo Klimant, Sergey M. Borisov

Research output: Contribution to journalArticleResearchpeer-review


Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic-receptor groups inducing fluorescence quenching via a photoinduced-electron-transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent pKa values of ∼5 and 7.5 for the p,p-dichlorophenol- and p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetimes (17-20 ns), high quantum yields (∼60%), and high photostabilities. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behavior, which makes them suitable for studying 2D pH distributions with the help of fluorescence-lifetime-imaging techniques. The lifetime response is particularly pronounced for the sensors with high dye concentrations (0.5-1 wt % with respect to the polymer) and is attributed to the efficient homo-FRET mechanism.

Original languageEnglish
Pages (from-to)808-816
Number of pages9
JournalAnalytical Chemistry
Issue number1
Publication statusPublished - 2 Jan 2019


ASJC Scopus subject areas

  • Analytical Chemistry

Cite this