Organic Room-Temperature Phosphorescence and Triplet-Singlet Energy Transfer in Aqueous (Bio)templated Coassemblies

Abstract

We report here (bio)polymer-template-induced generation of room-temperature phosphorescence (RTP) in trimeric halogenated phenylpyridinium derivatives in aqueous media and in the film state. For this purpose, two different types of anionic templates were introduced: heparin, a well-known biomacromolecule that is used as an anticoagulant, and polyacrylic acid (PAA), a synthetic anionic polymer. In the presence of templates, electrostatically driven coassemblies were formed that displayed noticeably enhanced RTP features. The enhancement in the RTP provided an efficient phosphorescence detection protocol for heparin. Moreover, the anionic-template-mediated coassemblies were utilized as triplet donors to construct light-harvesting systems in aqueous media via triplet-to-singlet energy transfer (TS-ET). Different commercially available dyes were selected as acceptors for this purpose, and they showed delayed sensitization due to the ET process. Polymer films of PAA coassemblies demonstrated pH-responsive multiple emission colors.