Systematic variation of the acceptor electrophilicity in donor-acceptor-donor emitters exhibiting efficient room temperature phosphorescence suited for digital luminescence

Purely organic materials showing efficient and persistent emission via room temperature phosphorescence (RTP) allow the design of minimalistic yet powerful technological solutions for sensing, bioimaging, information storage, and safety applications using the photonic design principle of digital luminescence. Although several promising materials exist, a deep understanding of the underlying structure-property relationship and, thus, development of rational design strategies are widely missing. Some of the best purely organic emitters follow the donor-acceptor-donor design motif. In this study, the influence of the acceptor unit on the photophysical properties is systematically analyzed by synthesizing and characterizing variations of the RTP emitter 4,4'-dithianthrene-1-yl-benzophenone (BP-2TA). The most promising candidates are also tested in programmable luminescent tags as a potential application field for information storage. While no significant influence by the electrophilicity index of the acceptor moiety on the RTP emission is observed, the results support the design of molecules with pronounced hybridization as obtained for the newly synthesized emitter demonstrating superior RTP efficiency combined with improved stability.