The effect of substituents and molecular aggregation on the room temperature phosphorescence of a twisted π-system

Considering the relevance of room temperature phosphorescent (RTP) materials, we discuss the influence of donor and acceptor groups substituted on to a twisted three-fold symmetric hydrocarbon homotruxene, which presents a persistent RTP, even in the absence of donor or acceptor moieties, under ambient conditions as a result of the twisted pi-system. Compared to a fluorine acceptor, a donor methoxy group increases the phosphorescence decay rate in solution, while in the solid-state, molecular aggregation and packing yield a very persistent phosphorescence visible by the eye. The RTP of the intrinsically apolar homotruxene is found to be modulated by polar substituents, whose main impact on the solid-state emission is due to altered packing in the crystal.

Automated summary

In this study, we investigated the influence of donor and acceptor groups substituted on a twisted three-fold symmetric hydrocarbon homotruxene. The results show that the twisted pi-system of the homotruxene allows it to exhibit persistent room temperature phosphorescence (RTP) even without any donor or acceptor moieties. In solution, a donor methoxy group increases the phosphorescence decay rate, while in the solid-state, molecular aggregation and packing result in a very persistent phosphorescence visible to the naked eye. Additionally, polar substituents modulate the RTP of the inherently nonpolar homotruxene mainly through altered crystal packing.