Abstract:

Based on the phenothiazine core, we have synthesized three pentacyclic derivativesE‑2NAP,Z‑2NAP, andPh‑ANT,together with two hexacyclic derivativesE‑NAP‑ANTandZ‑NAP‑ANT. In the pentacyclic series, the asymmetric derivativeE‑2NAPshows stronger afterglow emission in frozen solution (77 K) than that of the symmetricZ‑2NAP. In the solid state,Ph‑ANTexhibits distinct thermally responsive behavior, with an afterglow lifetime reaching a maximum of 119.68 ms at 293 K, which is primarily attributed to a thermally activated delayed fluorescence (TADF) mechanism. Above 293 K, competition emerges between the TADF pathway and non‑radiative decay channels of triplet excitons, resulting in a reduction in afterglow lifetime. In summary, through rational modulation of the fused‑ring number and substitution positions, this work demonstrates effective adjustment of molecular conformation, solid‑state packing, and room‑temperature afterglow properties, providing important insights for the molecular design of phenothiazine‑based room‑temperature afterglow materials.

Key words: Phenothiazine fused ring, molecular conformation, afterglow properties