Abstract
Organic cocrystals obtained from multicomponent self-assembly have garnered considerable attention due to their distinct phosphorescence properties and broad applications. Yet, there have been limited reports on cocrystal systems that showcase efficient deepred to near-infrared (NIR) charge transfer (CT) phosphorescence. Furthermore, effective strategies to modulate the emission pathways of both fluorescence and phosphorescence remain underexplored. In this work, we dedicated our work to four distinct self-assembled cocrystals "Pyrene Box" cages using 1,3,6,8-pyrenetetrasulfonate anions (PTS4-), 4-Iodoaniline (1), Guanidinium (G+), Diaminoguanidinium (A2G+), and hydrated K+ counter cations. The binding of such cations to PTS4-platforms adaptively modulating their supramolecular stacking self-assembly with guest molecules 1, allowing to steer the fluorescence and phosphorescence pathways. Notably, the confinement of guest molecule 1 within "Pyrene Box" PTSK{1} and PTSG{1} cages, leads to an efficient deep-red to NIR CT phosphorescence emission. The addition of fuming gases like triethylamine and HCl that allows a reversible pH modulations of guest binding, which in turn induce a reversible transition of the "pyrene box" cage between fluorescence and phosphorescence states. This capability was further illustrated through a proof-of-concept demonstration in shrimp freshness detection. Our findings not only lay a foundation for future supramolecular designs leveraging weak intermolecular host-guest interactions to engineer excited states in interacting chromophores, but also broaden the prospective applications of room temperature phosphorescence materials in food safety detection.