Manipulating Single-Molecule Exciplex TADF and Deep-Blue RTP Through Non-Covalent - Interaction in a Molecular Foldamer

Although the pi-pi stacking has been widely applied for constructing aggregated emitters in optoelectronics fields, the role of intramolecular non-covalent pi-pi interactions has not been well studied. Here, a supramolecular foldermer M-sigma-C, with the electron donor (D) and acceptor (A) units spatially separated with a non-covalent bond at a close distance by methylene linker is designed and synthesized. This gives a face-to-face D/A stacking configuration with supramolecular pi-pi interactions. Temperature-dependent nuclear magnetic resonance measurements and single crystal analyses confirm its folding configuration. In solutions, M-sigma-C exhibits a single-molecule exciplex thermally activated delayed fluorescence (TADF) property ascribing to the efficient intramolecular through-space charge transfer (CT) process. While single-molecule deep-blue room temperature phosphorescence (RTP) with a long afterglow lifetime of 236 ms is observed in a nonpolar matrix, which represents the record lifetime among current (CT)-C-3-character featured RTP. This work indicates that intramolecular non-covalent interactions play an important role in manipulating high-performance single-molecule exciplex TADF and RTP, and provide a feasible molecular design strategy for supramolecular chemistry involving the development of optoelectronic materials.