Virtual screening for ultra-small NIR emitter with only two isolated hexatomic rings

Unlocking the potential of weak interactions to govern the electronic structure of organic molecules remains a significant challenge. This study constructs a quantitative relationship between conformations and strength of electronic through-space interactions (TSI) for tetraarylethanes (TAEs). To identify long-wavelength emitters, a sophisticated virtual screening is executed for TAE by constructing a TSI-based database. Consequently, an ultra-small emitter (o-2Md), distinguished by a highly concentrated n-electron configuration, is synthesized and shows a remarkable near-infrared (NIR) emission with a luminescence quantum yield of 25% and an emission wavelength extending beyond 800 nm. Notably, the o-2Md stands out as one of the smallest known organic NIR emitters, showcasing the robustness of n-n TSI in designing efficient emitters. This work not only systematically reveals the important role of weak interactions in manipulating the electronic structure at the single-molecule level but also provides a new platform, the TSI database, for designing advanced optoelectronic materials.