Controlling Aggregation‐Induced Emission by Sterics in Nitrogen–Boron–Nitrogen (NBN)‐Doped Tetraphenylethylene‐Like Molecular Propellers

The phenomenon of aggregation-induced emission (AIE) serves as a promising tool to harness and boost emission properties in luminescent materials. Here, we report nitrogen-boron-nitrogen (NBN)-substituted molecular propellers with different degrees of steric hindrance. Photoluminescence measurements demonstrated that each compound presents AIE behavior in THF/water mixtures, where the less sterically hindered derivative was characterized by higher emission enhancement due to a more pronounced restriction of intramolecular rotations (RIR). A less common maximum behavior was observed upon further addition of water, and this became more pronounced for the more hindered derivative driven by stronger intermolecular electronic effects. Steric hindrance thus serves as an effective design tool to enhance maximum AIE behavior in molecular propellers and gain more precise solvent control.