From Benzene to [3]Radialene: Topological Engineering of Pure Hydrocarbons for Long‐Wavelength Aggregation‐Induced Emission Luminogens

Due to the topological divergence between [3]radialene and benzene, hexaphenyl[3]radialene exhibits a dramatic bathochromic shift in emission (619 nm) with a Stokes shift >150 nm, which is distinct from its structural analogue hexaphenylbenzene. Our mechanistic analyses revealed the localized bond rearrangement and moderate short‐range charge transfer, which lead to its long‐wavelength emission and enhanced aggregation‐induced emission character. Ring‐locked derivatives, tridibenzocycloheptadiene[3]radialene and tridimethylanthracene[3]radialene (TAR), were synthesized, exhibiting tunable emission wavelength (507–685 nm) and high crystalline‐state quantum yields (up to 49.2%). Finally, the potential of TAR for lysosome‐targeting bioimaging was demonstrated. Our results establish the [3]radialene backbone as a robust hydrocarbon scaffold for high‐performance, long‐wavelength emitters.