Rigid π-conjugation engineering in twisted molecules for efficient dual-state emission and lipid droplet bioimaging

Dual-state emission (DSE) luminophores hold great potential in optoelectronics and bioimaging, yet robust strategies for their efficient design remain elusive. Herein, we present a rational DSE design strategy by replacing one phenyl ring of the propeller-shaped triphenylamine (TPA) core with anthracene to extend π-conjugation, while methoxy groups fine-tune the electronic properties. This molecular design ensures sufficient π-π* transitions for high fluorescence in solution, while structural distortion suppresses π-π stacking, synergistically enhancing emission in the solid state. Thus, the resulting luminogens, TPAn and TPAn-OMe, exhibit highly efficient cyan (λ_em = 459 nm, Φ_PL = 73.5 %) and green (λ_em = 514 nm, Φ_PL = 61.2 %) emissions in n-hexane solution and ultrabright green (λ_em = 511 nm, Φ_PL = 77.1 %) and orange-yellow (λ_em = 567 nm, Φ_PL = 69.4 %) emissions in crystals. To our delight, these synergistic effects enable TPAn-OMe to targeted bioimaging of lipid droplets, even at nM concentrations. This strategy provides a versatile blueprint for designing efficient and tunable DSE luminophores across diverse molecular systems.