Efficient luminescent stable Chichibabin diradicaloid for near-infrared imaging and photothermal therapy

Diradicaloids have garnered significant attention due to their unique electronic, photophysical properties and potential applications in functional materials. Characterized by a narrow band gap and near-infrared (NIR) absorption, diradicaloids are promising candidates for NIR-guided photothermal therapy. However, they are often unstable and exhibit non-emissive properties due to high chemical reactivity and very efficient internal conversion. Herein, we report a remarkably stable Chichibabin diradicaloid, TT-CzPh, which exhibits NIR luminescence (λ_em = 821 nm) with an efficient photoluminescence quantum yield (PLQY) of 6.4%. Surprisingly, TT-CzPh not only exhibits excellent NIR imaging but also has a very high photothermal conversion efficiency (PCE) of 87.5%. In vivo experiments with TT-CzPh nanoparticles demonstrated their effectiveness in tumor photoablation guided by NIR imaging. This work not only advances the development of stable, efficient luminescent Chichibabin's hydrocarbons but also opens new avenues for bioimaging and cancer phototherapy applications.