biostudies-literatureTian XHaihe Laboratory of Sustainable Chemical TransformationsNational Natural Science Foundation of ChinaState Key Laboratory of Chemical OncogenomicsShenzhen Bay Laboratory389-398https://www.ebi.ac.uk/biostudies/studies/S-EPMC12308599biostudies-literatureUnknown3(7)Organic singlet diradicaloids are promising photothermal agents owing to their exceptional light-harvesting capabilities and efficient light-to-heat conversion. In this study, two stable dibenzononazethrene isomers, DBNZ1 and DBNZ2, are synthesized through a concise method and isolated in crystalline form. An open-shell singlet diradical ground state, with diradical indices of 0.67 and 0.69, is confirmed through a combination of theoretical and experimental approaches. Steady-state and time-resolved absorption spectroscopy demonstrated efficient light absorption in the far-red region and excellent light-to-heat conversion, attributed to a rapid nonradiative process. Encapsulation of DBNZ1 with an amphiphilic polymer produced water-dispersible nanoparticles (DBNZ1-NPs) with enhanced stability, achieving an impressive photothermal conversion efficiency of 72.9%. An <i>in vitro</i> photothermal therapy study demonstrated that DBNZ1-NPs functioned as biocompatible tumor ablation agents when activated by an 808 nm laser, highlighting their potential application in cancer photothermal therapy.Precision chemistryDibenzononazethrene Isomers: Stable Singlet Diradicaloids with Efficient Photothermal Conversion.PMC123085992222211024HHWCSS0000922371206Wang MYe LLv MMa LTian XGao YMa XYu GSun ZfalseDibenzononazethrene Isomers: Stable Singlet Diradicaloids with Efficient Photothermal Conversion.Organic singlet diradicaloids are promising photothermal agents owing to their exceptional light-harvesting capabilities and efficient light-to-heat conversion. In this study, two stable dibenzononazethrene isomers, DBNZ1 and DBNZ2, are synthesized through a concise method and isolated in crystalline form. An open-shell singlet diradical ground state, with diradical indices of 0.67 and 0.69, is confirmed through a combination of theoretical and experimental approaches. Steady-state and time-resolved absorption spectroscopy demonstrated efficient light absorption in the far-red region and excellent light-to-heat conversion, attributed to a rapid nonradiative process. Encapsulation of DBNZ1 with an amphiphilic polymer produced water-dispersible nanoparticles (DBNZ1-NPs) with enhanced stability, achieving an impressive photothermal conversion efficiency of 72.9%. An <i>in vitro</i> photothermal therapy study demonstrated that DBNZ1-NPs functioned as biocompatible tumor ablation agents when activated by an 808 nm laser, highlighting their potential application in cancer photothermal therapy.2025-01-01T00:00:00Z2025 Jul2026-03-27T16:05:04.407Z2025-08-27T03:06:37.58ZS-EPMC123085994074658710.1021/prechem.5c00026