Dibenzononazethrene Isomers: Stable Singlet Diradicaloids with Efficient Photothermal Conversion
Xiaoqi Tian, Mingzhe Wang, Lei Ye, Yixuan Gao, Yu Guo, Miaoqiang Lv, Xiaonan Ma, Lan Ma, Zhe Sun
Abstract
High Resolution Image Download MS PowerPoint Slide 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 in vitro 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.