Dibenzoperioctacene (DBPO) with extended zigzag edges was synthesized and unambiguously characterized by a combination of nuclear magnetic resonance (NMR), mass spectrometry, and single-crystal X-ray diffraction analysis. Variable-temperature (VT) NMR analysis indicated the closed-shell character of DBPO, yet an electron paramagnetic resonance (EPR) signal was observed at room temperature suggesting its potential open-shell diradicaloid nature. The bond lengths in the single-crystal structure of DBPO aligned more closely with those of open-shell teranthene than closed-shell bisanthene. Spin-unrestricted density functional theory (DFT) calculations using various methods supported that ground state of DBPO might be on the borderline between closed- and open-shell singlet states, with a large singlet-triplet energy gap (ΔEST), consistent with the VT-NMR and EPR results. UV-vis-near infrared (NIR) absorption spectrum showed the longest-wavelength peak at 905 nm, marking the NIR optical properties of DBPO. DBPO exhibited a tendency to react with atmospheric oxygen, which additionally hinted at its possible open-shell character. Furthermore, the oxidized species of non-fluorescent DBPO exhibited strong emission at 820 and 915 nm, which opens its potential for oxygen detection via a "turn-on" NIR fluorescence response.

中文翻译：

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二苯并熔融八十八烯的合成与表征


合成了具有延伸锯齿形边缘的二苯并八十八碳烯 （DBPO），并通过结合核磁共振 （NMR）、质谱和单晶 X 射线衍射分析进行了明确的表征。变温 （VT） NMR 分析表明 DBPO 具有闭壳特性，但在室温下观察到电子顺磁共振 （EPR） 信号，表明其潜在的开壳双自由体性质。DBPO 单晶结构中的键长与开壳 teranthene 的键长比闭壳 bisanthene 更接近。使用各种方法的自旋无限制密度泛函理论 （DFT） 计算支持 DBPO 的基态可能位于闭壳层和开壳单重态之间的边界上，具有较大的单重态-三重态能隙 （ΔEST），这与 VT-NMR 和 EPR 结果一致。UV-vis-near infrared （NIR） 吸收光谱在 905 nm 处显示出最长波长的峰值，标志着 DBPO 的 NIR 光学特性。DBPO 表现出与大气中的氧气反应的趋势，这也暗示了其可能的开壳特性。此外，非荧光 DBPO 的氧化物质在 820 和 915 nm 处表现出强烈的发射，这为其通过“开启”NIR 荧光响应进行氧检测提供了潜力。