Shen Jun-Jian, Han Yi, Dong Shaoqiang, Phan Hoa, Herng Tun Seng, Xu Tingting, Ding Jun, Chi Chunyan
Department of Chemistry, National University of Singapore, 3 Science drive 3, 117543, Singapore, Singapore.
Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore, Singapore.
Angew Chem Int Ed Engl. 2021 Feb 23;60(9):4464-4469. doi: 10.1002/anie.202012328. Epub 2020 Dec 28.
The synthesis of peri-fused acenes (peri-acenes) with two or more rows is challenging due to their intrinsic open-shell diradical character. Herein, we report the isolation of a derivative (4) of [4,3]peri-acene in crystalline form. The parent [4,3]peri-acene, containing three rows of tetracene, has a large diradical character (y =94.8 %) originating from aromatic stabilization. Due to kinetic blocking, 4 showed a reasonable stability with a half-life time of ≈157 h under ambient conditions. Its structure was determined by X-ray crystallographic analysis, and bond-length analysis revealed eight localized Clar's sextets. 4 exhibited an open-shell singlet ground state with a narrow electrochemical energy gap (1.13 eV) and a small singlet-triplet energy gap (-0.57 kcal mol from SQUID measurements). Its electronic properties are compared with previously reported peri-tetracene and teranthene derivatives.
合成具有两排或更多排的周边稠合并苯（周边并苯）具有挑战性，因为其具有固有的开壳双自由基特性。在此，我们报告了一种 [4,3] 周边并苯衍生物（4）的晶体形式的分离。母体 [4,3] 周边并苯包含三排并四苯，具有源自芳香稳定化的大双自由基特性（y = 94.8%）。由于动力学阻碍，4 在环境条件下表现出合理的稳定性，半衰期约为 157 小时。其结构通过 X 射线晶体学分析确定，键长分析揭示了八个局域化的克拉尔六隅体。4 表现出开壳单重基态，具有窄的电化学能隙（1.13 eV）和小的单重态 - 三重态能隙（根据超导量子干涉仪测量为 -0.57 kcal mol）。将其电子性质与先前报道的周边并四苯和四联苯衍生物进行了比较。
