Ni Yong, Gopalakrishna Tullimilli Y, Phan Hoa, Herng Tun Seng, Wu Shaofei, Han Yi, Ding Jun, Wu Jishan
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. 2018 Jul 26;57(31):9697-9701. doi: 10.1002/anie.201804276. Epub 2018 Jul 9.
Peri-acenes are good model compounds for zigzag graphene nanoribbons, but their synthesis is extremely challenging owing to their intrinsic open-shell diradical character. Now, the successful synthesis and isolation of a stable peri-tetracene derivative PT-2ClPh is reported; four 2,6-dichlorophenyl groups are attached onto the most reactive sites along the zigzag edges. The structure was confirmed by X-ray crystallographic analysis and its electronic properties were systematically investigated by both experiments and theoretical calculations. It exhibits an open-shell singlet ground state with a moderate diradical character (y =51.5 % by calculation) and a small singlet-triplet gap (ΔE =-2.5 kcal mol by SQUID measurement). It displays global aromatic character, which is different from the smaller-size bisanthene analogue BA-CF3.
并苯是锯齿形石墨烯纳米带的良好模型化合物，但由于其固有的开壳双自由基特性，其合成极具挑战性。现在，有报道成功合成并分离出了一种稳定的并四苯衍生物PT-2ClPh；四个2,6-二氯苯基连接在锯齿形边缘最具反应活性的位点上。通过X射线晶体学分析确定了其结构，并通过实验和理论计算系统地研究了其电子性质。它表现出开壳单重基态，具有适度的双自由基特性（计算得出y = 51.5%）和较小的单重态-三重态能隙（通过超导量子干涉仪测量，ΔE = -2.5 kcal mol）。它显示出整体芳香性，这与较小尺寸的联蒽类似物BA-CF3不同。
