Nagayama Shoko, Kawakatsu Hiroki, Asai Daisuke, Yokoyama Takumi, Yamashina Masahiro, Toyota Shinji, Tahara Kazukuni
Department of Applied Chemistry, School of Science and Technology, Meiji University 1-1-1 Higashimita, Tama-ku Kawasaki Kanagawa 214-8571 Japan
Department of Chemistry, School of Science, Institute of Science Tokyo 2-12-1 Ookayama, Meguro-ku Tokyo 152-8551 Japan.
Chem Sci. 2025 Aug 18. doi: 10.1039/d5sc04720j.
Herein, we report the synthesis and characterization of π-conjugated macrocycles, with diameters over 2.4 nanometers, composed of biphenylene and butadiyne units. Specifically, biphenylene-2,7-diyl-butadiyne-1,4-diyl (BB) macrocycles were synthesized the intermolecular Hay coupling reaction of a 2,7-diethynylbiphenylene derivative. The BB macrocycles exhibited absorption bands extending up to ∼600 nm and emitted red luminescence. Moreover, scanning tunneling microscopy observations revealed that the BB macrocycles formed self-assembled molecular networks at the liquid-graphite interface, showing higher tunneling efficiency. The BB macrocycles exhibited high energy levels of the highest occupied molecular orbitals and narrow energy gaps due to the elongated π-electron conjugation through the biphenylene units. Theoretically predicted responses to an external magnetic field using quantum chemical calculations of BB macrocycle models revealed reinforced antiaromatic character at four-membered rings. The present information will advance the structural design and property tuning of macrocyclic compounds with antiaromatic character.
在此，我们报道了由联亚苯基和丁二炔单元组成的直径超过2.4纳米的π共轭大环化合物的合成与表征。具体而言，通过2,7 - 二乙炔基联苯衍生物的分子间Hay偶联反应合成了联亚苯基 - 2,7 - 二基 - 丁二炔 - 1,4 - 二基（BB）大环化合物。BB大环化合物表现出延伸至约600纳米的吸收带并发出红色荧光。此外，扫描隧道显微镜观察表明，BB大环化合物在液 - 石墨界面形成了自组装分子网络，显示出更高的隧穿效率。由于通过联亚苯基单元的π电子共轭延长，BB大环化合物表现出较高的最高占据分子轨道能级和较窄的能隙。使用BB大环化合物模型的量子化学计算对外部磁场的理论预测响应表明，四元环处的反芳香性特征增强。目前的信息将推动具有反芳香性特征的大环化合物的结构设计和性能调控。
