Field of Energy and Environment, School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi 923-1292, Japan.
Department of Materials Molecular Science, Institute for Molecular Science, 38 Nishigo-naka, Myodaiji, Okazaki 444-8585, Japan.
Science. 2017 Aug 18;357(6352):673-676. doi: 10.1126/science.aan0202.
We synthesized a two-dimensional (2D) crystalline covalent organic framework (spc-COF) that was designed to be fully π-conjugated and constructed from all sp carbons by C=C condensation reactions of tetrakis(4-formylphenyl)pyrene and 1,4-phenylenediacetonitrile. The C=C linkages topologically connect pyrene knots at regular intervals into a 2D lattice with π conjugations extended along both and directions and develop an eclipsed layer framework rather than the more conventionally obtained disordered structures. The spc-COF is a semiconductor with a discrete band gap of 1.9 electron volts and can be chemically oxidized to enhance conductivity by 12 orders of magnitude. The generated radicals are confined on the pyrene knots, enabling the formation of a paramagnetic carbon structure with high spin density. The sp carbon framework induces ferromagnetic phase transition to develop spin-spin coherence and align spins unidirectionally across the material.
我们合成了一种二维（2D）结晶共价有机骨架（spc-COF），它完全由π共轭组成，由四（4-醛基苯基）芘和 1,4-苯二乙腈的 C=C 缩合反应构建而成。C=C 键在拓扑上以规则的间隔将芘结连接到二维晶格中，π共轭沿 和 方向延伸，并形成重叠层结构，而不是通常获得的无序结构。spc-COF 是一种半导体，具有 1.9 电子伏特的离散能带隙，可以通过化学氧化将电导率提高 12 个数量级。生成的自由基被限制在芘结上，从而形成具有高自旋密度的顺磁碳结构。sp 碳骨架诱导铁磁相变以发展自旋-自旋相干，并在整个材料中单向排列自旋。
