论文标题
化学掺杂共价有机框架中的无金属磁性
Metal-free magnetism in chemically doped covalent organic frameworks
论文作者
论文摘要
有机和基于分子的磁铁不容易获得，因为将稳定的顺磁中心引入纯有机系统是具有挑战性的。具有高可设计性和化学多样性的晶体共价有机框架（COF）构成了访问有机材料的有趣磁现象的理想平台。在这项工作中，我们提出了一种通用方法，以通过化学掺杂在窄带COF中获得未配对的电子自旋和无金属磁性。通过使用密度函数理论计算，我们发现，具有能量匹配的边界轨道的掺杂剂不仅向其注入电荷，而且还通过轨道杂交和超分子电荷转移络合物的形成进一步定位电荷。局部状态实现了引入非磁性COF的稳定顺磁中心。基于这一发现，我们设计了两个具有窄价带的新COF，它们在与碘掺杂后显示了前瞻性磁性。此外，我们在二维COF中阐明了磁各向异性，并表明可以通过操纵COF的构建块来调节自旋传导和磁相互作用。我们的工作强调了在COF和其他有机材料中获得磁性的实用情况，这对在有机旋转设备中的应用中充满希望。
Organic and molecule-based magnets are not easily attainable, because to introduce stable paramagnetic centers to pure organic systems is challenging. Crystalline covalent organic frameworks (COFs) with high designability and chemical diversity constitute ideal platforms to access intriguing magnetic phenomena of organic materials. In this work, we proposed a general approach to attain unpaired electron spin and metal-free magnetism in narrow-band COFs by chemical doping. By using density functional theory calculations, we found that dopants with energy-matched frontier orbitals to COFs not only inject charges to them but also further localize the charges through orbital hybridization and formation of supramolecular charge-transfer complex. The localized states enable stable paramagnetic centers introduced to nonmagnetic COFs. Based on this discovery, we designed two new COFs with narrow valence band, which show prospective magnetism after doping with iodine. Further, we unraveled magnetic anisotropy in two-dimensional COFs and showed that both spin-conduction and magnetic interactions can be modulated by manipulating the building blocks of COFs. Our work highlights a practical scenario to attain magnetism in COFs and other organic materials, which hold great promise for applications in organic spintronic devices.
