Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing, China.
J Am Chem Soc. 2011 Sep 28;133(38):15113-9. doi: 10.1021/ja204990j. Epub 2011 Aug 31.
A two-dimensional (2D) periodic Fe phthalocyanine (FePc) single-layer sheet has very recently been synthesized experimentally (Abel, M.; et al. J. Am. Chem. Soc.2011, 133, 1203), providing a novel pathway for achieving 2D atomic sheets with regularly and separately distributed transition-metal atoms for unprecedented applications. Here we present first-principles calculations based on density functional theory to investigate systematically the electronic and magnetic properties of such novel organometallics (labeled as TMPc, TM = Cr-Zn) as free-standing sheets. Among them, we found that only the 2D MnPc framework is ferromagnetic, while 2D CrPc, FePc, CoPc, and CuPc are antiferromagnetic and 2D NiPc and ZnPc are nonmagnetic. The difference in magnetic couplings for the studied systems is related to the different orbital interactions. Only MnPc displays metallic d(xz) and d(yz) orbitals that can hybridize with p electrons of Pc, which mediates the long-range ferromagnetic coupling. Monte Carlo simulations based on the Ising model suggest that the Curie temperature (T(C)) of the 2D MnPc framework is ∼150 K, which is comparable to the highest T(C) achieved experimentally, that of Mn-doped GaAs. The present study provides theoretical insight leading to a better understanding of novel phthalocyanine-based 2D structures beyond graphene and BN sheets.
一种二维（2D）周期性 Fe 酞菁（FePc）单层片最近已在实验中被合成（Abel，M.等人。J. Am. Chem. Soc.2011，133，1203），为实现具有规则且独立分布过渡金属原子的 2D 原子片提供了一条新途径，从而可实现前所未有的应用。在这里，我们基于密度泛函理论进行了第一性原理计算，系统地研究了此类新型有机金属（标记为 TMPc，TM=Cr-Zn）作为独立片的电子和磁性质。其中，我们发现只有二维 MnPc 骨架是铁磁的，而二维 CrPc、FePc、CoPc 和 CuPc 是反铁磁的，二维 NiPc 和 ZnPc 是非磁性的。所研究体系中磁耦合的差异与不同的轨道相互作用有关。只有 MnPc 显示出可以与 Pc 的 p 电子杂化的金属 dxz 和 dyz 轨道，这介导了长程铁磁耦合。基于伊辛模型的蒙特卡罗模拟表明，二维 MnPc 骨架的居里温度（T(C)）约为 150 K，与实验上实现的最高 T(C)相当，即 Mn 掺杂 GaAs 的 T(C)。本研究提供了理论见解，有助于更好地理解超越石墨烯和 BN 片的新型酞菁基 2D 结构。
