Hetero‐tri‐spin [2p‐3d‐4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo‐Ligands: Synthesis,Structure, and Magnetic Properties

Employing nitronyl nitroxide lanthanide(III) complexes as metallo‐ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero‐tri‐spin (Cu?Ln‐radical) one‐dimensional compounds. These 2p–3d–4f spin systems, namely [Ln₃Cu(hfac)₁₁(NitPhOAll)₄] (Ln^III=Gd 1_Gd , Tb 1_Tb , Dy 1_Dy ; NitPhOAll=2‐(4′‐allyloxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide), [Ln₃Cu(hfac)₁₁(NitPhOPr)₄] (Ln^III=Gd 2_Gd , Tb 2_Tb , Dy 2_Dy , Ho 2_Ho , Yb 2_Yb ; NitPhOPr=2‐(4′‐propoxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) and [Ln₃Cu(hfac)₁₁(NitPhOBz)₄] (Ln^III=Gd 3_Gd , Tb 3_Tb , Dy 3_Dy ; NitPhOBz=2‐(4′‐benzyloxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) involve O‐bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu‐Nit‐Ln‐Nit‐Ln‐Nit‐Ln‐Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal–radical interactions take place in these hetero‐tri‐spin chain complexes, these and the next‐neighbor interactions have been quantified for the Gd derivatives. Complexes 1_Tb and 2_Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single‐chain magnet behavior.     

Synthesis,Structure and Magnetic Property of One Ni~Ⅱ Based Coordination Polymer

One new coordination polymer, [Ni(m-bix)(m-BDC)](1, m-bix = 1,3-bis(imidazol-1-ylmethyl)benzene, m-BDC = 1,3-benzenedicarboxylic acids), has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TGA and X-ray single-crystal diffraction. The green block crystal of complex 1(C22H18N4Ni O4) belongs to monoclinic system, space group P21/c with a = 10.0418(3), b = 23.8651(6), c = 8.7872(2) A, β = 112.333(3)o, V = 1947.88(9)A3, Z = 4, Dc = 1.572 g/cm3, Mr = 461.11, F(000) = 952, R = 0.0335 and w R = 0.0683 for 2827 observed reflections(I 2σ(I)). Complex 1 exhibits a novel 6-connected 3D sxd type topological framework. The magnetic characterization of complex 1 shows antiferromagnetic coupling exchange.     

二维磁性纳米材料的可控合成及磁性调控

自旋电子学的研究重点在于同时利用电子的电荷和自旋两个自由度对信息进行处理和存储,其具有运行速度快、存储密度高和能耗低等优势。毫无疑问,发展二维磁性纳米材料的可控合成方法及磁性调控策略,对于新型自旋电子学器件的构筑具有重要的科学意义和应用价值。然而,目前得到的二维磁性纳米材料的种类十分有限,而且合成方法及磁性调控手段相对单一,极大地限制了该领域的发展。本文首先根据磁性的来源,对二维磁性纳米材料进行了分类,介绍了诱导产生的磁性和具有本征磁性的二维纳米材料,然后详细地归纳了二维磁性纳米材料常见的合成方法,如机械剥离法、电化学剥离法、化学气相沉积法以及液相合成方法等。此外,着重总结了二维材料磁性的主要调控手段,最后展望了该领域遇到的瓶颈、未来的研究重点及应用前景。     

Collective All‐Carbon Magnetism in Triangulene Dimers

Triangular zigzag nanographenes, such as triangulene and its π‐extended homologues, have received widespread attention as organic nanomagnets for molecular spintronics, and may serve as building blocks for high‐spin networks with long‐range magnetic order, which are of immense fundamental and technological relevance. As a first step towards these lines, we present the on‐surface synthesis and a proof‐of‐principle experimental study of magnetism in covalently bonded triangulene dimers. On‐surface reactions of rationally designed precursor molecules on Au(111) lead to the selective formation of triangulene dimers in which the triangulene units are either directly connected through their minority sublattice atoms, or are separated via a 1,4‐phenylene spacer. The chemical structures of the dimers have been characterized by bond‐resolved scanning tunneling microscopy. Scanning tunneling spectroscopy and inelastic electron tunneling spectroscopy measurements reveal collective singlet–triplet spin excitations in the dimers, demonstrating efficient intertriangulene magnetic coupling.     

A novel three‐dimensional tetranuclear CoII coordination polymer with water hexamers based on the V‐shaped tetracarboxylate ligand 4‐(2,4‐dicarboxylatophenoxy)phthalate

A new coordination polymer (CP), namely, poly[[diaquatris[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]bis[μ₆‐4‐(2,4‐dicarboxylatophenoxy)phthalato]tetracobalt(II)] hexahydrate], {[Co₄(C₁₆H₆O₉)₂(C₁₂H₁₀N₄)₃(H₂O)₂]·6H₂O}_n, has been synthesized by solvothermal reaction. The CP was fully characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, and powder and single‐crystal X‐ray diffraction. It presents a three‐dimensional (3D) structure based on tetranuclear Co^II secondary building units (SBUs) with a tfz‐d net and point symbol (4³)₂(4⁶·6¹⁸·8⁴). The 4‐(2,4‐dicarboxyphenoxy)phthalic acid (H₄dcppa) ligands are completely deprotonated and link {Co₄(COO)₄}^4? SBUs into two‐dimensional (2D) layers. Furthermore, adjacent layers are connected by 1,4‐bis(1H‐imidazol‐1‐yl)benzene (bib) ligands, giving rise to a 3D supramolecular architecture. Interestingly, there are numerous elliptical cavities in the CP where isolated unique discrete hexameric water clusters have been observed. The results of thermogravimetric and magnetic analyses are described in detail.     

人造金刚石合成中黑色低磁金刚石的研究

 通过对合成金刚石的原材料和合成产物——石墨、Ni₇₀Mn₂₅Co₅触媒、普通人造金刚石、黑色人造金刚石、NiMnCoC熔体的磁化率测试,以及对黑色人造金刚石和普通人造金刚石破碎断面扫描电镜的对比分析,认为黑色人造金刚石形成低磁性的原因是由于合成过程中温度偏高、压力偏低,生长的金刚石质量差、裂纹多。晶体内夹杂了很多石墨与触媒包裹体,同时金刚石表面与金刚石晶体内的触媒包裹体之间形成贯穿性的裂纹。在金刚石化学提纯处理过程中,金刚石晶体内的铁磁性触媒包裹体杂质被通过裂纹进入的酸除去。因而在检测金刚石磁性时,黑色金刚石的磁性很小,呈弱磁性。     

Synthesis,Crystal Structures,and Spectroscopic Properties of Novel Gadolinium and Erbium Triphenylsiloxide Coordination Entities

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li₄(OSiPh₃)₄(THF)₂] (1), and sodium [Na₄(OSiPh₃)₄] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh₃)₃(THF)₃]·THF (3), and erbium [Er(OSiPh₃)₃(THF)₃]·THF (4) configuration, it can result in res were determined for all 1–4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8–300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd³⁺ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er³⁺ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.     

Ionic liquid gating control of magnetic anisotropy in Ni0.81Fe0.19 thin films

Voltage control magnetism is one of the most energy efficient pathway towards magnetoelectric (ME) device. Ionic liquid gating (ILG) method has already shown impressive manipulation power at the IL/electrode interface to influence the structure, orbital as well as spin of the electrode materials. As key material in anisotropy magnetoresistance sensor and spin valve heterostructure, the permalloy Ni_0.81Fe_0.19 was utilized as the electrode to investigate the ILG induced magnetic anisotropy change. In this work, we realized magnetic anisotropy control in Au/[DEME]⁺[TFSI]^-/Ni_0.81Fe_0.19 (2.5 nm)/Ta heterostructure via ILG caused electrostatic doping. This is evidenced in situ reversible ferromagnetic field (H_r) shift with electron spin resonance (ESR) spectrometer. Aiming at the question whether the charge accumulation at the ionic liquid interface is the main control mechanism at low voltage, we carefully tested the relationship between the change of resonance field and the amount of surface charge. It was found that these two had a good linear relationship between −1 V and +1 V. Defining the linear parameter as A whose value is 28.7 mT m²/Col. Unlike previously reported chemical regulation of Co, this article used ionic liquids to physically regulate NiFe, which has not been studied in the previous ionic liquid regulation. And NiFe has a narrower resonance line width for easy reference to microwave devices. In addition, It also has a stronger ferromagnetic signal than Co, which can be more easily detected as a sensor device. Therefore, this system is more promising. The ILG control NiFe may lead to a new kind of magnetoelectric sensor devices and path a new way to low energy consumption spintronics.     

Co3O4纳米粒子的固相合成及磁性研究

以Co(NO3)2.6H2O和NaOH为原料,用固相法合成了Co3O4纳米微粒。用XRD和FT-IR研究了反应进程,证明Co3O4在焙烧阶段形成。用TEM观察了Co3O4纳米微粒的形貌,用磁天平测试了其磁性。结果表明,固相法可以制得平均粒径为22 nm的铁磁性Co3O4纳米微粒,属立方晶系,形状为多角形。400℃焙烧2 h所得纳米Co3O4的磁性强度为1.7922×10-2mT-1。