Cu（Ⅱ）－Ln（Ⅲ）双核配合物的合成、磁性和抗菌活性

合成和表征了６种以草酰胺为桥联的异双核配合物Ｃｕ（ｏｘｅｎ）Ｌｎ（ｐｈｅｎ）２（ＣｌＯ４）３（ｏｘｅｎ代表Ｎ，Ｎ′－双（２－氨乙基）草酰胺根阴离子；ｐｈｅｎ为１，１０－邻菲咯琳；Ｌｎ表示Ｙ、Ｌａ、Ｃｅ、Ｎｄ、Ｇｄ和Ｙｂ）．测定了Ｃｕ（ｏｘｅｎ）Ｇｄ（ｐｈｅｎ）２（ＣｌＯ４）３·Ｈ２Ｏ的变温磁化率（４～３００Ｋ）；井用最小二乘法和从自旋Ｈａｍｉｌｔｏｎｉａｎ算符导出的磁方程拟合，求得交换积分Ｊ＝２．３ｃｍ－１；表明配合物中Ｃｕ（Ⅱ）和Ｇｄ（Ⅲ）离子间存在弱的铁磁性超交换作用。测试了配合物的抗菌活性。     

酚氧桥联铜钴异双核配合物的密度泛函研究

用密度泛函方法,在ROB3LYP/SDD//ROB3LYP/LanL2MB水平上,对酚氧桥联CuⅡ-CoⅡ异双核配合物CuCo(TS)(H2O),进行了理论计算.优化得到了它的单、三重态的平衡几何构型,计算了它们的谐振动频率.结果表明,该配合物分子的三重态比单重态稳定;电子自旋布居高度集中在Co(6)及其周围的配体原子上,而Cu（1）则没有发现电子自旋布居; 体系中存在较强的自旋离域效应.体系的前线分子轨道主要由Co(6)的d轨道和配体原子的p轨道组成,这有利于配体原子与Co(6)之间的电子转移.计算结果与实验符合得很好.     

基于2-吡啶甲醛肟配体的NiⅡ2ZnⅡ2簇配合物的合成、晶体结构、磁性及光催化性能

在溶剂热条件下，以2-吡啶甲醛肟(HL)为主配体，Zn(OAc)₂·2H₂O和NiCl₂·6H₂O为金属盐，合成了一个Ni^Ⅱ₂Zn^Ⅱ₂簇配合物[Ni₂Zn₂(L)₄Cl₂(CH₃O)₂](1)，通过元素分析、红外光谱、单晶X射线衍射等对其结构进行了表征。研究了该配合物的磁性及光催化降解染料的性能，结果表明：配合物1属于正交晶系，Pna2₁空间群，其分子中包含2个Ni^Ⅱ离子，2个Zn^Ⅱ离子，4个L-配体，2个Cl^-离子和2个CH₃O^-离子。磁性研究表明Ni^Ⅱ…Ni^Ⅱ离子间存在弱的反铁磁相互作用。光催化降解染料的研究结果表明该配合物对甲基橙和罗丹明B有较好的降解活性，降解率分别达到83.9%和71.1%。进一步探讨了光催化降解染料的作用机理。     

Luminescent and magnetic bifunctional coordination complex based on a chiral tartaric acid derivative and europium

A new mononuclear europium complex incorporating the (+)‐di‐p‐toluoyl‐d ‐tartaric acid (d ‐H₂DTTA) ligand, namely, catena‐poly[tris{μ₂‐3‐carboxy‐2,3‐bis[(4‐methylphenyl)carbonyloxy]propanoato}tris(methanol)europium(III)], [Eu(C₂₀H₁₇O₈)₃(CH₃OH)₃]_n, (I), has been synthesized and characterized by IR spectroscopy, elemental analysis, powder X‐ray diffraction and single‐crystal X‐ray diffraction analysis. The structure analysis indicates that complex (I) crystallizes in the trigonal space group R3 and exhibits an infinite one‐dimensional chain structure, in which the Eu³⁺ ion is surrounded by six O atoms from six d ‐HDTTA^? ligands and three O atoms from three coordinated methanol molecules, thus forming a tricapped trigonal prism geometry. The d ‐H₂DTTA ligand is partially deprotonated and adopts a μ_1,6‐coordination mode via two carboxylate groups to link adjacent Eu³⁺ ions, affording an infinite one‐dimensional propeller‐shaped coordination polymer chain along the c axis, with an Eu…Eu distance of 7.622 (1) Å. Moreover, C—H…π interactions lead to the formation of helical chains running along the c axis and the whole structure displays a snowflake pattern in the ab plane. The circular dichroism spectrum confirms the chirality of complex (I). The solid‐state photoluminescence properties were also investigated at room temperature and (I) exhibits characteristic red emission bands derived from the Eu³⁺ ion (CIE 0.63, 0.32), with a reasonably long lifetime of 0.394 ms, indicating effective energy transfer from the ligand to the metal centre. In addition, a magnetic investigation reveals single‐ion magnetic behaviour. The spin‐orbit coupling parameter (λ) between the ground and excited states is fitted to be 360 (2) cm^?1 through Zeeman perturbation. Therefore, complex (I) may be regarded as a chiral optical‐magneto bifunctional material.     

Synthesis, Crystal Structure and Magnetic Properties of a Cobalt（II） Coordination Polymer with 4,4＇-（Propane-2,2-diyl）dibenzoate and 4,4 ＇-Bis（1-imidazolyl）biphenyl

A novel coordination polymer, {[Co（CBA）（BIMB）0.5]＇H20}n （1, H2CBA = 4,4＇- （propane-2,2-diyl）dibenzoic acid, and BIMB = 4,4＇-bis（1-imidazolyl）biphenyl）, has been hydro- thermally prepared and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal is of monoclinic system, space group P2/c with a = 14.909（3）, b = 7.1963（15）, c = 24.592（5） A, β = 104.312（2）, V = 2556.5（9） A3, C26H23N2OsCo, Mr = 502.39, Dc = 1.305 g/cm3, F（000） = 1040,μ = 0.708 mm-1 and Z = 4. The final R= 0.0580 and wR = 0.1605 for 3228 observed reflections （1 〉 2a（I））. Single-crystal structure analysis shows that complex 1 exhibits a three-dimensional 2-fold interpenetrating pillared helical-layer open framework of a-Po topology based upon binuclear paddlewheel units. Moreover, its magnetic properties have also been investigated.     

A MOLECULE LIKE SODIUM

The use of neutral π-radicals as building blocks for molecular conductors holds both appeal and challenge. Such systems obviate the need for counterions, as charge transfer is not required to generate charge carriers. Essentially an array of π-radicals should function like atoms in an elemental metal, e.g., sodium, affording a half-filled energy band. Most radicals, however, tend to dimerize, and even when association can be suppressed the resulting low bandwidth W, coupled with a high on-site Coulomb repulsion U, leads to a Mott insulating state. We are pursuing the design and synthesis of stable heterocyclic thiazyl radicals, with a view to generating stable, crystalline materials with a high W/U ratio. The search for these new radicals, the molecular analogues of sodium, is the subject of this presentation.     

Modulation of the ferromagnetic insulating phase in Pr0.8Ca0.2MnO3 by Co substitution

Ferromagnetic insulator Pr_0.8Ca_0.2Mn_1–yCo_y O₃ (0 ≤ y ≤ 0.7) thin films were epitaxially grown by pulsed laser deposition on substrates of (LaAlO₃)_0.3(SrAl_0.5Ta_0.5O₃)_0.7 (100). To probe the ferromagnetic insulator state, the Co content dependences of the structural, magnetic, and transport properties were studied. Variation of lattice constant by the Co substitution is well reproduced considering that divalent and trivalent Co ions substitute for Mn ions at the perovskite B‐sites. For 0 ≤ y ≤ 0.3, the Curie temperature, saturation magnetization, and magnetoresistance increase with increasing Co content, retaining the insulating properties. Detailed analyses of transport and magnetic properties indicate the contribution of both double exchange and superexchange interactions to the appearance of the ferromagnetic insulating phase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spontaneous surface magnetisation of single crystal MnF2 in the antiferromagnetic state

Spontaneous magnetisation of (100) and (010) surfaces of single crystal MnF₂ in the antiferromagnetic state has been discovered. The sign of the surface magnetisation is determined by the difference in dielectric constants of MnF₂ and ambient matter: magnetisation is directed to the substance with smaller . Received 28 August 1998 and Received in final form 15 December 1998