Synthesis,characterization, and magnetochemical properties of two Mn4 clusters derived from 2-pyridinecarboxaldehyde Schiff base ligands

Two tetranuclear manganese complexes, [Mn₄(L¹)₆](ClO₄)₂?2.75H₂O (1) [HL¹ = 4-methyl-2-((pyridin-2-ylmethylene)amino)phenol] and [Mn₄(L²)₄(NO₃)₃(OH)]?pz?3H₂O (2) [HL² = (1H-pyrazol-1-yl)(pyridin-2-yl)methanol, pz = pyrazole], have been synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and magnetic measurements. The structural analysis revealed that the central manganese ion is linked with three apical manganese ions through six phenoxo-bridges creating a Mn₄O₆ core for 1; 2 has a cubane-like topology with the Mn(II) ions and the deprotonated oxygens from L² alternatively occupying vertices. The magnetic studies indicated a weak ferromagnetic coupling interaction (J = 0.48 ± 0.087 cm^?1, g = 2.00, θ = ?0.78 K) for 1 and a weak antiferromagnetic spin-exchange interaction (J₁ = ?0.50 ± 0.075 cm^?1, J₂ = ?0.13 ± 0.082 cm^?1, g = 1.98) between Mn(II) ions for 2. The magnetostructural correlations of the two Mn₄ clusters have been discussed tentatively.     

Detection and Characterization of Compounds in the Mn‐W‐Cl System through a Combined Thermal Scanning ‐ XRD Approach

A procedure combining thermal analyses and XRD powder diffraction is used to scan and detect a series of new compounds in the Mn‐W‐Cl system. Four new ternary Mn‐W‐Cl compounds are formed in a progressive reaction of tungsten hexachloride (WCl₆) with manganese powder, in which tungsten is gradually reduced from W⁶⁺ to W²⁺. Among several DSC signals, the new compounds Mn_xWCl₆, MnW₂Cl₁₀, (Mn, W)_1–xCl₂, and MnW₆Cl₁₄ are detected and their crystal structures are assigned or identified by X‐ray diffraction techniques. Magnetic properties are reported for MnW₂Cl₁₀ and MnW₆Cl₁₄.     

A 1,2,4‐Triazole‐based Polynuclear Mixed‐valence MnIIMnIII Complex: Synthesis,Characterization, and Magnetic Property

A mixed‐valence Mn complex {[Mn^IIMn^III(HL)₂(4,4′‐bpy)(H₂O)₂] · (ClO₄)(DMF)₃(4,4′‐bpy)_0.5}_n ( 1 ) [H₂L = 3‐(2‐phenol)‐5‐(pyridin‐2‐yl)‐1,2,4‐triazole] was synthesized and characterized by X‐ray single‐crystal structure analysis and magnetic susceptibility. Single‐crystal X‐ray analysis revealed that complex 1 has a dinuclear core, in which adjacent central Mn^III atoms are linked by 4,4′‐bipyridine to form an infinite one‐dimensional (1D) molecular configuration. According to the Mn surrounding bond lengths and bond valence sum (BVS) calculations, we demonstrated that the Mn atom coordinated to the pyridine N atoms is in the +2 oxidation state, while another Mn atom coordinated to the phenolic oxygen atoms is in the +3 oxidation state. Magnetic susceptibility data of the complex 1 indicate that the ferromagnetic interaction dominates in this complex.     

Synthesis,Structures and Magnetic Properties of Cyano‐bridged FeIII/MnIII Heterobimetallic 1D Chain Complexes

Using the tricyanometalate building block, (nBu₄N)[(Tp*)Fe(CN)₃] [Bu₄N⁺ = tetrabutylammonium cation; Tp*^– = hydrotris(3,5‐dimethylpyrazol‐1‐yl)borate], and bidentate Schiff base ligands, HL1 or HL2 {HL1 = 2‐[[(2‐phenylethyl)imino]methyl]phenol; HL2 = 4‐methoxy‐2‐[[(2‐phenylethyl)imino]methyl]phenol}, two heterobimetallic one‐dimensional (1D) chain complexes, [Mn(L1)₂Fe(Tp*)(CN)₃]_n ( 1 ) and [Mn(L2)₂Fe(Tp*)(CN)₃]_n ( 2 ), were synthesized. Single crystal X‐ray diffraction reveal the formation of neutral cyano‐bridged zigzag single chains in 1 and 2 . Magnetic studies demonstrate that both complexes show ferromagnetic interactions between central Fe^III and Mn^III atoms.     

Review: Recent advances in the investigations of NO activation on cobalt and manganese porphyrins: a brief review

Cobalt and manganese porphyrins are known for their ability to activate small molecules. This is particularly important in the case of nitric oxide, whose role and mechanism of action in the redox biological systems have not yet been fully recognized. The goal of this article is to draw attention to some of the current trends of research in this area. The interactions involving NO itself and the primary products of its oxidation (nitrite) and reduction (nitroxyl) have been distinguished and separately discussed. The diversity of undertaken issues sheds light on both the expected behavior in biologically relevant systems as well as potential practical applications.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂）,制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射（XRD）,热重分析（TGA）对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构;MnO₂纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极,活性炭（AC）为负极,1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器,发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g^-1,且表现出良好的电容特性和大电流放电性能.     

Low Temperature Synthesis of Mn3O4 Nanoparticles Using Starch as Capping Agent

In this communication, manganese oxide (Mn₃O₄) nanoparticles were prepared by a facile solution method using starch as capping agent. The nanoparticles were characterized by means of X‐ray diffraction (XRD) and AFM. The results showed that the Mn₃O₄ nanoparticles were single phase, spherical, and uniformly dispersive. The average particle size was evaluated to be approximately 35 nm.     

Ce掺杂对碳纳米管负载Mn催化剂结构及SCR反应性能的影响

采用等体积浸渍法制备多壁碳纳米管(MWCNTs)负载Ce-Mn的催化剂,考察了Ce掺杂对Mn/MWCNTs催化剂上NH₃选择性催化还原(SCR)NO_x反应活性的影响.并运用透射电镜扫描、N₂吸附-脱附、程序升温还原、X射线光电子能谱、X射线衍射等手段,重点考察了Ce掺杂对Mn/MWCNTs催化剂结构性质的影响.结果表明,Ce掺杂能显著提高催化剂的SCR活性,其活性增量随着Ce含量的增加先增大后减小;当Ce/Mn为0.6时,催化剂活性最佳.表征结果显示,Mn/MWCNTs中添加Ce后,金属氧化物在MWCNTs上的分散程度提高;催化剂的比表面积和孔体积增大,平均孔径减小;氧化能力提高;表面氧含量增加,Mn化合价升高;结晶度降低,Mn主要以无定形或微晶形式存在,Ce主要以CeO₂物相存在.     

纳米MnO锂离子电池负极材料的制备与性能

以高锰酸钾和抗坏血酸合成的MnC₂O₄·2H₂O为前驱体, 通过固相烧结制备了纳米MnO材料. 分别采用X射线衍射(XRD)、扫描电子显微镜(SEM)和恒电流充放电技术考察了其晶相结构、颗粒形貌和电化学性能.分析结果表明, 该纳米MnO具有面心立方的岩盐结构, 结晶度良好. 其颗粒是由粒径为50-100 nm的一次颗粒结合而成的二次颗粒, 大小约为400-600 nm. 当充放电电流密度为46.3 mA·g^-1时, 纳米MnO的首次库仑效率可达68.9%, 可逆比容量为679.7 mAh·g^-1. 在141.1 mA·g^-1的电流密度下循环50圈后, 比容量由584.5mAh·g^-1降至581.5 mAh·g^-1, 容量保持率高达99.5%, 表现出优异的循环性能. 此外, 当电流密度增加到494.7 mA·g^-1 (~2C)时, 其比容量依然可达290 mAh·g^-1, 表现出较好的倍率性能和快速充放电能力. 因此, 纳米MnO具有比容量高、循环稳定、倍率性能好和安全环保等优点,是一种非常有前景的锂离子电池负极材料.     

Manganese(III) Acetate Mediated Oxidation of Flavanones: A Facile Synthesis of Flavones

Oxidation of flavanones (1a–o) with manganese(III) acetate by heating in acetic acid in presence of perchloric acid afforded exclusively flavones (2a–o) by dehydrogenation in almost quantitative yields.