Organometallic Derivatives of Polyphosphazenes as Precursors for Metallic Nanostructured Materials

Co-polyphosphazenes containing anchored organometallic fragments are useful precursors for nanostructured metallic materials. Pyrolysis in air at 800°C yields metallic nanoparticles of the type, M°/M _x O _y /M _z (P _x O _y )/P₄O₇, depending on the metal used; i.e., M° when the metal is a noble metal, metal oxide when the metal is Cr, W and Ru, metallic pyrophosphate when M = Mn and Fe. The organic spacer of the polyphosphazene influences strongly the morphology of the pyrolytic product. The mechanism of formation of the nanostructured materials involves carbonization of the organic matter, which produces holes where the nanoparticles are grown. Reaction of the phosphorus polymeric chain with O₂ yield phosphorus oxide units, which act as a P₄O₇ matrix to stabilize the nanoparticles and/or P _x O _y ⁻ⁿ for the formation of metallic pyrophosphates. The method appears to be a general and versatile new route to metallic nanostructured materials. Dedicated to Professor Harry Allcock for his pioneering and persevering work on Polyphosphazene and their projection in another field as materials and recently nanomaterials.     

Photoluminiscent Manganese Nanoparticles from Solid State Polyphosphazenes Organometallic Derivatives

Pyrolysis in air at 800°C of [{NP(OC₁₂H₁₀)}_0.6{NP(OC₆H₄PPh₂·(π-CH₃C₅H₄)−Mn(CO)₂)₂}_0.4] _n (1) in the solid state affords product 2 containing nanoclusters of Mn₂P₂O₇ with sizes ranging from 50 to 90 nm and averaging about 74 nm. The egg-shape of the unpyrolyzed organometallic polymer is retained but with increased particle size after pyrolysis. The pyrolytic material shows near-infrared photoluminescence attributed to the emission of tetrahedral Mn²⁺ embedded in a matrix of Mn₂P₂O₇. The solid-state pyrolysis of organometallic derivatives of polyphosphazenes may be a useful and general route to nano-structured Mn₂P₂O₇. An erratum to this article can be found at     

Supramolecular Chemistry in Solid State Materials such as Metal-Organic Frameworks

Supramolecular chemistry has enriched the scientific research for more than fifty years reaching one of its summits in 2016, when the Chemistry Nobel Prize was awarded for the design and synthesis of molecular machines, in which host-guest chemistry plays a fundamental role. Recently, the groups of Omar Yaghi and Fraser Stoddart, among others, have demonstrated that this chemistry can be extended to the pores of metal-organic frameworks (MOFs). This heterogenization of supramolecular chemistry can be achieved through the incorporation of macrocycles to the organic struts of these highly porous and crystalline materials. Throughout this short review we summarize interesting examples of selective recognition by naturally occurring and synthetic macrocycles in solution and solid state; and later we survey important milestones to achieve specific recognition sites and develop host-guest chemistry at the pores of MOFs. This summary contains examples of different synthetic strategies to incorporate macrocycles to solid state materials, and in particular, to prepare supramolecular MOFs with particular properties and related applications. Specifically, the revised research includes the incorporation of both naturally occurring and synthetic macrocycles to solid state materials such as polymers, metal nanoparticles, etc., as prelude of the solid phase recognition studied in MOFs. An important number of the contributions presented here feature porous solids with smooth access to the host's cavity incorporated in the pores, allowing specific recognition of guest molecules. This smooth access to those active recognition sites in materials with extremely high surface area such as MOFs, open the possibility to develop the next generation of frontier materials with application in fields such as selective capture of water toxins and heterogeneous catalysis, among others.     

Development and Characterization of Inorganic-Organic (Si-O-Al) Hybrid Geopolymeric Precursors via Solid State Method

Silicon - In this study, an innovative one part, solution free concept applied for the development of hybrid inorganic–organic geopolymeric precursors having Si-O-Al networks at the precursor...     

Silicon-Boron Alloys as New Ultra-High Temperature Phase-Change Materials: Solid/Liquid State Interaction with the h-BN Composite

Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S     

Aminoborane Polymers as Precursors of C-N-B Ceramic Materials

Aminoborane polymers were prepared via condensation reactions between polyfunctional amines and either triethylborane or tris(dimethylamino)borane. The products were characterized by chemical and spectroscopic analyses. The thermal degradation of these materials was studied to establish pyrolytic pathways and to evaluate their potential as precursors to C-N-B ceramic materials. The borane condensation products with 4,4'-methylenedipyrazole, o -phenylenediamine, and 3,3'-diaminobenzidine produced relatively high ceramic yields at 800°C, whereas that with diethylenetriamine decomposed into partially volatile oligomers.     

Metal Chelate Monomers as Precursors of Polymeric Materials

The principal advances and problems of the preparation of polymeric materials based on metal chelate monomers containing metal chelate cycle and functionality are analysed. The data are systematized according to methods for preparing polymeric materials: homopolymerization, copolymerization, living and controlled polymerization, grafting polymerization, electropolymerization, polycondensation, as well as synthesis of dendrimers and hyperbranched polymers based on metal chelate monomers. Special attention is paid to the effect of a metal on both the synthesis mechanism and properties of the products formed. The principal applications of polymeric materials based on metal chelate monomers are considered.     

Synthesis of Cobalt-Containing Hyperbranched Polyynes and Their Utilization as Precursors to Nanostructured Magnetoceramics

Complexation of the acetylene moieties of a hyperbranched polyynes with cobalt carbonyls at room temperature furnishes cobalt-containing organometallic polymers in high yields. The inorganic–organic hybrid materials can be graphitized into nanostructured cobalt ceramics when pyrolyzed at high temperatures, with char yields up to ∼65 wt%. The ceramics are highly magnetizable (M _s up to ∼118 emu/g) and show near-zero remanence and coercivity (H _c down to ∼0.045 kOe), suggesting that they are outstanding soft ferromagnets with high magnetic susceptibilities and practically nil hysteresis loss.     

The Inclusion of Organometallic Derivatives of Cyclotriphosphazenes Inside SiO2 Matrix and Their Conversion to Nanostructured Metal-Oxides and Phosphates

Organometallic derivatives of the cyclotriphosphazene N₃P₃[OC₆H₄CH₂CN·TiClCp₂]₆ (1), N₃P₃(O₆H₅)₅[OC₆H₄N·W(CO)₅] (2), N₃P₃[OC₆H₄CH₂CN·Mo(CO)₅]₆ (3), [N₃P₃(O₆H₅)₅(OC₅H₄N·CpRu(PPh₃)₂)][PF₆] (4), [N₃P₃(O₂C₁₂H₈)₂OC₅H₄N·Ag(PPh₃)][OSO₂CF₃] (5), N₃P₃[OC₆H₅]₅ [OC₅H₄N·Cu][PF₆] (6) and N₃P₃[OC₆H₄CH₂CN·CuCl]₆[PF₆]₆ (7),were incorporated inside SiO₂ through the sol–gel method. The metal–organic nanocomposites of the general formula N₃P₃[OC₆H₄CH₂CN·TiClCp₂]₆·nSiO₂ (G ₁ ), N₃P₃[OC₆H₄N·W(CO)₅]·nSiO₂ (G ₂ ), N₃P₃[OC₆H₄CH₂CN·Mo(CO)₅]₆·nSiO₂ (G ₃ ), N₃P₃(O₆H₅)₅OC₅H₄N·CpRu(PPh₃)₂][PF₆]·nSiO₂ (G ₄ ), [N₃P₃(O₂C₁₂H₈)₂OC₅H₄N·Ag(PPh₃)][OSO₂CF₃]·nSiO₂ (G ₅ ), N₃P₃[OC₆H₅]₅[OC₅H₄N·Cu][PF₆]·(SiO₂) _n (G ₆ ), and N₃P₃[OC₆H₄CH₂CN·CuCl]₆[PF₆]₆·(SiO₂) _n (G ₇ ), were characterized by IR spectroscopy; ¹²C, ³¹ P and ²⁹Si MAS NMR measurements as well as UV–Visible diffuse reflectance spectra, indicating the presence of the respective organometallic derivatives of the cyclotriphosphazene incorporated into SiO₂. Pyrolysis of these nanocomposites under air at 800 °C gives rise to nanostructured metal-oxides and metal phosphates incorporated into amorphous SiO₂, with the presence in some cases of complexes phase mixtures. From some precursors, we obtained metal-oxides/phosphates nanoparticles separated from the SiO₂ nanoparticles instead the oxides/phosphates nanoparticles inside the SiO₂ matrix. Additionally and for comparison purposes, we used the compound N₃P₃[NH(CH₂)₃Si(OEt)₃]₆ as gelator. Nanocomposites (G′ ₁ ), (G′ ₂ ) and (G′ ₃ ) exhibited mainly morphological differences while in some cases composition differences when using TEOS as gelator. Some simple metal-containing compounds as (O₃SCF₃)Ag(PPh₃)(HOC₅H₄N), [CuCl₂·NC₅H₄OH] and [CuCl₂·NCCH₂C₆H₄OH]—which are useful models of the most complexes (G ₅ ), (G ₆ ) and (G ₇ ) were also prepared and incorporated in amorphous silica. Their pyrolytic products were compared with those of more complex cyclotriphosphazene analogous. Interestingly, the pyrolysis of the nanocomposite [(O₃SCF₃)Ag(PPh₃)(HOC₅H₄N)][SiO₂] _n affords the firstly-reported materials containing Ag₂O along with SiO₂ nanoparticles.     

一种合成环丁烯酮衍生物的新方法

介绍了一种在碱性条件下以α-丙酰基二硫缩烯酮与胺类化合物为反应原料,DMSO为反应溶剂,发生分子内环化反应合成环丁烯酮衍生物的新方法。其中合成了3个新化合物,产物结构经1H NMR确证。     

光敏热显成像材料中组分山嵛酸银与邻苯二甲酸的固相反应动力学

采用液相沉淀法合成了山嵛酸银与邻苯二甲酸的固相反应产物邻苯二甲酸二银,并通过元素分析、ICP-AES、FT-IR等方法对其进行了表征分析.在此基础上,采用X射线衍射K值分析法,在光敏热显成像材料热显影温度范围内(100～123 ℃),研究了山嵛酸银与邻苯二甲酸的固相反应过程.结果表明,山嵛酸银与邻苯二甲酸的固相反应为固态扩散控制过程.在一定的反应时间内,Jander方程能够较好地描述山嵛酸银与邻苯二甲酸的固相反应动力学,反应的表观活化能为84.5 kJ·mol-1,表观频率因子为7.06×107 min-1.在光敏热显成像材料热显影过程中,提高调色剂邻苯二甲酸在涂层中的扩散速度有利于提高其显影速率.     

大豆油及其衍生物在新能源和新材料中的应用研究进展

大豆油及其衍生物以其良好的环保性和资源可再生性,在新能源和新材料等领域有着广泛应用。本文介绍了作为可再生资源的大豆油的结构和组成成分,大豆油及其衍生物在生物柴油、油墨以及聚氨酯新材料等方面的应用研究进展。     

Luster Pottery from the Thirteenth Century to the Sixteenth Century: A Nanostructured Thin Metallic Film

Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans.     

低温固相反应法在纳米电极材料合成中的应用

介绍了低温固相合成技术的特点和优势，以及该技术在制备二次碱锰电池正极材料及其改性添加剂中的应用，纳米级MnO2正极材料以及由纳米改性添加剂修饰的MnO2正极材料在深度放电时具有更优越的性能。     

新型杀菌剂磷酸铜的固相合成及表征

采用固相合成法,以Cu(Ⅱ)和PO43-为原料,在740℃反应1 h合成磷酸铜Cu3(PO4)2。使用化学分析、热重分析和XRD分析等方法对产物进行了表征。结果表明,能用高温固相合成法来制备磷酸铜Cu3(PO4)2。通过正交实验得到了最佳工艺条件:n[Cu(Ⅱ)]/n[PO43-]=1.51;温度740℃;反应时间1 h。     

Catalytic and Electrochemical Properties of Doped Lanthanum Chromites as New Anode Materials for Solid Oxide Fuel Cells

Defective perovskites contained in the general formula La(Sr)Cr(Ru,Mn)O_3–δ are successfully synthesized by spray pyrolysis. Powders of high phase purity are obtained after annealing, and they are used to prepare homogeneous films by spray printing. From a catalytic point of view for the methane steam reforming, these powdered perovskites do not generate a carbon deposit. Catalytic results, focused on doped ruthenium perovskites, confirm that the insertion of ruthenium in the structure of the lanthanum chromite presents a real benefit for the methane steam reforming. The electrochemical properties of La(Sr)CrO_3–δ, either pure and doped with manganese, show that the perovskite films can be potential electrodes, depending on their doping, for hydrogen anodic oxidation in solid oxide fuel cells.     

固态相变法制备纳米复合氧化物陶瓷的研究进展

氧化物陶瓷具有较高的机械强度、电绝缘性能、化学稳定性等,是用途最宽、应用最广、产量最大的陶瓷材料,已经应用于航空航天、军事国防、工业生产等领域。然而,氧化物陶瓷的脆性,严重制约了其在尖端领域的更广泛应用。针对这一难题,近几十年来,国内外学者开始探索固态相变法制备精细纳米结构的氧化物复合陶瓷。通过固态相变法构筑纳米复合氧化物陶瓷的纳米/亚微米/微米尺度的结构,以提高纳米复合氧化物陶瓷的力学性能。本文系统综述了固态相变法对纳米复合氧化物陶瓷结构和性能的影响,旨在阐明相关的原理及工艺,为高性能纳米复合氧化物陶瓷的制备提供参考与借鉴。     

工业固体废弃物作为合成微晶玻璃原料的开发和利用

概述了以工业废渣、尾矿尾砂、冶炼炉渣等工业固体废弃物为原料制备微晶玻璃的研究现状.对固体废弃物作为制备微晶玻璃原料的前景进行了展望,指出利用页岩残渣制备微晶玻璃的研究将开辟页岩残渣综合利用的新途径.