Inorganic-Organic Hybrid Polymers Based on Surface-Modified Metal Oxide Clusters

Transition metal oxide clusters with unsaturated carboxylate ligands bonded to their surface were polymerized in the presence of organic co-monomers by various polymerization techniques to form cluster-reinforced polymers. The properties of the cluster-crosslinked hybrid polymers are distinctly different to those of the parent polymers and originate from both crosslinking and filler effects. Variation of the cluster proportion, the kind of employed cluster, the ratio of functional and non-functional capping ligands and the polymerization conditions allows modifying the materials properties of the hybrid materials. The most important changes in materials properties compared with the cluster-free polymers relate to the swelling behavior, thermal stability and mechanical properties. Furthermore, cluster-specific properties can be introduced into the polymers, such as magnetic properties.     

Metal Oxide Nanosheets as 2D Building Blocks for the Design of Novel Materials

Research into 2-dimensional materials has soared during the last couple of years. Next to van der Waals type 2D materials such as graphene and h-BN, less well-known oxidic 2D equivalents also exist. Most 2D oxide nanosheets are derived from layered metal oxide phases, although few 2D oxide phases can be also made by bottom-up solution syntheses. Owing to the strong electrostatic interactions within layered metal oxide crystals, a chemical process is usually needed to delaminate them into their 2D constituents. This Review article provides an overview of the synthesis of oxide nanosheets, and methods to assemble them into nanocomposites, mono- or multilayer films. In particular, the use of Langmuir–Blodgett methods to form monolayer films over large surface areas, and the emerging use of ink jet printing to form patterned functional films is emphasized. The utilization of nanosheets in various areas of technology, for example, electronics, energy storage and tribology, is illustrated, with special focus on their use as seed layers for epitaxial growth of thin films, and as electrochemically active electrodes for supercapacitors and Li ion batteries.     

Some New Data for Metal Desorption on Inorganic-Organic Hybrid Materials

A 2(4-1) fractional factorial design is employed to study Cu(II) desorption on organofunctionalized silicas. Two types of silicas, at amounts of 100 and 200 mg and two acidic levels, and contact times were employed. Our study indicates that the effects of HCl and contact time on the percentage number of moles of copper are 13.23 and 18.53, respectively. However, the binary interaction of these factors is very small. Three important antagonistic and synergistic binary effects involving the silica type, acidic quantity, and contact time factors are found. The silica mass showed an insignificant principal effect. The desorption data are compared with those previously published concerning adsorption processes on both functionalized silicas. Copyright 2000 Academic Press.     

An Inorganic-Organic Hybrid Composite Featuring Metal-Chalcogenide Clusters

The cluster complex, Re₆( ₃-Se)₈(PEt₃)₅(4-vinylpyridine)(SbF₆)₂ (1), featuring the face-capped octahedral Re₆( ₃-Se)₈²⁺ cluster core and site-differentiating triethylphosphine and 4-vinylpyridine ligands has been synthesized and structurally characterized. The complex crystallized in monoclinic space group P2₁ with a=11.748(1)Å, b=15.1212(2)Å, c=19.941(2)Å, =90°, =94.411(3)°, =90°, V=3531.8(7)ų, Z=2, R1=0.0531, wR2=0.0774. Copolymerization of styrene with 1 via the polymerizable 4-vinylpyridine ligand afforded a novel inorganic-organic hybrid composite of high molecular weight and a low polydispersity index. Structural integrity of the cluster building block is maintained upon hybrid formation.     

Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials

This review describes the major advances made on titanium-oxo clusters chemistry and their derived hybrid materials. The main synthesis procedures, the cluster structures presented in literature, and the relation between the titanium-oxo clusters condensation degree and poisoning ratio are discussed. The tuned organo-functionalisation of the titanium-oxo based nanobuilding blocks allows to develop a LEGO-like chemistry, able to direct the assembling of a large variety of structurally well defined complex hybrid architectures.     

Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials

Summary. This review describes the major advances made on titanium-oxo clusters chemistry and their derived hybrid materials. The main synthesis procedures, the cluster structures presented in literature, and the relation between the titanium-oxo clusters condensation degree and poisoning ratio are discussed. The tuned organo-functionalisation of the titanium-oxo based nanobuilding blocks allows to develop a LEGO-like chemistry, able to direct the assembling of a large variety of structurally well defined complex hybrid architectures.     

无机-有机多金属砷钒氧簇合物的合成及研究进展

多金属砷钒氧簇合物由于具有结构多样性、优良的物理特性以及广泛的应用前景而引起人们的关注。该类簇合物的合成战略是将有机配体和过渡金属配合物连接到砷钒氧骨架上以获得各种新奇结构。按此策略人们合成出一系列新奇的无机有机砷钒氧簇合物。本文综述了多金属砷钒氧簇合物的合成方法、结构性质等方面的研究进展,并对其今后研究前景进行了展望。     

Organo-Metallic Compounds of Aluminum and Iron as Components of Hybrid Inorganic-Organic Materials

Inorganic-organic hybrid materials were prepared in one-step process by mixing Al(OBu^s)₂(Etac) or Fe(acac)₃ and 2-hydroxyethyl methacrylate (HEMA) with benzoyl peroxide (BPO) as polymerization initiator. Molar ratio HEMA/metal compound between 3 and 4 was used. The mixtures stiffened after mild thermal treatment at 80°C, producing monoliths. The material obtained from Al(OBu^s)₂(Etac) is transparent and homogeneous, whereas that derived from Fe(acac)₃ is opaque and dark red. Differential Scanning Calorimetric (DSC) and Thermo-Gravimetric and Mass Spectroscopic (TG-MS) analyses were performed in order to establish the nature and the extent of the chemical interaction between the organic and the inorganic components. With respect pure p-HEMA, the hybrids show modified and additional properties due to the presence of inorganic domains. These are generated in situ by hydrolysis and polycondensation when the aluminum precursor is used, whereas iron hybrid materials are mainly constituted of domains of Fe(acac)₃, coordinated to poly-HEMA. The inorganic component of both the hybrid materials is supposed to be responsible for the weight changes recorded after the immersion in distilled water. Elastic modulus and strength of monoliths have been evaluated by four points bending test, whereas Dynamical Mechanical Thermal Analysis (DMTA) provided information on their behavior under heating. The aluminum-based hybrid is a brittle cross-linked material, even after a long time in water. On the other hand, the iron-based materials show a thermoplastic behavior and an interesting capacity of being shaped after heating or swelling in water.     

Magnesium-Based Clusters as Building Blocks of Electrolytes in Lithium-Ion Batteries

Superhalogens, owing to their large electron affinity (EA, exceeding those of any halogen atom), play an essential role in physical chemistry as well as new material design. They have applications in hydrogen storage and lithium-ion batteries. Owing to the unique geometries and electronic features of magnesium-based clusters, their potential to form a new class of lithium salts has been investigated here theoretically. The idea is assessed by conducting ab initio computations on Li⁺/Mg_nF_2n+1-2mO_m⁻ compounds (n=2, 3; m=0-3) and analyzing their performance as potential Li-ion battery electrolytes. The Mg₃F₇⁻ cluster, with large electron binding energy (EA of 7.93 eV), has been proven to serve as a building block for lithium salts. It is shown that, apart from high electronic stability, the new superhalogen-based electrolytes exhibit a set of desirable properties, including a large band gap, high electrolyte stability window, easy mobility of the Li⁺, and favorable insensitivity to water.     

Metal Oxoclusters as Molecular Building Blocks for the Development of Nanostructured Inorganic–Organic Hybrid Thin Films

Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf₄O₂(OMc)₁₂, OMc=OC(O)–C(CH₃)=CH₂) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH₂=C(CH₃)C(O)O)(CH₂)₃Si(OCH₃)₃). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate interfaces. Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C.     

Metal Oxoclusters as Molecular Building Blocks for the Development of Nanostructured Inorganic–Organic Hybrid Thin Films

Summary. Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf₄O₂(OMc)₁₂, OMc=OC(O)–C(CH₃)=CH₂) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH₂=C(CH₃)C(O)O)(CH₂)₃Si(OCH₃)₃). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate interfaces. Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C.     

超级电容器用镍锰基二元金属氧化物电极材料

赝电容电容器相比于双电层电容器拥有更高的比容量(大约10~100倍),由于在充电/放电过程中法拉第反应同时在电极材料表面和内部发生。因此,会产生更多电子,拥有更大的比容量。目前,赝电容电极材料的研究主要集中在金属氧化物和导电聚合物。镍锰基金属氧化物具有较高的理论比容量、成本低、无毒、环境友好等优点,但是其实际的电化学性能远低于理论值。因此,为了提升材料的电化学表现,研究者提出许多有效的策略,例如:制备不同种类金属氧化物作为电极材料;采用不同的工艺制备高比表面积的材料以及不同材料之间的复合产生协同作用等。本文综述了镍锰基二元金属氧化物(NiMnO₃、NiMn₂O₄和Ni₆MnO₈)作为赝电容电极材料在超级电容器上的应用进展,同时结合目前研究方法进一步提出未来金属氧化物电极材料方面的发展方向,为继续深入研究提供一定的指导作用。     

Polyoxometalates as Inorganic Building Blocks of Multifunctional Molecular Materials

The use of polyoxometalates (pOM's) as inorganic component in the synthesis of new molecular hybrid materials is presented. Here we show that the combination of organic molecules of the tetrathiafulvalene (TTF) type or perylene (per) with POM's yields new radical salts with unprecedented structures that present interesting magnetic and/or electrical properties or coexistence of both. The first true metallic radical salt containing a POM has been prepared and characterized. We also describe the recent results obtained by combining magnetic POM's with the organometallic cation decamethylferrocene.     

Thermal Stability of SiO2-Based Inorganic-Organic Hybrid Materials

The hydrolysis-polycondensation of organically modified Si-alkoxides leads to the obtaining of inorganic-organic hybrid materials in which the organic moieties remain as permanent groups bonded to the inorganic network. The molecular species previously determinated by GC-MS during the gelation process have been significantly different according to the type of the alkoxide used. In the present work, thermal stability of SiO₂-based inorganic-organic hybrid materials starting with TEOS (tetraethoxysilan), MTEOS (triethoxymethylsilan), VTEOS (triethoxyvinylsilan) and MTMOS (trimethoxymethylsilan) was studied. The molecular structure of the gels obtained determines differences in their thermal behaviour. Gels obtained starting with MTEOS show the highest thermal stability, while gels obtained using VTEOS the lowest, among the substituted alkoxides. A particular behaviour presents the gel obtained with MTMOS that decomposes in four steps. This could be explained by the presence in the gel of some prevalent types of molecular species with different thermal stability. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modification of Thermo-Optic Characteristics of Sol-Gel Inorganic-Organic Hybrid Materials

The effect of the inorganic oxide network on the variation of thermo-optic characteristics (dn/dT) in inorganic-organic hybrid material prepared through the sol-gel process was investigated. The dn/dT values were negative for all samples, and decreased in magnitude with the increasing concentration of the inorganic oxide or heterometallic oxide network. The dn/dT also became less negative with the increase in the degree of inorganic condensation in sol-gel reaction. A negative dn/dT value is consistent with thermal expansion of the material, and it is believed that the value of the dn/dT in our inorganic-organic hybrid materials was principally sensitive to variations in expansion term.     

Silica-Based and Transition Metal-Based Inorganic-Organic Hybrid Materials—A Comparison

Organically substituted metal alkoxides can be prepared by reaction of the parent alkoxides with complexing organic compounds. The chemical and structural consequences of such substitutions are discussed in this article. Examples are given showing how functional organic moieties, such as polymerizable groups, can be incorporated into sol-gel materials via the complexing ligands. Major structural differences between silica-based and metal-based hybrid materials originate from the different charge/coordination number ratios of silicon and most metals. This results in a high tendency for the molecular building blocks to aggregate. In many cases, metal oxide clusters are formed which are capped by the organic ligands. Such surface-modified clusters are themselves very valuable condensed matter units for materials syntheses.