有机无机复合温差电材料的无机掺杂剂

有机导电高分子因其低的热导率在温差电方面受到广泛的关注,但低电导率限制了其发展.掺杂无机半导体或CNT等纳米材料可有效改善有机导电高分子的热电性能.以PEDOT/PSS有机高分子为代表介绍有机无机复合温差电材料的无机掺杂剂的最新进展,并展望有机无机复合温差电材料未来的发展与应用.     

Origin of ferromagnetic exchange interactions in a fullerene-organic compound

Organic ferromagnets, which exhibit exchange interactions between unpaired electrons in pi-orbitals, are rare, and the origin of ferromagnetism in these compounds has so far remained unexplained. Tetrakis(dimethylamino)ethylene-fullerene[60] (TDAE-C60) shows a transition to a ferromagnetic state with fully saturated s = 1/2 molecular spins at the relatively high Curie temperature (for organic materials) of 16 K (ref. 4). It has been suggested that the orientations of the C60 molecules may be important for ferromagnetism in this material, but in the absence of structural data at low temperatures there has been little progress towards understanding these microscopic interactions. Here we report the results of a comparative structural study of two different magnetic forms of TDAE-C60 crystals at low temperatures, correlating the structural properties--in particular, the intermolecular orientations--with the magnetic properties. We find that both ferromagnetism and spin-glass-like ordering are possible in this material, and depend on the orientational state of C60 molecules. This resolves the apparent contradictions posed by different macroscopic measurements, and opens the way to a microscopic understanding of pi-electron ferromagnetic exchange interactions in organic materials.     

A general strategy for nanocrystal synthesis

New strategies for materials fabrication are of fundamental importance in the advancement of science and technology. Organometallic and other organic solution phase synthetic routes have enabled the synthesis of functional inorganic quantum dots or nanocrystals. These nanomaterials form the building blocks for new bottom-up approaches to materials assembly for a range of uses; such materials also receive attention because of their intrinsic size-dependent properties and resulting applications. Here we report a unified approach to the synthesis of a large variety of nanocrystals with different chemistries and properties and with low dispersity; these include noble metal, magnetic/dielectric, semiconducting, rare-earth fluorescent, biomedical, organic optoelectronic semiconducting and conducting polymer nanoparticles. This strategy is based on a general phase transfer and separation mechanism occurring at the interfaces of the liquid, solid and solution phases present during the synthesis. We believe our methodology provides a simple and convenient route to a variety of building blocks for assembling materials with novel structure and function in nanotechnology.     

有机分子磁体的研究进展

在大量文献的基础上对有机分子磁体进行分类，从有机分子铁磁体、有机金属分子铁磁体和无机分子铁磁体三个方面介绍了有机分子磁体的最新研究进展。     

Magnetic and non-magnetic phases of a quantum spin liquid

A quantum spin-liquid phase is an intriguing possibility for a system of strongly interacting magnetic units in which the usual magnetically ordered ground state is avoided owing to strong quantum fluctuations. It was first predicted theoretically for a triangular-lattice model with antiferromagnetically coupled S = 1/2 spins. Recently, materials have become available showing persuasive experimental evidence for such a state. Although many studies show that the ideal triangular lattice of S = 1/2 Heisenberg spins actually orders magnetically into a three-sublattice, non-collinear 120° arrangement, quantum fluctuations significantly reduce the size of the ordered moment. This residual ordering can be completely suppressed when higher-order ring-exchange magnetic interactions are significant, as found in nearly metallic Mott insulators. The layered molecular system κ-(BEDT-TTF)(2)Cu(2)(CN)(3) is a Mott insulator with an almost isotropic, triangular magnetic lattice of spin-1/2 BEDT-TTF dimers that provides a prime example of a spin liquid formed in this way. Despite a high-temperature exchange coupling, J, of 250 K (ref. 6), no obvious signature of conventional magnetic ordering is seen down to 20 mK (refs 7, 8). Here we show, using muon spin rotation, that applying a small magnetic field to this system produces a quantum phase transition between the spin-liquid phase and an antiferromagnetic phase with a strongly suppressed moment. This can be described as Bose-Einstein condensation of spin excitations with an extremely small spin gap. At higher fields, a second transition is found that suggests a threshold for deconfinement of the spin excitations. Our studies reveal the low-temperature magnetic phase diagram and enable us to measure characteristic critical properties. We compare our results closely with current theoretical models, and this gives some further insight into the nature of the spin-liquid phase.     

Synthetic design of crystalline inorganic chalcogenides exhibiting fast-ion conductivity

Natural porous solids such as zeolites are invariably formed with inorganic cations such as Na(+) and K(+) (refs 1, 2). However, current research on new porous materials is mainly focused on the use of organic species as either structure-directing or structure-building units; purely inorganic systems have received relatively little attention in exploratory synthetic work. Here we report the synthesis of a series of three-dimensional sulphides and selenides containing highly mobile alkali metal cations as charge-balancing extra-framework cations. Such crystalline inorganic chalcogenides integrate zeolite-like architecture with high anionic framework polarizability and high concentrations of mobile cations. Such structural features are particularly desirable for the development of fast-ion conductors. These materials demonstrate high ionic conductivity (up to 1.8 x 10(-2) ohm(-1) cm(-1)) at room temperature and moderate to high humidity. This synthetic methodology, together with novel structural, physical and chemical properties, may lead to the development of new microporous and open-framework materials with potential applications in areas such as batteries, fuel cells, electrochemical sensors and photocatalysis.     

Self-organization of supramolecular helical dendrimers into complex electronic materials

The discovery of electrically conducting organic crystals and polymers has widened the range of potential optoelectronic materials, provided these exhibit sufficiently high charge carrier mobilities and are easy to make and process. Organic single crystals have high charge carrier mobilities but are usually impractical, whereas polymers have good processability but low mobilities. Liquid crystals exhibit mobilities approaching those of single crystals and are suitable for applications, but demanding fabrication and processing methods limit their use. Here we show that the self-assembly of fluorinated tapered dendrons can drive the formation of supramolecular liquid crystals with promising optoelectronic properties from a wide range of organic materials. We find that attaching conducting organic donor or acceptor groups to the apex of the dendrons leads to supramolecular nanometre-scale columns that contain in their cores pi-stacks of donors, acceptors or donor-acceptor complexes exhibiting high charge carrier mobilities. When we use functionalized dendrons and amorphous polymers carrying compatible side groups, these co-assemble so that the polymer is incorporated in the centre of the columns through donor-acceptor interactions and exhibits enhanced charge carrier mobilities. We anticipate that this simple and versatile strategy for producing conductive pi-stacks of aromatic groups, surrounded by helical dendrons, will lead to a new class of supramolecular materials suitable for electronic and optoelectronic applications.     

Electric-field control of ferromagnetism

It is often assumed that it is not possible to alter the properties of magnetic materials once they have been prepared and put into use. For example, although magnetic materials are used in information technology to store trillions of bits (in the form of magnetization directions established by applying external magnetic fields), the properties of the magnetic medium itself remain unchanged on magnetization reversal. The ability to externally control the properties of magnetic materials would be highly desirable from fundamental and technological viewpoints, particularly in view of recent developments in magnetoelectronics and spintronics. In semiconductors, the conductivity can be varied by applying an electric field, but the electrical manipulation of magnetism has proved elusive. Here we demonstrate electric-field control of ferromagnetism in a thin-film semiconducting alloy, using an insulating-gate field-effect transistor structure. By applying electric fields, we are able to vary isothermally and reversibly the transition temperature of hole-induced ferromagnetism.     

Self-directed self-assembly of nanoparticle/copolymer mixtures

The organization of inorganic nanostructures within self-assembled organic or biological templates is receiving the attention of scientists interested in developing functional hybrid materials. Previous efforts have concentrated on using such scaffolds to spatially arrange nanoscopic elements as a strategy for tailoring the electrical, magnetic or photonic properties of the material. Recent theoretical arguments have suggested that synergistic interactions between self-organizing particles and a self-assembling matrix material can lead to hierarchically ordered structures. Here we show that mixtures of diblock copolymers and either cadmium selenide- or ferritin-based nanoparticles exhibit cooperative, coupled self-assembly on the nanoscale. In thin films, the copolymers assemble into cylindrical domains, which dictate the spatial distribution of the nanoparticles; segregation of the particles to the interfaces mediates interfacial interactions and orients the copolymer domains normal to the surface, even when one of the blocks is strongly attracted to the substrate. Organization of both the polymeric and particulate entities is thus achieved without the use of external fields, opening a simple and general route for fabrication of nanostructured materials with hierarchical order.     

刺激响应型的多金属氧簇-紫精基化合物的合成与应用

多金属氧簇-紫精基化合物是一类由紫精和多金属氧簇通过配位作用、阴阳离子的静电吸引以及氢键等相互作用构建的化合物.在此类化合物中多金属氧簇作为富电子的无机构筑块起到了提供电子的作用，将电子提供给紫精阳离子，从而赋予材料结构设计多变、良好的光热稳定性、多刺激响应等优点，实现了有机-无机杂化材料应用的升华.文中综述了近年来多金属氧簇-紫精基晶态化合物的合成、结构与性能、刺激响应中的电子转移途径，及其在智能传感、光催化领域的应用研究，最后总结了目前该领域发展的难点和不足，并提出未来的研究方向.      

Migration of Cations and Anions in Amorphous Polymer Electrolytes

1 Results Polymer electrolytes are used as ion conductors in batteries and fuel cells.Simple systems consist of a polymer matrix complexing an inorganic salt and are fully amorphous at the temperatures of interest.Both cations and anions are mobile and contribute to charge transport.Most studies on polymer electrolytes use the electrical conductivity to characterize the ion mobility.However,conductivity measurements cannot discriminate between cations and anions.This paper reports some recent results fr...     

Magnetic properties of heteropolyoxometalates

The progress of the study on the magnetic properties of heteropolyoxometalates during the late decade is reviewed. Some anions of heteropolyoxometalates containing magnetic atoms, such as [M4(H2O)4(PW9O34)2]10- and[M4(H2O)4(P2W15O56)2]16-[M = Co(Ⅱ), Zn( Ⅱ ), Cu( Ⅱ ), Mn(Ⅱ ), Ni(Ⅱ)], and [GaW9O37M3(H2O)3]n-[M = Fe(Ⅲ), Cu(Ⅱ), Co(Ⅱ)] showed ferromagnetic and antiferromagnetic properties. The combination of heteropoly anions and organic π-donor of TTF+ (te-trathiofulvalene cation) results in a variety of magnetic properties. Furthermore, there is an interaction between the inorganic and organic components. The electrocrystallization technique can prepare the organic-inorganic salts of this kind, which will become the new member of molecular magnetic materials. Heteropoly blue is a kind of the mixed-valence complexes and its reduction electrons can be delocalized over anionic framework. The further study on the magnetic properties of heteropolyoxometalates will provide important information for the design of molecular materials.     

Modular and predictable assembly of porous organic molecular crystals

Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitation for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules.     

Effect of TiO_2 Addition to the Microwave Absortion Property of Polyaniline Micro/Nanocomposites

1 Results Recently,conducting polymers as molecular wires have attracted considerable attention because of their long conjugated length,metal conductivity and promising potential application in nanodevices.It is important to manipulate the synthesis parameters or additives used in order to produce conducting polymer showing moderate conductivity,magnetic and dielectric properties that could enhance its microwave absorbing and shielding properties.As nano-material possessing moderate conductivity,dielect...     

导电聚合物聚苯胺的研究进展

聚苯胺是一种典型的导电聚合物,因其具有多样化的结构,较高的电导率,独特的掺杂机制,优异的物理性能,良好的环境稳定性,且原料廉价易得,合成方法简便等优点,而成为最具有应用前景的导电高分子材料之一.较全面地介绍了聚苯胺(PAn)的合成方法、性质及其应用.     

NMR Studies on Diffusion and Molecular Motions of Imidazolium Ionic Liquids doped by Lithium Salts Related to Ionic Conductivity and Computational Interaction Energy

1 Results Room-temperature Ionic liquids (RTILs) are special class of compounds, where a combination of cations and anions produces neutral, stable and viscous liquids with high ionic conductivity. Widely spread applications are proposed to use conductors, electrolytes, clean solvents and others. Especially, RTILs are expected to be safe electrolytes in the ion-lithium batteries. In this study, NMR methods are used to clarify the basic properties of the individual movements of the anions and cations of ...     

Single crystals of an ionic anthracene aggregate with a triplet ground state

Crystalline supramolecular aggregates consisting of charged organic molecules, held together through metal-cluster-mediated Coulomb interactions, have attracted interest owing to their unusual structural, chemical and electronic properties. Aggregates containing metal cation clusters 'wrapped' by lipophilic molecular anions have, for example, been shown to be kinetically stable and soluble in nonpolar liquids such as saturated hydrocarbons. The formation of supramolecular aggregates can even be exploited to generate aromatic hydrocarbons that carry four negative charges and crystallize in the form of organic poly(metal cation) clusters or helical polymers. Here we report the anaerobic crystallization of an ionic organic aggregate--a contact ion septuple consisting of a fourfold negatively charged 'tripledecker' of three anthracene molecules bridged by four solvated potassium cations. Its electronic ground state is shown experimentally, using temperature-dependent electron paramagnetic resonance spectroscopy, to be a triplet. Although the spins in this biradical ionic solid are separated by a considerable distance, density functional theory calculations indicate that the triplet ground state is 84 kJ mol(-1) more stable than the first excited singlet state. We expect that the successful crystallization of the ionic solid we report here, and that of a covalent organic compound with a triplet ground state at room temperature, will stimulate further attempts to develop new triplet-ground-state materials for practical use.     

Progress in the research of radical anion ligands and their complexes

Recent progress in the research of radical anion ligands and their complexes with metals were summarized in this review. Radical anions were sorted into several types including iminosemiquinonate and iminoquinonate radical, nitroxide radical, heterocycle radical etc. Structural characteristics and properties of the corresponding complexes were introduced. The complexes exhibited novel properties and possibility for applications in organic magnetic materials and transition metal catalysis.     

Co掺杂CaO材料的铁磁性研究

利用固态反应法制备了具有铁磁性的Co掺杂CaO纳米粉末材料,并对材料的结构和磁学性质进行了研究.X射线衍射和高分辨率透射电镜测试结果表明,材料为单相的CaO立方结构,Co掺杂导致了晶格常数的减小,表明Co离子通过替位Ca离子融入了CaO晶格.磁性分析表明,该Co掺杂CaO纳米粉末表现出了明显的铁磁特性,临界温度高于70K.通过分析认为,材料的铁磁性是由浅施主缺陷O空位与Co离子耦合形成束缚磁极化子引起的.     

High-temperature metal-organic magnets

For over two decades there have been intense efforts aimed at the development of alternatives to conventional magnets, particularly materials comprised in part or wholly of molecular components. Such alternatives offer the prospect of realizing magnets fabricated through controlled, low-temperature, solution-based chemistry, as opposed to high-temperature metallurgical routes, and also the possibility of tuning magnetic properties through synthesis. However, examples of magnetically ordered molecular materials at or near room temperature are extremely rare, and the properties of these materials are often capricious and difficult to reproduce. Here we present a versatile solution-based route to a new class of metal-organic materials exhibiting magnetic order well above room temperature. Reactions of the metal (M) precursor complex bis(1,5-cyclooctadiene)nickel with three different organics A-TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)--proceed via electron transfer from nickel to A and lead to materials containing Ni(II) ions and reduced forms of A in a 2:1 Ni:A ratio--that is, opposite to that of conventional (low Curie temperature) MA(2)-type magnets. These materials also contain oxygen-based species within their architectures. Magnetic characterization of the three compounds reveals spontaneous field-dependent magnetization and hysteresis at room temperature, with ordering temperatures well above ambient. The unusual stoichiometry and striking magnetic properties highlight these three compounds as members of a class of stable magnets that are at the interface between conventional inorganic magnets and genuine molecule-based magnets.