Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

J. Appl. Cryst.の発刊に際して

The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.

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Reticular synthesis and the design of new materials

The design and synthesis of new molecular compounds whose physical properties can be controlled by external stimuli have recently attracted much attention. Until now, various switchable compounds have been developed. An important challenge in this field is controlling the magnetic properties of molecular nanomagnets, that is, single-molecule magnets (SMMs) and single-chain magnets (SCMs). Molecular nanomagnets that exhibit slow magnetic relaxation can retain spin information over long time periods at a nanometer scale, and thus have potential applications in highdensity information storage, quantum computation, and spintronics. Although several examples of switchable nanomagnets have been reported, the number thereof, especially that of SCMs, is very limited. Guest-tuned SCMs with microporous metal–organic frameworks are an important development, and pressure control of nanomagnets has been reported. However, photocontrol of the magnetic properties of SCMs has not yet been disclosed. To observe light-induced SCM behavior, the developed compounds should have both SCM and photoswitching properties. Because simultaneously fulfilling these requirements is difficult, light-induced SCMs have not yet been successfully fabricated. In this study on developing a phototunable SCM, we designed an Fe2Co bimetallic one-dimensional system with an N6 coordination environment around Co ions with the expectation of charge-transfer-induced spin transition between the Fe and Co sites. Furthermore, to prevent through-bond magnetic interactions between chains, we used bulky [Fe(pzTp)(CN)3] (pzTp = tetrakis(pyrazolyl)borate) building blocks to increase the metal–metal distances between neighboring chains and adopted the monodentate 4-styrylpyridine ligand. Note that it has recently been revealed that some of the reported SCMs, including ours, which show slow magnetic relaxation are not actual SCMs but are their antiferromagnetic phases. Hence, we have carefully designed a one-dimensional (1D) system, in which 1D chains are sufficiently separated by bulky ligands. With the above strategy, we synthesized novel switchable complex {[Fe(pzTp)(CN)3]2Co(4-styrylpyridine)2}·2H2O·2CH3OH (1), which is composed of well-isolated {Fe2Co} chains. Complex 1 exhibits thermally induced charge transfer, wherein all Co ions and half of the Fe ions are involved in the metal-tometal charge-transfer (MMCT) process. At low temperatures, Fe and Fe are regularly arranged, in contrast to the typical randomly arranged examples. Furthermore, when 1 was irradiated, it showed SCM behavior with no antiferromagnetic ordering. This means that 1 is the first example of a photoswitchable SCM. The target compound was synthesized by a diffusion method in a test tube. A solution of Bu4N[Fe(pzTp)(CN)3] and 4-styrylpyridine in methanol was slowly layered over an aqueous solution of Co(ClO4)2·6H2O. [13] Crystallization required several weeks. Single-crystal X-ray diffraction analysis revealed that 1 crystallizes in space group P1̄. The crystal structure comprises neutral bimetallic double-zigzag [Fe(pzTp)(CN)3]2Co(4-styrylpyridine)2 chains with uncoordinated water and methanol molecules located between them (Figure 1). In the neutral chain, the [Fe(pzTp)(CN)3] unit bridges two Co ions through two of its three cyanide ligands in the cis position, and each Co ion is coordinated to four nitrogen atoms from the CN bridges. Dihedral angles of 38.78 are formed between the planes of the triangular Fe2Co units owing to the steric effect of the bulky [Fe(pzTp)(CN)3] building blocks. In contrast, in other reported Fe2Co complexes, four metal ions of the Fe2Co2 units are nearly aligned in a plane and the mean planes of the square units are parallel to each other. The crystal structure contains two unique iron and cobalt centers. Each iron center is located in an octahedral environment with three nitrogen atoms from the pzTp units and three cyanide carbon atoms. The equatorial plane of the cobalt center is occupied by four cyanide nitrogen atoms, and two nitrogen atoms from 4-styrylpyridine occupy its apical positions, providing an N6 coordination sphere. At 260 K, the Co Nequatorial bond lengths are 2.092–2.115 and 2.087– 2.112 , and the Co Napical distances are 2.150 and 2.162 for Co1 and Co2, respectively. The elongated N6 octahedral environment of cobalt suggests a negative anisotropy constant D, which is essential for SCM behavior. However, the apical axis of the neighboring Co ion shows an angle of 47.08, which is expected to counteract part of the Co ion [*] Dr. D.-P. Dong, Prof. T. Liu, Prof. C. He, Prof. C.-Y. Duan State Key Laboratory of Fine Chemicals Dalian University of Technology 2 Linggong Rd., 116024 Dalian (China) E-mail: liutao@dlut.edu.cn cyduan@dlut.edu.cn

Photoswitchable Dynamic Magnetic Relaxation in a Well-Isolated {Fe2Co} Double-Zigzag Chain

The electronic structure of a cobalt iron cyanide thin film, Na0.4Co1.3[Fe(CN)6]5H2O, was switched from FeIII(low spin)−CN−CoII(high spin) to FeII(low spin)−CN−CoIII(low spin) by exchanging cations in interstitial sites from Na+ to K+. The reverse process was also induced by replacing Na+ with K+. That is, the alkali cations in the interstitial sites dominate the electronic and spin states of the host compound. This type of switching phenomenon can be achieved by choosing a compound with both electronic degeneracy and zeolitic properties.

Cation-driven electron transfer involving a spin transition at room temperature in a cobalt iron cyanide thin film

Slow interfacial charge recombination in solid-state dye-sensitized solar cell using Al2O3-coated nanoporous TiO2 films

Background Infiltration by perforin-secreting killer lymphocytes, such as T cells and natural killer cells, has been shown to be involved in the pathogenesis of vascular cell damage in Takayasu’s arteritis.

Methods and Results To investigate the immunological mechanisms involved, especially the nature of T-cell infiltration in Takayasu’s arteritis as well as atherosclerosis, we analyzed the expression of T-cell receptor (TCR) Vα and Vβ genes in infiltrating cells in the aortic tissue of patients with Takayasu’s arteritis and atherosclerotic aortic aneurysm by polymerase chain reaction (PCR). We also analyzed the expression of cytokine genes by PCR. We found that the repertoires of TCR Vα as well as Vβ gene transcripts in Takayasu’s arteritis were restricted. The infiltrating cells expressing Vα2, Vα16, Vα17, Vβ7, and Vβ13.1 were found in 3 of 4 patients. In contrast, TCR Vα-Vβ repertoires in atherosclerotic aortic aneurysm were polyclonal. There was no significant difference in the pattern of cytokine gene expression between the two diseases.

Conclusions The restricted usage of TCR Vα as well as Vβ genes by infiltrating T cells in Takayasu’s arteritis may indicate that a specific antigen in the aortic tissue was targeted. Our findings provide the evidence that distinct immunological mechanisms are involved in the pathogenesis of Takayasu’s arteritis and atherosclerotic aortic aneurysm.

Osamu Sato

Papers

Photoswitchable Dynamic Magnetic Relaxation in a Well-Isolated {Fe2Co} Double-Zigzag Chain

Cation-driven electron transfer involving a spin transition at room temperature in a cobalt iron cyanide thin film

Slow interfacial charge recombination in solid-state dye-sensitized solar cell using Al2O3-coated nanoporous TiO2 films

Restricted Usage of T-Cell Receptor Vα-Vβ Genes in Infiltrating Cells in Aortic Tissue of Patients With Takayasu’s Arteritis

Three-Dimensionally Ordered Macroporous Polymer Materials: An Approach for Biosensor Applications