There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Polyoxometalates (POMs) are a subset of metal oxides that represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form dynamic structures that can range in size from the nano- to the micrometer scale Herein we present the very latest developments from synthesis to structure and function of POMs We discuss the possibilities of creating highly sophisticated functional hierarchical systems with multiple, interdependent, functionalities along with a critical analysis that allows the non-specialist to learn the salient features We propose and present a "periodic table of polyoxometalate building blocks" We also highlight some of the current issues and challenges that need to be addressed to work towards the design of functional systems based upon POM building blocks and look ahead to possible emerging application areas

Polyoxometalates: Building Blocks for Functional Nanoscale Systems

Recent Advances in Polyoxometalate-Catalyzed Reactions

Polyoxometalate (POM)-based metal–organic framework (MOF) materials contain POM units and generally generate MOF materials with open networks. POM-based MOF materials, which utilize the advantages of both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades. They have good prospects in catalysis owing to the electronic and physical properties of POMs that are tunable by varying constituent elements. In this review, we present recent developments in porous POM-based MOF materials, including their classification, synthesis strategies, and applications, especially in the field of catalysis.

Recent advances in porous polyoxometalate-based metal-organic framework materials.

The development of visible-light-induced photocatalysts for chemoselective functional group transformations has received considerable attention. Polyoxometalates (POMs) are potential materials for efficient photocatalysts because their properties can be precisely tuned by changing their constituent elements and structures and by the introduction of additional metal cations. Furthermore, they are thermally and oxidatively more stable than the frequently utilized organometallic complexes. The visible-light-responsive tetranuclear cerium(III)-containing silicotungstate TBA6[{Ce(H2O)}2{Ce(CH3CN)}2(μ4-O)(γ-SiW10O36)2] (CePOM; TBA=tetra-n-butylammonium) has now been synthesized; when CePOM was irradiated with visible light (λ>400 nm), a unique intramolecular CeIII-to-POM(WVI) charge transfer was observed. With CePOM, the photocatalytic oxidative dehydrogenation of primary and secondary amines as well as the α-cyanation of tertiary amines smoothly proceeded in the presence of O2 (1 atm) as the sole oxidant.

Visible‐Light‐Induced Photoredox Catalysis with a Tetracerium‐Containing Silicotungstate

The di- and tetranuclear metal sandwich-type silicotungstates of Cs10[(γ-SiW10O36)2{Zr(H2O)}2(μ-OH)2]·18H2O (Zr2, monoclinic, C2/c (No. 15), a = 25.3315(8) A, b = 22.6699(7) A, c = 18.5533(6) A, β = 123.9000(12)°, V = 8843.3(5) A3, Z = 4), Cs10[(γ-SiW10O36)2{Hf(H2O)}2(μ-OH)2]·17H2O (Hf2, monoclinic, space group C2/c (No. 15), a = 25.3847(16) A, b = 22.6121(14) A, c = 18.8703(11) A, β = 124.046(3)°, V = 8974.9(9) A3, Z = 4), Cs8[(γ-SiW10O36)2{Zr(H2O)}4(μ4-O)(μ-OH)6]·26H2O (Zr4, tetragonal, P41212 (No. 92), a = 12.67370(10) A, c = 61.6213(8) A, V = 9897.78(17) A3, Z = 4), and Cs8[(γ-SiW10O36)2{Hf(H2O)}4(μ4-O)(μ-OH)6]·23H2O (Hf4, tetragonal, P41212 (No. 92), a = 12.68130(10) A, c = 61.5483(9) A, V = 9897.91(18) A3, Z = 4) were obtained as single crystals suitable for X-ray crystallographic analyses by the reaction of a dilacunary γ-Keggin silicotungstate K8[γ-SiW10O36] with ZrOCl2·8H2O or HfOCl2·8H2O. These dimeric polyoxometalates consisted of two [γ-SiW10O36]8− units sandwiching metal–oxygen clusters such ...

Synthesis and catalysis of di- and tetranuclear metal sandwich-type silicotungstates [(gamma-SiW10O36)2M2(mu-OH)2]10- and [(gamma-SiW10O36)2M4(mu4-O)(mu-OH)6]8- (M = Zr or Hf).

The synthesis of AGC is developed and the material is successfully tested as heterogeneous catalyst for the title reaction.

Diamond-Shaped [Ag4]4+ Cluster Encapsulated by Silicotungstate Ligands: Synthesis and Catalysis of Hydrolytic Oxidation of Silanes†

Cyanohydrins are a very important class of compounds in chemistry as well as biology, and have been widely utilized as important synthetic intermediates for organic compounds, such as a-hydroxy acids, a-hydroxy aldehydes, and b-amino alcohols. For the synthesis of cyanohydrins, various cyanating reagents have been employed, and trimethylsilyl cyanide (TMSCN) is one of the most useful and safe cyanating reagents for nucleophilic addition to carbonyl compounds to give cyanohydrin trimethylsilyl ether. Hence, the development of efficient catalysts for cyanosilylation of carbonyl compounds with TMSCN is a very important subject in current research, and several efficient catalysts have been developed so far. Lewis acid catalysts can act as electrophilic catalysts to activate carbonyl compounds and have been extensively investigated for cyanosilylation (see Table S1 in the Supporting Information). 3] Several nucleophilic catalysts, such as amines, phosphines, phosphazanes, and alkalineearth metal oxides, can activate TMSCN and promote cyanosilylation (Table S1). 3] Asymmetric cyanosilylations have also been successfully developed by employing customly designed chiral ligands. Polyoxometalates (POMs) are a large family of anionic metal–oxygen clusters that consist of Group V and VI metals in their highest oxidation states, and are thermally and oxidatively stable in comparison with commonly utilized organometallic catalysts and organocatalysts. The chemical properties of POMs, for example, redox potentials, (multi)electron-transfer properties, acidities, and solubilities, and negative charges, can be finely tuned by choosing the constituent anion and countercations, and diverse structures can be synthesized. In addition to the above-mentioned properties, the important feature of POMs is the presence of bare nucleophilic surfaces as a result of external oxygen atoms (M O M and M=O species, M = W or Mo), which might act as nucleophilic sites as well as stabilizers of cationic intermediates. 6] In particular, it is expected that POMs with large negative charges can nucleophilically activate TMSCN, thus resulting in promotion of cyanosilylations, as observed for Lewis base catalyzed cyanosilylations. 3h] Initially, the cyanosilylation of 2-adamantanone (1a) with TMSCN was carried out with the 8-charged POM TBA4H4[g-SiW10O36] (SiW10, TBA = tetra-n-butylammonium) in 1,2-dichloroethane at 30 8C. SiW10 promoted the cyanosilylation, giving the corresponding cyanohydrin trimethylsilyl ether 2a in 15% yield after 20 minutes (Scheme 1). In the case of TBA4H4[a-SiW11O39] (SiW11), 2a was also obtained in 16% yield (Table S2). In the absence of the catalysts, cyanosilylation was not observed under the present conditions.

Cyanosilylation of Carbonyl Compounds with Trimethylsilyl Cyanide Catalyzed by an Yttrium‐Pillared Silicotungstate Dimer

Reaction of a polyoxymetalate with Zn(acac)2 provides access towards a novel γ-Keggin zinc-containing sandwich-type polyoxymetalate.

Yuji Kikukawa

Papers

Visible‐Light‐Induced Photoredox Catalysis with a Tetracerium‐Containing Silicotungstate

Synthesis and catalysis of di- and tetranuclear metal sandwich-type silicotungstates [(gamma-SiW10O36)2M2(mu-OH)2]10- and [(gamma-SiW10O36)2M4(mu4-O)(mu-OH)6]8- (M = Zr or Hf).

Diamond-Shaped [Ag4]4+ Cluster Encapsulated by Silicotungstate Ligands: Synthesis and Catalysis of Hydrolytic Oxidation of Silanes†

Cyanosilylation of Carbonyl Compounds with Trimethylsilyl Cyanide Catalyzed by an Yttrium‐Pillared Silicotungstate Dimer

Zinc(II) Containing γ‐Keggin Sandwich‐Type Silicotungstate: Synthesis in Organic Media and Oxidation Catalysis