Polyoxometalates (POMs) are discrete anionic metaloxygen clusters which can be regarded as soluble oxide fragments. They exhibit a great diversity of sizes, nuclearities, and shapes. They are built from the connection of {MOx} polyhedra, M being a d-block element in high oxidation state, usually VIV,V, MoVI, or WVI.1 While these species have been known for almost two centuries, they still attract much interest partly based on their large domains of applications. They play a great role in various areas ranging from catalysis,2 medicine,3 electrochemistry,4 photochromism,5 to magnetism.6 This palette of applications is intrinsically due to the combination of their added value properties (redox properties, large sizes, high negative charges, nucleophilicity...). Parallel to this domain, the organic-inorganic hybrids area has followed a similar expansion during the last 10 years. The concept of organic-inorganic hybrid materials * To whom correspondence should be addressed. E-mail: dolbecq@ chimie.uvsq.fr. Chem. Rev. 2010, 110, 6009–6048 6009

Hybrid Organic−Inorganic Polyoxometalate Compounds: From Structural Diversity to Applications

Recent Developments in the Preparation and Chemistry of Metallacycles and Metallacages via Coordination

Efficient removal of organic pollutants from wastewater has become a hot research topic due to its ecological and environmental importance. Traditional water treatment methods such as adsorption, coagulation, and membrane separation suffer from high operating costs, and even generate secondary pollutants. Photocatalysis on semiconductor catalysts (TiO2, ZnO, Fe2O3, CdS, GaP, and ZnS) has demonstrated efficiency in degrading a wide range of organic pollutants into biodegradable or less toxic organic compounds, as well as inorganic CO2, H2O, NO3−, PO43−, and halide ions. However, the difficult post-separation, easy agglomeration, and low solar energy conversion efficiency of these inorganic catalysts limit their large scale applications. Exploitation of new catalysts has been attracting great attention in the related research communities. In the past two decades, a class of newly-developed inorganic–organic hybrid porous materials, namely metal–organic frameworks (MOFs) has generated rapid development due to their versatile applications such as in catalysis and separation. Recent research has showed that these materials, acting as catalysts, are quite effective in the photocatalytic degradation of organic pollutants. This review highlights research progress in the application of MOFs in this area. The reported examples are collected and analyzed; and the reaction mechanism, the influence of various factors on the catalytic performance, the involved challenges, and the prospect are discussed and estimated. It is clear that MOFs have a bright future in photocatalysis for pollutant degradation.

Photocatalytic organic pollutants degradation in metal–organic frameworks

2.4.2. Interpenetrated Ladders 711 2.4.3. Unusual Motifs of Ladders 713 2.4.4. Properties of Ladderlike Chains 713 2.5. Rotaxane Polymers 714 2.5.1. 1D Polyrotaxanes 714 2.5.2. 2D Polyrotaxanes 715 2.5.3. 3D Polyrotaxanes 716 2.5.4. Hydrogen-Bonded Polyrotaxanes 716 2.6. Ribbon/Tape Polymers 717 2.7. Metal Cluster As Building Blocks for 1D CP 718 2.7.1. Metal Carboxylate Clusters 718 2.7.2. Metal Halide Clusters 719 2.7.3. Metal Chalcogenide Clusters 720 2.7.4. Polyoxometalate Clusters 721 2.7.5. Single Molecular Magnets as Building Blocks 722

One-Dimensional Coordination Polymers: Complexity and Diversity in Structures, Properties, and Applications

Functionalization of polyoxometalates: towards advanced applications in catalysis and materials science

Fourteen lanthanide (Ln)-containing hetero selenato-phosphato-peroxopolyoxoniobates in three series: (1) Cs2{[Ln(H2O)4][H4P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Ce (I-Ce), Pr (I-Pr), Sm (I-Sm), Eu (I-Eu), Gd (I-Gd); I-Ce, I-Pr, I-Eu, I-Gd n = 12; I-Sm n = 16]; (2) Cs2K3{[Ln(H2O)6][H2.5P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Dy (II-Dy), Tm (II-Tm), Yb (II-Yb), Lu (II-Lu); II-Dy n = 14; II-Tm n = 24; II-Yb, II-Lu n = 13]; (3) Cs5K2Hm{[Ln(H2O)6][P2Se2Nb6(O2)6O22]}2{[Lnx(H2O)y]2[P2Se2Nb6(O2)6O22]}·nH2O [Ln = Ho (III-Ho), Er (III-Er), Tm (III-Tm), Yb (III-Yb), Lu (III-Lu), III-Ho-III-Yb m = 5, x = 1; y = 5; III-Lu m = 6.5; x = 0.75; y = 4; III-Ho-III-Tm n = 19, III-Yb n = 34; III-Lu n = 31], have been isolated by a one-pot reaction and structurally characterized by various physical and chemical analyses. These compounds represent the first group of Ln-functionalized polyoxoniobates with mixed heteroatoms. In addition, the photoluminescence properties of compounds I-Sm, I-Eu, and II-Dy were measured, and the time-resolved emission spectra showed that the {P2Se2Nb6} segment contributed to the energy transfer from the polyoxoniobate units to the Ln3+ center, which effectively promoted the emission of the Ln3+ center.

Three Types of Lanthanide-Containing Polyoxoniobates and Their Luminescence Properties.

A high-nuclearity nickel-substituted polyoxotungstate, Na6K5.5H4.5 {[Ni8(OH)6(H2O)2](CO3)3(SiW9O34)2}·22H2O (1), has been obtained by the reaction of Na10[α-SiW9O34]·18H2O, Ni(NO3)2·6H2O and K2CO3 ...

Synthesis and characterization of an octanuclear nickel(II) polyoxometalate cluster

A dl-alanine covalently bonded giant arsenotungstate, namely, Na3Ba11H16[(AsW9O33)6{W2O5(H2O)(dl-Ala)}2{W3O6(H2O)(dl-Ala)}2{W2O5(dl-Ala)}] (1; dl-Ala = dl-alanine), has been synthesized and is composed of six [AsW9O33]9- fragments fused together via two [W2O5(H2O)(dl-Ala)]+ segments, two [W3O6(H2O)(dl-Ala)]5+ segments, and a [W2O5(dl-Ala)]+ segment. This complex represents the first carboxylate-based hybrid polyoxotungstate without the introduction of lanthanide ions. Besides, compound 1 demonstrates not only fast photochromic properties but also interesting proton conductivity properties, with an achieved conductivity of 2.830 × 10-4 S·cm-1 (65 °C, 75% relative humidity).

dl-Alanine Covalently Bonded Giant Arsenotungstate with Rapid Photochromic and Decent Proton Conduction Properties.

Card games are regarded as an idealized model for many real-world problems for their rich hidden information and strategic decision-making process. It provides a fertile environment for artificial intelligence (AI), especially reinforcement learning algorithms. With the boom of deep neural networks, increasing breakthroughs have been made in this challenging domain. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Koi-Koi</i> is a traditional two-player imperfect-information playing card game. However, due to its unique deck and complex rules, related researches are mostly based on handcrafted features and the custom network architecture. In this paper, we design a more general AI framework, relying a Transformer encoder as the network backbone with tokenized card state input, which is trained by Monte-Carlo reinforcement learning with phased round reward. Experimental results show that our AI achieves a winning rate of 53% and +2.02 average difference point versus experienced human players in multi-round <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Koi-Koi</i> games. Moreover, with the aid of attention mechanism, we provide a novel view for analyzing the playing strategy. Such framework design can be applied to various card games. This project is available at <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><uri>https://github.com/guansanghai/KoiKoi-AI</uri></monospace> . 

Learning to Play Koi-Koi Hanafuda Card Games With Transformers

Since the famous Swedish chemist Scheele described molybdenum blue for the first time in 1778, polyoxometalate (POM) chemistry has made significant progress in its more than 200-year history. Compared with the POM chemistry of Mo, W and V, significant improvement of polyoxotantalates (POTas) occurred mainly during the last few years. In this paper, complexes with different structures, including isopolyoxotantalates (IPOTas), organic-inorganic hybrid POTas, Ta/W mixed POMs and heteropolyoxotantalates (HPOTas) with their derivatives, are reviewed, aiming at providing some useful guidance for further exploration and discovery of more exciting POTas with innovative architectures and excellent performances. Herein, we highlight and discuss the structural features of POTas according to various structural types. In addition, the synthesis strategies and related applications, especially in photocatalysis, are reviewed.

Jingping Wang

Papers

Three Types of Lanthanide-Containing Polyoxoniobates and Their Luminescence Properties.

Synthesis and characterization of an octanuclear nickel(II) polyoxometalate cluster

dl-Alanine Covalently Bonded Giant Arsenotungstate with Rapid Photochromic and Decent Proton Conduction Properties.

Learning to Play Koi-Koi Hanafuda Card Games With Transformers

Polyoxotantalate chemistry: from synthetic strategies to structural diversity and applications.