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.

This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

It is possible to say that zeolites are the most widely used catalysts in industry They are crystalline microporous materials which have become extremely successful as catalysts for oil refining, petrochemistry, and organic synthesis in the production of fine and speciality chemicals, particularly when dealing with molecules having kinetic diameters below 10 A The reason for their success in catalysis is related to the following specific features of these materials:1 (1) They have very high surface area and adsorption capacity (2) The adsorption properties of the zeolites can be controlled, and they can be varied from hydrophobic to hydrophilic type materials (3) Active sites, such as acid sites for instance, can be generated in the framework and their strength and concentration can be tailored for a particular application (4) The sizes of their channels and cavities are in the range typical for many molecules of interest (5-12 A), and the strong electric fields2 existing in those micropores together with an electronic confinement of the guest molecules3 are responsible for a preactivation of the reactants (5) Their intricate channel structure allows the zeolites to present different types of shape selectivity, ie, product, reactant, and transition state, which can be used to direct a given catalytic reaction toward the desired product avoiding undesired side reactions (6) All of these properties of zeolites, which are of paramount importance in catalysis and make them attractive choices for the types of processes listed above, are ultimately dependent on the thermal and hydrothermal stability of these materials In the case of zeolites, they can be activated to produce very stable materials not just resistant to heat and steam but also to chemical attacks Avelino Corma Canos was born in Moncofar, Spain, in 1951 He studied chemistry at the Universidad de Valencia (1967−1973) and received his PhD at the Universidad Complutense de Madrid in 1976 He became director of the Instituto de Tecnologia Quimica (UPV-CSIC) at the Universidad Politecnica de Valencia in 1990 His current research field is zeolites as catalysts, covering aspects of synthesis, characterization and reactivity in acid−base and redox catalysis A Corma has written about 250 articles on these subjects in international journals, three books, and a number of reviews and book chapters He is a member of the Editorial Board of Zeolites, Catalysis Review Science and Engineering, Catalysis Letters, Applied Catalysis, Journal of Molecular Catalysis, Research Trends, CaTTech, and Journal of the Chemical Society, Chemical Communications A Corma is coauthor of 20 patents, five of them being for commercial applications He has been awarded with the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996) 2373 Chem Rev 1997, 97, 2373−2419

From Microporous to Mesoporous Molecular-Sieve Materials and Their Use in Catalysis

3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

We investigate the excited-state dynamics of 2,2′-bipyridine (BPy) moieties in a framework of BPy-bridged periodic mesoporous organosilica (BPy-PMO), which is a unique solid chelating ligand that has densely and regularly arranged BPy units that are exposed on the pore surfaces. The steady-state absorption spectrum of BPy-PMO shows broad absorption bands and a prolonged absorption tail compared to its precursor molecule, which suggests that a part of the BPy moieties form dimers and/or aggregates in the ground state. Transient absorption spectra of BPy-PMO after excitation with 295 nm light show mainly intersystem crossing from the lowest singlet excited state (S₁) to the lowest triplet excited state (T₁) of BPy moieties with a lifetime of 52 ps. Energy transfer (7.2 ps) from the S₁ of a BPy monomer to BPy dimers and/or aggregates is also suggested. The lifetime of the excited BPy dimers and/or aggregates is estimated by selective excitation (355 nm) to be 3.4 ns. The lifetime for the T₁ of the BPy monomer is estimated to be 700 ns from transient absorption spectra of BPy-PMO after nanosecond 266 nm pulse irradiation. The characteristics of the excitation-relaxation processes of BPy-PMO are discussed.

Excited-State Dynamics of 2,2′-Bipyridine Moieties Embedded in the Framework of Periodic Mesoporous Organosilica

The film growth of 4 He adsorbed in mesoporous substrates was investigated by accurate vapor pressure measurements for various pore sizes between 18 A and 47 A The 4 He film adsorbed on the pore wall forms a cylindrical tube, but does not show the capillary condensation Completion of the first layer and the full pore coverage could be identified for all pore sizes studied In the first layer, no pore size dependence of the film growth was found, indicating that the growth of this layer was dominated primarily by the van der Waals force from the substrate Film growth after the first layer completion, however, has a strong pore size dependence The ratio of the first layer completion and the full pore coverage agrees well with that expected from the pore dimensions

Film growth of 4He adsorbed in mesopores

Pt, Rh, Pt-Rh, and Pt-Pd nanowires were synthesized by a photoreduction method using mesoporous silicas FSM-16 and HMM-1 as templates. The metal nanowires occluded in the mesopores were characterized by several physicochemical methods. The TEM and XAFS studies have demonstrated that the nanowires grow by the reduction of Pt precursors on small nanoparticles initially formed in the mesopores. Dissolution of silica matrix with HF separated the nanowires that are stabilized in solutions. The Pt nanowires and nanoparticles in FSM-16 were used as catalysts in water-gas-shift reaction and hydrogenolysis of butane. It is noteworthy that Pt nanowire/FSM-16 shows higher activities than Pt nanoparticle/FSM-16.

31 Template synthesis, formation mechanism and catalysis of metal nanowires in mesoporous materials

Periodic mesoporous organosilicas (PMOs), synthesized via surfactant-directed self-assembly of a polysilylated organic precursor (R[Si(OR')3]n; n≥2, R: organic group), are promising candidates such as catalysts and adsorbents, and for use in optical and electrical devices, owing to their high surface area, well-defined nanoporous structure, and highly functional organosilica framework. Their framework functionality can be widely tuned by selecting appropriate organic groups and controlling their arrangement. This chapter describes the synthesis and structure of PMOs with simple organic groups such as ethane and benzene, and the unique properties and optical applications of functional PMOs. Special light-harvesting properties and their exploitation in photocatalysis, highly emissive PMOs and their application to color-tunable transparent films, hole-transporting PMOs and their use in organic solar cells, and PMOs containing chelating ligands and their use as solid supports for heterogeneous metal complex catalysis are described.

Shinji Inagaki

Papers

Excited-State Dynamics of 2,2′-Bipyridine Moieties Embedded in the Framework of Periodic Mesoporous Organosilica

Film growth of 4He adsorbed in mesopores

31 Template synthesis, formation mechanism and catalysis of metal nanowires in mesoporous materials

Synthesis and Optical Applications of Periodic Mesoporous Organosilicas.

Luminescent Nanorattles Based on Bipyridine Periodic Mesoporous Organosilicas for Simultaneous Thermometry and Catalysis