Chemical Record

Bulk gold is chemically inert and is generally regarded as a poor catalyst. However, when gold is in very small particles with diameters below 10 nm and is deposited on metal oxides or activated carbon, it becomes surprisingly active, especially at low temperatures, for many reactions such as CO oxidation and propylene epoxidation. The catalytic performance of Au is defined by three major factors: contact structure, support selection, and particle size. The role of the perimeter interfaces of Au particles as the sites for reactions is discussed as well as the change in chemical reactivity of Au clusters composed of fewer than 300 atoms. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 75–87; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10053

Studies on ciguatera fish poisoning led to clarification of the absolute stereochemistry of ciguatoxin, gambierol, gambieric acids, and maitotoxin. Anisotropic NMR reagents and fluorometric chiral HPLC reagents were effectively used together with synthesis of partial structures. Structures of 16 ciguatoxin congeners were successfully elucidated by FAB/MS/MS using samples of 5 μg or less. Stereochemical assignments were also achieved on dinophysistoxin‐1, pectenotoxins, yessotoxins, polycavernoside‐A, azaspiracid, and prymnesins. The toxins possessed poly‐cyclic‐ether structures and originated from unicellular algae. Biological functions are briefly described. © 2000 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:228–242, 2001

The pyridoxal‐5′‐phosphate (vitamin B₆)‐dependent enzymes that act on amino acid substrates have multiple evolutionary origins. Thus, the common mechanistic features of B₆ enzymes are not accidental historical traits but reflect evolutionary or chemical necessities. The B₆ enzymes belong to four independent evolutionary lineages of paralogous proteins, of which the α family (with aspartate aminotransferase as the prototype enzyme) is by far the largest and most diverse. The considerably smaller β family (tryptophan synthase β as the prototype enzyme) is structurally and functionally more homogenous. Both the D‐alanine aminotransferase family and the alanine racemase family consist of only a few enzymes. The primordial pyridoxal‐5′‐phosphate‐dependent protein catalysts apparently first diverged into reaction‐specific protoenzymes, which then diverged further by specializing for substrate specificity. Aminotransferases as well as amino acid decarboxylases are found in two different evolutionary lineages, providing examples of convergent enzyme evolution. The functional specialization of most B₆ enzymes seems to have already occurred in the universal ancestor cell before the divergence of eukaryotes, archebacteria, and eubacteria 1500 million years ago. Pyridoxal‐5′‐phosphate must have emerged very early in biological evolution; conceivably, metal ions and organic cofactors were the first biological catalysts. To simulate particular steps of molecular evolution, both the substrate and reaction specificity of existent B₆ enzymes were changed by substitution of active‐site residues, and monoclonal pyridoxal‐5′‐phosphate‐dependent catalytic antibodies were produced with selection criteria that might have been operative in the evolution of protein‐assisted pyridoxal catalysis. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:436–447, 2001

Research into materials displaying oxide ion conductivity is attracting considerable attention due to their potential technological applications in devices such as Solid Oxide Fuel Cells. In this paper, recent work on apatite‐type oxide ion conductors is reviewed, showing that a wide range of cation substitutions are possible, due to the flexibility of the apatite structure in accommodating a range of ion sizes. The conductivity studies on these doped samples show that to achieve high oxide ion conduction, non‐stoichiometry in terms of cation vacancies and/or oxygen excess is required, with the latter resulting in the highest conductivities. In contrast to most common oxide ion conductors, e.g. perovskite and fluorite in which oxide ion conduction proceeds via oxygen vacancies, the research on these apatite systems suggests that the conductivity involves interstitial oxide ions. With further optimization of these materials, particularly in terms of the Ge‐containing systems, significant improvements in conductivity are likely, leading to the very real possibility of the application of apatite‐type electrolytes in fuel cell and other applications. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 373–384; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20028

Selected problems of electrochemical synthesis, characterization and applications of titanium dioxide are reviewed. These issues have attracted considerable attention from addressing purely academic questions up to promising applications in devices for energy storage and energy conversion. DOI 10.1002/tcr.201100012

This personal account concerns novel recent discoveries in the area of mesoporous materials. Most of the papers discussed have been published within the last two to three years. A major emphasis of most of these papers is the synthesis of unique mesoporous materials by a variety of synthetic methods. Many of these articles focus on the control of the pore sizes and shapes of mesoporous materials. Synthetic methods of various types have been used for such control of porosity including soft templating, hard templating, nano‐casting, electrochemical methods, surface functionalization, and trapping of species in pores. The types of mesoporous materials range from carbon materials, metal oxides, metal sulfides, metal nitrides, carbonitriles, metal organic frameworks (MOFs), and composite materials. The vast majority of recent publications have centered around biological applications with a majority dealing with drug delivery systems. Several other bio‐based articles on mesoporous systems concern biomass conversion and biofuels, magnetic resonance imaging (MRI) studies, ultrasound therapy, enzyme immobilization, antigen targeting, biodegradation of inorganic materials, applications for improved digestion, and antitumor activity. Numerous nonbiological applications of mesoporous materials have been pursued recently. Some specific examples are photocatalysis, photo‐electrocatalysis, lithium ion batteries, heterogeneous catalysis, extraction of metals, extraction of lanthanide and actinide species, chiral separations and catalysis, capturing and the mode of binding of carbon dioxide (CO₂), optical devices, and magneto‐optical devices. Of this latter class of applications, heterogeneous catalysis is predominant. Some of the types of catalytic reactions being pursued include hydrogen generation, selective oxidations, aminolysis, Suzuki coupling and other coupling reactions, oxygen reduction reactions (ORR), oxygen evolution reactions (OER), and bifunctional catalysis. For perspective, there have been over 40,000 articles on mesoporous materials published in the last 4 years and about 1388 reviews. By no means is this personal account thorough or all inclusive. One objective has been to choose a variety of articles of different types to obtain a flavor of the breadth of diversity involved in the area of mesoporous materials.

The carbon‐carbon and carbon‐heteroatom bonds catalytic formation is among the most significant reactions in organic synthesis which extensively applied for synthesis of natural products, heterocycles, dendrimers, biologically active molecules and useful compounds. This review provides the latest advances in the preparation of graphene supported metal nanoparticles and their application in the catalytic formation of both carbon‐carbon (C−C) and carbon‐heteroatom (C−X) bonds including the Suzuki, Heck, Hiyama, Ullmann, Buchwald and Sonogashira coupling reactions. Numerous examples are given concerning the use of these catalysts in C−C and C−X coupling reactions along with the reliable and simple preparation methods of these catalysts, their characterization and catalytic properties and also the recycling possibilities.

This review gives an overview of the synthesis, surface and electrochemical investigations over ternary nanocomposite of conductive polymers in the development of new supercapacitors. They utilize both Faradaic and non‐Faradaic procedures to store charge, leading to higher specific capacitance and energy density, higher cell voltage, longer life cycle and moderated power density. Owing to a unique combination of features such as superb electrical conductivity, corrosion resistance in aqueous electrolytes, highly modifiable nanostructures, long cycle life and the large theoretical specific‐surface area, the use of ternary nanocomposites as a supercapacitor electrode material has become the focus of a significant amount of current scientific researches in the field of energy storage devices. In these nanocomposites, graphene not only can be utilized to provide a substrate for growing nanostructured polymers in a polymer‐carbon nanocomposite structure in order to overcome the insulating nature of conductive polymers at dedoped states, but also is capable of providing a platform for the decoration of metal oxide nanoparticles to avoid their agglomeration. In this regard, synthesis, characterization and performance of different ternary nanocomposites of conductive polymer/graphene/metal oxide are discussed in detail. These remarkable results demonstrate the exciting commercial potential for high performance, environmentally friendly and low‐cost electrical energy storage devices based on ternary nanocomposite of conductive polymer/graphene/metal oxide.

For the last decade, the fabrication of ordered structures of phage has been of great interest as a means of utilizing the outstanding biochemical properties of phage in developing useful materials. Combined with other organic/inorganic substances, it has been demonstrated that phage is a superior building block for fabricating various functional devices, such as the electrode in lithium‐ion batteries, photovoltaic cells, sensors, and cell‐culture supports. Although previous research has expanded the utility of phage when combined with genetic engineering, most improvements in device functionality have relied upon increases in efficiency owing to the compact, more densely packable unit size of phage rather than on the unique properties of the ordered nanostructures themselves. Recently, self‐templating methods, which control both thermodynamic and kinetic factors during the deposition process, have opened up new routes to exploiting the ordered structural properties of hierarchically organized phage architectures. In addition, ordered phage films have exhibited unexpected functional properties, such as structural color and optical filtering. Structural colors or optical filtering from phage films can be used for optical phage‐based sensors, which combine the structural properties of phage with target‐specific binding motifs on the phage‐coat proteins. This self‐templating method may contribute not only to practical applications, but also provide insight into the fundamental study of biomacromolecule assembly in in vivo systems under complicated and dynamic conditions.