The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

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The chemistry of graphene oxide

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

The transition metal dichalcogenides are about 60 in number. Two-thirds of these assume layer structures. Crystals of such materials can be cleaved down to less than 1000 A and are then transparent in the region of direct band-to-band transitions. The transmission spectra of the family have been correlated group by group with the wide range of electrical and structural data available to yield useful working band models that are in accord with a molecular orbital approach. Several special topics have arisen; these include exciton screening, d-band formation, and the metal/insulator transition; also magnetism and superconductivity in such compounds. High pressure work seems to offer the possibility for testing the recent theory of excitonic insulators.

The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties

Copper is an essential trace element in living systems, present in the parts per million concentration range. It is a key cofactor in a diverse array of biological oxidation-reduction reactions. These involve either outer-sphere electron transfer, as in the blue copper proteins and the Cu{sub A} site of cytochrome oxidase and nitrous oxide redutase, or inner-sphere electron transfer in the binding, activation, and reduction of dioxygen, superoxide, nitrite, and nitrous oxide. Copper sites have historically been divided into three classes based on their spectroscopic features, which reflect the geometric and electronic structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centers. 428 refs.

Multicopper Oxidases and Oxygenases

The reported novel compounds [H3O·(dibenzo-18-crown-6)][Te2Br9], [H5O2][Te2Cl9]·2C4H8O2 and [H5O2·(bis-dibromo-dibenzo-24-crown-8)]2[Se3Br8] highlight the large structural and chemical variety of halogen chalcogen chemistry. Both [Te2X9]− anions (X = Cl, Br) consist of one square pyramidal TeX5 fragment connected to a TeX6 octahedron by a common edge. The linear [Se3Br8]2− anion is built by three square planar SeBr4-fragments. The three counterions offer a convenient possibility for controlled synthesis of supramolecular oxonium systems.

New Oxonium Halochalcogenates(IV) and -(II)

The cover picture shows a polyhedral representation of a polyoxovanadate core {V6O13(OMe)6}2−, which is linked to two vanadyl moieties. These are coordinated through the N2O2 donor set of organic ligands, which additionally stabilize the hexavanadate through two hydrogen bonds. This compound can be considered as “bridging the gap” between polyoxometalates and classic coordination compounds. Fittingly, in the background, is Mungsten railway bridge near Wuppertal, Germany, which links the towns of Remscheid and Solingen. The bridge, which was built in 1897, at a height of 107 m, an arch width of 170 m, and a total length of 500 m was considered an engineering masterpiece of its time in Europe. More about the successful linkage of two important classes of compounds is reported in the communication by M. Piepenbrink, M. U. Triller, N. H. J. Gorman, and B. Krebs on pp. 2523 ff.

Cover Picture: Angew. Chem. Int. Ed. 14/2002

Darstellung und struktur von na4sns4.14h2o

Li7B7Se15: A novel selenoborate with a zeolite-like polymeric anion structure

The reaction of 6-phenyl-3-pentafluorophenoxy-tetrafluorocyclohexa- 2,4-dien-1-one (1) with one equivalent of triphenylphosphane leads to the spectroscopically detectable 5-phenyl-4-pentafluorophenoxy- 3,3,6,6-tetrafluoro-2-triphenylphosphoranylidene- 4-cyclohexen-1-one (2), which upon hydrolysis or reaction with hydroxyl groups of the glass surface yields 5-phenyl-4-pentafluorophenoxy- 6,6-difluoro-2-triphenylphosphoranylidene- 4-cyclohexene-1,3-dione (3). The structure of 3 was determined by NMR measurements and an X-ray diffraction study.

Notizen: Neue fluorhaltige Phosphorylide aus 6-Phenyl-3-pentafluorphenoxy-tetrafluorcyclohexa- 2,4-dien-1-on und Triphenylphosphan / Novel Fluorine-Containing Phosphorus Ylids from 6-Phenyl-3-pentafluorophenoxy-tetrafluorocyclohexa- 2,4-dien-1-one and Triphenylphosphane

Bernt Krebs

Papers

New Oxonium Halochalcogenates(IV) and -(II)

Cover Picture: Angew. Chem. Int. Ed. 14/2002

Darstellung und struktur von na4sns4.14h2o

Li7B7Se15: A novel selenoborate with a zeolite-like polymeric anion structure

Notizen: Neue fluorhaltige Phosphorylide aus 6-Phenyl-3-pentafluorphenoxy-tetrafluorcyclohexa- 2,4-dien-1-on und Triphenylphosphan / Novel Fluorine-Containing Phosphorus Ylids from 6-Phenyl-3-pentafluorophenoxy-tetrafluorocyclohexa- 2,4-dien-1-one and Triphenylphosphane