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

A selective method for the determination of hydrogen peroxide in the presence of other oxidants is presented. The formation of a coloured adduct in the reaction of a dinuclear iron(III) complex with hydrogen peroxide is used for the quantification of the peroxide. The reaction product is detected at wavelengths between 570 and 600 nm. The major advantage of the method is the immediate reaction. Other peroxides exhibit little interfence, typically contributing to an error of 0.1% for the same concentration. The method was optimized for the determination of hydrogen peroxide in household products using microplate spectrophotometry. The limit of detection is 3 µmol l–1 (100 ppb) under these conditions. Calibration functions are linear over the range 9–300 µmol l–1 (300 ppb–10 ppm). The method was compared with established methods for peroxide analysis, including the spectrophotometric titanyl method and an HPLC method based on the oxidation of triphenylphosphine. The method described is suitable for the analysis of real samples.

Selective determination of hydrogen peroxide in household products using its molecular recognition by a dinuclear iron(III) complex

[V(SNC9H6)3] und [V(SNH2C6H4)2(SNHC6H4)]−, homoleptische Vanadium(III)‐Komplexe mit Schwefel‐Stickstoff‐Donorliganden, und [V(SNC5H4)3]−, der erste Thiolatovanadium(II)‐Komplex

Polymere Oktamolybdat-Ionen in der Kristallstruktur von (NH4)6Mo8O27 4H2O

Crystal and molecular structure of dichloronicotinemercury(II)

From solutions of TeBr4 in concentrated aqueous HBr red needles of the crystalline hexabromotellurous acid with the stoichiometric composition H2TeBr6 · 8H2O (1) were isolated (space group P21/n, a = 7.662(5), b = 9.796(6), c = 11.987(8) Å, β = 91.35(4)° at 259 Κ). If the HBr:TeBr4 concentration ratio in the system TeBr4/HBr/H2O was kept low, a novel acid with formal composition HTe3Br13 ·4 H2O (2) could be prepared (space group Cm, a = 13.501(5), b = 15.453(6), c = 9.153(3) Å, β = 138.11(2)° at 140 Κ). The X-ray structural analysis of 1 shows the acid to contain, besides regular octahedral [TeBr6]2- ions (Te-Br: 2.671(4)-2.716(4) Å), [Η9Ο4]+ hydroxonium ions (O ··· O: 2.48(3)-2.62(3) Å). The [H9O4]+ units are linked through a hydrogen bond system (O ··· O: 2.80(3)-2.97(4) Å) to form a three-dimen-sional network. The formula has to be written as [H9O4]2[TeBr6]. 2 is the first acid in this class with a trinuclear anion. Its structural formula is [H9O4][Te3Br13]. As a fragment of the Te4Br,6 cube the anion consists of three edge-sharing octahedra with a central triply bridging Br. The mean bond distances are 2.515 Å for terminal Te-Br, 2.944 Å for Te-μ2Br and 3.077 Å for Te—μ3Br. The Ο···Ο distances in the isolated [H9O4]+ hydroxonium ions are 2.45(3)-2.57(2) A. Raman spectra of both acids are reported.

Synthese, Struktur und Eigenschaften der Hexabromotellur(IV)- und Tridekabromotritellur(IV)säure-Hydrate. Kristallstrukturen der Oxonium-Salze [H9O4]2[TeBr6] und [H9O4][Te3Br13] / Synthesis, Structure and Properties of Hexabromotellurous and Tridecabromotritellurous Acid Hydrates. Crystal Structures of the Oxonium Salts [H9O4]2[TeBr6] and [H9O4][Te3Br13]

Bernt Krebs

Papers

Selective determination of hydrogen peroxide in household products using its molecular recognition by a dinuclear iron(III) complex

[V(SNC9H6)3] und [V(SNH2C6H4)2(SNHC6H4)]−, homoleptische Vanadium(III)‐Komplexe mit Schwefel‐Stickstoff‐Donorliganden, und [V(SNC5H4)3]−, der erste Thiolatovanadium(II)‐Komplex

Polymere Oktamolybdat-Ionen in der Kristallstruktur von (NH4)6Mo8O27 4H2O

Crystal and molecular structure of dichloronicotinemercury(II)