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

Utilisation de la spectrometrie RMN de 11 B pour etudier la nature structurale des differentes phases obtenues dans les systemes bore-soufre, bore-selenium, bore-soufre-selenium et bore-tellure

Solid-state 11B NMR studies on boron-chalcogenide systems

[Au2(WS4)2]2−, A Novel Inorganic Ring System

Metal Complexes of Unsymmetrically Bridged [N4] Macrocycles: Synthesis, Structure and Redox Behaviour



Metal complexes M-5a (M = Cu, Ni, Co, Fe, and I-Fe11) of 6,13-Di(ethoxycarbonyl)-7,12-dimethyl-benzo[b]-1,4,8,11-tetraaza-cyclotetradeca-2,5,7,11,13-pentaene and the free ligand H2-5a have been synthesized. The crystals of Cu-5a · H2O and Ni-5a · H2O consist of planar complex molecules which are linked by H bridges between the water molecules and the peripheric ester groups to give 1D chains. The average M-N distances are equal for both complexes (Cu 1.928, Ni 1.924 A), being unexpectedly large for the nickel complex. The redox properties of all the new compounds as well as some acetyl derivatives M-5b have been examined by cyclic voltammetry and compared with those of the previously reported symmetrically phenylene (M-4) and ethylene (M-6) bridged derivatives. All complexes give a reversible single electron reduction which clearly shows the increasing electron density around the central atom in the order M-4 < M-5 < M-6. Like the carbonyl substituted tetraazaannulenes M-4 the copper complexes Cu-5 give two, the cobalt complexes Co-5 three, and the iron complex Fe-5a probably four reversible single electron oxidations. They can be attributed to the species [MIIIL−II]+, [MIILo]2+, [MIIILo]3+, and [FeIVLo]4+ with Lo being a “non innocent” neutral 1,2-quinodiimine ligand. Very surprisingly, since in contrast to Ni-4 and Ni-6, the nickel complexes Ni-5 gave no reversible oxidation.

Bernt Krebs

Papers

Solid-state 11B NMR studies on boron-chalcogenide systems

[Au2(WS4)2]2−, A Novel Inorganic Ring System

Metallkomplexe unsymmetrisch überbrückter [N4]-Makrocyclen: Synthese, Struktur und Redoxverhalten

Neue Titanhalogenide mit Metall‐Metall‐Bindung: Ti 7 Cl 16 und Ti 7 Br 16

Unusual Coordination of the 1,3-Diphosphacyclobutadiene Derivative (iPr2NCP)2 to Two [Ni(CO)3] Fragments†