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

(R2NPO)3: A Novel Heterocycle with λ3‐Phosphorus by Trimerization of an Aminooxophosphane

Preparation a partir de SeBr 4 et bromures avec de gros cations dans des solvants faiblement polaires. Structures

Bromoselenate(II,IV), ein neuer Typ gemischtvalenter Verbindungen

Durch Verbesserung der Synthese- und Transportbedingungen wurde α-PtCl2, die Hochtemperaturmodifikation des Platin(II)-chlorids, rein und in Form von Einkristallen dargestellt. Wie neue Experimente zeigen, kann auser Cl2 und Al2Cl6 auch Ga2Cl6 bzw. GaCl3 als Transportmittel zur Abscheidung von α-PtCl2 eingesetzt werden; hierbei bildet sich der Komplex PtGa2Cl8 in der Gasphase. Die in schwarzen Nadeln Kristallisierende Verbindung ist monoklin und bildet eine fehlgeordnete Struktur. Die Elementarzelle der Uberlagerungs-Substruktur kann in der Raumgruppe C2/m mit a = 13,258(3), b = 3,194(1), c = 6,802(2) A, β = 107,75(3)°, Z = 4 beschrieben werden. Die Strukturanalyse auf der Basis von Einkristall-Diffraktometerdaten zeigt parallel zur b-Achse verlaufende Doppelbander kanten- und/oder eckenverknupfter quadratisch-planarer PtCl4-Einheiten. Die relative Anordnung der (PtCl4/2)n-Doppelbander ist fehlgeordnet. α-PtCl2 ist nicht isotyp mit α-PdCl2.



New Investigations on α-PtCl2: Preparation and Structure



The high-temperature modification of platinum(II) chloride, α-PtCl2, was prepared in pure from as single crystals by improvements of the synthetic and transport procedures. The experiments show that Ga2Cl6 and GaCl3 can be employed besides Cl2 and Al2Cl6 as a transporting agent for the preparation of α-PtCl2; PtGa2Cl8 is formed in the transport process. The compound crystallizes in black needles and forms a disordered structure. The unit cell of the averaged substructure can be described in the space group C2/m with a = 13.258, b = 3.194, c = 6.802 A, β = 107.75°, Z = 4. The crystal structure analysis based on single crystal diffractometer substructure reflections shows double strings of edge- and/or corner-sharing square-planar PtCl4 units which are running parallel to the b axis. The arrangement of the strings relative to each other is disordered. α-PtCl2 is not isotypic with α-PdCl2.

Neue Untersuchungen an α-Platindichlorid Darstellung und Struktur

Kristall- und molekülstruktur von hexaphenyldistannylselenid (C6H5)3SnSeSn(C6H5)3

Ein Verfahren zur FeCl3-katalysierten Hydrolyse von Trichlorsilanen im Zweiphasensystem wird untersucht und das dargestellte, neue Silasesquioxan (BrCH2CH2CH2)8Si8O12 isoliert und charakterisiert.



Synthesis and Structures of γ-Halopropyl-octa(silasesquioxanes)



As a more rapid and versatile synthetic approach, we have studied the FeCl3-catalyzed hydrolytic polycondensation of suited trichlorosilanes in a biphasic system which yields e.g. the new octa(silasesquioxane) (BrCH2CH2CH2)8Si8O12.

Bernt Krebs

Papers

(R2NPO)3: A Novel Heterocycle with λ3‐Phosphorus by Trimerization of an Aminooxophosphane

Bromoselenate(II,IV), ein neuer Typ gemischtvalenter Verbindungen

Neue Untersuchungen an α-Platindichlorid Darstellung und Struktur

Kristall- und molekülstruktur von hexaphenyldistannylselenid (C6H5)3SnSeSn(C6H5)3

Synthese und Struktur von γ‐Halogenpropyl‐octa(silasesquioxanen)