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 compounds [(C₆H₅)₄As]₂ TeCl₄ (1), [(C₂H₅)₄ N]₂ TeBr₄ · CH₃CN (2), and [(C₂H₅)₄N]₂TeI₄ (3) were prepared by the reaction of Te, X₂ , and excess (C₂H₅)₄NX (X = Br, I) in acetonitrile solution or by heating of [(C₆H₅)₄ As]₂TeCl₆ , Te, and (C₆H₅)₄ ASCl for several hours in the same solvent.The structures of 1-3 were determined from single crystal X-ray data.1 crystallizes in the monoclinic space group P2₁/n with a = 1061.8(2), b = 1614.2(3), c = 1341.7(3) pm, β = 94.21° and Z = 2; 2: tetragonal, P4/mmm, a = 1039.7(2), c = 690.5(1), Z = 1; 3: tetragonal, I4/mmm, a = 1061.7(2), c = 1342.8(4), Z = 2. In 1-3 Te(II) exhibits a square planar coordination. The Te -CI, Te -Br, and Te-I bond lengths were found to be 260.7 (mean), 275.3, and 298.5 pm, respectively.

Tetrahalogenotellurate(II): Synthese und Kristallstrukturen von Verbindungen mit den Ionen TeX42- (X = Cl, Br, I)/Tetrahalotellurates(II): Syntheses and Crystal Structures of Compounds with TeX42- Ions (X = Cl, Br, I)

Hexamanganato(VII)manganic(IV) Acid: A “Pseudopermanganic Acid”

Systematic studies on quaternary thio- and selenoborates containing heavier alkaline earth metal cations led to the two new isotypic crystalline phases Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se. Both compounds consist of trigonal-planar BQ3 (Q = S, Se) units, isolated Q2– anions and the corresponding counter-ions. The two new chalcogenoborates were prepared in solid state reactions from the metal sulfides (selenides), amorphous boron and sulfur (selenium). Evacuated carbon coated silica tubes were used as reaction vessels since temperatures up to 870 K were applied. Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se crystallize in the monoclinic space group C2/c (no. 15) with a = 9.902(3) A, b = 23.504(9) A, c = 9.884(3) A, β = 90.01(3)° and Z = 4 in the case of the thioborate, while for the selenoborate the lattice parameters a = 10.513(2) A, b = 25.021(5) A, c = 10.513(2) A, β = 90.10(3)° were determined.



X-ray powder patterns are compared to calculated diffraction data obtained from single crystal X-ray structure determination.



Neue Chalkogenoborate der Erdalkalimetalle: Synthesen und Kristallstrukturen von Sr4,2Ba2,8(BS3)4S und Ba7(BSe3)4Se



Versuche zur Synthese gemischter Erdalkalithio- und selenoborate fuhrten in den quaternaren Phasengebieten Sr/Ba/B/S(Se) zu den beiden neuen isotypen Verbindungen Sr4,2Ba2,8(BS3)4S und Ba7(BSe3)4Se. In beiden Strukturen treten isolierte, trigonal-planare BQ3-Einheiten (Q = S, Se) sowie zusatzliche Q2–-Anionen als anionische Strukturmerkmale auf. Die neuen Chalkogenoborate wurden in Hochtemperatur-Feststoffreaktionen aus den entsprechenden Metallsulfiden bzw. -seleniden, amorphem Bor und Schwefel (Selen) in graphitierten, evakuierten Quarzglasampullen hergestellt. Sr4,2Ba2,8(BS3)4S und Ba7(BSe3)4Se kristallisieren in der monoklinen Raumgruppe C2/c (Nr. 15) mit den Gitterparametern a = 9,902(3) A, b = 23,504(9) A, c = 9,884(3) A, β = 90,01(3)° und Z = 4 fur das Thioborat und a = 10,513(2) A, b = 25,021(5) A, c = 10,513(2) A, β = 90,10(3)° fur das Selenoborat. Pulver-Rontgenbeugungsdiagramme werden mit aus den Einkristall-Rontgenstrukturanalysen berechneten Daten verglichen.

Novel Alkaline Earth Metal Chalcogenoborates: Syntheses and Crystal Structures of Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se

Notizen: Die Kristallstruktur von Ammoniumtetraselenowolframat

Reaction of (pentamethylcyclopentadienyl)(tert-butylimino)-phosphane with tris(acetonitrile)tricarbonylmolybdenum(0): evidence for a metalloiminophosphane intermediate

Bernt Krebs

Papers

Tetrahalogenotellurate(II): Synthese und Kristallstrukturen von Verbindungen mit den Ionen TeX42- (X = Cl, Br, I)/Tetrahalotellurates(II): Syntheses and Crystal Structures of Compounds with TeX42- Ions (X = Cl, Br, I)

Hexamanganato(VII)manganic(IV) Acid: A “Pseudopermanganic Acid”

Novel Alkaline Earth Metal Chalcogenoborates: Syntheses and Crystal Structures of Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se

Notizen: Die Kristallstruktur von Ammoniumtetraselenowolframat

Reaction of (pentamethylcyclopentadienyl)(tert-butylimino)-phosphane with tris(acetonitrile)tricarbonylmolybdenum(0): evidence for a metalloiminophosphane intermediate