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 complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 506. DOI:10.1002/anie.198205060

Doubly Metalated Carbon by Metal-Induced Vinyl-Ethylidene Rearrangement†

An extremely high thermal and chemical stability as well as a unique "out-of-plane" position of the metal atom is shown by the first stable transition metal complexes formed with the proton sponge 1 as the ligand. The properties of these complexes await wide application in catalysis and medicine.

Transition Metal Complexes with the Proton Sponge 4,9-Dichloroquino[7,8-h]quinoline: Highly Twisted Aromatic Systems and an Extreme “Out-of-Plane” Position of the Coordinated Transition Metal Atom

The essential trace element copper plays a key role in living systems. Its metalloproteins are involved in various reactions. The IT ononuclear blue copper type-1 proteins take, part in electron transfer processes. Type-2 proteins can either act as oxidases, oxygenases, dioxygenases, or superoxide dismutases, containing one copper core. Dinuclear copper centers of Type-3 proteins are the oxygen transport system hemocyanin, oxidases and oxygenases. Due to this variety of functions copper deficiency and also abundance can cause severe damage of any life form.

Kupfer — Die biochemische Bedeutung eines Metalls

Mn 2 O 7 cristallise dans le systeme monoclinique, groupe d'espace P2 1/c et sa structure est affinee jusqu'a R=0,043

Die Kristallstruktur von Mn2O7

The trinuclear manganese(II) complexes [Mn-3(L-1)(2)(mu-OAc)(4)]center dot 2Et(2)O {HL1 = (1-hydroxy-4-nitrobenzyl)((2- pyridyl)methyl) ((1-methylimidazol-2-yl)methyl)amine} (1.2EtOH), [Mn-3(L-2)(2)(mu-OAc)(4)] {HL2 = ((1-methylimidazol-2-yl)methyl)(1-hydroxybenzyl)amine (2) and [Mn-3(L-3)(2)(mu-OAc)6] {L-3 = bis(1-methylimidazol-2-yl)methanonel (3) were synthesized. The compounds were characterized by X-ray crystallography, mass spectrometry, IR, UV-vis spectroscopy, and elemental analysis. The manganese atoms in 1 and 2 are bridged by phenol moieties of the ligands and acetates. In 3 they are only bridged by acetates in a mono- and bi-dentate way. The resulting Mn...Mn distances are 3.233(1) angstrom (1), 3.364(1) angstrom (2) and 3.643(7) angstrom (3). In the present compounds different limiting cases for the phenomenon of the carboxylate shift are realized. Besides symmetric mono- and bi-dentate bridging an unusual intermediate is also observed. 1.2EtOH is the first example of a trinuclear model for the OEC that shows catalase activity. Furthermore it was characterized by temperature dependent magnetic susceptibility measurements and a total spin ground state of S-t = 5/2 was found. The results for 1 reveals antiferromagnetic coupling between the central and the terminal manganese ions, with J = 1.2 cm(-1), g = 2.00 (fixed), chi(TIP) = 150 x 10(-6) cm(3) mol(-1).

Bernt Krebs

Papers

Doubly Metalated Carbon by Metal-Induced Vinyl-Ethylidene Rearrangement†

Transition Metal Complexes with the Proton Sponge 4,9-Dichloroquino[7,8-h]quinoline: Highly Twisted Aromatic Systems and an Extreme “Out-of-Plane” Position of the Coordinated Transition Metal Atom

Kupfer — Die biochemische Bedeutung eines Metalls

Die Kristallstruktur von Mn2O7

Novel Trinuclear MnII/MnII/MnII Complexes – Crystal Structures and Catalytic Properties