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 monomeric SeOCl₃- ion, which can be prepared as the tetraphenylarsonium salt from SeOCl₂ and As(C₆H₅)₄Cl, was structurally characterized by a low-temperature single crystal X-ray diffraction analysis. [As(C₆H₅)₄]SeOCl₃ is monoclinic, space group P2₁/c, with a = 9,332(3), b = 13,761(4), c = 18,985(6) A, β = 110,97(3)° (at -135 °C), Z = 4; it contains a novel type of ψ-trigonal bipyramidal oxotrichloroselenate(IV) anion which is not associated to dimers or polymer chains as in known structures. The equatorial positions are occupied by doubly bonded oxygen (Se-O 1,601(3) A) and by one Cl(Se-Cl 2,234(1) A), the axial Se-Cl bonds (2,430(1) and 2,475(1) A) being significantly longer. [N(C₂H₅)₄]SeOCl₃, which was obtained as crystals by oxidation of trichloroselenate(II), is triclinic, space group P1, with a = 10,607(3), b = 8,950(2), c = 8,862(2) A, α = 119,79(2)°, β = 101,07(2)°, γ = 96,28(2)°, Z = 2. The X-ray structure analysis shows the anions to be present as centrosymmetric dimers Se₂O₂Cl₆²⁻ like in the [P(C₆H₅)₄]⁺ salt, with two tetragonal SeOCl₄ pyramids linked through a Cl···Cl edge and the lone pairs trans to the axial Se-O bonds (1,589(4) A). Se-Cl bond lengths are 2.270(1) and 2,351(2) A (terminal); 2,698(1) and 2,920(1) A (bridging). The results show that the nature of the reaction products of the Lewis acid SeOCl₂ with halogenides as bases changes very sensitively with small variations in cations and environment. The vibrational spectra are discussed.

Monomere und dimere Oxotrihalogenoselenate(IV): Darstellung, Struktur und Eigenschaften von [As(C6H5)4]SeOCl3 und [N(C2H5)4]SeOCl3 / Monomerie and Dimeric Oxotrihalogenoselenates(IV): Preparation, Structure and Properties of [As(C6H5)4]SeOCl3 and [N(C2H5)4]SeOCl3

The addition of CF₃SCl (2) to the fluorinated nitriles RfCN[Rf = CF₃ (3), NSF₂ (4), NSOF₂ (5)] leads to N-perfluoromethanesulphenyl-formylimidoylchlorides CF₃S-N = C(Cl)Rƒ (6, 11, 12). From the reactions of SCl₂ (1) with (3) and (5), which yielded the N-sulphenyl-chlorides ClS-N = C(Cl)-Rƒ(7, 13), it proved possible also to isolate the oxidation product [CF₃CCl₂NSCl₂ (8)] and an oligomer of the nitrile [(NCNSOF₂)₃ (14)]. Dechlorination of 7 with Hg gives the corresponding di-and tri-sulphides (CF₃C(Cl) = N-)₂Sₓ; (9, 10, x =2, 3). Crystals of (14) are triclinic with a = 1133.6(5), b = 1332.6(5), c = 1715.1(8) pm, α = 109.31(3), β = 105.30(3), γ = 97.84(3)° at 170 K, Z = 8, space group P1. The structure was refined to R = 0.028 for 8290 diffractometer data with F > 4σ (F). The four crystallographically independent molecules adopt similar unsymmetrical conformations.

Reactions of Fluorinated Nitriles with Sulphur(II) Chlorides; Crystal Structure of 2,4,6-Tris(difluorosulphoximido)-1,3,5-triazene at 170 K

/pdf/mechanism-of-feiii-znii-purple-acid-phosphatase-based-on-110iqjsjud.pdf

Mechanism of FeIII–ZnII purple acid phosphatase based on crystal structures

Fünfkernige Platin(II)‐Makrocyclen mit Nucleobasen

[In2SCl6]2−, [In2SBr6]2−, [In3S3Cl6]3−, [In3Se3Cl6]3− und [Ga3S3Cl6]3− wurden als erste bisher bekannte Chalkogenohalogenoanionen von Elementen der 3. Hauptgruppe dargestellt. [Ph4P]2[In2SCl6] (1) (P1; a = 10,876(4) A, b = 12,711(6) A, c = 19,634(7) A, α = 107,21(3)°, β = 96,80(3)°, γ = 109,78(3)°; Z = 2) und [Ph4P]2[In2SBr6] (2) (C2/c; a = 48,290(9) A, b = 11,974(4) A, c = 17,188(5) A, β = 93,57(3)°, Z = 8) werden durch Reaktion von InX3, (CH3)3SiSSi(CH3)3 und Ph4PX (X = Cl, Br) in Acetonitril gebildet. [Et4N]3[In3S3Cl6] · MeCN (3) (P21/c; a = 17,328(4) A, b = 12,694(3) A, c = 21,409(4) A, β = 112,18(1)°, Z = 4), [Et4N]3[In3Se3Cl6] · MeCN (4) (P21/c; a = 17,460(4) A, b = 12,816(2) A, c = 21,513(4) A, β = 112,16(2)°, Z = 4) und [Et4N]3[Ga3S3Cl6] · THF (5) (P21/n; a = 11,967(3) A, b = 23,404(9) A, c = 16,260(3) A, β = 90,75(2)°, Z = 4) konnen durch Umsetzung von MCl3 (M = Ga, In) mit Et4NSH (3), (5) bzw. Et4NSeH (4) in Acetonitril (3), (4) bzw. Tetrahydrofuran (5) erhalten werden. In den Kristallstrukturen der Titelverbindungen 1 bis 5 liegen isolierte Anionen und Kationen vor. Die [In2SCl6]2−- und [In2SBr6]2−-Anionen in 1 und 2 lassen sich als Anordnung zweier uber ein gemeinsames Schwefelatom eckenverknupfter InSCl3- bzw. InSBr3- Tetraeder beschreiben. Die anionischen Teilstrukturen in 3, 4 und 5 werden durch drei Metallatome, die uber μ2-E-Atome (E = Schwefel, Selen) zu einem Sechsring miteinander verbunden sind, aufgebaut, wobei zwei Chloratome an jedem Metallatom dessen verzerrt-tetraedrische Koordination vervollstandigen.



Chalcogenohalogenogallates(III) and -indates(III): A New Class of Compounds for Elements of the Third Main Group. Preparation and Structure of [Ph4P]2[In2SX6], [Et4N]3[In3E3Cl6] · MeCN and [Et4N]3[Ga3S3Cl6] · THF (X = Cl, Br; E = S, Se)



[In2SCl6]2−, [In2SBr6]2−, [In3S3Cl6]3−, [In3Se3Cl6]3−, and [Ga3S3Cl6]3− were synthesised as the first known chalcogenohalogeno anions of main group 3 elements. [Ph4P]2[In2SCl6] (1) (P1; a = 10.876(4) A, b = 12.711(6) A, c = 19.634(7) A, α = 107.21(3)°, β = 96.80(3)°, γ = 109.78(3)°; Z = 2) and [Ph4P]2[In2SBr6] (2) (C2/c; a = 48.290(9) A, b = 11.974(4) A, c = 17.188(5) A, β = 93.57(3)°, Z = 8) were prepared by reaction of InX3, (CH3)3SiSSi(CH3)3 and Ph4PX (X = Cl, Br) in acetonitrile. The reaction of MCl3 (M = Ga, In) with Et4NSH/Et4NSeH in acetonitrile gave [Et4N]3[In3S3Cl6] · MeCN (3) (P21/c; a = 17.328(4) A, b = 12.694(3) A, c = 21.409(4) A, β = 112.18(1)°, Z = 4), [Et4N]3[In3Se3Cl6] · MeCN (4) (P21/c; a = 17.460(4) A, b = 12.816(2) A, c = 21.513(4) A, β = 112.16(2)°, Z = 4), and [Et4N]3[Ga3S3Cl6] · THF (5) (P21/n; a = 11.967(3) A, b = 23.404(9) A, c = 16.260(3) A, β = 90.75(2)°, Z = 4). The [In2SX6]2− anions (X = Cl, Br) in 1 and 2 consist of two InSX3 tetrahedra sharing a common sulfur atom. The frameworks of 3, 4 and 5 each contain a six-membered ring of alternating metal and chalcogen atoms. Two terminal chlorine atoms complete a distorted tetrahedral coordination sphere around each metal atom.

Chalkogenohalogenogallate(III) und -indate(III): Eine neue Verbindungsklasse in der dritten Hauptgruppe. Synthese und Struktur von [Ph4P]2[In2SX6], [Et4N]3[In3E3Cl6] · MeCN und [Et4N]3[Ga3S3Cl6] · THF (X = Cl, Br; E = S, Se)†

Bernt Krebs

Papers

Monomere und dimere Oxotrihalogenoselenate(IV): Darstellung, Struktur und Eigenschaften von [As(C6H5)4]SeOCl3 und [N(C2H5)4]SeOCl3 / Monomerie and Dimeric Oxotrihalogenoselenates(IV): Preparation, Structure and Properties of [As(C6H5)4]SeOCl3 and [N(C2H5)4]SeOCl3

Reactions of Fluorinated Nitriles with Sulphur(II) Chlorides; Crystal Structure of 2,4,6-Tris(difluorosulphoximido)-1,3,5-triazene at 170 K

Mechanism of FeIII–ZnII purple acid phosphatase based on crystal structures

Fünfkernige Platin(II)‐Makrocyclen mit Nucleobasen

Chalkogenohalogenogallate(III) und -indate(III): Eine neue Verbindungsklasse in der dritten Hauptgruppe. Synthese und Struktur von [Ph4P]2[In2SX6], [Et4N]3[In3E3Cl6] · MeCN und [Et4N]3[Ga3S3Cl6] · THF (X = Cl, Br; E = S, Se)†