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  • 1. Abbasi, Alireza
    et al.
    Badiei, Alireza
    Khaniani, Yeganeh
    Golchoubian, Hamid
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    N,N '-bis(2,6-dichlorobenzyl)ethylene-diimine2007Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, s. o3773-U2712Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the centrosymmetric title compound, C16H12Cl4N2, the asymmetric unit is one half-molecule. Weak van der Waals interactions between the molecules are effective in the molecular packing. This is the first reported structure of a chloro-substituted benzaldehyde derivative that can potentially form a tetradentate ligand.

  • 2. Abbasi, Alireza
    et al.
    Damian Risberg, Emiliana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Mink, Janos
    Persson, Ingmar
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sidorov, Yurii V.
    Skripkin, Mikhail Yu.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Ullström, Ann-Sofi
    Crystallographic and Vibrational Spectroscopic Studies of Octakis(dimethyl sulfoxide)lanthanoid(III) Iodides2007Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, nr 19, s. 7731-7741Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal−oxygen (Ln−O) bond. To resolve the atomic positions and achieve reliable Ln−O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln−O bond distances are distributed over a range of about 0.1 Å. The average value increases from Ln−O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 Å (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 Å (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La−O and Nd−O bond distances remained unchanged at 100 K, 2.49 and 2.43 Å, respectively. Despite longer bond distances and larger Ln−O−S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln−O and S−O stretching modes in the complexes increase with decreasing Ln−O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions.

  • 3.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Das, Arindam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Huang, Genping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective allylboration of imines and indoles under mild conditions. An in situ E/Z isomerization of imines by allylboroxines2014Inngår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 5, nr 7, s. 2732-2738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct allylboration of various acyclic and cyclic aldimine, ketimine and indole substrates was performed using allylboronic acids. The reaction proceeds with very high anti-stereoselectivity for both E and Z imines. The allylboroxines formed by dehydration of allylboronic acids have a dual effect: promoting E/Z isomerization of aldimines and triggering the allylation by efficient electron withdrawal from the imine substrate.

  • 4.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mihai, Raducan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selective Formation of Adjacent Stereocenters by Allylboration of Ketones under Mild Neutral Conditions2013Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 15, nr 10, s. 2546-2549Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allylboronic acids readily react with a broad variety of ketones, affording homoallylic alcohols with adjacent quaternary and tertiary stereocenters. The reaction proceeds with very high anti stereoselectivity even if the substituents of the keto group have a similar size. a-Keto acids react with syn stereoselectivity probably due to the formation of acyl boronate intermediates. The allylation reactions proceed without added acids/bases under mild conditions. Because of this, many functionalities are tolerated even with in situ generated allylboronic acids.

  • 5.
    Anderlund, Magnus F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zheng, J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ghiladi, M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kritikos, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Rivière, Erik
    Sun, Licheng
    Girerd, Jean-Jaques
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A New, Dinuclear High Spin Manganese(III) Complex with Bridging Phenoxy and Methoxy Groups. Structure and Magnetic Properties2006Inngår i: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 9, nr 12, s. 1195-1198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new μ-phenoxy-μ-metoxy di-manganese(III) complex with the trisphenolic ligand, 2,6-bis[((2-hydroxybenzyl)(2-pyridylmethyl)amino)methyl]-4-methylphenol, was isolated as a perchlorate salt. The X-ray structure shows that the two manganese(III) ions are in a distorted octrahedral enviroment with approximately perpendicular Jahn–Teller axes. Investigation of the molar magnetic susceptibility reveals a ferromagnetic coupling between the two high-spin manganese(III) ions. Fitting of the data led to g = 2 and J = 12.5 cm−1

  • 6. Aramburo, Luis R.
    et al.
    Karwacki, Lukasz
    Cubillas, Pablo
    Asahina, Shunsuke
    de Winter, D. A. Matthijs
    Drury, Martyn R.
    Buurmans, Inge L. C.
    Stavitski, Eli
    Mores, Davide
    Daturi, Marco
    Bazin, Philippe
    Dumas, Paul
    Thibault-Starzyk, Frederic
    Post, Jan A.
    Anderson, Michael W.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Weckhuysen, Bert M.
    The Porosity, Acidity, and Reactivity of Dealuminated Zeolite ZSM-5 at the Single Particle Level: The Influence of the Zeolite Architecture2011Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 49, s. 13773-13781Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combination of atomic force microscopy (AFM), high-resolution scanning electron microscopy (HR-SEM), focused-ion-beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), confocal fluorescence microscopy (CFM), and UV/Vis and synchrotron-based IR microspectroscopy was used to investigate the dealumination processes of zeolite ZSM-5 at the individual crystal level. It was shown that steaming has a significant impact on the porosity, acidity, and reactivity of the zeolite materials. The catalytic performance, tested by the styrene oligomerization and methanol-to-olefin reactions, led to the conclusion that mild steaming conditions resulted in greatly enhanced acidity and reactivity of dealuminated zeolite ZSM-5. Interestingly, only residual surface mesoporosity was generated in the mildly steamed ZSM-5 zeolite, leading to rapid crystal coloration and coking upon catalytic testing and indicating an enhanced deactivation of the zeolites. In contrast, harsh steaming conditions generated 550 nm mesopores, extensively improving the accessibility of the zeolites. However, severe dealumination decreased the strength of the Bronsted acid sites, causing a depletion of the overall acidity, which resulted in a major drop in catalytic activity.

  • 7. Atluri, Rambabu
    et al.
    Iqbal, Muhammad Naeem
    Bacsik, Zoltan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Villaescusa, Luis Angel
    Garcia-Bennett, Alfonso E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi. alfonso@mmk.su.se.
    Self-Assembly Mechanism of Folate-Templated Mesoporous Silica2013Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, nr 38, s. 12003-12012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method to form ordered mesoporous silica based on the use of folate supramolecular templates has been developed. Evidence based on in situ small-angle X-ray scattering (SAXS), electron microscopy, infrared spectroscopy, and in situ conductivity measurements are used to investigate the organic inorganic interactions and synthesis mechanism. The behavior of folate molecules in solution differs distinctively from that of surfactants commonly used for the preparation of ordered mesoporous silica phases, notably with the absence of a critical micellar concentration. In situ SAXS studies reveal fluctuations in X-ray scattering intensities consistent with the condensation of the silica precursor surrounding the folate template and the growth of the silica mesostructure in the initial stages. High-angle X-ray diffraction shows that the folate template is well-ordered within the pores even after a few minutes of synthesis. Direct structural data for the self-assembly of folates into chiral tetramers within the pores of mesoporous silica provide evidence for the in register stacking of folate tetramers, resulting in a chiral surface of rotated tetramers, with a rotation angle of 30 degrees. Additionally, the self-assembled folates within pores were capable of adsorbing a considerable amount of CO2 gas through the cavity space of the tetramers. The study demonstrates the validity of using a naturally occurring template to produce relevant and functional mesoporous materials.

  • 8.
    Becker, Richard
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Johnsson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Berger, Helmuth
    Crystal Structure of the New Cobalt Tellurite Chloride Co5Te4O11Cl42007Inngår i: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 633, nr 3, s. 422-424Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystal structure of the new compound Co5Te4O11Cl4 is described. It crystallizes in the triclinic system, space group P-1 with the unit cell parameters a = 822.26(8) pm, b = 1029.7(1) pm, c = 1031.1(1) pm, = 110.80(1)°, β = 97.950(9)°, = 98.260(9)° and Z = 2. The structure is layered along the bc–plane and built by [CoO5Cl], [CoO4Cl2] and [CoO4Cl] polyhedra sandwiched by [TeO3E] and [TeO4E] polyhedra. The layers can be regarded as infinite molecules without any net charge and only weak van der Waals forces connect them to each other. The halides and the lone-pair, E, of TeIV protrude from the layers.

  • 9.
    Becker, Richard
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Prester, Mladen
    Berger, Helmuth
    Johnsson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Drobac, Djuro
    Zivkovic, Ivica
    Crystal structure and magnetic properties of the new cobalt tellurite halide Co5(TeO3)4X2 (X = Cl, Br)2007Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 9, nr 3-4, s. 223-230Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new cobalt tellurite halides Co5(TeO3)4Cl2 and Co5(TeO3)4Br2 have been synthesized and found to be iso-structural with Ni5(TeO3)4X2 (X = Cl, Br). Co5(TeO3)4X2 crystallizes in the monoclinic system space group C2/c, and the Br-phase has the lattice parameters a = 20.440(1) Å, b = 5.2760(2) Å, c = 16.4710(7) Å, β = 124.790(5)°, and Z = 4. The crystal structures were solved from single-crystal X-ray data, R1 = 1.90 and 1.77, respectively, for the Cl- and Br-phases. The crystal structure is layered with only weak van der Waals' interactions in between the layers. The layers are built by large [Co5O16X2] groups consisting of five edge- and face-sharing Co-octahedra. Each group is connected to adjacent groups via corner sharing through common oxygen atoms as well as through [TeO3E] groups. Magnetic susceptibility measurements on oriented single crystals reveal pronounced anisotropy in a broad temperature range and clear signs of antiferromagnetic ordering at low temperatures. Anisotropic susceptibility of an iso-structural Ni-based compound was also studied and compared with the corresponding results of Co5(TeO3)4X2. Magnetic anisotropy is discussed in framework of single-ion anisotropy effects.

  • 10. Berggren, Gustav
    et al.
    Huang, Ping
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Styring, Stenbjorn
    Anderlund, Magnus F.
    Thapper, Anders
    Synthesis and characterisation of low valent Mn-complexes as models for Mn-catalases2010Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, nr 45, s. 11035-11044Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work we report the synthesis of two novel manganese complexes, [L1(3)Mn(6)(II)](ClO4)(6) (1 center dot(ClO4)(6)) and [L2Mn(2)(II)(mu-OAc)(mu-Cl)](ClO4)(2) (2 center dot(ClO4)(2)), where L1(2-) is the 2,2'-(1,3-phenylenebis(methylene))bis-((2-(bis(pyridin-2-ylmethyl)amino)ethyl)azanediyl)diacetic acid anion and L2 is N1,N1'-(1,3-phenylenebis(methylene))bis(N2,N2'-bis(pyridin-2-ylmethyl)ethane-1,2-diamine). The ligands Na(2)L1 and L2 are built on the same backbone, L2 only contains nitrogen donors, while two carboxylate arms have been introduced in Na(2)L1. The two complexes have been characterized by single-crystal X-ray diffraction, magnetic susceptibility, EPR spectroscopy, and electrochemistry. X-Ray crystallography revealed that 1 is a manganese(II) hexamer and 2 is a manganese(II) dimer featuring an unprecedented mono-mu-acetato, mono-mu-chlorido bridging motif. The ability of the complexes to catalyse H2O2 disproportionation, thereby acting as models for manganese catalases, has been investigated and compared to the activity of two other related manganese complexes. The introduction of carboxylate donors in the ligands, leading to increased denticity, resulted in a drop in H2O2 disproportionation activity.

  • 11. Berggren, Gustav
    et al.
    Thapper, Anders
    Huang, Ping
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Styring, Stenbjörn
    Ander, Magnus F.
    Mechanistic Studies on the Water-Oxidizing Reaction of Homogeneous Manganese-Based Catalysts: Isolation and Characterization of a Suggested Catalytic Intermediate2011Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, nr 8, s. 3425-3430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis, isolation, and characterization of two high-valent manganese dimers with isomeric ligands are reported. The complexes are synthesized and crystallized from solutions of low-valent precursors exposed to tert-butyl hydroperoxide. The crystal structures display centrosymmetric complexes consisting of Mn(2)(IV,IV)(mu-O)(2) cores, with one ligand coordinating to each manganese. The ligands coordinate with the diaminoethane backbone, the carboxylate, and one of the two pyridines, while the second pyridine is noncoordinating. The activity of these complexes, under water oxidation conditions, is discussed in light of a proposed mechanism for water oxidation, in which this type of complexes have been suggested as a key intermediate.

  • 12. Bhatt, Aarti Sripathi
    et al.
    Bhat, Denthaje Krishna
    Santosh, Mysore Sridhar
    Tai, Cheuk-wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Chitosan/NiO nanocomposites: a potential new dielectric material2011Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, nr 35, s. 13490-13497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study of electrochemical behavior of organic-inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 x 10(-2) S cm(-1) is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol(-1).

  • 13. Breistein, Palle
    et al.
    Johansson, Jonas
    Ibrahem, Ismail
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Cordova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    One-Step Catalytic Enantioselective a-Quaternary 5-Hydroxyproline Synthesis: An Asymmetric Entry to Highly Functionalized a-Quaternary Proline Derivatives2012Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, nr 6, s. 1156-1162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The highly enantioselective cascade reaction between N-protected a-cyanoglycine esters and a,beta-unsaturated aldehydes is disclosed. The reaction represents a one-step entry to polysubstituted 5-hydroxyproline derivatives having a quaternary a-stereocenter generally in high yields with up to >95:5 dr and 99:1 er. It is also a direct catalytic two-step entry to functionalized a-quaternary proline derivatives.

  • 14. Brent, Rhea
    et al.
    Cubillas, Pablo
    Stevens, Sam M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Jelfs, Kim E.
    Umemura, Ayako
    Gebbie, James T.
    Slater, Ben
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Holden, Mark A.
    Anderson, Michael W.
    Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation2010Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, nr 39, s. 13858-13868Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A molecular-scale understanding of crystal growth is critical to the development of important materials such as pharmaceuticals, semiconductors and catalysts. Only recently has this been possible with the advent of atomic force microscopy that permits observation of nanoscopic features on solid surfaces under a liquid or solution environment. This allows in Situ measurement of important chemical transformations such as crystal growth and dissolution. Further, the microscope can access not only an accurate height measurement of surface topography, important to deduce structural elements, but also the forces involved during nanoscopic processes. We have discovered that it is possible to use these features to "illuminate" critical nanoscopic chemical events at crystal surfaces and at the same time extract the associated energies and unstitch the details of the stepwise mechanism of growth and dissolution. This approach has been developed using nanoporous crystals of the heterogeneous catalyst zeolite L; however, in principle the approach could be adapted to many crystal growth problems.

  • 15. Brent, Rhea
    et al.
    Stevens, Sam M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Anderson, Michael W.
    Coaxial Core Shell Overgrowth of Zeolite L - Dependence on Original Crystal Growth Mechanism2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 12, s. 5182-5186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the first reported core-shell material combining zeolite L (LTL) and barium-exchanged zeolite L (Ba-LTL) is described The use of atomic force microscopy to probe the LTL surface growth mechanism was employed to understand the growth pattern of the resultant Ba-LTL coaxial overgrowth layer Additionally the dependence of the original crystal surface on the resulting habit of the Ba-LTL core-shell layer is explained High-resolution scanning electron microscopy (HRSEM) was employed to observe the fine detail of the Ba-LTL layer, and cross-sectional polishing was used to view the boundary between the two crystalline materials

  • 16. Brouwer, Darren H.
    et al.
    Cadars, Sylvian
    Eckert, Juergen
    Liu, Zheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Chmelka, Bradley F.
    A General Protocol for Determining the Structures of Molecularly Ordered but Noncrystalline Silicate Frameworks2013Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, nr 15, s. 5641-5655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A general protocol is demonstrated for determining the structures of molecularly ordered but noncrystalline solids, which combines constraints provided by X-ray diffraction (XRD), one- and two-dimensional solid-state nuclear magnetic resonance (NMR) spectroscopy, and first-principles quantum chemical calculations. The approach is used to determine the structure(s) of a surfactant-directed layered silicate with short-range order in two dimensions but without long-range periodicity in three-dimensions (3D). The absence of long-range 3D molecular order and corresponding indexable XRD reflections precludes determination of a space group for this layered silicate. Nevertheless, by combining structural constraints obtained from solid-state Si-29 NMR analyses, including the types and relative populations of distinct Si-29 sites, their respective Si-29-O-Si-29 connectivities and separation distances, with unit cell parameters (though not space group symmetry) provided by XRD, a comprehensive search of candidate framework structures leads to the identification of a small number of candidate structures that are each compatible with all of the experimental data. Subsequent refinement of the candidate structures using density functional theory calculations allows their evaluation and identification of best framework representations, based on their respective lattice energies and quantitative comparisons between experimental and calculated Si-29 isotropic chemical shifts and (2)J(Si-29-O-Si-29) scalar couplings. The comprehensive analysis identifies three closely related and topologically equivalent framework configurations that are in close agreement with all experimental and theoretical structural constraints. The subtle differences among such similar structural models embody the complexity of the actual framework(s), which likely contain coexisting or subtle distributions of structural order that are intrinsic to the material.

  • 17. Buxhuku, Mika
    et al.
    Hansen, Vidar
    Oleynikov, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Gjonnes, Jon
    The Determination of Rotation Axis in the Rotation Electron Diffraction Technique2013Inngår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 19, nr 5, s. 1276-1280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Methods to determine the rotation axis using the rotation electron diffraction technique are described. A combination of rotation axis tilt, beam tilt, and simulated experimental diffraction patterns with nonintegers zone axis has been used. Accurate knowledge of the crystallographic direction of the incident beam for deducing the excitation error of reflections simultaneously near Bragg positions is essential in quantitative electron diffraction. Experimental patterns from CoP3 are used as examples.

  • 18. Cederkrantz, D.
    et al.
    Nygren, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Palmqvist, A. E. C.
    Thermoelectric properties of partly Sb- and Zn-substituted Ba(8)Ga(16)Ge(30) clathrates2010Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, nr 11, s. 113711-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects on the thermoelectric properties of n-Ba(8)Ga(16)Ge(30) when substituting small amounts of the Ga or Ge with Sb or Zn have been investigated. A number of syntheses were prepared in quaternary systems of Ba(8)Ga(16)Ge(30) substituted with either Sb or Zn but only three samples were found to yield single phase products with nominal compositions of Ba(8)Ga(15)Sb(1)Ge(30), Ba(8)Ga(15)Zn(1)Ge(30) and Ba(8)Ga(16)Ge(28)Zn(2), respectively. When Ge was substituted for Zn the resulting sample remained n-type and an increase in thermopower and a decrease in thermal conductivity were achieved. These positive effects were accompanied with an increased electrical resistivity and thus the ZT was only somewhat improved up to about 400 degrees C. When substituting Ga with either Sb or Zn samples remained n-type but showed decreased thermopower and increased electrical resistivity and thermal conductivity. It is thus concluded that substitution of Ga with Zn or Sb is detrimental for the thermoelectric properties of Ba(8)Ga(16)Ge(30), whereas substitution of Ge with Zn appears a potent method for improving its performance.

  • 19.
    Chen, Hong
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Deng, Youqian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yu, Zhengbao
    Zhao, Huishuang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yao, Qingxia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    3D Open-Framework Vanadoborate as a Highly Effective Heterogeneous Pre-catalyst for the Oxidation of Alkylbenzenes2013Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 25, nr 24, s. 5031-5036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three three-dimensional (3D) open-framework vanadoborates, denoted as SUT-6-Zn, SUT-6-Mn, and SUT-6-Ni, were synthesized using diethylenetriamine as a template. SUT-6-Zn, SUT-6-Mn, and SUT-6-Ni are isostructural and built from (VO)(12)O-6 B18O36(OH)(6) clusters bridged by ZnO5, MnO6, and NiO6 polyhedra, respectively, to form the 3D frameworks. SUT-6 is the first vanadoborate with a 3D framework. The framework follows a semiregular hxg net topology with a 2-fold interpenetrated diamond-like channel system. The amount of template used in the synthesis played an important role in the dimensionality of the resulting vanadoborate structures. A small amount of diethylenetriamine led to the formation of this first 3D vanadoborate framework, while an increased amount of diethylenetriamine resulted in vanadoborates with zero-dimensional (0D) and one-dimensional (1D) structures. SUT-6-Zn was proved to be an efficient heterogeneous precatalyst for the oxidation of alkylbenzenes.

  • 20. Cheon, Jae Yeong
    et al.
    Kim, Taeyoung
    Choi, YongMan
    Jeong, Hu Young
    Kim, Min Gyu
    Sa, Young Jin
    Kim, Jaesik
    Lee, Zonghoon
    Yang, Tae-Hyun
    Kwon, Kyungjung
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi. Korea Advanced Institute of Science and Technology, Republic of Korea.
    Park, Gu-Gon
    Adzic, Radoslav R.
    Joo, Sang Hoon
    Ordered mesoporous porphyrinic carbons with very high electrocatalytic activity for the oxygen reduction reaction2013Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, s. 2715-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high cost of the platinum-based cathode catalysts for the oxygen reduction reaction (ORR) has impeded the widespread application of polymer electrolyte fuel cells. We report on a new family of non-precious metal catalysts based on ordered mesoporous porphyrinic carbons (M-OMPC; M = Fe, Co, or FeCo) with high surface areas and tunable pore structures, which were prepared by nanocasting mesoporous silica templates with metalloporphyrin precursors. The FeCo-OMPC catalyst exhibited an excellent ORR activity in an acidic medium, higher than other non-precious metal catalysts. It showed higher kinetic current at 0.9 V than Pt/C catalysts, as well as superior long-term durability and MeOH-tolerance. Density functional theory calculations in combination with extended X-ray absorption fine structure analysis revealed a weakening of the interaction between oxygen atom and FeCo-OMPC compared to Pt/C. This effect and high surface area of FeCo-OMPC appear responsible for its significantly high ORR activity.

  • 21. Cho, Hae Sung
    et al.
    Miyasaka, Keiichi
    Kim, Hyungjun
    Kubota, Yoshiki
    Takata, Masaki
    Kitagawa, Susumu
    Ryoo, Ryong
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Study of Argon Gas Adsorption in Ordered Mesoporous MFI Zeolite Framework2012Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, nr 48, s. 25300-25308Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An ordered mesoporous MFI zeolite material (Meso-MFI) was prepared by using CMK-type mesoporous carbons as a hard template. The Meso-MFI exhibits both structural and adsorption differences compared to the conventional bulk MFI zeolite. To study the argon (Ar) adsorption process in Meso-MFI, an in situ gas adsorption powder X-ray diffraction (XRD) analysis was performed using synchrotron X-ray source. Structural rearrangement of the mesoporous MFI zeolite upon Ar adsorption at low temperature (83 K) was intensively studied together with Ar adsorption process in Meso-MFI. We observed that a structural transition of the Meso-MFI zeolite framework from monoclinic (P2(1)/n) to orthorhombic (Pnma) occurred at around 126 Pa at 83 K. Positions of Ar atoms are determined as a function of the Ar gas pressure through Rietveld refinement of powder XRD data. Ar atoms are observed at straight channels, sinusoidal channels, and the intersection of these channels at low pressure. As gas pressure increases, Ar atoms in the pore intersection are pulled off from the intersection toward the straight and sinusoidal channels. The pore shape of the straight channel is changed accordingly with the amount of adsorbed Ar atoms within the pores from circular to oval. These results indicate that Ar adsorption induces not only continuous rearrangement of framework atoms but also symmetry change in the Meso-MFI. A molecular simulation study combined with Rietveld refinement of in situ XRD data provided a full understanding of the adsorption process of Ar in Meso-MFI.

  • 22. Cong, Rihong
    et al.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Yang, Tao
    Li, Mingrun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liao, Fuhui
    Wang, Yingxia
    Lin, Jianhua
    Syntheses and Crystal Structures of Two New Bismuth Hydroxyl Borates Containing [Bi(2)O(2)](2+) Layers: Bi(2)O(2)[B(3)O(5)(OH)] and Bi(2)O(2)[BO(2)(OH)]2011Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, nr 11, s. 5098-5104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new bismuth hydroxyl borates, Bi(2)O(2)[B(3)O5-(OH)] (I) and Bi(2)O(2)[BO(2)(OH)] (II), have been synthesized under hydrothermal conditions. Their structures were determined by single-crystal and powder X-ray diffraction data, respectively. Compound I crystallizes in the orthorhombic space group Pbca with the lattice constants of a = 6.0268(3) angstrom, b = 11.3635(6) angstrom, and c = 19.348(1) angstrom. Compound II crystallizes in the monoclinic space group Cm with the lattice constants of a = 5.4676(6) angstrom, b = 14.6643(5) angstrom, c = 3.9058(1) angstrom, and beta = 135.587(6)degrees. The borate fundamental building block (FBB) in I is a three-ring unit [B(3)O(6)(OH)](4-), which connects one by one via sharing corners, forming an infinite zigzag chain along the a direction. The borate chains are further linked by hydrogen bonds, showing as a borate layer within the ab plane. The FBB in II is an isolated [BO(2)(OH)](2-) triangle, which links to two neighboring FBBs by strong hydrogen bonds, resulting in a borate chain along the a direction. Both compounds contain [Bi(2)O(2)](2+) layers, and the [Bi(2)O(2)](2+) layers combine with the corresponding borate layers alternatively, forming the whole structures. These two new bismuth borates are the first ones containing [Bi(2)O(2)](2+) layers in borates. The appearance of Bi(2)O(2)[BO(2)(OH)] (II) completes the series of compounds Bi(2)O(2)[BO(2)(OH)], Bi(2)O(2)CO(3), and Bi(2)O(2)[NO(3)(OH)] and the formation of Bi(2)O(2)[B(3)O(5)(OH)] provides another example in demonstrating the polymerization tendency of borate groups.

  • 23. Cong, Rihong
    et al.
    Yang, Tao
    Wang, Zheming
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liao, Fuhui
    Wang, Yingxia
    Lin, Jianhua
    Syntheses, Structure, and Luminescent Properties of Novel Hydrated Rare Earth Borates Ln(2)B(6)O(10)(OH)(4)center dot H(2)O (Ln = Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Y)2011Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, nr 5, s. 1767-1774Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ln(2)B(6)O(10)(OH)(4)center dot H(2)O (Ln = Pr, Nd, Sm-Gd, Dy, Ho, and Y), a new series of hydrated rare earth borates, have been synthesized under hydrothermal conditions. A single crystal of Nd analogue was used for the structure determination by X-ray diffraction. It crystallizes in the monoclinic space group C2/c with lattice constants a = 21.756(4), b = 4.3671(9), c = 12.192(2) angstrom, and beta = 108.29(3)degrees. The other compounds are isostructural to Nd(2)B(6)O(10)(OH)(4)center dot H(2)O. The fundamental building block (FBB) of the polyborate anion in this structure is a three-membered ring [B(3)O(6)(OH)(2)](5-). The FBBs are connected by sharing oxygen atoms forming an infinite [B(3)O(5)(OH)(2)](3-) chain, and the chains are linked by hydrogen bonds, establishing a two-dimensional (2-D) [B(610)(OH)(4)center dot H(2)O](6-) layer. The 2-D borate layers are thus interconnected by Ln(3+) ions to form the complex three-dimensional structure. Ln(2)B(6)O(10)(OH)(4)center dot H(2)O dehydrates stepwise, giving rise to two new intermediate compounds Ln(2)B(6)O(10)(OH)(4) and Ln(2)B(6)O(11) (OH)(2). The investigation on the luminescent properties of Gd(2-2x)Eu(2x)B(6)O(10)(OH)(4)center dot H(2)O (x = 0.01-1.00) shows a high efficiency of Eu(3+) f-f transitions and the existence of the energy transfer process from Gd(3+) to Eu(3+). Eu(2)B(6)O(10)(OH)(4)center dot H(2)O and its two dehydrated products, Eu(2)B(6)O(10)(OH)(4) and Eu(2)B(6)O(11)(OH)(2), present the strongest emission peak at 620 nm ((5)D(0) -> (7)F(2) transition), which may be potential red phosphors.

  • 24. Cubillas, Pablo
    et al.
    Castro, Maria
    Jelfs, Kim E.
    Lobo, Alan J. W.
    Slater, Ben
    Lewis, Dewi W.
    Wright, Paul A.
    Stevens, Sam M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Anderson, Michael W.
    Spiral Growth on Nanoporous Silicoaluminophosphate STA-7 as Observed by Atomic Force Microscopy2009Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 9, nr 9, s. 4041-4050Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Atomic force microscopy was used to study the surface of STA-7 crystals. STA-7 is a silicoaluminophosphate, nanoporous solid formed by interlinked double six ring units (D6R). Observations showed the formation of three distinct types of spirals at tow supersaturation conditions. The {001} face shows spirals with isotropic shapes and a Burgers vector of 0.9 nm, which corresponds to one D6R or one unit cell along the < 001 > direction. The {100} face contains two distinct types of spirals. The first has a Burgers vector of 0.9 rim, or half a unit cell along < 100 >. This dislocation produces a change in the ""stacking"" sequence of the D6Rs generating all overgrowth with the AEI structure. The second type is an interlaced spiral and is generated by a dislocation with a Burgers vector of 1.8 nm or one unit cell, leading to the formation of two substeps each with a different growth anisotropy. This anisotropy is directed by the shape of the substep and the energetics of template attachment. The preponderance of a surface coating of a secondary phase will have significant consequences on applications reliant on intracrystalline diffusion, such as catalysis, where, owing to diffusion limitations, the outermost structure dominates the functional properties.

  • 25. Cubillas, Pablo
    et al.
    Gebbie, James T.
    Stevens, Sam M.
    Blake, Nicola
    Umemura, Ayako
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Anderson, Michael W.
    Atomic Force Microscopy and High Resolution Scanning Electron Microscopy Investigation of Zeolite A Crystal Growth. Part 2: In Presence of Organic Additives2014Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, nr 40, s. 23092-23099Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nanoscopic details of the crystal growth of zeolite. A in the presence of the organic modifiers. diethanolmaine (DEA) and triethanolamine (TEA) has been determined using a combination of atomic force microscopy (AFM) and high-resolution scanning electron microscopy (HRSEM) coupled with Monte Carlo simulations. Crystallization of zeolite A in the presence of TEA was faster than when the growing solution contained DEA. In addition, the morphology of the final zeolite A crystals depended on the type of organic molecule, with TEA producing crystals bound only by {100} facets and DEA leading to the formation of relatively large {110} faces. These features can be explained in terms of the relative Si/Al in the growing medium and its control due to the different affinity of the organic molecules to Al. In addition, synthesis Si/Al in the growing medium and its contorl due to the different affinity of the organic molecules to Al. In additon synthesis performed at 90 degrees C showed the apperance of {211} facets Careful review of the HRSEM and AFM images, in addition to comparion with the MC simulations, reveals that these are in fact pseudofacets products of the slow dissolution of the metastable zeolite. A crsytals. This proves that the final habit of the LTA crystals can be governed by very small changes in saturation of the growing medium, and control of this parameter can prove advantageous when designing crystals for industrial applications.

  • 26. Cubillas, Pablo
    et al.
    Stevens, Sam M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Blake, Nicola
    Umemura, Ayako
    Chong, Chin B.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Anderson, Michael W.
    AFM and HRSEM Invesitigation of Zeolite A Crystal Growth. Part 1: In the Absence of Organic Additives2011Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, nr 25, s. 12567-12574Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystallization of zeolite A by the verified synthesis method was studied by means of high-resolution scanning electron microscopy (HRSEM) and atomic force microscopy (AFM). These methods show an evolution in the growth mode of zeolite A from an adhesive type at the beginning of the synthesis (high supersaturation) to birth-and-spread growth at the end of the synthesis (low supersaturation). Additionally, HRSEM provides direct proof on the formation of zeolite A crystals at the surface of the amorphous gel and the aggregation of crystals at early stages of synthesis, which leads to intergrowth formation. For the first time, high-resolution AFM images were taken on the {110} and {111} faces of zeolite A. Growth on {110} faces takes place by a birth-and-spread mechanism, and the shape of the terraces is rectangular, with growth along the < 100 > directions being twice as fast as in the < 110 > directions. Growth on the {111} faces also takes place by a birth-and-spread mechanism via triangular-shaped terraces with edges parallel to < 110 > directions. Possible surface terminations for both faces are discussed, and crystal habit and surface topography are modeled by Monte Carlo simulations.

  • 27.
    Das, Arindam
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Alam, Rauful
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereocontrol in Synthesis of Homoallylic Amines. Syn Selective Direct Allylation of Hydrazones with Allylboronic Acids2014Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, nr 14, s. 3808-3811Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allylboronic acids directly react with acyl hydrazones, affording homoallylic amine derivatives. The reaction proceeds with very high syn selectivity, which is the opposite of the stereochemistry observed for allylboration of imines. The reaction can be carried out with both aromatic and aliphatic acyl hydrazones. Based on our studies the excellent syn stereochemistry can be explained by chelation control of the acyl hydrazone and the B(OH)(2) moiety.

  • 28. Deng, Hexiang
    et al.
    Grunder, Sergio
    Cordova, Kyle E.
    Valente, Cory
    Furukawa, Hiroyasu
    Hmadeh, Mohamad
    Gandara, Felipe
    Whalley, Adam C.
    Liu, Zheng
    Asahina, Shunsuke
    Kazumori, Hiroyoshi
    O'Keeffe, Michael
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Stoddart, J. Fraser
    Yaghi, Omar M.
    Large pore apertures in a series of metal organic frameworks2012Inngår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 336, nr 6084, s. 1018-1023Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a strategy to expand the pore aperture of metal-organic frameworks (MOFs) into a previously unattained size regime (>32 angstroms). Specifically, the systematic expansion of a well-known MOF structure, MOF-74, from its original link of one phenylene ring (I) to two, three, four, five, six, seven, nine, and eleven (II to XI, respectively), afforded an isoreticular series of MOF-74 structures (termed IRMOF-74-I to XI) with pore apertures ranging from 14 to 98 angstroms. All members of this series have non-interpenetrating structures and exhibit robust architectures, as evidenced by their permanent porosity and high thermal stability (up to 300 degrees C). The pore apertures of an oligoethylene glycol-functionalized IRMOF-74-VII and IRMOF-74-IX are large enough for natural proteins to enter the pores.

  • 29.
    Deng, Hong-Ping
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Allylic sp (3) C-H borylation of alkenes via allyl-Pd intermediates: an efficient route to allylboronates2014Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, nr 65, s. 9207-9210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium catalyzed allylic C-H functionalization was performed using exocyclic alkene substrates. Multi-component synthesis of stereodefined homoallylic alcohols could be performed using a reaction sequence involving allylic C-H borylation and allylation of aldehydes.

  • 30.
    Dey, Kalpana R.
    et al.
    Leibniz Univ Hannover, Inst Mineral, Hannover, Germany .
    Debnath, Tapas
    Leibniz Univ Hannover, Inst Mineral, Hannover, Germany .
    Ruescher, Claus H.
    Leibniz Univ Hannover, Inst Mineral, Hannover, Germany .
    Sundberg, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Hussain, Altaf
    Univ Dhaka, Dept Chem, Dhaka 1000, Bangladesh .
    Synthesis and characterization of niobium doped hexagonal tungsten bronze in the systems, Cs(x)Nb(y)W(1-y)O(3)2011Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 46, nr 5, s. 1388-1395Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Samples of nominal compositions, Cs(0.25)Nb (y) W(1-y) O(3) and Cs(0.3)Nb (y) W(1-y) O(3) with 0.0 a parts per thousand currency sign y a parts per thousand currency sign 0.25 and 0.0 a parts per thousand currency sign y a parts per thousand currency sign 0.3 were synthesized using appropriate amounts of Cs(2)WO(4), WO(3) and WO(2) in evacuated and closed silica glass tubes at 800 A degrees C. The polycrystalline products contain hexagonal shaped crystals of up to 15 mu m diameter as long as y a parts per thousand currency sign 0.15. X-ray powder patterns of the samples reveal the formation of hexagonal tungsten bronze (HTB-I) type phase with y < 0.1. A mixture of HTB-I and an analogous less reduced hexagonal tungsten bronze (HTB-II) type phase is seen when y a parts per thousand yen 0.1. HTB-II content increases with increasing y, revealing close similarity to bronzoid type phases when y = x. Results of SEM/EDX analysis also support a partial substitution of tungsten by niobium in the HTB-I type phase. Infrared absorption and optical reflectivity data shows the effect of increasing amount of non-metallic phase for y > 0.1 and the effect of counterdoping by Nb(5+)/W(5+) substitution in the metallic HTB-I type phase for y a parts per thousand currency sign 0.1, respectively. Reinvestigations in the system Rb(0.3)Nb (y) W(1-y) O(3) (0.0 a parts per thousand currency sign y a parts per thousand currency sign 0.175) show similar results with increasing content of HTB-II type phase related with y.

  • 31.
    Eden, Mattias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för fysikalisk kemi.
    Grins, Jekabs
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för oorganisk kemi.
    Jansson, Kjell
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Shen, Zhijian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Al and O substitutions in BaS-phases, Ba2AlxSi12-xN16-xO2+x: A TEM, XRD and solid-state NMR study2008Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 10, nr 1, s. 50-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a series of Ba-based oxonitrido-silicate S-phases (Ba2AlxSi12-xN16-xO2+x) spanning a compositional range up to x approximate to 3, we examine the incorporation of Al and O by Si-29 and Al-27 magic-angle spinning (MAS) solid state nuclear magnetic resonance (NMR) and Al-27 triple-quantum MAS (3QMAS). The 3QMAS spectra reveal Al-27 signals from two distinct structural environments, assigned to AlN4 or AlN3O tetrahedra, respectively, and with their relative amounts depending on the S-phase substitution parameter x. Si-29 NMR show variable fractions of SiN4 and SiN3O environments. The NMR results accord overall with a structural substitution model for which O enters at one crystallographic position (occupied according to N4-xOx), in conjunction with a random Al for Si substitution at two distinct crystallographic positions. This leads to S-phase frameworks built from SiN4, SiN3O, AlN4 and AlN3O tetrahedra.

  • 32.
    Eklöf, Daniel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Fischer, A.
    Wu, Y.
    Scheidt, E. -W
    Scherer, W.
    Haussermann, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Transport properties of the ii v semiconductor znsb2013Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 1, nr 4, s. 1407-1414Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The intermetallic compound ZnSb is an electron poor (II-V) semiconductor with interesting thermoelectric properties. Electrical resistivity, thermopower and thermal conductivity were measured on single crystalline and various polycrystalline specimens. The work establishes the presence of impurity band conduction as an intrinsic phenomenon of ZnSb. The impurity band governs electrical transport properties at temperatures up to 300-400 K after which ZnSb becomes an intrinsic conductor. Furthermore this work establishes an inherently low lattice thermal conductivity of ZnSb, which is comparable to the state-of-the- art thermoelectric material PbTe. It is argued that the impurity band relates to the presence of Zn defects and the low thermal conductivity to the electron-poor bonding properties of ZnSb.

  • 33.
    Eriksson, Lars
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Melcher, Charles L.
    Eriksson, Marita
    Rothfuss, Harold
    Grazioso, Ron
    Aykac, Mehmet
    Design Considerations of Phoswich Detectors for High Resolution Positron Emission Tomography2009Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 56, nr 1, s. 182-188Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A way to improve the spatial resolution in positron emission tomography (PET) is to determine the depth-of-interaction (DOI) in the detector. A way to achieve this is to use the phoswich approach, a detector with two or more layers of different scintitlators. The layer identification is done by using differences in scintillation decay time and pulse shape discrimination techniques. The advantages of the concept have been demonstrated in the HRRT high resolution PET system using a LSO/LYSO combination giving a high spatial resolution uniformity of around 2.5 mm within a larger part of the imaged volume. A phoswich combination that lately has received attention is LuAP/LSO or LuYAP/LSO. The suggestions come from the Crystal Clear Collaboration and there is a patent application for its use in PET. This particular combination of phoswich may, however, have a complication since both LuAP and LuYAP emit in the excitation band of LSO, thus making the functionality more complex. In the present paper we have looked into this and suggested different ways to overcome potential drawbacks.

  • 34.
    Fahlquist, Henrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Kadir, Abdulkarim
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Structural characterization of Sr4Mg4H4[CoH5]3 shows the importance of support from polarizingcounter ions to 3d transition metal hydrido complexesInngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of the title compound was refined from neutronpowder diffraction data in the cubic space group P-43m (215). The unitcell contains one formula unit with 3 structurally equivalent [Co(I)H5]4-complexes as well as 4 interstitial hydride (H-) ions. The presence ofthe larger and less polarizing Sr2+ ions weakens the bond in thecomplexes and probably also the stability of the structure. Attempts tosynthesize the corresponding Ba analogue failed in contrast to usingsmaller and more polarizing Ca2+ and Yb2+ counterions.

  • 35.
    Fahlquist, Henrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Moser, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Refson, Keith
    STFC Rutherford Appleton Laboratory.
    Parker, Stewart F.
    STFC Rutherford Appleton Laboratory.
    SrH2Mg2[Co(I)H5], BaH2Mg5[Co(-I)H4]2 and RbH2Mg5[Co(-I)H4 Ni(0)H4] illustrate how small variations in counter ions are important for the solid state stabilization of 3d-transition metal hydrido complexes as well as influencing electrical and magnetic propertiesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Variations in the counter ion support to low valent 3d transition metal hydrido complexes in solids state hydrides influence formal oxidation states as well as their electrical properties. In a combined study using neutron scattering and first principle calculations a very low formal oxidation state of (-I) can be described for cobalt in a slightly distorted tetrahedral Co(-I)H4-complex in BaH2Mg5[Co(-I)H4]2 and in the structurally closely related RbH2Mg5[Co(-I)H4 Ni(0)H4]. This indicates that the electron “back donating” effect via the polarisable hydride ions to the counter ions in the solid state hydrides, can be compared to more conventional “back bonding” and reduce the oxidation state down to -I. The hydrides were synthesised by hot sintering of transition metal powders with the corresponding binary alkali- and alkaline earth hydrides. In the similarly synthesized SrH2Mg2[Co(I)H5] cobalt is formally +I-valent,  showing a high sensitivity to subtle differences in the counter ion framework.

  • 36. Fan, Chaxing
    et al.
    Qiu, Huibin
    Ruan, Juanfang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Yan, Yong
    Wei, Zhixiang
    Che, Shunai
    Formation of chiral mesopores in conducting polymers by chiral lipid ribbon templating and “seeding” route2008Inngår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, nr 18, s. 2699-2707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conducting polymer nanofibers with controllable chiral mesopores in the size, the shape, and handedness have been synthesized by chiral lipid ribbon templating and “seeding” route. Chiral mesoporous conducting poly(pyrrole) (CMPP) synthesized with very small amount of chiral amphiphilic molecules (usually < 3%) has helically twisted channels with well-defined controllable pore size of 5–20 nm in central axis of the twisted fibers. The structure and chirality of helical mesopores have been characterized by high-resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM) and electron tomography. The average pore diameters of chiral mesopores were approximately estimated from the N2 adsorption–desorption data and calculated by the conversion calculation from helical ribbons to a rectangular straight tape. The pore size of CMPP has been controlled by choosing different alkyl chain lengths of chiral lipid molecules or precisely adjusting the H2O/EtOH volume ratio.

  • 37. Feng, Dawei
    et al.
    Wang, Kecheng
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liu, Tian-Fu
    Park, Jihye
    Wei, Zhangwen
    Bosch, Mathieu
    Yakovenko, Andrey
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Zhou, Hong-Cai
    A Highly Stable Zeotype Mesoporous Zirconium Metal-Organic Framework with Ultralarge Pores2015Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 1, s. 149-154Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Through topological rationalization, a zeotype mesoporous Zr-containing metal-organic framework (MOF), namely PCN-777, has been designed and synthesized. PCN-777 exhibits the largest cage size of 3.8nm and the highest pore volume of 2.8cm(3)g(-1) among reported Zr-MOFs. Moreover, PCN-777 shows excellent stability in aqueous environments, which makes it an ideal candidate as a support to incorporate different functional moieties. Through facile internal surface modification, the interaction between PCN-777 and different guests can be varied to realize efficient immobilization.

  • 38. Fischer, Christian E.
    et al.
    Mink, Janos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Hajba, Laszlo
    Bacsik, Zoltan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Nemeth, Csaba
    Mihaly, Judith
    Raith, Alexander
    Cokoja, Mirza
    Kuehn, Fritz E.
    Vibrational spectroscopic study of SiO2-based nanotubes2013Inngår i: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 66, s. 104-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel organic-inorganic hybrid nanotubes containing silica and ethane (EtSNT), ethylene (ESNT) and acetylene (ASNT) units, as well as brominated ESNT (Br-ESNT) and glycine-modified Br-ESNT (Gly-ESNT) have been studied by IR and Raman spectroscopy. The results are compared with the spectral features for conventional silica nanotubes (SNT) and amorphous silica. Bands peculiar to organic moieties have been detected and assigned. Assignment of the silicate backbone vibrations was based on the results of normal coordinate calculations. Furthermore, characteristic silicate, so-called 'nanotube' vibrations have been identified and their band positions have been summarized to serve as a future reference for such compounds. SiOSi antisymmetric stretchings were observed in the range 1000-1110 cm(-1), while the symmetric stretchings appeared between 760 and 960 cm(-1) for EtSNT, ESNT and Br-ESNT. Force constants have been refined for models of the repeating structure units: O3SiOSi(OSi)(3) for SNT and SiCHnCHnSi(OSi)(3) for organosilica nanotubes (n = 2, EtSNT: n = 1, ESNT and n = 0, ASNT). The calculated SiO stretching force constants were increased from 4.79 to 4.88 and 5.11 N cm(-1) for EtSNT, ESNT and ASNT, respectively. The force constants have been compared with those for several silicates and SiO bond length are predicted and discussed.

  • 39.
    Fors, Yvonne
    et al.
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur.
    Jalilehvand, Farideh
    Department of Chemistry, University of Calgary.
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Analytical Aspects of Waterlogged Wood in Historical Shipwrecks2011Inngår i: Analytical Sciences, ISSN 0910-6340, E-ISSN 1348-2246, Vol. 27, nr 8, s. 785-792Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Conservation methods applied to historical shipwrecks increasingly rely on combining modern analytical techniques to obtain new insights for specially adapted conservation treatments. Crystalline salts formed on waterlogged wood are identified by powder X-ray diffraction while X-ray fluorescence measurements along wood cores show penetration profiles of contaminating elements. Dedicated synchrotron-based X-ray absorption spectroscopy, especially sulfur and iron K-edge XANES, allows speciation of the large amounts of detrimental sulfur and iron compounds that often are found accumulated within the hull timbers, while high resolution X-ray imaging shows the distribution within the wood microstructure. By fitting spectra of model compounds to high quality sulfur K-edge XANES spectra one can obtain the relative amounts of different types of functional sulfur groups. FT-IR, NMR, ESCA, MALDI-TOF mass spectrometry and size exclusion chromatography are other useful techniques to analyze the status of the wood and of the consolidation agent polyethylene glycol. Examples are given from analyses of famous artifacts.

  • 40.
    Fredrickson, Daniel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Boström, Magnus
    Sandvik Materials Technology,.
    Grin, Yuri
    Max-Planck-Institut für Chemische Physik fester Stoffe.
    Lidin, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Re4Si7, First in a New MoSi2-Based Family of 14-Electron Phases2009Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, nr 33, s. 8108-8112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The compound Re4Si7 poses a long-standing structural mystery at the intersection of the quantum chemical and material properties areas of interest. Its atomic structure has gradually emerged over X-ray and electron diffraction studies since 1941 to be a complex ordering of Si vacancies on a MoSi2-type lattice, the details of which remain unresolved. In 1941, it was originally identified as ReSi2, adopting the MoSi2-type crystal structure (Figure 1).1a In this structure, Re atoms form a body-centered tetragonal lattice, while the Si atoms lie in the square-pyramidal interstitial spaces of this Re lattice. This was followed by two structure reports in progressively lower symmetry: an orthorhombic Immm solution (1983),1b and a triclinic P1 solution (1995),1c in which fractional occupancies on the Si sites adjust the composition to the Re4Si7 stoichiometry reported in a redetermination of the Re–Si phase diagram.1d Electron microscopy investigations then revealed complex superstructures and incommensurability in Re4Si7 samples.2 This work culminated in an attempt to solve its structure as an eight-fold supercell in the space group Cm from single-crystal synchrotron X-ray diffraction data (2004).1e Severe refinement instabilities were encountered, and the published structure shows chemically implausible Re–Si and Si–Si distances

  • 41. Fredrickson, Daniel C.
    et al.
    Lidin, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Venturini, Gerard
    Malaman, Bernard
    Christensen, Jeppe
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    The Origins of Superstructure Ordering and Incommensurability in Stuffed CoSn-type Phases2008Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, nr 26, s. 8195-8214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The CoSn structure type contains large interstitial void spaces that frequently host electropositive guest atoms, such as rare earth elements. In this stuffing process, an intriguing ordering occurs between the neighboring void spaces leading to a family of long-period superstructures comprising intergrowths of the ScFe6Ge6 and ScFe6Ga6 structure types. This superstucture ordering culminates in incommensurability in the REFe6Ge6–δGaδ systems with RE = Sc, Tb, and Lu. In this work, we derive a 3 + 1D superspace model encompassing this series of structures and investigate the origins of the structural trends in this family with electronic structure calculations, at both the LDA-DFT and extended Hckel levels. Using our 3 + 1D model, we refine the structures of four new ErFe6Ge6−δGaδ (0 ≤ δ ≤ 6) phases, two commensurate and two incommensurate, from powder X-ray diffraction data. The refinement results confirm trends observed in the Sc-, Tb-, and Lu-based series: a gradual lengthening and, eventually, turning of the q-vector as Ge is progressively exchanged for Ga. These trends, and the incommensurate ordering as a whole, are traced to a tension between two modes by which the host lattice responds to stuffing atom insertion: (1) an atomic charge modulation enhancing the anionic character of the cavity walls around the guest atoms, and (2) a positional modulation expanding the cavities occupied by guest atoms. These two modes direct the stuffing atom ordering pattern toward opposite ends of the ScFe6Ge6−ScFe6Ga6 intergrowth series. The full series of structures, complex and incommensurate, reflects various degrees of balance between these two factors.

  • 42.
    Fredrickson, Rie Takagi
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Hjelmqvist, Daisy Torino
    Johnsson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Lidin, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Helical chains of [MO5Cl] octahedra – Three compounds in the new family AEM2Te3O8Cl2 (AE = Ca, Sr and M = Co, Ni):  2009Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 11, nr 1, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The compounds CaCo2Te3O8Cl2, SrCo2Te3O8Cl2 and SrNi2Te3O8Cl2 were synthesized via solid–gas reactions and investigated using single-crystal X-ray diffraction. While the compound CaCo2Te3O8Cl2 formed large enough single crystals to allow for a detailed structural analysis, crystals of the Sr-containing compounds yielded evidence that they are isostructural. CaCo2Te3O8Cl2 crystallizes in the monoclinic system, space group P21/c, a = 6.537(2) Å, b = 9.088(2) Å, c = 19.500(9) Å, β = 113.36(4)°, Z = 4. It exhibits [CoO5Cl] helical chains along the [010] direction, connected by [CaO8] polyhedra, [TeO3E] tetrahedra and [TeO4E] trigonal bipyramids (the lone pair of electrons on TeIV is designated as E) to form a layer. The layers are held together only by weak van der Waals forces; the shortest interlayer distance is a TeCl contact of 3.432(4) Å.

  • 43.
    Frigell, Jens
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Cumpstey, Ian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Carbasugar analogues of galactofuranosides: beta-O-linked derivatives and towards beta-S-linked derivatives2011Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 346, nr 11, s. 1277-1290Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A selectively protected carbasugar analogue of beta-galactofuranose was synthesised from glucose using ring-closing metathesis as the key step. The carbasugar was converted into an alpha-galacto configured 1,2-epoxide, which was an effective electrophile in Lewis acid catalysed coupling reactions with alcohols. The epoxide was opened with regioselective attack at C-1 to give beta-galacto configured C-1 ethers. Using carbohydrates as nucleophiles, we synthesised a number of pseudodisaccharides. The epoxide was also regioselectively opened at C-1 with a sulfur nucleophile under basic conditions to give a beta-galacto configured C-1 thioether.

  • 44.
    Gao, Chuanbo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Sakamoto, Yasuhiro
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Che, Shunai
    Formation of Diverse Mesophases Templated by a Diprotic Anionic Surfactant2008Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, nr 36, s. 11423-11428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis system for mesophase formation, using the diprotic anionic surfactant N-myristoyl-l-glutamic acid (C14GluA) as the structuredirecting agent (SDA) and N-trimethoxylsilylpropyl-N,N,N-trimethylammonium chloride (TMAPS) as the co-structure-directing agent (CSDA), has been investigated and a full-scaled synthesis-field diagram is presented. In this system we have obtained mesophases including three-dimensional (3D) micellar cubic Fm-3m, Pm-3n, Fd-3m, micellar tetragonal P42/mnm, two-dimensional (2D) hexagonal p6mm and bicontinuous cubic Pn-3m, by varying the C14GluA/NaOH/TMAPS composition ratios. From the diagram it can be concluded that the mesophase formation is affected to a high degree by the organic/inorganicinterface curvature and the mesocage–mesocage electrostatic interaction. Bicontinuous cubic and 2D-hexagonalphases were found in the low organic/inorganic-interface curvature zones, whereas micellar cubic and tetragonal mesophases were found in the high organic/inorganic-interface curvature zones. Formation of cubic Fm-3m and tetragonal P42/mnm was favoured in highly alkaline zones with strong mesocage–mesocage interactions, and formation of cubic Pm-3n and Fd-3m was favoured with moderate mesocage–mesocage interactions in the less alkaline zones of the diagram.

  • 45.
    Gao, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Li, Mingrun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Romare, Kristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Royal Institute of Technology (KTH), Department of Organic Chemistry.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of a [3Fe2S] cluster with low redox potential from [2Fe2S] hydrogenase models: electrochemical and photochemical generation of hydrogen2011Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, Vol. 2011, nr 7, s. 1100-1105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the attempted replacement of carbon monoxide by the bis(phosphane) dppv in a dinuclear [2Fe2S] complex, a trinuclear [3Fe2S] complex with two bis(phosphane) ligands was unexpectedly obtained. On protonation, this gave a bridged hydride complex with an unusually low potential for the reduction of protons to molecular hydrogen. The redox potential also appears sufficiently positive for direct electron transfer from an excited [Ru(bpy)(3)](2+) sensitizer.

  • 46.
    Gebauer, Denis
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Gunawidjaja, Philips N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för fysikalisk kemi.
    Ko, J. Y. Peter
    Bacsik, Zoltan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Aziz, Baroz
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Liu, Lijia
    Hu, Yongfeng
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sham, Tsun-Kong
    Edén, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för fysikalisk kemi.
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Proto-Calcite and Proto-Vaterite in Amorphous Calcium Carbonates2010Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, nr 47, s. 8889-8891Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Amorphous order: Amorphous calcium carbonates (ACC) have an intrinsic structure relating to the crystalline polymorphs of calcite and vaterite. The proto-crystalline structures of calcite and vaterite (pc-ACC and pv-ACC) are analyzed by NMR (see picture), IR, and EXAFS spectroscopy, which shows that the structuring of ACC relates to the underlying pH-dependent equilibria.

  • 47. Grushko, B.
    et al.
    Kapush, D.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Wan, Wei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Hovmöller, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Al-rich region of Al-Pt2013Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 580, s. 618-625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The constitution of the Al-rich part of the Al-Pt alloy system is revised. Apart from the previously reported equilibrium Al4Pt, Al21Pt8 and Al2Pt phases, a complex intermetallic was revealed at 7576 at.% Al between 801 and 915 degrees C. Its structure determined by electron diffraction is orthorhombic (Bmmb, a = 1.983, b = 1.636 and c = 1.422 nm).

  • 48. Gueguen, Yann
    et al.
    Sharafat, Ali
    Grins, Jekabs
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Rouxel, Tanguy
    Viscosity of high-nitrogen content Ca-Si-O-N glasses2010Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 30, nr 16, s. 3455-3458Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The viscosity of three high-nitrogen content Ca-Si-O-N glasses, with 30-58 e/o N and 36-39 e/o Ca, was determined by micro-indentation. The measurements were made using an automated set-up, designed and built in-house, capable of measurements up to 1200 degrees C with applied loads of 0.01-15 N. The viscosity increases significantly with the nitrogen content and reaches viscosity values close to reported values for rare-earth silica oxynitride glasses. The glass transition temperatures range between 878 and 995 degrees C and are in very good agreement with values measured by differential thermal analysis. The apparent viscosity activation energies are very high, ranging from 855 to 2170 kJ/mol. The glasses can accordingly be classified as being both very refractory and very fragile. Implications of the viscosity values and mechanical properties of the glasses for their structures are discussed.

  • 49.
    Guo, Peng
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Yun, Yifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Wan, Wei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Gies, Hermann
    Zhang, Haiyan
    Xiao, Feng-Shou
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Ab initio structure determination of interlayer expanded zeolites by single crystal rotation electron diffraction2014Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, nr 27, s. 10593-10601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Layered solids often form thin plate-like crystals that are too small to be studied by single-crystal X-ray diffraction. Although powder X-ray diffraction (PXRD) is the conventional method for studying such solids, it has limitations because of peak broadening and peak overlapping. We have recently developed a software-based rotation electron diffraction (RED) method for automated collection and processing of 3D electron diffraction data. Here we demonstrate the ab initio structure determination of two interlayer expanded zeolites, the microporous silicates COE-3 and COE-4 (COE-n stands for International Network of Centers of Excellence-n), from submicron-sized crystals by the RED method. COE-3 and COE-4 are built of ferrierite-type layers pillared by (-O-Si(CH3)(2)-O-) and (-O-Si(OH)(2)-O-) linker groups, respectively. The structures contain 2D intersecting 10-ring channels running parallel to the ferrierite layers. Because both COE-3 and COE-4 are electron-beam sensitive, a combination of RED datasets from 2 to 3 different crystals was needed for the structure solution and subsequent structure refinement. The structures were further refined by Rietveld refinement against the PXRD data. The structure models obtained from RED and PXRD were compared.

  • 50.
    Gustafsson, Mikaela
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Crystal Formation and Size Control of Zeolitic Imidazolate Frameworks with Mixed Imidazolate Linkers2013Inngår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, nr 1, s. 55-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of synthesis parameters, such as batch composition and synthesis temperature, on the formationand crystal size of zeolitic imidazolate frameworks(ZIFs) using mixed linkers, imidazole (Im) and benzimidazole(bIm), were studied by X-ray powder diffraction(XRPD) and scanning electron microscopy (SEM). ZIF-7and ZIF-62 were identified as the main phases and a phasediagram relating the batch composition and the finalproduct was constructed based on XRPD and SEM. Therange of batch composition giving rise to ZIF-7 and ZIF-62was identified from the phase diagram. Changes of crystalsize and morphology of ZIF-7 and ZIF-62 in terms of batchcomposition and synthesis temperature were studied bySEM and different trends were observed for the two ZIFs.Thermogravimetric analysis (TGA) and in situ XRPDshowed that ZIF-62 possesses a similar high thermal stabilityas ZIF-7.

1234 1 - 50 of 169
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