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  • 151. Elversson, Jessica
    et al.
    Andersson, Karin
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Millqvist-Fureby, Anna
    An atomic force microscopy approach for assessment of particle density applied to single spray-dried carbohydrate particles2007In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 96, no 4, p. 905-912Article in journal (Refereed)
    Abstract [en]

    To evaluate an atomic force microscopy (A-FM) approach for effective density analysis of single spray dried carbohydrate particles in order to investigate the internal structure of the particles. In addition, the AFM method was compared to an established technique, that is gas pycnometry. Resonant frequency AFM analysis was employed for determination of the mass of individual particles of spray-dried lactose, mannitol, and a mixture of sucrose/dextran (4:1). The effective particle density was calculated using the diameter of the spherical particles obtained from light microscopy. The apparent particle density was further analyzed with gas pycnometry. It was observed by microscopy that particles appeared either ""solid"" or ""hollow."" A solid appearance applied to an effective particle density close to the true density of the material, whereas a density around 1 g/cm(3) corresponded to a hollow appearance. However, carbohydrates, which crystallized during spray drying, for example, mannitol appeared solid but the 3 average effective particle density was 0.95 g/cm, indicating a continuous but porous structure. AFM measurements of effective particle density corroborate the suggestion of differences in particle structure caused by the varying propensity of carbohydrates to crystallize during spray drying, resulting in mainly either amorphous hollow or crystalline porous particles.

  • 152.
    Engman, Bertel
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Physical Chemistry.
    Optical lifetime studies using time-resolved spectroscopy with applications to the solar chemical composition1985Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This survey presents six previously published papers dealing with time-resolved atomic and molecular spectroscopy with applications to the chemical composition of the solar atmosphere. Three methods of measuring mean lives of excited states have been used:

    Beam-foil spectroscopy Beam-laser spectroscopy High-frequency deflection

    The methods used to estimate the abundances of the chemical elements in the sun will also be outlined. The experimental work has been carried out at the Research Institute of Physics in Stockholm.

  • 153. Eriksson, Annika K
    et al.
    Lindberg, Fredrik
    Svensson, G
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Svedlindh, P
    Eriksson, Sten G
    Knee, Christopher S
    Influence of iron addition on the oxygen deficient Sr0.85Bi0.15Co1-xFexO3-d (0.0 ≤ x ≤ 1.0) perovskites2008In: Journal of Solid State Chemistry, Vol. 181, p. 2031-2040Article in journal (Refereed)
  • 154. Eriksson, Annika K.
    et al.
    Tran, Thuy
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Saxin, S
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Effects of A-site substitution on the structure and magnetic properties of Bi0.15Sr0.85-yAeyCo1-xFexO3-? perovskites2009In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 11, no 11, p. 1945-1954Article in journal (Refereed)
    Abstract [en]

    The effects of partial substitution of Sr2+ by Ca2+ and Ba2+ on the A-site of oxygen deficient perovskites, Bi0.15Sr0.85-yAeyCo1-xFexO3-?, where y = 0.29 for Ae = Ba and y = 0.17 for Ae =  Ca, and 0.0 ? x ? 1.0, have been investigated. The differing ionic size of the Ca2+ and Ba2+ cations influences both the crystal structure and the properties of the materials. The smaller Ca2+ cation favoured formation of an oxygen vacancy ordered perovskite superstructure (I4/mmm, a = 2ap, c = 4ap), meanwhile the presence of the larger Ba2+ cation promoted a disordered simple cubic structure (Pm-3m, a = ap) that was also found for all Fe containing samples, i.e. x ? 0.25. The samples were studied with PXRD, NPD, TGA, HREM and magnetic susceptibility measurements. All as-prepared samples exhibited long range G-type antiferromagnetic ordering. The effect of oxygen annealing was dramatic for the Bi0.15Sr0.68Ca0.17Co1-xFexO3-? series with a disappearance of magnetic order for x ? 0.25 linked to increasing spin glass properties. The oxygen content of the Bi0.15Sr0.56Ba0.29Co1-xFexO3-? as-prepared materials was generally higher than their Ca substituted counterparts, and the long range antiferromagnetic order was more resistant to oxygen annealing.

  • 155.
    Eriksson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Structural Chemistry.
    2,2’,6,6’-Tetrachloro-4,4’-propane-2,2-diyldiphenol, 2,2’,6-tribromo-4,4’-propane-2,2-diyldi phenol and 2,2’,6,6’-tetrabromo-4,4’-propane-2,2-diyldiphenol2001In: Acta crystallographica Section C, ISSN 0108-2701, Vol. 57, no 11, p. 1308-1312Article in journal (Refereed)
    Abstract [en]

    Three flame retardants with very similar molecular structures showing three different packing patterns have been studied. The crystal structure of 2,2',6,6'-tetrachloro-4,4'-propane-2,2-diyldiphenol, C15H12Cl4O2, can be described as a packing of sheets. The packing shows a very short intermolecular ClCl contact distance of 3.094  (2)  Å between pairs of molecules inside each sheet. The crystal structure of 2,2',6-tribromo-4,4'-propane-2,2-diyldiphenol, C15H13Br3O2, can be described as a packing of doubly stranded helical square tubes. These square helices are interconnected through BrBr contacts between different helices. Finally, a previously known structure, 2,2',6,6'-tetrabromo-4,4'-propane-2,2-diyldiphenol [Simonov, Cheban, Rotaru & Bels'skii (1986). Kristallografiya, 31, 397-399], C15H12Br4O2, which is the most commonly used flame retardant and which has twofold rotational symmetry, has been refined in the correct absolute configuration. The structure shows large differences from the chloro analogue with regard to packing, van der Waals distances and hydrogen-bond distances.

  • 156.
    Eriksson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Structural Chemistry.
    Jakobsson, Eva
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Structural Chemistry.
    Decabromodiphenyl ether1999In: Acta crystallographica Section C, ISSN 0108-2701, Vol. 55, no 12, p. 2169-2171Article in journal (Refereed)
    Abstract [en]

    Bis(pentabromophenyl) ether, C12Br100, shows strangedifferences in the endocyclic angles between the twodifferent rings, although they are both substituted inthe same manner. Several short van der Waals contact distances give clues to the anomalous endocyclic anglesand some hints to the formation of decompositionproducts. We suggest that the intermolecular Br...Brcontacts contribute to the distortions of the ring systems.Usually distortions of this kind would be explained fromhighly anisotropic TLS behaviour, but the data from thetitle compound do not show any conclusive TLS effects.

  • 157.
    Eriksson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Marsh, G
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Bergman, Å
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Structural Chemistry.
    3,4,5,6-Tetrabromo phenyl-2,3,4,5,6-pentabromo phenyl ether, C12HBr9O, 2,4,5,6-tetrabromo phenyl-2,3,4,5,6-pentabromo phenyl ether, C12HBr9O and 2,3,5,6-tetrabromo phenyl-2,3,4,5,6-pentabromo phenyl ether, C12HBr9O2004Manuscript (preprint) (Other (popular science, discussion, etc.))
  • 158.
    Eriksson, Lars
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Persson, Ingmar
    D’Angelo, Paola
    Lundberg, Daniel
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    A structural study of the N,N′-dimethylpropyleneurea solvated zinc(II) and cadmium(II) ions in solution and crystalline state2007In: Journal of Molecular Liquids, Vol. 131-32,, p. 105-112Article in journal (Refereed)
  • 159.
    Eriksson, Lars
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Department of Organic Chemistry.
    Methyl 3-O-alpha-D-mannopyranosyl beta-D-glucopyranoside tetrahydrate2008In: Acta Crystallographica Section E, ISSN 1600-5368, Vol. E64, no 8, p. o1639-o1640Article in journal (Refereed)
  • 160.
    Eriksson, Mirva
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2 composites2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Titanium has been used as a model substance to study how it behaves in a SPS apparatus when heating rate and/or pressure were varied during the sintering and deformation process. The sintering and deformation of Ti in SPS were compared with that occurring in the conventional hot pressing (HP) in order to reveal if there are any positive effects added by the use of SPS. The ductility of Ti was explored in order to understand the sintering and deformation of (Ti) x (TiB2)1-x composites with x = 0.05, 0.1, and 0.2, respectively, expressed in mol ratio. The temperature difference (DT) between the monitored and the temperature that the samples are exposed to was evaluated.

    It was noticed that Ti can be sintered at relatively low temperatures. High heating rate implied that the onset temperatures of the sintering and deformation processes decreased. Increasing pressure did not affect the onset temperature but revealed that the deformation of Ti is different if the experiments are conducted within the stability region of the a -phase region of Ti or if the deformation takes place in a temperature region that covers both a-and b-phase areas, i. e. the use of high pressures implied a one step deformation process while the use of low implied that the main part of the deformation took place in the b-phase region.

    (Ti) x (TiB2)1-x composites were prepared to full densities at 1500 °C using a holding time of 3 min and pressure of 50 MPa. During the SPS sintering the composite with x= 0.2 revealed the presence of TiB due to the reaction Ti + TiB 2 -> 2TiB while the composites with low x values did not show any formation of TiB. The formation of TiB impaired the mechanical properties. The deformation of composites was very difficult. Their deformability increased with increasing x and temperature as well as pressure. During the deformations of pre-sintered samples TiB was formed in all of the composites.

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  • 161.
    Eriksson, Mirva
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Nygren, Mats
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Fast densification and deformation of titanium powder2005In: Powder Metallurgy, ISSN 0032-5899, Vol. 48, no 3, p. 231-236Article in journal (Refereed)
    Abstract [en]

     A coarse titanium powder containing 0.2 wt-% oxygen with an average particle size of 45 micrometers was rapidly densified using the spark plasma sintering (SPS) technique. The fully consolidated specimens were also deformed in compression in the SPS unit and in a conventional hot pressing (HP) furnace. The densification and deformation behaviours were investigated by microstructural observation and examining the shrinkage and shrinkage rate recorded in real time. The efforts were focused on clarifying to what extent the possible spark discharging and intensive Joule heating at the particle contact points contribute to the densification, and what effect if any the pulsed electrical heating has on the densification. The results showed that what contributed to the densification were neither spark discharging nor anisotropic heating, but the particle deformation. Deformation occurs throughout the entire particle both in SPS and HP conditions, with a higher strain rate under SPS condition especially in the a phase region.

  • 162.
    Ertan, Anne
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Structural studies of dipyridylmethane based ligands and metal complexes1995Doctoral thesis, comprehensive summary (Other academic)
  • 163.
    Esmaeilzadeh, Saeid
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Crystal chemistry of manganese tantalum oxides2000Doctoral thesis, comprehensive summary (Other academic)
  • 164.
    Esmaeilzadeh, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, J.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sharafat, Ali
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Glass forming region in Ca-Si-O-N system using CaH2 as Ca source2008In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 28, no 14, p. 2659-2664Article in journal (Refereed)
    Abstract [en]

    The present work explores the glass-forming region in the Ca–Si–O–N system, particularly in the N-rich part of the system. Bulk oxynitride glasses in the Ca–Si–O–N system were prepared by melting mixtures of CaH2, SiO2 and Si3N4 powders in a nitrogen atmosphere at 1500–1650 °C. The glasses were characterized by X-ray powder diffraction, differential thermal analysis, scanning electron microscopy and transmission electron microscopy. Glass compositions were calculated from analyses obtained by energy dispersive X-ray (EDX) spectroscopy and combustion analysis, for cation and anion compositions, respectively. The glasses were found to be X-ray amorphous and gray to black in color. The glasses retain up to 58 e/o of nitrogen and 42 e/o of calcium. The glass formation depends on reaction kinetics and the precursor used. A strong exothermic reaction is observed at 850–1000 °C, leading to formation of amorphous and crystalline oxynitride phases that melt at high temperatures upon further heating. Glass transition temperatures (Tg) were observed to vary between 798 °C and 1050 °C, and crystallization occurs typically 130 °C above the glass transition temperature. The glass densities vary between 2.79 g/cm3 and 3.25 g/cm3.

  • 165.
    Esmaeilzadeh, Saeid
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Cai, Yanbing
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sialon ceramics prepared by using CaH2 as a sintering additive2008In: Journal of American Ceramic Society, Vol. 91, no 9, p. 2997-3004Article in journal (Refereed)
  • 166. Fan, C
    et al.
    Che, S
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Ruan, J
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Qiu, H
    Formation of Chiral Mesopores in Conducting Polymer by Chiral-Lipid-Ribbon Templating and “Seeding” Route2008In: Advanced Functional Materials, Vol. 18, p. 2699-2707Article in journal (Refereed)
  • 167. Fan, Chaxing
    et al.
    Qiu, Huibin
    Ruan, Juanfang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Yan, Yong
    Wei, Zhixiang
    Che, Shunai
    Formation of chiral mesopores in conducting polymers by chiral lipid ribbon templating and “seeding” route2008In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 18, p. 2699-2707Article in journal (Refereed)
    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.

  • 168.
    Feng, Xiaolong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Estimating molecular conformations by solid-state NMR spectroscopy1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Our understanding of structure-function relationships in biological systems demands new and more sophisticated methods for examining molecular structure. This thesis presents an effort of methodology development for molecular structure determination by solid-state NMR spectroscopy and applications to biological systems.

    Rotational Resonance NMR is established as a major tool for extracting molecular structural information in solids. Some further aspects of the technique are explored. The technique is applied to obtain the binding conformation of an inhibitor, TMPIP, bound to gastric H+/K+-ATPase, an ab heterodimer with a molecular weight of over 150 kDa.

    A novel solid-state NMR method for the determination of the torsional angle of a 13C-labeled H-C-C-H moiety is developed. A detailed theoretical introduction of the method is presented. The technique has been applied to determine the H-C10-C11-H torsional angle of the retinylidene chromophore in bovine rhodopsin, a 41 kDa integral membrane protein, and its photo-intermediate metarhodopsin-I.

    A new solid-state NMR method is developed. It may be used to estimate the Ramachandran ( angle in a protein backbone chain. A detailed theory is presented. It is demonstrated on an isotopically labeled tripeptide.

  • 169. Feuerbacher, M.
    et al.
    Thomas, C.
    Makongo, J.P.A.
    Hoffmann, S.
    Carrillo-Cabrera, W.
    Cardoso, R.
    Grin, Yu.
    Kreiner, G.
    Joubert, J.-M.
    Schenk, Th.
    Gastaldi, J.
    Nguyen-Thi, H.
    Mangelinck-Noël, N.
    Billia, B.
    Donnadieu, P.
    Czyrska-Filemonowicz, A.
    Zielinska-Lipiec, A.
    Dubiel, B.
    Weber, Th.
    Schaub, P.
    Krauss, G.
    Gramlich, V.
    Christensen, J.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Lidin, S.
    Fredrickson, D.
    Mihalkovic, M.
    Sikora, W.
    Malinowski, J.
    Brühne, S.
    Proffen, Th.
    Assmus, W.
    de Boissieu, M.
    Bley, F.
    Chemin, J.L.
    Schreuer, J.
    Steurer, W.
    The Samson phase, β-Mg2Al3, Revisited2007In: Zeitschrift für Kristallographie, ISSN 0044-2968, Vol. 222, no 6, p. 259-288Article in journal (Refereed)
  • 170. Feuerbacher, M.
    et al.
    Thomas, C.
    Makongo, JPA
    Hoffmann, S.
    Carrillo-Cabrera, Wilder
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Cardoso, R.
    Grin, Y.
    Kreiner, G.
    Joubert, JM.
    Schenk, T.
    Gastaldi, J.
    Nguyen-Thi, H.
    Mangelinck-Noël, N.
    Billia, B.
    Donnadieu, P.
    Czyrska-Filemonowicz, A.
    Zielinska-Lipiec, A.
    Dubiel, B.
    Weber, T.
    Schaub, P.
    Krauss, G.
    Gramlich, V.
    Christensen, Jeppe
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Fredrickson, Daniel
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Mihalkovic, M.
    Sikora, W.
    Malinowski, J.
    Brühne, S.
    Proffen, T.
    Assmus, W.
    Boissieu, M.
    Bley, F.
    Chemin, JL.
    Schreuer, J.
    The Samson phase, β-Mg2Al3, revisited2007In: Zeitschrift für Kristallographie, Vol. 222, no 6, p. 259-288Article in journal (Refereed)
  • 171.
    Flemström, Andreas
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Bis(2-ammonio-5-chloropyridine) tetradecachlorohexamolybdate2004In: Acta Crystallographica, Section E, ISSN 1600-5368, Vol. E60, p. M1303-m1305Article in journal (Refereed)
  • 172.
    Flemström, Andreas
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Dianilinium tetradecachlorohexamolybdate dihydrate: (PhNH3)2[(Mo6Cl8)Cl6]·2H2O2003In: Acta Crystallographica, Section E, ISSN 1600-5368, Vol. 59, no 4, p. m162-m164Article in journal (Refereed)
  • 173.
    Flemström, Andreas
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Solide Molydbenum(II) Chloride Cluster compounds From a Hudrogen Bonding Poin of View2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is based on a study of solid Molybdenum(II) chloride cluster compounds. The emphasis of the text is on the hydrogen network in the different compounds. The main analysis tool has been single crystal x-ray diffraction, and in some cases theoretical calculations have been performed to confirm the hydrogen positions.

    It has been shown that the Mo(II) cluster is a very good promoter for hydrogen bonds. The hydrogen bond networks studied here are fairly rigid and strong, except for one compound where the easy loss of a water molecule changes the water structure dramatically.

    There are several ways to alter the crystal structure and of course alter the hydrogen bond network.

    Ø Change the syntheses with respect to pH

    Ø Change the apical halogenides

    Ø Introducing cations instead of H3O+

    Ø Using protonated organic amino bases as cations and different organic solvents

    All of these methods have been tested and evaluated. The general conclusion is that the cluster units are nicely ordered in the hydrogen bond network.

  • 174.
    Flemström, Andreas
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hirsch, Tomas
    Eriksson, Lars
    Lidin, Sven
    The structures of X2[(Mo6Cl8)Cl6].nH2O, X = NH4, K, Rb, Cs2004In: Solid State Sciences, ISSN 1297-2558, Vol. 6, no 6, p. 509-517Article in journal (Refereed)
  • 175.
    Flemström, Andreas
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hirsch, Tomas
    Sehlstedt, Lina
    Lidin, Sven
    Ojamäe, Lars
    Effects from hydrogen bonds on water structure in (H3O)2[Mo6Cl8X6].yH2O X = Cl (y = 7), Br (y = 6), or I (y = 6)2002In: Solid State Sciences, ISSN 1297-2558, Vol. 4, no 8, p. 1017-1022Article in journal (Refereed)
  • 176.
    Flemström, Andreas
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Vintila, Simina
    Lidin, Sven
    Inheritance of guanidinium chloride structure in two Molybdenum(II) chloride salts2005In: Comptes rendus. Chimie, ISSN 1631-0748, E-ISSN 1878-1543, Vol. 8, no 11-12, p. 1750-1759Article in journal (Refereed)
    Abstract [en]

    Depending on the proticity of the solvent, two different salts may be crystallized from the combination of solutions of guanidinium chloride, C(NH2)3Cl, and the acidic hydrate of molybdenum dichloride, [(Mo6Cl8)Cl6](H20O9). From aprotic solvents such as dimethyl sulfoxide (DMSO) or formamide (FA), compound I, [(Mo6Cl8)Cl6]Cl6(C(NH2)3)8, crystallizes, while from protic solvents such as ethanol or water, compound II, [(Mo6Cl8)Cl6]Cl3(C(NH2)3)5, crystallises. In both compounds, the basic motif of the two parent structures, the octahedral [(Mo6Cl8)Cl6]2– cluster and the planar, triangular, C(NH2)3Cl3 entity are fairly well preserved. The assembly of the blocks, however, differs distinctly, and while both compounds are rather porous, compound I (s.g. Fm

    m, No. 225) has a volume of 27 Å3/non-hydrogen atom, compound II (s.g. C2/c, No. 15) is somewhat denser, with a volume of 24 Å3/non-hydrogen atom.

  • 177.
    Fors, Yvonne
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sulfur-Related Conservation Concerns in Marine Archaeological Wood: The Origin, Speciation and Distribution of Accumulated Sulfur with Some Remedies for the Vasa2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Synchrotron-based sulfur spectroscopy reveals a common concern for marine archaeological wood from seawater: accumulation of reduced sulfur compounds in two pathways. The distribution of sulfur species in the oak wood cell structure was mapped by scanning x-ray spectro-microscopy (SXM). Organically bound sulfur was found within lignin-rich parts, identified mainly as thiols and disulfides by sulfur K-edge x-ray absorption near edge structure (XANES) spectroscopy. Particles of iron sulfides, which may form in the presence of corroding iron, appeared in wood cavities. Cores scanned by x-ray fluorescence (XRF) show that high sulfur accumulation is restricted to the surface layers for the Swedish shipwreck Vasa, while the distribution is rather uniform throughout the hull timbers of the Mary Rose, U.K. Laboratory experiments, exposing fresh pine to simulated seabed conditions, show that the organically bound sulfur develop in reactions between lignin, exposed by cellulose-degrading erosion bacteria, and hydrogen sulfide produced in situ by scavenging sulfate reducing bacteria. With bacteria inoculated from shipwreck samples also iron sulfides formed. The iron sulfides oxidise in high humidity, and are the probable main cause of the numerous outbreaks on the Vasa’s hull of acidic sulfate salts, which were identified by x-ray powder diffraction (XRD). The iron ions catalyse several wood-degrading oxidative processes. Multi-elemental analyses were performed by scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (ESCA). The present amounts of total S remaining in the Vasa and the Mary Rose are estimated to at least 2 tonnes. After the Vasa´s spray treatment with polyethylene glycol solutions ceased in 1979, the continuing oxidation processes are estimated to have produced 2 tonnes of sulfuric acid in the wood. Laboratory experiments to gently neutralize acidic Vasa wood by ammonia gas have been conducted with promising results.

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  • 178.
    Fors, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Egsgaard, Helge
    Wickholm, Kristina
    Ammonia Treatment of Acidic Vasa Wood2009In: Proceedings 10th ICOM-CC WOAM Conference, Amsterdam 2007 / [ed] Per Hoffmann, Bremerhaven, 2009, p. 539-561Conference paper (Other academic)
    Abstract [en]

    Outbreaks of acidic sulfate salts have been reported in numerous areas on the wooden surfaces of the Swedish historical shipwreck Vasa (from 1628) in the Vasa Museum. Effects of ammonia vapour treatment to reduce the acidity in Vasa wood, similar to that previously applied to the Dutch East Indiaman Batavia (from 1629), have been investigated by means of solid state 13C-NMR and MALDI-TOF spectrometry. No major changes were found in the molecular weight distribution of the bulking agent polyethylene glycol (PEG) or in the crystallinity of pulp cellulose after mild exposure to ammonia vapour. Further studies on the long-term pH stability and the post-treatment properties of the wood using spectroscopic methods and mechanical testing are in progress.

  • 179.
    Fors, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Nilsson, Thomas
    Damian Risberg, Emiliana
    Sandström, Magnus
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Torssander, Peter
    Sulfur Accumulation in Pine Wood (Pinus sylvestris) Induced by Bacteria in Simulated Seabed Environment: Implications for Marine Archaeological Wood and Fossil Fuels2008In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, no 62, p. 336-347Article in journal (Refereed)
    Abstract [en]

    Fresh pine wood blocks were submerged in sulfate and iron(II) containing media, inoculated with bacterial consortia isolated from seawater, aiming to simulate the seabed conditions of the Vasa shipwreck (1628). The consortia contained erosion (EB) and sulfate-reducing bacteria (SRB). Sulfur K-edge x-ray absorption near edge structure (XANES) spectroscopy and scanning x-ray spectromicroscopy images showed that organic sulfur, mainly thiols (R-SH), had accumulated in the lignin-rich middle lamella in EB-degraded parts of the wood. The sulfur content in the wood increased more than 10 times in two years. In another series with active inoculums from marine archaeological wood, the sulfur XANES spectra showed after four years anaerobic treatment considerable amounts also of inorganic iron sulfides, Fe1-xS, which oxidized at atmospheric exposure. A sediment sample from the Vasa’s seabed was also rich in iron sulfides, including pyrite FeS2. X-ray fluorescence mappings of sulfur and phosphorous distributions indicate that scavenging SRB penetration, producing hydrogen sulfide in situ, is restricted to EB-degraded parts of the wood structure. The sulfur isotope depletion of 34S from d34S = 21‰ in marine sulfate to d34S = 6‰ and 1.8‰ for fractions of reduced sulfur and sulfate separated from a Vasa wood sample, respectively, suggests bacterial transformation. A fuller understanding of the routes of sulfur accumulation, as reactive iron sulfides and as organic sulfur, has important implications for improving conservation methods of marine archaeological wood. Moreover, the biogenic accumulation of organically bound sulfur specifically in lignin-rich parts of waterlogged wood has wider geochemical significance for fossil fuels of marine origin, as lignin-rich humic matter is important for the diagenetic formation of kerogens from anoxic marine sediments.

  • 180.
    Fors, Yvonne
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sandström, Magnus
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sulfur and Iron in Shipwrecks Create Conservation Concerns2006In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 35, no 5, p. 399-415Article in journal (Refereed)
    Abstract [en]

    Synchrotron-based sulfur X-ray absorption spectroscopy reveals considerable accumulation of organosulfur (e.g. thiols), pyrite and iron(II) sulfides in marine-archaeological wood preserved in seawater, e.g. for historical shipwrecks such as the Vasa and Mary Rose. In the museum, oxidation of the sulfur compounds in the presence of iron ions may cause severe acidity in the moist wood. This tutorial review discusses developments of conservation methods to remove acid and iron, and how to analyse and stabilise sulfur compounds in the wood.

  • 181.
    Fredrickson, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Boström, Magnus
    Sandvik Materials Technology,.
    Grin, Yuri
    Max-Planck-Institut für Chemische Physik fester Stoffe.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Re4Si7, First in a New MoSi2-Based Family of 14-Electron Phases2009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 33, p. 8108-8112Article in journal (Refereed)
    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

  • 182. Fredrickson, Daniel C.
    et al.
    Lee, Stephen
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Hoffmann, Roald
    Interpenetrating polar and nonpolar sublattices in intermetallics: The NaCd2 structure2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, no 12, p. 1958-1976Article, review/survey (Refereed)
  • 183. Fredrickson, Daniel C.
    et al.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Venturini, Gerard
    Malaman, Bernard
    Christensen, Jeppe
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    The Origins of Superstructure Ordering and Incommensurability in Stuffed CoSn-type Phases2008In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 26, p. 8195-8214Article in journal (Refereed)
    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.

  • 184.
    Fredrickson, Rie Takagi
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    A new synthetic strategy for low-dimensional compounds: Lone pair cations and alkaline earth spacers2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Complex transition metals oxyhalides containing a lone pair element, such as tellurium (IV), form an attractive research field because there is a high probability of finding new low-dimensionally arranged compounds and, particularly, a low-dimensionally arranged transition metals substructures, leading to interesting physical properties. Tellurium (IV) can drive the formation of many unusual structures because of its stereochemically active lone pair electrons, E. It commonly takes a coordination of three or four oxygen atoms to form either a TeO3E square pyramid or a TeO3+1E trigonal bipyramid. These lone pairs are very important players involved in lowering the dimensionality of crystal structures. Previous studies in transition metal tellurium (IV) oxohalide quarternary systems revealed a family of compounds, many of which exhibit interesting properties e.g. magnetic frustration. The unique point of this thesis is to employ alkaline earth elements (AE) to augment this ability of lone pair elements to lower the dimensionality of the transition metal arrangements. By this double usage of “chemical scissors” (a lone pair element used in conjunction with alkaline earth elements) we obtained new types of low-dimensionally arranged compounds.

    This thesis is focused on the syntheses and characterization of a series of compounds in the pentanary (five components) system AE-TeIV-TM-O-X (AE=alkaline earth metal, TM=transition metal and X=halogen), in which nine new compounds were found. The crystal structures of each of these compounds were determined by the single crystal X-ray diffraction data.

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  • 185.
    Fredrickson, Rie Takagi
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hjelmqvist, Daisy Torino
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Helical chains of [MO5Cl] octahedra – Three compounds in the new family AEM2Te3O8Cl2 (AE = Ca, Sr and M = Co, Ni):  2009In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 11, no 1, p. 13-17Article in journal (Refereed)
    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.

  • 186.
    Fredrickson, Rie Takagi
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Single-Crystal X-ray Study of Ba2Cu2Te4O11Br2 and Its Incommensurately Modulated Superstructure Companion2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 11, p. 3434-3441Article in journal (Refereed)
    Abstract [en]

    Compounds containing lone-pair elements such as TeIV are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features—Ba2Cu2Te4O11Br2 (I) and Ba2Cu2Te4O11−δ(OH)2δBr2 (II, δ≈0.57)—as members of the AE-M-Te-O-X (AE=alkaline-earth metal, M=transition metal, X=halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved unsatisfactory. Closer inspection of the reciprocal lattice revealed systematic, non-crystallographic absences that indicate twinning. The structure is in fact triclinic, space group C (equivalent to P), with unit cell parameters (at 120 K) of a=10.9027(9), b=15.0864(7), c=9.379(2) Å, β=106.8947°. It is layered and built from [TeO3E] tetrahedra, [TeO3+1E] trigonal bipyramids (where E is the lone pair of TeIV), [CuO4] squares and irregular [BaO10Br] polyhedra. The crystal structure of II shows the same basic structure as I but contains additional oxygen, probably in the form of OH groups. The presence of satellites reveals that ordering on this O site creates an incommensurate modulation, primarily affecting Br and Te. The modulated structure of II was solved in the triclinic superspace group X(αβγ)0 with the vector q≈1/16 c*.

  • 187.
    Fredrickson Takagi, Rie
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Torino Hjelmquist, D.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    The solid solution Co3.6Mg1.4Cl2 (TeO3)42007In: Acta Crystallographica, Vol. E63, p. i146-i147Article in journal (Refereed)
  • 188.
    Furusho, Hirotoshi
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Mishima, Yumiko
    Kameta, Naohiro
    Yamane, Midori
    Lipid Nanotube Encapsulating Method in Low-Energy Scanning Transmission Electron Microscopy Analyses2009In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 48, p. -097001Article in journal (Refereed)
    Abstract [en]

    The lipid nanotube (LNT) encapsulating method is a rational sample fixation method that can be used to mount samples for transmission electron microscopy analyses. By employing the LNT encapsulating method in 30 kV low-voltage scanning transmission electron microscopy (LV-STEM), it is possible to record multiangle images of ferritin without using the negative staining method. We have also recorded a tilted series of high-contrast LV-STEM images and reconstructed three-dimensional images. These results show that LNTs have sufficient durability for LV electron beam, and indicate the potential of the LNT encapsulating method as a sample fixation method of LV electron microscopy

  • 189. Färnbäck, Doğdaş E.,
    et al.
    Ertan, M
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Yeşilada, E
    Küpeli, E
    Kaynak, F B
    Tozkoparan, B
    Design and synthesis of some new thiazolo [3,2-b]-1,2,4-triazole-5(6H)-ones substituted with flurbiprofen as anti-inflammatory and analgesic agents2007In: Arzneimittel-Forschung, Vol. 57, no 4, p. 196-202Article in journal (Refereed)
  • 190.
    Färnbäck, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Methyl 2-O-beta-L-fucopyranosyl alpha-D-glucopyranoside monohydrate: a synchrotron study2008In: Acta Crystallographica Section C, ISSN 0108-2701, Vol. 64, no 2, p. o31-o32Article in journal (Refereed)
  • 191.
    Färnbäck, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Söderman, Peter
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-azido-alpha-D-galactopyranosyl-(1-2)-: [3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl-(1-3)]-4-O-benzoyl-alpha-L-rhamnopyranoside n-hexane 0.1-solvate2007In: Acta Crystallographica: Section E, Vol. E63, p. o1581-o1583Article in journal (Refereed)
  • 192. Gao, C.
    et al.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Yasuhiro, Sakamoto
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Che, S.
    Molecular design of the surfactant and the co-structure-directing agent (CSDA) toward rational synthesis of targeted anionic surfactant templated mesoporous silica2007In: Journal of Materials Chemistry, Vol. 17, p. 3591-3602Article in journal (Refereed)
  • 193.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Formation Mechanism of Anionic Surfactant-Templated Mesoporous Silica2006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, p. 3904-3914Article in journal (Refereed)
    Abstract [en]

    The synthesis mechanism of anionic surfactant-templated mesoporous silica (AMS) is described. A family of highly ordered mesoporous silica structures have been synthesized via an approach based on the self-assembly of anionic surfactants and inorganic precursors by using aminopropylsiloxane or quaternized aminopropylsiloxane as the co-structure-directing agent (CSDA), which is a different route from previous pathways. Mesophases with differing surface curvatures, varying from cage type (tetragonal P42/mnm; cubic Pm-3n with modulations; cubic Fd-3m) to cylindrical (two-dimensional hexagonal p6mm), bicontinuous (cubic Ia-3d and Pn-3m), and lamellar have been obtained by controlling the charge density of the micelle surfaces by varying the degree of ionization of the carboxylate surfactants. Changing the degree of ionization of the surfactant results in changes of the surfactant packing parameter g, which leads to different mesostructures. Furthermore, variation of the charge density of positively charged amino groups of the CSDA also gives rise to different values of g. Mesoporous silicas, functionalized with amino and quaternary ammonium groups and with the various structures given above, have been obtained by extraction of the surfactant. This report leads to a deeper understanding of the interactions between the surfactant anions and the CSDA and provides a feasible and facile approach to the mesophase design of AMS materials.

  • 194.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Formation mechanism of anionic-surfactant-templated mesoporous silica (AMS)2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation is focused on synthesis, characterization and formation mechanism of anionic-surfactant-templated mesoporous silica (AMS).

    Structural control mechanisms of AMS are investigated. First, different ionization degree of anionic surfactant affected by the acidity or alkalinity of the synthesis system gives rise to different charging density of micelles and therefore determines the organic/inorganic interface curvature, producing mesophases from cage-type to cylindrical, bicontinuous and lamellar. Second, mesocage/mesocage electrostatic repulsive interaction affects the formation of cage-type mesostructure, which is derived from a full-scaled synthesis-field diagram of AMS. The mesocage/mesocage interaction changes with charge density of mesocages and gives rise to their different packing manners. Third, the structural properties of AMS materials could be tuned by molecular features of surfactant and co-structure-directing agent (CSDA).

    The pore size of AMS is found to be controlled by alkyl chain length, ionization degree of surfactant and the CSDA/surfactant ratio. Alkyl chain length of surfactant determines size of micelles and thus mesopores. Larger ionization degrees of anionic surfactant give rise to smaller pore sizes due to thermodynamic coiling of alkyl chains of surfactant. The hydrophobic interactions between the pendant organic groups of CSDA on the silica wall and the hydrophobic core of the micelles drive a contraction of the mesopores.

    A mesoporous silica with novel bicontinuous cubic Pn-3m structure has been prepared using a diprotic anionic surfactant. 3d-reconstruction of the structure shows that it is bicontinuous composed of an enantiomeric pair of 3d mesoporous networks that are interwoven with each other, divided by a D surface. Inverse replication suggests the possible presence of ordered complimentary micropores in the material.

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  • 195.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Formation of mesoporous Co3O4 replicas of different mesostructureswith different pore sizes2009In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 123, p. 314-323Article in journal (Refereed)
    Abstract [en]

    Mesoporous metal oxides Co3O4 are prepared via hard templating synthesis method by using various mesoporous silicas with different pore size as templates. The pore size of the mesoporous silicas with the symmetry of two-dimensional (2d)-hexagonal p6mm, bicontinuous cubic Ia-3d and Pn-3m have been controlled in the range of 6.6–10.7, 4.2–7.5 and 5.1–6.7 nm, respectively, by choosing different surfactants and co-surfactants and by adjusting either the aging temperature or the ionization degree of the surfactant. The pore size of the silica template has been considered to be an important factor that determines the mesostructure of the resulting metal oxides. It has been found that for p6mm, it is easier to replicate the mesoporous symmetry at large size of mesopores. For Ia-3d, at large-pore size two sets of bicontinuous meso-channels are replicated into mesoporous Co3O4, while small-pore Ia-3d leads to replication of both one set and two sets of meso-channels. Co3O4 can replicate both one set and two sets of bicontinuous Pn-3m meso-channels at all pore sizes that can be obtained (5.1–6.7 nm), indicating the existence of ordered complementary micropores within the silica walls.

  • 196.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Molecular design of AEC tri-block anionic surfactant towards rational synthesis of targeted thick-walled mesoporous silica2009In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 19, p. 3404-3411Article in journal (Refereed)
    Abstract [en]

    Here we report a new synthesis strategy to synthesize thick-walled two dimensional hexagonal mesoporous silicas, using tri-block surfactant fatty alcohol ether carboxylate [AEC: CnH2n+1O(CH2CH2O)mCH2COONa] with two different hydrophilic head groups of (EO)x-block and anionic carboxylate. The unique formation of double-layer silica wall arose from two types of hydrophilic head groups via the silica source condensation led to an obvious increase in the wall thickness. The successful carbon replication proved the existence of micropores formed by imbedded (EO)x-block and electrostatic bonding of carboxylate head group and organic group of co-structuredirecting agent. The template-free mesoporous silica showed a high hydrothermal stability due to the thick wall.

  • 197.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Molecular design of the surfactant and the co-structure-directing agent (CSDA) toward rational synthesis of targeted anionic surfactant templatedmesoporous silica2007In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 17, p. 3591-3602Article in journal (Refereed)
    Abstract [en]

    The formation of anionic surfactant templated mesoporous silica (AMS) is investigated from the perspective of the geometrical molecular design of the surfactant and the co-structure-directing agent (CSDA) toward the rational synthesis of the targeted mesostructure. Increasing the geometrical size of two types of head group of the anionic surfactant in the order (i) sulfonate, sulfate and phosphate, and (ii) carboxylate, N-acylalanate/N-acylglycinate and N-acylglutamate, resulted in the mesophase changing from a disordered or lamellar phase to two-dimensional (2D) hexagonal (p6mm) and three-dimensional (3D) cage-type (hexagonal and a modulated cubic phase) with increasing order of the organic/inorganic interface curvature. A change in the chain length of the surfactant also led to different surfactant packing and mesophase interfacial curvatures, and resulted in a change in mesophase from a modulated cage-type mesophase to cubic Fd-3m, cubic Pm-3n and a disordered cage-type mesophase. The geometrical change in the CSDA resulted in an increasing micellar curvature in the order: aminopropyl , N-methylaminopropyl, N,N-dimethylaminopropyl trimethoxysilane, which led to a change of mesophase from bicontinuous cubic Pn-3m to 2D-hexagonal p6mm. An increase in the CSDA/surfactant ratio in the synthesis gave rise to the mesophase change from a disordered cage-type mesophase to cubic Fm-3m or from lamellar to 2D-hexagonal p6mm, and elemental analysis results showed that the mesoporous silicas have an increased loading of organic moieties using the CSDA method.

  • 198.
    Gao, Chuanbo
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Synthesis and characterization of mesoporous silica AMS-10 with bicontinuous cubic Pn-3m symmetry2006In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 45, p. 4295-4298Article in journal (Refereed)
    Abstract [en]

    A mesoporous silica AMS-10 with novel bicontunuous cubic Pn-3m symmetry was synthesized and chracterized by electron crystallography.

  • 199.
    Gao, Chuanbo
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Izquierdo-Barba, Isabel
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Nakase, Ikuhiko
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Mesostructured silica based delivery system for a drug with a peptide as a cell-penetrating vector2009In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 122, no 1-3, p. 201-207Article in journal (Refereed)
    Abstract [en]

    A drug delivery system using mesostructured silica as a reservoir has been developed for the storage and controlled release of a drug with a cell-penetrating peptide (CPP) as a vector. We use fluorescein isothiocyanate (FITC) as the drug model and octaarginine (R8) as a vector to endow the drug with cell-penetrating property. The mesostructured silica reservoir system was prepared by using a one-pot liquid?crystal templating method, which is suitable for the encapsulation of intact FITC-R8 conjugates and sustained release of drugs without hampering their properties. The hydrophobic poly(propyl oxide) (PPO) shell of the pore-filling Pluronic F127 and the electrostatic interaction between R8 and siloxide ions on the pore walls act as the diffusion-limiting factors of the FITC-R8 conjugate. A sigmoidal in vitro release of FITC-R8 from mesostructured silica into phosphate buffered saline (PBS, pH 7.4) was observed and the typical release duration was 5 days at 37 ‹C. Release from the reservoir yielded significant elongation in duration of the FITC signals in DU145 cells by confocal microscopic analysis, compared with a single administration of FITC-R8.

     

  • 200.
    Gao, Chuanbo
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sakamoto, Yasuhiro
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Che, Shunai
    Formation of Diverse Mesophases Templated by a Diprotic Anionic Surfactant2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 36, p. 11423-11428Article in journal (Refereed)
    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.

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