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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Mechanics Simulations in Structure Analysis of Intercalate VOPO4·2CH3CH2OH (1998)
    Springer
    Journal of molecular modeling 4 (1998), S. 150-157 
    Details
    ISSN: 0948-5023
    Keywords: Molecular mechanics ; Structure of intercalates ; Vanadyl phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Molecular mechanics simulations using Cerius2 combined with X-ray diffraction and supported with vibrational spectroscopy have been used to investigate the layered structure of vanadyl phosphate VOPO4 intercalated with ethanol. This intercalated structure exhibits certain degree of disorder, which affects the diffraction diagram and obstructs the conventional structure analysis based on diffraction methods only. Present structure analysis is focused to the crystal packing in the interlayer space and layer stacking in the intercalate. The bilayer arrangement of ethanol molecules in the interlayer has been found, giving the basal spacing d = 13.21 Å, experimental d-value obtained from X-ray diffraction is 13.17 Å. One half from the total number of CH3CH2OH molecules is anchored with their oxygens to VOPO4 layers to complete vanadium octahedra and their orientation is not very strictly defined. The second half of ethanoles is linked with hydrogen bridges to the anchored etahanoles and sometimes also to the layer oxygens. Positions and orientations of these unachored ethanoles with respect to VOPO4 layers exhibit certain degree of disorder, resulting in the disorder in layer stacking. Molecular mechanics simulations revealed the character of this displacement disorder in layer stacking and enabled to determine the components of the displacement vector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0089480040150
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  • 2
    Electronic Resource
    Electronic Resource
    Modeling in Structure Analysis of Vanadyl Phosphate Intercalated with 1-Alkanols (2000)
    Springer
    Journal of molecular modeling 6 (2000), S. 9-15 
    Details
    ISSN: 0948-5023
    Keywords: Keywords Vanadyl phosphate-alkanol intercalates, Molecular mechanics, Structure analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Molecular mechanics simulations supported by X-ray powder diffraction measurements have been used to investigate the structure of vanadyl phosphate intercalated with 1-alkanols CnH2n+1OH for n = 2, 3, 4. Modeling revealed the specific features and differences in arrangement of alkanol molecules with different chain length, depending on the relation between the parameters of active sites network and size of guest molecules. This result enabled us to explain the irregularities in dependence of basal spacing on the chain length. The comparison of experimental dexp and calculated dcalc values of basal spacing showed the good agreement of modeling with x-ray powder diffraction. While we obtained dcalc(Univ) = 13.05 Å for vanadyl phosphate-ethanol using the Universal force field (dexp=13.17 Å), for vanadyl phosphate-propanol and vanadyl phosphate-butanol better agreement with experiment was obtained using the Tripos force field. In the case of vanadyl phosphate-propanol the calculated basal spacing dcalc(Tripos) = 14.49 Å, compared with an experimental value of dexp=14.36 Å. For vanadyl phosphate-butanol dcalc(Tripos) = 17.71 Å and dexp=17.90 Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010722
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  • 3
    Electronic Resource
    Electronic Resource
    Structure Analysis of Intercalated Zirconium Phosphate Using Molecular Simulation (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 31 (1998), S. 845-850 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Molecular simulation supported by X-ray diffraction and IR spectroscopy has been used to analyse the structure of α-zirconium phosphate intercalated by ethanol, Zr(HPO4)2.2C2H5OH. Molecular-mechanics simulations using the Crystal Packer module in the Cerius2 modelling environment revealed the crystal packing in the interlayer, i.e. the positions of ethanol with respect to the Zr(HPO4)2 layers and the layer stacking in the intercalated structure. The average interlayer distance d\,=\,14.03 (13) Å obtained by modelling is in agreement with the experimental d value of 14.05 (4) Å obtained from the X-ray diffraction analysis. The disorder in the Zr(HPO4)2.2C2H5OH structure found by molecular simulation has been confirmed by the character of the X-ray diffraction pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889898006773
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  • 4
    Electronic Resource
    Electronic Resource
    Structure determination of two intercalated compounds VOPO4·(CH2)4O and VOPO4·OH—(CH2)2—O—(CH2)2—OH; synchrotron powder diffraction and molecular modelling (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 178-183 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The crystal structures of two intercalated compounds have been determined using a combination of synchrotron powder diffraction and molecular mechanics simulations: (1) vanadyl phosphate intercalated with tetrahydrofuran, VOPO4·(CH2)4O, and (2) vanadyl phosphate intercalated with diethylene glycol, VOPO4·HO(CH2)2O(CH2)2OH. Both intercalates preserve the tetragonal space group P4/n, as found in the host structure VOPO4·2H2O. (1): a = 6.208, c = 8.930 Å, Z = 2, Dx = 2.51 g cm−3; (2): a = 6.223, c = 11.417 Å, Z = 2, Dx = 2.66 g cm−3. Both intercalates exhibit the same type of orientational disorder in the arrangement of guest molecules, as observed in the same host compound intercalated with water. These two intercalates also exhibit, rather surprisingly, perfect ordering in layer stacking without the displacement disorder, characteristic of many intercalated layered structures. Thanks to this regularity in the arrangement of guests and layers, synchrotron powder diffraction could be used in the present structure determination. The present results also enabled the analysis of the effect of geometrical parameters characterizing the mutual host–guest complementarity and the effect of host–guest and guest–guest interaction on the crystal packing of intercalates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768100015603
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  • 5
    Electronic Resource
    Electronic Resource
    Intercalation of 1-Alkanol Binary Mixtures into the Layered Structure of Vanadyl Phosphate (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 391-402 
    Details
    ISSN: 1573-1111
    Keywords: intercalation ; 1-alkanols ; vanadyl phosphate ; mixed layer-type complexes ; x-ray powder diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mixed intercalates VOPO4.C2H5 OH.C4 H9OH, VOPO4.C3H7 OH.C5H11OH, VOPO4.C3H7 OH.C6H13OH and VOPO4.C4H9 OH.C6H13OH have been prepared by reaction of polycrystalline vanadyl phosphate dihydrate with liquid mixtures of the 1-alkanols in a microwave field. The same mixed layer-type complexes were also obtained as intermediary products of exchange reactions consisting in substitution of one alkanol bound in the solid intercalate by another alkanol introduced in the form of vapour. The composition of products has been determined, and the basal spacing of all the mixed layer-type complexes prepared has been found by diffraction. A structural principle is suggested which governs the depositing of two kinds of 1-alkanol molecules (differing in the lengths of their aliphatic chains) while acting as guests in the layered structure of vanadyl phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008046724727
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  • 6
    Electronic Resource
    Electronic Resource
    Possible Mechanisms of Intercalation (1998)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 31 (1998), S. 275-286 
    Details
    ISSN: 1573-1111
    Keywords: intercalation ; mechanism ; kinetics ; vanadyl phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recent knowledge of the kinetics and intercalation mechanisms are summarized and accompanied by examples of intercalation reactions of water and ethanol into anhydrous vanadyl phosphate and redox intercalation of alkali metal cations into vanadyl phosphate dihydrate. Three possible mechanisms of intercalation are presented which are based on: (i) a concept of exfoliation of layers; (ii) the formation of stages and randomly stacked layers; (iii) co-existence of intercalated and non-intercalated parts of crystals of the host separated by an advancing phase boundary. The corresponding kinetic curves are ascribed to mechanisms (ii) and (iii).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007976213743
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  • 7
    Electronic Resource
    Electronic Resource
    Intercalation of 1,2-alkanediols into Vanadyl and Niobyl Phosphate (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 301-309 
    Details
    ISSN: 1573-1111
    Keywords: vanadyl phosphate ; niobyl phosphate ; intercalation ; alkanediols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Intercalation compounds of VOPO4and NbOPO4 with 1,2-alkanediols (from C3 to C16)have been prepared. The diol molecules are placedbetween host layers in a bimolecular way with theiraliphatic chains tilted at an angle of 70°. Itwas found that the intercalates contain 1.5 moleculesof diol per formula unit. Three ways of bonding of thediol molecules to the host layers are proposed. Twomolecules of diol are coordinated to the metal atomsby their first and second oxygen, respectively. Thethird diol molecule is anchored in the interlayerspace by H-bonds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008066629211
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  • 8
    Electronic Resource
    Electronic Resource
    A Study of the Hydration and Dehydration of Vanadyl Arsenate by X-ray Diffraction Analysis, Infrared and Raman Spectroscopy (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 895-900 
    Details
    ISSN: 1434-1948
    Keywords: Vanadyl arsenate ; Hydrates ; Layered compounds ; Vibrational spectroscopy ; X-ray scattering ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The course of the intercalation and deintercalation of water molecules in vanadyl arsenate has been studied by X-ray diffraction analysis and by infrared and Raman spectroscopies. The formation of VOAsO4 hydrates at ambient temperature has been found to depend on relative humidity (r.h.): VOAsO4 · 5 H2O (basal spacing c = 10.48 Å) is formed at r.h. above 76%, VOAsO4 · 3 H2O (c = 8.03 Å) at 43-76% r.h., VOAsO4 · 2 H2O (c = 7.33 Å) at 11-43% r.h.; dehydrated VOAsO4 (c = 4.18 Å) exists near 0% r.h. Like the thermal dehydration of VOPO4 · 2 H2O, the thermal dehydration of VOAsO4 · 3 H2O proceeds in a stepwise manner so that the dihydrate and monohydrate are formed en route to the anhydrous compound. The arsenate monohydrate is gradually dehydrated over a broad temperature range. The broad diffraction lines observed can be explained in terms of the existence of a disordered phase containing monohydrated and anhydrous forms of vanadyl arsenate. A similar phenomenon has been observed during the dehydration of VOAsO4 · 3 H2O over phosphorus pentoxide at ambient temperature. The hydration of VOAsO4 is different from that of VOPO4. The first step, i.e. the insertion of water that coordinates to the vanadium atoms, is very slow. On the contrary, the uptake of further water molecules with the formation of higher hydrates is fast. It thus seems likely that the filling of one interlayer space with water facilitates the intercalation of further water into neighboring interlayer spaces. Therefore, only higher hydrates together with the original anhydrous phase are observed. Impedance spectral measurements indicate that the conductivity of the trihydrate has a mixed ionic/electronic character.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    Water/Ethanol Displacement Reactions in Vanadyl Phosphate (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2289-2294 
    Details
    ISSN: 1434-1948
    Keywords: Intercalations ; Vanadyl phosphate ; Ethanol ; Hydration ; Kinetics ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The course of the replacement of ethanol by water molecules in the VOPO4·2C2H5OH intercalate, and of water by ethanol in VOPO4·2H2O has been studied by X-ray diffraction and infrared and Raman spectroscopy. Formation of mixed phase VOPO4·C2H5OH·H2O was not observed. The shape of the kinetics curves indicates a transition of at least one reaction zone through the crystal. A delay in formation of the product in comparison with the decrease in the amount of starting material can be explained by the existence of non-diffracting advancing phase boundary. In a VOPO4/ethanol/water system, VOPO4·2C2H5OH is formed as the only product when the system contained more than 96 vol% of ethanol, whereas in the system with less than 94 vol% of ethanol only VOPO4·2H2O is present.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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