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SU-12: a silicon-substituted ASU- 16 with circular 24-rings and templated by a monoamine
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
2005 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, no 10, 2530-2536 p.Article in journal (Refereed) Published
Abstract [en]

A new silicogermanate, SU-12, |(CH3CH2CH2NH3)3(H2O)2.5|[(Ge6.44Si0.56)O14.5F2], with 24-ring channel systems was synthesized under hydro/solvothermal conditions, and its structure was determined by single-crystal X-ray diffraction. It is the first silicogermanate with extra-large 24-rings templated by a primary monoamine. Crystallographic data: tetragonal, space group I2m, unit cell parameters a = 27.6460(22) Å and c = 17.0885(14) Å, V = 13060.8(17) Å3, Z = 16, ρcalcd = 1.797 g/cm3, R1 = 0.0512 [5471 observed reflections with I > 2σ(I)], wR2 = 0.1487, S (goodness-of-fit on F2) = 1.08. SU-12 has a structure topology similar to that of the pure germanate ASU-16. However, the symmetry of SU-12 is higher than that of ASU-16, and the 24-rings become more circular than those in ASU-16. The interaction between the templates and framework is compared for ASU-16 and SU-12, and their thermal stabilities are studied. The orthorhombic ASU-16 is thermally less stable than the tetragonal SU-12 and transformed to SU-12 by heating. The ion-exchange property of SU-12 is also studied.

Place, publisher, year, edition, pages
American Chemical Society , 2005. Vol. 17, no 10, 2530-2536 p.
National Category
Chemical Sciences
URN: urn:nbn:se:su:diva-23659DOI: 10.1021/cm049373fOAI: diva2:193887
Part of urn:nbn:se:su:diva-440Available from: 2005-04-05 Created: 2005-04-05 Last updated: 2011-01-31Bibliographically approved
In thesis
1. Novel framework materials: organically templated silicogermanates and hybrid fluorotitanates
Open this publication in new window or tab >>Novel framework materials: organically templated silicogermanates and hybrid fluorotitanates
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two types of novel framework materials, including six organically templated silicogermanates and five hybrid fluorotitanates, have been synthesized, and their structures have been determined by single crystal X-ray diffraction. Their structures and the interactions between the organic and inorganic species are discussed in some detail.

The frameworks of the six silicogermanates, SU-9, SU-10, SU-11, SU-12, SU-14 and SU-21, are built up from either tetrahedra exclusively, or from mixed polyhedra. SU-9, SU-10 and SU-11 consist only of tetrahedra, and SU-12, SU-14 and SU-21 are built up from mixed polyhedra. In all silicogermanates, Si and Ge share the tetrahedrally coordinated positions, and only Ge occupies the 5- and 6-coordinated positions.

The frameworks of SU-9, SU-10 and SU-11 belong to zeolite frameworks. SU-9 and SU-10 are built up from the same periodic building units (PBUs) that are formed by 4/4-4 units, and they adopt the known zeolite framework types AST and ASV, respectively. SU-11 is built up from 5-1 units and adopts the known zeolite framework type MFI. This is the first time that the frameworks of AST, ASV and MFI have been prepared in silicogermanate form.

The 3-D frameworks of SU-12 and SU-14 contain (Ge,Si)7 composite building units that form one-dimensional 24-ring channels along the c axis. Their structures contain intersecting channels. SU-12 contains 8-, 10- 12- and 24-ring channels; while SU-14 has 9-, 10-, 12- and 24-ring channels. SU-21 is a two-dimensional framework structure containing 10-ring channels. It is the first silicogermanate with the template covalently bonded to Ge.

All silicogermanates were synthesized by using organic amines as templates. The templates play a very important role in directing the structure of the inorganic framework.

The obtained five hybrid fluorotitanates are SUF-1, SUF-2, SUF-3, SUF-4 and SUF-5. Their hybrid frameworks are built up from fluorotitanate anions, N-containing cations and crystal water/oxonium cations. Zero-dimensional fluorotitanate clusters are normally obtained when cyclic organic amines such as 1,4-diazabicyclo[2,2,2]octane (DABCO) and piperazine are used. Increasing the pH value of the starting solutions led to more condensed fluorotitanate anions, from isolated octahedra to pairs and eventually chains of octahedra. The formation of the hybrid frameworks of fluorotitanates is strongly dependent on hydrogen bonds between the fluorotitanate anions, N-containing organic cations and water molecules/oxonium ions.

Place, publisher, year, edition, pages
Stockholm: Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2005. 88 p.
framework materials, silicogermanates, hybrid fluorotitananates
National Category
Chemical Sciences
urn:nbn:se:su:diva-440 (URN)91-7155-048-8 (ISBN)
Public defence
2005-05-02, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00
Available from: 2005-04-05 Created: 2005-04-05Bibliographically approved

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