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The ITQ-37 mesoporous chiral zeolite
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
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2009 (English)In: Nature, ISSN 0028-0836, Vol. 458, no 7242, 1154-1157 p.Article in journal (Refereed) Published
Abstract [en]

The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest(1-3). The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis(4) of ITQ-33, a stable zeolite with 18 x 10 x 10 ring windows, and the synthesis(5) of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction ( SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm(6). The framework follows the SrSi2 (srs) minimal net(7) and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 angstrom(3)) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm(3) g(-1).

Place, publisher, year, edition, pages
2009. Vol. 458, no 7242, 1154-1157 p.
URN: urn:nbn:se:su:diva-31943DOI: 10.1038/nature07957ISI: 000265754600044ISBN: 0028-0836OAI: diva2:279048
Available from: 2009-12-01 Created: 2009-12-01 Last updated: 2010-05-14Bibliographically approved
In thesis
1. 3D Electron crystallography: Real space reconstruction and reciprocal space tomography
Open this publication in new window or tab >>3D Electron crystallography: Real space reconstruction and reciprocal space tomography
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electron crystallography is an important technique for studying micro- and nano-sized materials. It has two important advantages over X-ray crystallography for structural studies: 1) crystals millions of times smaller than those needed for X-ray diffraction can be studied; 2) it is possible to; focus the electrons to form an image. The local atomic arrangement can be seen directly by high-resolution transmission electron microscopy (HRTEM). The crystallographic structure factor phases, which are lost in recording diffraction patterns, are present in HRTEM images and can be determined experimentally. The main disadvantages of electron crystallography compared to X-ray diffraction are that the data are difficult to collect, often incomplete and suffer from dynamic scattering. New methods need to be developed to overcome these problems. In this work, structure determination of several unique and complex porous materials including zeolites and mesoporous silica is demonstrated. None of the structures of these materials could be solved by X-ray crystallography. New techniques are also developed in order to overcome the disadvantages of electron crystallography. The new techniques include a digital sampling method for collecting precession electron diffraction data and a rotation method for automatic collection of complete 3D electron diffraction data. A number of practical issues concerning data collection and data processing are described and the data quality is analysed.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2010. 72 p.
Electron crystallography, Electron microscopy, Porous materials
National Category
Chemical Sciences
Research subject
Structural Chemistry
urn:nbn:se:su:diva-39034 (URN)978-91-7447-044-4 (ISBN)
Public defence
2010-06-08, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted.Available from: 2010-05-17 Created: 2010-05-06 Last updated: 2010-05-14Bibliographically approved

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Sun, JunliangZhang, Daliang
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