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Weaving of organic threads into a crystalline covalent organic framework
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
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2016 (English)In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 351, 365-369 p.Article in journal (Refereed) Published
Abstract [en]

A three-dimensional covalent organic framework (COF-505) constructed from helical organic threads, designed to be mutually weaving at regular intervals, has been synthesized by imine condensation reactions of aldehyde functionalized copper(I)-bisphenanthroline tetrafluoroborate, Cu(PDB)2(BF4), and benzidine (BZ). The copper centers are topologically independent of the weaving within the COF structure and serve as templates for bringing the threads into a woven pattern rather than the more commonly observed parallel arrangement. The copper(I) ions can be reversibly removed and added without loss of the COF structure, for which a tenfold increase in elasticity accompanies its demetalation. The threads in COF-505 have many degrees of freedom for enormous deviations to take place between them, throughout the material, without undoing the weaving of the overall structure.

Place, publisher, year, edition, pages
2016. Vol. 351, 365-369 p.
National Category
Chemical Sciences
Research subject
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-129172DOI: 10.1126/science.aad4011OAI: oai:DiVA.org:su-129172DiVA: diva2:920179
Available from: 2016-04-17 Created: 2016-04-17 Last updated: 2016-05-04Bibliographically approved
In thesis
1. Structural study of nano-structured materials: electron crystallography approaches
Open this publication in new window or tab >>Structural study of nano-structured materials: electron crystallography approaches
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The structural analysis serves as a bridge to link the structure of materials to their properties. Revealing the structure details allows a better understanding on the growth mechanisms and properties of materials, and a further designed synthesis of functional materials. The widely used methods based on X-ray diffraction have certain limitations for the structural analysis when crystals are small, poorly crystallized or contain many defects. As electrons interact strongly with matter and can be focused by electromagnetic lenses to form an image, electron crystallography (EC) approaches become prime candidates for the structural analysis of a wide range of materials that cannot be done using X-rays, particularly nanomaterials with poor crystallinity.

Three-dimensional electron diffraction tomography (3D EDT) is a recently developed method to automatically collect 3D electron diffraction data. By combining mechanical specimen tilt and electronic e-beam tilt, a large volume of reciprocal space can be swept at a fine step size to ensure the completeness and accuracy of the diffraction data with respect to both position and intensity. Effects of the dynamical scattering are enormously reduced as most of the patterns are collected at conditions off the zone axes. In this thesis, 3D EDT has been used for unit cell determination (COF-505), phase identifications and structure solutions (ZnO, Ba-Ta3N5, Zn-Sc, and V4O9), and the study of layer stacking faults (ETS-10 and SAPO-34 nanosheets).

High-resolution transmission electron microscope (HRTEM) imaging shows its particular advantages over diffraction by allowing observations of crystal structure projections and the 3D potential map reconstruction. HRTEM imaging has been used to visualize fine structures of different materials (hierarchical zeolites, ETS-10, and SAPO-34). Reconstructed 3D potential maps have been used to locate the positions of metal ions in a woven framework (COF-505) and elucidate the pore shape and connectivity in a silica mesoporous crystal.

The last part of this thesis explores the combination with X-ray crystallography to obtain more structure details.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2016. 101 p.
Keyword
structural analysis, electron crystallography, 3D EDT, HRTEM imaging, defects
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-129233 (URN)978-91-7649-425-7 (ISBN)
Public defence
2016-06-08, Magnéli Hall, Arrhenius Laboratory, Svante arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 1486801
Available from: 2016-05-16 Created: 2016-04-18 Last updated: 2016-06-16Bibliographically approved

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Ma, YanhangOleynikov, PeterTerasaki, Osamu
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