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- Lebedkin, Sergei, et al.
(författare)
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Structure and Properties of the Fullerene Dimer C140 Produced by Pressure Treatment of C70
- 2000
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 104:17, s. 4101-4110
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Tidskriftsartikel (refereegranskat)abstract
- A [2+2] cycloaddition cap-to-cap C70 dimer with C2h molecular symmetry was synthesized in high yield by pressure treatment of polycrystalline C70 at 1 GPa and 200 °C. It was separated from unreacted monomers by chromatography and characterized by 13C NMR, Raman, and infrared spectroscopy, and other methods. Remarkably, only one isomer was produced out of the five possible [2+2] cycloaddition products which have equally low formation energies according to semiempirical modeling calculations. The dimer obtained is the one favored when C70 molecules adopt an ordered packing with parallel D5 axes. The intercage bonding in C140, its thermal stability, and intercage vibrational modes are similar to those found for the C60 dimer, C120. Both dimers photodissociate to the monomers in solution, probably via excited triplet states. The UV absorption and fluorescence properties of C140 are not very different from those of C70, suggesting only weak electronic interactions between the two cages of C140. In comparison, the pressure-induced dimerization of C60, under the conditions used for C70, results mainly in C60 oligomers and polymeric chains, but the dimer C120 could be isolated at low yield when short reaction times (≤5 min) were used.
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2. |
- von der Lieth, Claus-Wilhelm, et al.
(författare)
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EUROCarbDB : an open-access platform for glycoinformatics
- 2011
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 21:4, s. 493-502
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Tidskriftsartikel (refereegranskat)abstract
- The EUROCarbDB project is a design study for a technical framework, which provides sophisticated, freely accessible, open-source informatics tools and databases to support glycobiology and glycomic research. EUROCarbDB is a relational database containing glycan structures, their biological context and, when available, primary and interpreted analytical data from high-performance liquid chromatography, mass spectrometry and nuclear magnetic resonance experiments. Database content can be accessed via a web-based user interface. The database is complemented by a suite of glycoinformatics tools, specifically designed to assist the elucidation and submission of glycan structure and experimental data when used in conjunction with contemporary carbohydrate research workflows. All software tools and source code are licensed under the terms of the Lesser General Public License, and publicly contributed structures and data are freely accessible. The public test version of the web interface to the EUROCarbDB can be found at http://www.ebi.ac.uk/eurocarb.
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