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- Ma, C. B., et al.
(author)
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Great framework variation of polymers in the manganese(II) maleate/alpha,alpha' - Diimine system : Syntheses, structures, and magneto-structural correlation
- 2003
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In: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :15, s. 2872-2879
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Journal article (peer-reviewed)abstract
- Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)](n) (1; phen = 1,10-phenanthroline), [Mn-(maleate)(phen)](n).nH(2)O (2), and [Mn(maleate)(bpy)](n) (3; bpy = 2,2'-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal, X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn-anti in 1 and 2, syn-syn and anti-anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent Mn-II ions, with J = -0.06 cm(-1) (2) and J = -1.3 cm(-1), zJ' = -0.27 cm(-1) (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carb oxylate-bridging coordination of maleate.
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- Ma, C. B., et al.
(author)
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Structural transformation mediated by o-, m-, and p-phthalates from two to three dimensions for manganese/phthalate/4,4 '-bpy complexes (4,4 '-bpy=4,4 '-bipyridine)
- 2003
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In: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1144-0546 .- 1369-9261. ; 27:5, s. 890-894
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Journal article (peer-reviewed)abstract
- Three isomers of o-, m-, and p-phthalate are used to link together Mn centres, resulting in [Mn(phth)(H2O)(x)](n) moieties ( phth = phthalate dianion) with single-chain, double-chain and sheet structures, respectively, which predetermine the extended structures derived from the crosslinkage of 4,4'-bipyridine, and show the influence of isomerism of the phthalate on topological changes of the final polymers from two dimensional (2D) single-layer, double-layer to 3D network architectures. These structural changes in topology are correlated with the differences in the magnetic and optical properties of the polymers.
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- Scherer, SW, et al.
(author)
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Human chromosome 7: DNA sequence and biology
- 2003
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In: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 300:5620, s. 767-772
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Journal article (peer-reviewed)abstract
- DNA sequence and annotation of the entire human chromosome 7, encompassing nearly 158 million nucleotides of DNA and 1917 gene structures, are presented. To generate a higher order description, additional structural features such as imprinted genes, fragile sites, and segmental duplications were integrated at the level of the DNA sequence with medical genetic data, including 440 chromosome rearrangement breakpoints associated with disease. This approach enabled the discovery of candidate genes for developmental diseases including autism.
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