118 research outputs found
Novel Polypyridyl Ruthenium(II) Complexes Containing Oxalamidines as Ligands.
The complexes [Ru(bpy)2(H2TPOA)](PF6)2 â
4H2O, (1); [Ru(Me-bpy)2(H2TPOA)](PF6)2
â
2H2O, (2); [Ru(bpy)2(H2TTOA)](PF6)2 â
2H2O, (3); [Ru(Me-bpy)2(H2TTOA)](PF6)2 â
2H2O,
(4) and {[Ru(bpy)2]2(TPOA)}(PF6)2 â
2H2O, (5) (where bpy is 2,2´bipyridine; Me-bpy is 4,4´-
dimethyl-2,2´-bipyridine; H2TPOA is N, N´, N´´, N´´´- tetraphenyloxalamidine; H2TTOA is
N, N´, N´´, N´´´- tetratolyloxalamidine) have been synthesized and characterized by 1H-NMR,
FAB-MS, infrared spectroscopy and elemental analysis. The X-ray investigation shows the
coordination of the still protonated oxalamidine moiety via the 1,2âdiimine unit. The dimeric
compound (5) could be separated in its diastereoisomers (5´) and (5´´) by repeated
recrystallisation. The diastereomeric forms exhibit different 1H-NMR spectra and slightly
shifted electronic spectra. Compared with the model compound [Ru(bpy)3]2+, the absorption
maxima of (1)â(5) are shifted to lower energies. The mononuclear complexes show Ru(III/II)-
couples at about 0.9 V vs SCE, while for the dinuclear complex two well defined metal based
redox couples are observed at 0.45 and 0.65 V indicating substantial interaction between the
two metal centres
Angular Forces Around Transition Metals in Biomolecules
Quantum-mechanical analysis based on an exact sum rule is used to extract an
semiclassical angle-dependent energy function for transition metal ions in
biomolecules. The angular dependence is simple but different from existing
classical potentials. Comparison of predicted energies with a
computer-generated database shows that the semiclassical energy function is
remarkably accurate, and that its angular dependence is optimal.Comment: Tex file plus 4 postscript figure
Different Mi-2 Complexes for Various Developmental Functions in Caenorhabditis elegans
Biochemical purifications from mammalian cells and Xenopus oocytes revealed that vertebrate Mi-2 proteins reside in multisubunit NuRD (Nucleosome Remodeling and Deacetylase) complexes. Since all NuRD subunits are highly conserved in the genomes of C. elegans and Drosophila, it was suggested that NuRD complexes also exist in invertebrates. Recently, a novel dMec complex, composed of dMi-2 and dMEP-1 was identified in Drosophila. The genome of C. elegans encodes two highly homologous Mi-2 orthologues, LET-418 and CHD-3. Here we demonstrate that these proteins define at least three different protein complexes, two distinct NuRD complexes and one MEC complex. The two canonical NuRD complexes share the same core subunits HDA-1/HDAC, LIN-53/RbAp and LIN-40/MTA, but differ in their Mi-2 orthologues LET-418 or CHD-3. LET-418 but not CHD-3, interacts with the KrĂźppel-like protein MEP-1 in a distinct complex, the MEC complex. Based on microarrays analyses, we propose that MEC constitutes an important LET-418 containing regulatory complex during C. elegans embryonic and early larval development. It is required for the repression of germline potential in somatic cells and acts when blastomeres are still dividing and differentiating. The two NuRD complexes may not be important for the early development, but may act later during postembryonic development. Altogether, our data suggest a considerable complexity in the composition, the developmental function and the tissue-specificity of the different C. elegans Mi-2 complexes
Associated Society Members of the New Swiss Chemical Society (NSCS) : Kollektivmitgliedgesellschaften der Neuen Schweizerischen Chemischen Gesellschaft (NSCG)
Design, synthesis and photophysics of ruthenium and osmium complexes through 20 years of collaboration
In this article we report some results obtained during 20 years of collaboration with the group of Prof. Balzani. The small review covers Ruthenium and some Osmium compounds, from cage to multinuclear complexes and molecular switches. The review does not intend to be comprehensive but it is only a general overview of the most important achievements in the field of photophysics and photochemistry of luminescent metal complexes
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