Supertetrahedral and bi-supertetrahedral cages: Synthesis, structures, and magnetic properties of deca- and enneadecametallic cobalt(II) clusters

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Link between Affinity and Cu(II) Binding Sites to Amyloid-β Peptides Evaluated by a New Water-Soluble UV-Visible Ratiometric Dye with a Moderate Cu(II) Affinity

Being able to easily determine the Cu(II) affinity for biomolecules of moderate affinity is important. Such biomolecules include amyloidogenic peptides, such as the well-known amyloid-β peptide involved in Alzheimer's disease. Here, we report the synthesis of a new water-soluble ratiometric Cu(II) dye with a moderate affinity (109 M-1 at pH 7.1) and the characterizations of the Cu(II) corresponding complex by X-ray crystallography, EPR, and XAS spectroscopic methods. UV-vis competition was performed on the Aβ peptide as well as on a wide series of modified peptides, leading to an affinity value of 1.6 × 109 M-1 at pH 7.1 for the Aβ peptide and to a coordination model for the Cu(II) site within the Aβ peptide that agrees with the one mostly accepted currently

An {Fe₆₀} tetrahedral cage: building nanoscopic molecular assemblies through cyanometallate and alkoxo linkers

International audienceA nanoscopic {Fe60} coordination cage (approximately 3 nm) was prepared by the self assembly of a partially blocked tricyanidoferrate(III) complex and tris(alkoxo)-based iron(III) coordination motifs. This cage is a rare example of a mixed cyanido/alkoxo-bridged high nuclearity complex and it exemplifies the great potential of this new synthetic route to generate uncommon molecular architectures using cyanometallates as metalloligands versus alkoxo-based polynuclear entities

CCDC 1409712: Experimental Crystal Structure Determination

Related Article: J.-R. Jiménez, A. Mondal, L.-M. Chamoreau, P. Fertey, F. Tuna, M. Julve, A. Bousseksou, R. Lescouëzec, L. Lisnard|2016|Dalton Trans.|45|17610|doi:10.1039/C6DT03151

Solution and Solid-State Study of the Spin-Crossover [Fe-II(R-bik)(3)](BF4)(2) Complexes (R = Me, Et, Vinyl)

The magnetic properties of three spin-crossover complexes, [Fe-II(R-bik)(3)](BF4)(2)center dot nH(2)O (1-3), based on bis(imidazolyl) ketone ligands, were investigated in solution and the solid state. Their properties were compared with those of the ketone-free analogue, [Fe-II(bim)(3)](OTf)(2) (4). The alkyl and vinyl R groups have weak influence on the transition temperature, T-1/2, in solution, while stronger differences are observed in the solid state, because different intermolecular interactions occur in 1-3. The spin-state equilibria in solution were followed by SQUID magnetometry and the Evans NMR spectroscopy method. Interestingly, the equilibria can also be simply and efficiently probed by following the temperature dependence of an adequately chosen H-1 chemical shift. Overall, these experiments give coherent results, with T-1/2 located between 320 and 335 K, a narrow range, in comparison with the solid state. DFT calculations have allowed the rationalization of the magnetic differences. The molecular-orbital and spin-density calculations reveal that the presence of the C=O group between the imidazolyl units in the ligands of 1-3 leads to an extended aromatic system, an effective pi-acceptor effect, stabilizing the LS state and reducing the LS-HS gap, in comparison with 4