Dissymmetrical U-Shaped π-Stacked Supramolecular Assemblies by Using a Dinuclear CuI Clip with Organophosphorus Ligands and Monotopic Fully π-Conjugated Ligands

International audienceReactions between the U-shape binuclear CuI complex A bearing short metal-metal distances and the cyano-capped monotopic π-conjugated ligands 1-5 carrying gradually bulkier polyaromatic terminal fragments lead to the formation of π-stacked supramolecular assemblies 6-10 respectively in 50-80 % yields. These derivatives have been characterized by multinuclear NMR spectroscopy and X-ray diffraction studies. Their solid state structures show the selective formation of U-shaped supramolecular assemblies in which two monotopic π-conjugated systems present large (6,7,9) or medium (8,10) intramolecular π-overlap revealing π-π interactions. These assemblies self-organize into head-to-tail π-stacked dimers that in turn self-assemble affording infinite columnar π-stacks. The nature, the extentand the complexity of the intermolecular contacts within the head-to-tail π-stacked dimer depends on the nature of the terminal polyaromatic fragment carried by the cyano-capped monotopic ligand but it does not alter the result of the self-assembling process. These results demonstrate that the dinuclear molecular clip A bearing short metal-metal distance allows selective supramolecular assembling processes driven by the formation of intra- and intermolecular short π-π interactions in the resulting self-assembled structures demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extented π-stacked columns based on dissymmetrical and functionnal π-conjugated systems

Rhenium complexes bearing phosphole-pyridine chelates: simple molecules with large chiroptical properties.

International audienceThe synthesis and chiroptical properties of chiral rhenium complexes bearing mono- or di-topic phosphole ligands are described. [on SciFinder(R)

NleG Type 3 Effectors from Enterohaemorrhagic Escherichia coli Are U-Box E3 Ubiquitin Ligases

NleG homologues constitute the largest family of type 3 effectors delivered by pathogenic E. coli, with fourteen members in the enterohaemorrhagic (EHEC) O157:H7 strain alone. Identified recently as part of the non-LEE-encoded (Nle) effector set, this family remained uncharacterised and shared no sequence homology to other proteins including those of known function. The C-terminal domain of NleG2-3 (residues 90 to 191) is the most conserved region in NleG proteins and was solved by NMR. Structural analysis of this structure revealed the presence of a RING finger/U-box motif. Functional assays demonstrated that NleG2-3 as well as NleG5-1, NleG6-2 and NleG9′ family members exhibited a strong autoubiquitination activity in vitro; a characteristic usually expressed by eukaryotic ubiquitin E3 ligases. When screened for activity against a panel of 30 human E2 enzymes, the NleG2-3 and NleG5-1 homologues showed an identical profile with only UBE2E2, UBE2E3 and UBE2D2 enzymes supporting NleG activity. Fluorescence polarization analysis yielded a binding affinity constant of 56±2 µM for the UBE2D2/NleG5-1 interaction, a value comparable with previous studies on E2/E3 affinities. The UBE2D2 interaction interface on NleG2-3 defined by NMR chemical shift perturbation and mutagenesis was shown to be generally similar to that characterised for human RING finger ubiquitin ligases. The alanine substitutions of UBE2D2 residues Arg5 and Lys63, critical for activation of eukaryotic E3 ligases, also significantly decreased both NleG binding and autoubiquitination activity. These results demonstrate that bacteria-encoded NleG effectors are E3 ubiquitin ligases analogous to RING finger and U-box enzymes in eukaryotes

Coordination-Driven Syntheses of Compact Supramolecular Metallacycles toward Extended Metallo-organic Stacked Supramolecular Assemblies

International audienc

Coordination-driven Supramolecular Synthesis based on Bimetallic Cu(I) Precursors: Adaptive Behavior and Luminescence

International audiencePre-organized adaptive Cu(I) bimetallic precursors can be successfully engaged in coordination-driven supramolecular reactions. Selective formation either of a large family of compact metallacycles or of polymetallic discrete assemblies and one-dimensional coordination polymers is rationalized taking into account the relative amplitudes of conformational flexibility allowed by the precursors used. It reveals the originality of the self-assembly processes conducted with such Cu(I)-based building blocks. In addition, exalted luminescence properties can be embedded in the resulting supramolecular assemblies due to the specific photophysical behaviors of Cu(I)-luminophores. General and straightforward access toward coordination-driven supramolecular assemblies featuring original architectures and multifunctional luminescence properties is therefore highlighted, taking advantage of both the specificities of the coordination chemistry and the electronic structure of derivatives based on the Cu(I) ion

CHIMIE DE COORDINATION DE RADICAUX LIBRES NITROXYDE BISBIDENTES ET CHIRAUX (SYNTHESES, CARACTERISATIONS ET PROPRIETES MAGNETIQUES)

GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Étude de corrélation IRM-échoendoscopie dans le bilan d'extension locorégionale initial du cancer du rectum

ANGERS-BU Médecine-Pharmacie (490072105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Syntheses and coordination chemistry of bis(4-pyridyl)- and mixed (4-pyridyl) (2-pyridyl)-phospholes

International audienceThe syntheses, spectroscopic characterizations, and X-ray structures of two new N,P,N-ligands 1 and 2 are described. These ligands are based on a central 2,5-substituted phosphole ring and have, respectively, two 4-pyridyl moieties, or one 4-pyridyl moiety and one 2-pyridyl moiety as substituents. The coordination chemistry of these ligands has been investigated. A Au(I)-complex 5 bearing ligand 1 as a P-donor and a Pt(II) complex 6 featuring ligand 2 as a P,N-chelate were obtained. Complex 6 spontaneously evolves to complex 7 bearing a 2-phospholene ring. Spectroscopic characterizations for complexes 5-7 as well as the X-ray crystal structure of 7 are described