Soumaila Zebret

Rational design of a ternary supramolecular system: self-assembly of pentanuclear lanthanide helicates.

The self-assembly of the first pentanuclear helicate was predicted on the structural basis obtained for linear and tetranuclear parent supramolecular compounds. Accordingly, the designed ternary supramolecular system requires appropriate polytopic organic receptors, which were successfully synthesized. Indeed, the formation of pentanuclear complexes was experimentally evidenced with NMR and ESMS spectra that perfectly reflect the expected pattern. The structural features in the europium pentanuclear complex are highlighted with semiempirical molecular modeling. The present work validates the combinatorial approach leading to the thermodynamically driven formation of tower-like pentanuclear edifices.

Self‐Assembly of a Trinuclear Luminescent Europium Complex

Triangular luminescent box: Self-assembly of a new multidentate receptor with europium cations results in the formation of trinuclear discrete complexes. X-ray crystallography shows that nine-coordinate cations are linked by ligands to provide a triangular complex in the solid state and in solution. Despite the coordinated solvent molecules, this topologically unusual complex exhibits remarkable luminescent properties.

Designing Artificial 3D Helicates: Unprecedented Self‐Assembly of Homo‐octanuclear Tetrapods with Europium

Herein, we report on the rational design, preparation and characterization of a novel homo-octanuclear helicate, which results from a spatial extension of the central tetranuclear platform. The 3D supramolecular assembly is obtained by complexing europium(III) with a new hexatopic tripodal ligand. The isolated octanuclear helicate is fully characterized by different methods clearly evidencing the structure predicted with molecular modelling. The ligand preorganization plays a crucial role in a successful self-assembly process and induces the formation of a well-defined triple-stranded helical structure. This prototypal octanuclear edifice accommodating functional lanthanides within a 3D scaffold offers attractive perspectives for further applications.

Functionalized Triptycene-Derived Tripodal Ligands: Privileged Formation of Tetranuclear Cage Assemblies with Larger Ln(III)

In this Article, we report the self-assembly of lanthanide complexes formed with two new tripodal ligands, L2 and L3, where binding strands are connected to a rigid triptycene anchor. The pyridine moieties are functionalized with methoxy and PEG groups to enhance ligand solubility and to evaluate the effect of these substituents on lanthanide coordination. These ligands were successfully synthesized and characterized, and their coordination properties were examined along the lanthanide series through speciation studies with NMR and ESI-MS. Well-defined tetranuclear complexes are formed with both ligands, but their stabilities with heavier lanthanides are considerably reduced, especially for complexes with L3. This is attributed to a destabilizing effect of pending PEG arms in combination with increased steric hindrance between binding strands upon complexation with smaller cations. The sensitization of lanthanide luminescence in tetranuclear complexes occurs despite one water molecule being coordinated to a metal ion.

Lanthanide-mediated triangular cationic assemblies: structural and physico-chemical properties

This contribution investigates Ln(III) complexes formed with a small ditopic ligand, L1, and their structural, thermodynamic and photophysical properties. The spectrophotometric and NMR titrations evidence the triangular assemblies [Ln(3)(L1-H)(3)](6+) at stoichiometric conditions and their properties are discussed in relation to L2-containing analogues. In addition, the dinuclear species, [Ln(2)(L1-H)](5+), is observed with an excess of metal.

Tris(6-carb-oxy-pyridine-2-carboxyl-ato)terbium(III) 2.75-hydrate.

In the title compound, [Tb(C7H4NO4)3]·2.75H2O, the Tb3+ atom is coordinated by three tridentate 6-carboxypyridine-2-carboxylate ligands and lies on a crystallographic threefold rotation axis. The coordination polyhedron around TbIII adopts a distorted tricapped trigonal–prismatic geometry. Disordered water molecules with partial occupancy are also present in the crystal, one of which is associated with each of the carboxylate O atoms of the complex unit.

CCDC 1514581: Experimental Crystal Structure Determination

Related Article: Alexandra Vuillamy, Soumaila Zebret, Celine Besnard, Virginie Placide, Stephane Petoud, Josef Hamacek|2017|Inorg.Chem.|56|2742|doi:10.1021/acs.inorgchem.6b02900