Cyanomethylene-bis(phosphonate)-Based Lanthanide Complexes: Structural, Photophysical, and Magnetic Investigations

10 pagesInternational audienceThe syntheses, structural investigations, magnetic and photophysical properties of a series of 10 lanthanide mononuclear complexes, containing the heteroditopic ligand cyanomethylene-bis(5,5-dimethyl-2-oxo-1,3,2λ5-dioxa-phosphorinane) (L), are described. The crystallographic analyses indicate two structural types: in the first one, [LnIII(L)3(H2O)2]*H2O (Ln = La, Pr, Nd), the metal ions are eight-coordinated within a square antiprism geometry, while the second one, [LnIII(L)3(H2O)]*8H2O (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er), contains seven-coordinated LnIII ions within distorted monocapped trigonal prisms...

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

Chiroptical properties of carbo[6]helicene derivatives bearing extended π-conjugated cyano substituents.

International audienceNew carbo[6]helicene derivatives grafted with π-conjugated cyano-phenyl arms were synthesized in enantiopure forms and their π-conjugation examined by UV-vis spectroscopy. The influence of the π-conjugation on the circular dichroism spectra and molar rotations is discussed based on comparing experimental data with results from quantum-chemical calculations. The results highlight the fact that increasing the spatial extension of the π-system in a helicene molecule is an efficient way of increasing its molar rotation

<i>DiffractWD</i>: an open-source program for powder pattern comparison and visualization

A new program for basic powder pattern manipulations and visualization is described. It provides a user-friendly interface for comparison of spectra with each other and with simulated patterns based on single-crystal data. The program contains all necessary tools for the preparation of routine images for qualitative phase analysis and can be downloaded free of charge from http://diffractwd.com.</jats:p

Synthesis of small tetranuclear Cu(I) metallacycles based on bridging pseudohalogenide ions.

International audienceThree new 'short' metallacycles are selectively obtained from the reaction of a bimetallic Cu(I) 'U-shape' molecular clip with, respectively, the cyano CN(-), tricyanomethanide C(CN)(3)(-), and azido N(3)(-) pseudohalogenide ions. These supramolecular assemblies have been characterized by spectroscopic methods, single-crystal X-ray diffraction, and elemental analysis. The single-crystal X-ray structures of these complexes reveal no short contact interaction between the pseudohalogenide ions within these self-assembled structures despite the short Cu(I)***Cu(I) distances within the molecular clips. The formation of these discrete metallacycles is rationalized by analyzing the structural features of the Cu(I) 'U-shape' molecular clip

Bis[(cyanido-κ C

The title compound, [Cu(CN)(C(12)H(8)N(2))(2)](2)[Fe(CN)(5)(NO)]·C(3)H(7)NO, is formed of discrete [Cu(phen)(2)CN](+) cations (phen is 1,10-phenanthroline), nitro­prusside [Fe(CN)(5)(NO)](2−) anions and dimethyl­formamide (DMF) mol­ecules of crystallization. The metal atom has a distorted trigonal–bipyra­midal coordination environment, defined by four N atoms of two phen mol­ecules and a C atom of the cyanide group (in the equatorial position). The [Fe(CN)(5)(NO)](2−) anion was found to be disordered about (but not on) a crystallographic twofold rotation axis. Geometries were restrained to ideal values. The dimethyl­formamide solvent mol­ecule was found to be disordered about a crystallographic inversion centre