Modular enhancement of circularly polarized luminescence in Pd2A2B2 heteroleptic cages

Metal-mediated assembly allows us to combine an achiral emissive ligand A with different chiral ligands (such as B) in a non-statistical fashion, obtaining Pd2A2B2 heteroleptic cages showing circularly polarized luminescence (CPL). By using the ‘shape complementary assembly’ (SCA) strategy, the cages are exclusively obtained as cis-Pd2A2B2 stereoisomers, as confirmed by NMR, MS and DFT analyses. Their unique chiroptical properties derive from the synergy of all the building blocks. Ligand B imparts the chiral information of its aliphatic backbone, comprising two stereogenic sp3 carbon centres, to the overall structure, causing CD and CPL signal induction for the chromophore on ligand A. The heteroleptic cage shows CPL with a |glum| value of 2.5 × 10−3, which is 3-times higher than that for a progenitor based on aromatic helical building block H, thus opening a rational route towards optimizing the CPL properties of self-assembled nanostructures in a modular way

Binuclear Copper(I) Complexes for Near-Infrared Light-Emitting Electrochemical Cells

Two binuclear heteroleptic CuI complexes, namely Cu−NIR1 and Cu−NIR2, bearing rigid chelating diphosphines and π-conjugated 2,5-di(pyridin-2-yl)thiazolo[5,4-d]thiazole as the bis-bidentate ligand are presented. The proposed dinuclearization strategy yields a large bathochromic shift of the emission when compared to the mononuclear counterparts (M1–M2) and enables shifting luminescence into the near-infrared (NIR) region in both solution and solid state, showing emission maximum at ca. 750 and 712 nm, respectively. The radiative process is assigned to an excited state with triplet metal-to-ligand charge transfer (3MLCT) character as demonstrated by in-depth photophysical and computational investigation. Noteworthy, X-ray analysis of the binuclear complexes unravels two interligand π–π-stacking interactions yielding a doubly locked structure that disfavours flattening of the tetrahedral coordination around the CuI centre in the excited state and maintain enhanced NIR luminescence. No such interaction is present in M1–M2. These findings prompt the successful use of Cu−NIR1 and Cu−NIR2 in NIR light-emitting electrochemical cells (LECs), which display electroluminescence maximum up to 756 nm and peak external quantum efficiency (EQE) of 0.43 %. Their suitability for the fabrication of white-emitting LECs is also demonstrated. To the best of our knowledge, these are the first examples of NIR electroluminescent devices based on earth-abundant CuI emitters

Activation electrochimique de petites molecules par des composes bi-metalliques et elaboration de films polymeres conducteurs

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

An EPR/ENDOR study of the reduction products of symmetrical isomers of dipyridylacetylene

The reduction potentials of the three symmetrical isomers (para–para, ortho–ortho and meta–meta) of dipyridylacetylene were measured by cyclic voltametry. These compounds were reacted on alkali metal mirrors and the resulting radical anions were studied by electron paramagnetic resonance/electron–nuclear double resonance/triple resonance spectroscopies. The reduction products were identified after comparison of the measured hyperfine couplings with those predicted by density functional theory calculations. The mono-radical anion was observed for the two former isomers [coupling with the counter ion was detected for the ion pair (ortho–ortho)-39K+]; the third isomer led to the radical anion of dipyridylethylene

Tectonique moléculaire (Correlation entre flexibilité des tectons et topologie des réseaux)

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Tectonique moléculaire (conception et formation de polymères de coordination chiraux)

La formation de polymères de coordination poreux et chiraux ainsi que leur utilisation pour des processus énantiosélectifs est actuellement un des domaines de grand intérêt en chimie. La formation de ces matériaux est rendue possible par le biais des concepts développés dans le domaine de la tectonique moléculaire. Les travaux présentés dans cette thèse s inscriventdirectement dans cette thématique. Les synthèses de tectons organiques chiraux sont présentées. Leur combinaison avec divers centres métalliques, via différentes méthodes de cristallisation, a permis l obtention de monocristaux qui ont été étudiés par diffraction des rayons X sur monocristal. Dans un premier temps, des polymères de coordination homochiraux, obtenus par l utilisation de tectons dotés de sites coordinants neutres sont présentés. Des réseaux de type cuboïde présentant des canaux monodimensionnels au sein de leur architecture sont notamment décrits. Par la suite, des édifices mono- et bi-dimensionnels de géométries diverses sont discutés. Pour certains de ces cristaux, des interactions de plus faible énergie que la liaison de coordination permettent la formation de réseaux moléculaires de plus haute dimensionnalité. Enfin, dans une dernière partie, l utilisation de tectons dotés de sites coordinants chargés est discutée. Des réseaux tridimensionnels homochiraux poreux et robustes sont décrits. Ces derniers sont des candidats de choix pour des procédés énantiosélectifs de séparation. Leur propension à encapsuler des gaz (N2 et CO2) est présentée.The synthesis and the use of porous chiral coordination polymers for enantioselective processes are of current interest and prime importance in chemistry. These crystalline materials are mainly obtained by combinations of well-designed organic tectons and properly chosen metallic components. This thesis deals with the synthesis of organic chiral building blocks and their combinations with a variety of metallic salts leading to chiral coordination networks. In a first part, the use of tectons bearing neutral coordinating sites is described. Homochiral cuboid architectures displaying monodimensional channels are presented. In the second part, mono- and bi-dimensional networks of various geometries are described. In some cases, within crystals, interactions lower in energy than the coordination bond are observed and are responsible for the formation of molecular networks of higher dimensionality. Finally, the use of organic tectons displaying charged interaction sites is presented. Their combination with metallatectons under thermal treatments affords robust tridimensional homochiralarchitectures displaying cavities. These materials are interesting candidates for enantioselective recognition and separation. Their gas adsorption propensity (N2 and CO2) is briefly discussed.STRASBOURG-Bib.electronique 063 (674829902) / SudocSudocFranceF

Synthesis and characterisation of a heterodinuclear ruthenium(II)-palladium(II) complex with two different cyclometallating sites

A bis-cyclometallating ligand bearing two different terdentate coordination sites (N---C---N: dipyridyI-benzene; P---C---P: diphosphaalkenebenzene moieties) has been synthesised. Selective reactions of appropriate metal complex precursors afforded a heterodinuclear ruthenium(II)-palladium(II) complex characterised by 1H, 13P NMR spectroscopy and FAB-MS techniques. We have compared its electrochemical and spectroscopic properties (absorption and emission) with the individual ruthenium(II) and palladium(II) subunits

1,2-Bis[2,4,6-tri-tert-butylphenyl]phosphanediylmethyl]benzene, L : synthesis and structure of L, of the chelated complex [PdLCl2] and of a derived cyclometallated chiral complex

The synthesis and crystal structure of 1,2-bis[2-(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]benzene, L, are reported as well as the preparation and conformation of the novel seven-membered ring complex [PdLCl2]; this complex reacts with alcohols (MeOH, EtOH) to give a chiral cyclometallated complex [rac(R)P, (R)C; (S)P, (S)C] where the metal is bound to both a phosphaalkene and a phosphite phosphorus atom

3,3',5,5' tetra(phosphaalkene) biphenyl : synthesis of a novel bicyclometalating bridging ligand and structure of its dipalladium complex

A biphenyl derivative bearing four phosphaalkene groups in positions 3,3',5,5' has been synthesized and is shown to be a bis-terdentate chelating agent; this novel bridging ligand forms a complex with two palladium ions and the crystal structure of this dinuclear species has been obtained