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Molecules bearing a 4,4-difluoro-8-(aryl)-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene (bodipy) core and 1-pyrenyl-1-phenyl-4-(1-ethynylpyrene), or 1-phenyl-4-[1-ethynyl-(6-ethynylpyrene)pyrene] units were constructed in a step-by-step procedure based on palladium(0)-promoted cross-coupling reactions with the required preconstructed modules. X-ray structures of single crystals reveal a twisted arrangement of the two chromophores. In one case, an almost perfect orthogonal arrangement is found. These dyes are strongly luminescent in solution and display rich electrochemistry in which all redox processes of the bodipy and pyrene fragments are clearly resolved. The absorption spectra indicate that the bodipy and pyrene chromophores are spectrally isolated, thereby inducing a large "virtual" Stokes shift. The latter is realised by efficient transfer of intramolecular excitation energy by the Förster dipole-dipole mechanism. The rate of energy transfer depends on the structure of the dual-dye system and decreases as the centre-to-centre separation increases. The energy transfer efficiency, however, exceeds 90 % in all cases. The linkage of two pyrene residues by an ethyne group leads to a decrease in the energy-transfer efficiency, with the two polycycles acting as a single chromophore. The directly linked bodipy-pyrene dual dye binds to DNA and operates as an efficient solar concentrator when dispersed in plastic.

Two new dithiazolylethenes, 1a {1,2-bis[5′-methyl-2′-(2′′-pyridyl)thiazolyl]perfluorocyclopentene} and 2a {1,2-bis[4′-methyl-2′-(2′′-pyridyl)thiazolyl]perfluorocyclopentene}, have been synthesized. Their photochromic behavior has been fully investigated in solution as well as in the crystalline phase. They display both fatigue-resistant and thermally irreversible photochromic reactions, with more than 80% of the closed-ring forms (1b and 2b, respectively) in the photo-stationary state. Upon UV irradiation, a colorless solution of 1a turns purple while the yellow color of a 2a solution becomes more intense. Such marked differences in their electronic absorption spectra are reproduced by DFT calculations. Finally, although structurally closely related, only 1a shows photochromism in the crystalline phase whereas 2a displays reversible photo-modulation of fluorescence in solution.

A novel family of highly functionalized molecules consisting of a central 4-methyl-3,5-diacylaminobenzene platform linked in close proximity to the methyl group by two lateral aromatic rings each equipped with two long alkoxy chains has been rationally designed. The presence of amide tethers and a chelating phenanthroline fragment connected via an ester dipole formed a new class of gelating reagents and mesomorphic materials. A few of these compounds have the tendency to form macromolecule-like aggregates through noncovalent interactions in hydrocarbon solvents and were found to exhibit thermotropic cubic mesophases. In light of the X-ray molecular structure of the methoxy ligand, an infinite network maintained by intermolecular hydrogen bonds as well as by pi-pi stacking of the phenyl subunits was evidenced. FT-IR studies confirm that the common driving force for aggregation in the organogels and microsegregation in the mesophase is the occurrence of a tight intermolecular H-bonded network that does not persist in diluted solution. This situation is switched when the ligands are interlocked by a copper(I) cation. A strong intramolecular H-bond confirmed by X-ray diffraction of a single crystal for the methoxy case provides very stable complexes but inhibits the gelation of the solvents. Heating the complexes bearing long paraffin chains (n = 12 and 16) in the dried state leads to a self-organization into a columnar liquid-crystalline phase in which the columns are arranged along a 2D oblique symmetry as deduced from powder XRD experiments. In this case, the complexes with the appended counteranions self-assemble in a specific way to form columns. A striking observation is that the intramolecular hydrogen bond persists in the mesophase as it does in solution without any evidence of an extended network. As far as we are aware, these ligands and complexes are rare examples in which organogelation and thermotropic mesomorphic behavior could be observed in parallel with molecules bearing a chelating platform. Due to the synthetic availability of the 4-methyl-3,5-diacylaminobenzene core and the simplicity by which the chelating platforms can be graphed, this methodology represents a practical alternative to the production of functionalized organogelators and mesomorphic materials.

The g-tensors and hyperfine tensors of the S = (1)/(2) ground state of the mixed valence [LMn(IIImu-O)(2)Mn(IV)L](3+) complex (L = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine) was deter-mined in the solid-state and frozen acetonitrile solution by high-field EPR. Both samples exhibited complex anisotropic temperature behaviors that precluded the use of routine spectrum simulation procedures to extract the spin parameters. To circumvent this problem, the parameters were measured directly by using multifrequency techniques. In the case of the frozen solution, this approach yielded seven of the nine spin parameters with varying uncertainty, the two extreme principal g-values, the four hyperfine couplings associated with each of these two g-values, and the middle g-value. This latter parameter was obtained from a first moment analysis. Unlike simulations, the statistical errors associated with each value could be assigned in a straightforward and rigorous manner. The directly measured g-values were different in frozen solution and polycrystalline powder. The temperature dependence of the high-field EPR spectra of the polycrystalline powder revealed a spin-spin interaction between the neighboring binuclear complexes.

The catalytic asymmetric synthesis of an axially chiral biaryl, potentially useful intermediate in the synthesis of dibenzocyclooctadiene lignans, has been performed. The key step consisted of a diastereoselective Suzuki coupling between a chiral benzylic alcohol and a sterically hindered boronic ester. The 1,3-induction from the benzylic stereocenter to the biaryl axis proceeded with very good diastereoselectivity.

The palladium-catalyzed, two-step, one-pot borylation/Suzuki coupling (BSC) reaction was developed to synthesize sterically hindered 2,2'-disubstituted biphenyl and phenyl-indole compounds in a short, simple, and efficient manner from two easily accessible aryl halides. High yields can be obtained by choosing properly both components according to their rough electronic properties. The illustration of the utility of this method was provided by the solution and solid-phase synthesis of seven- or eight-membered biphenyl lactams 5a-e, as well as paullone 3a. These compounds exhibit moderate albeit significant cytotoxicities and may serve as structural models for future medicinal chemistry developments.

Ligand L, containing two 6-methyl-6′-methyl-yl-2,2′-bipyridine moieties linked by a “PhPO” spacer, has been prepared. Subsequent complexation with [Cu(CH3CN)4](BF4) led to a unique complex of formula [CuL](BF4). The molecular structure has been determined by X-ray crystallography in the solid state and NMR studies in solution. The complex displays an intense absorption band in the visible wavelength range with maxima at 418 and 509 nm, and is oxidised reversibly at +0.66 V (ΔEp = 80 mV) to the corresponding Cu(II) species, while two successive reductions of the coordinated bipyridine fragments occur at −1.60 (ΔEp = 66) and −1.84 V (ΔEp = 70 mV) s. SCE. Direct spectrophotometric titrations with global analysis allowed us to elicit stability constants for the emergent complex and to highlight the formation of a dinuclear complex in the presence of excess copper.

Three macrobicyclic octamines 1–3 and the macrotricyclic hexadecamine 14 have been synthesized. The octamines 1–3 bind anionic substrates when protonated. The stability constants of the complexes between the protonated forms of the macrobicyclic polyamines and halide anions have been determined by pH-metric measurements. The stability constants in H2O are very high; 1 in its hexaprotonated form binds F− with high selectivity (selectivity F−/Cl− > 108), while 3 exhibits strong stability constants for both F− and Cl−. Three X-ray structures have been obtained, one where F− is held inside the cavity of 1 · 6H+, one where Cl− is included in 3 · 6H+, and 3 · 6H+ where the cavity is empty.

A new manganese(II) complex, Mn(II)−tris[2-[N-(2-pyridylmethyl)amino]ethyl]bishexafluorophosphate (Mn−TPAA), has been synthesized, its X-ray crystal structure resolved, and its superoxide stoichiometric scavenging activity established. The complex has been formed with the tripodal potentially heptadentate ligand TPAA which turns out to be the single ligand coordinated to the metal ion and therefore achieves the seven coordination. The complex crystallizes in the space group P212121, a = 19.654(9) A, b = 15.416(5) A, c = 10.425(4) A, with four formula units per unit cell. The manganese is bonded to three pyridine nitrogen atoms, to three amine groups, and to the tripodal bridging nitrogen N. The reactivity toward superoxide has been investigated using the indirect xanthine−xanthine oxidase−cytochrome c method, the electrochemical reaction of in-situ generated superoxide, and γ and pulse radiolysis measurements. From the cytochrome c assay, it has been found that the IC50 value is equal to 4.4 μM. From elec...

The compound [Mn2III,IVO2(bisimMe2en)2](ClO4)3·H2O (bisimMe2en = N,N‘-dimethyl-N,N‘-bis(imidazol-4-ylmethyl)ethane-1,2-diamine) was synthesized. It crystallizes in the monoclinic space group C2/c with a = 18.139(8) A, b = 12.694(5) A, c = 17.694(8) A, β = 107.5(6)°, V = 3885(6) A3, and Z = 4. The cation [Mn2III,IVO2(bisimMe2en)2]3+ contains a di-manganese di-μ-oxo unit. The Mn−Mn axis is a C2 axis. The Mn−imidazole distances for MnIII or MnIV are distinct: respectively, 2.208(9) and 2.004(8) A. The ground state is a |SA2,SB3/2,S1/2〉 state separated by 420 cm-1 from the S = 3/2 state. The EPR spectrum has been simulated with |A1x,y| = 160.10-4 cm-1, |A1z| = 136.10-4 cm-1, |A2x,y| = 72.10-4 cm-1, |A2z| = 71.10-4 cm-1, gxy = 1.997, gz = 1.993. The ESEEM spectrum is reported. The 2H nuclei corresponding to the exchangeable hydrogen atoms of imidazole groups in D2O have been detected at 2.4 MHz at 3480 G. In cyclic voltammetry, [Mn2III,IVO2(bisimMe2en)2]3+ presents in oxidation two reversible waves at 1.04 an...

The palladium-catalyzed, two-step, one-pot borylation/Suzuki coupling (BSC) reaction was developed to synthesize sterically hindered 2,2'-disubstituted biphenyl and phenyl-indole compounds in a short, simple, and efficient manner from two easily accessible aryl halides. High yields can be obtained by choosing properly both components according to their rough electronic properties. The illustration of the utility of this method was provided by the solution and solid-phase synthesis of seven- or eight-membered biphenyl lactams 5a-e, as well as paullone 3a. These compounds exhibit moderate albeit significant cytotoxicities and may serve as structural models for future medicinal chemistry developments.

The crystal structures of the LiBr complexes of two macrobicyclic ligands, [py.py.bpy]1 and [py.biqi.biqi] 2, have been determined. They confirm the cryptate nature of these species. In 3, the Li+ cation is bound in the shallow cavity of a ligand of flattened shape, whereas in 4, it is buried inside the macrobicycle and surrounded by its three bridges.

A new class of highly luminescent dyes is reported. The characteristic feature of these compounds is that a terpyridine fragment is closely appended to a boradiazaindacene moiety in such a way that cation binding to the vacant terpyridine causes strong perturbations of the photophysical properties of the boradiazaindacene unit. In particular, these sensors are especially applicable to the fluorescence detection of trace quantities of zinc(II) ions in solution. The mechanism of the cation-induced quenching process has been investigated by a combination of electrochemistry, UV/Vis absorption, emission, and NMR spectroscopy. Highly luminescent arrays can be formed by doping transparent polymers with low concentrations of these new dyes. In such materials, the change in photophysical properties upon cation binding is so marked that "cation writing" becomes feasible under routine conditions.

There has been considerable interest in metal complexes of binucleating ligands as models for the coordination environment of the active sites in binucleating metalloenzymes. Numerous synthetic systems, like di-copper or di-cobalt complexes, have been demonstrated to function as catalysts for the transformation (oxidation, hydrolysis) of organic substrates other than the ligand itself. The catalytic efficiency and the selectivity depends critically on the distance between the metallic centers, the conformation of the spacer and the stability of the complex.

International audience; Studies of the properties of a series of amphiphilic calixarenes show that they can form stable monolayers, Langmuir-Blodgett layers and solid lipid nanoparticles, the mesostructures were investigated by atomic force microscopy and the crystal structure of one compound shows a partially interdigitated tilted bilayer structure.Studies of the properties of a series of amphiphilic calixarenes show that they can form stable monolayers, Langmuir-Blodgett layers and solid lipid nanoparticles, the mesostructures were investigated by atomic force microscopy and the crystal structure of one compound shows a partially interdigitated tilted bilayer structure.

A newly-synthesized 4′-[bis(diphenylphosphino)methane]–2,2′∶6′,2 ″-terpyridine-based (dppm–terpy) ligand forms complexes by selective complexation of the terpy or diphos segment, respectively, with Fe(II) or Pd(II) salts; in the latter case, an X-ray structural analysis reveals the formation of a neutral square-planar complex assembled from the deprotonated ligands.

International audience; The use of a C3 complex bearing three imidazolate groups as a `building block' allowed us to synthesize an infinite corrugated two-dimensional (2D) low-spin Fe(III)-high-spin Mn(II) polymer exhibiting weak ferromagnetic intralayer interaction through imidazolate bridge.