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International audience; Fluorinated proline derivatives have found diverse applications in areas ranging from medicinal chemistry over structural biochemistry to organocatalysis. Depending on the stereochemistry of monofluorination at the proline 3- or 4-position, different effects on the conformational properties of proline (ring pucker, cis/ trans isomerization) are introduced. With fluorination at both 3- and 4-positions, matching or mismatching effects can occur depending on the relative stereochemistry. Here we report, in full, the syntheses and conformational properties of three out of the four possible 3,4-difluoro-l-proline diastereoisomers. The yet unreported conformational properties are described for (3 S,4 S)- and (3 R,4 R)-difluoro-l-proline, which are shown to bias ring pucker and cis/ trans ratios on the same order of magnitude as their respective monofluorinated progenitors, although with significantly faster amide cis/ trans isomerization rates. The reported analogues thus expand the scope of available fluorinated proline analogues as tools to tailor proline's distinct conformational and dynamical properties, allowing for the interrogation of its role in, for instance, protein stability or folding.

There is an increasing interest in investigating how polyfluorination of carbohydrates modifies their physical and biological properties. An example that has caught much attention is 2,3,4-trideoxy-2,3,4-trifluoroglucose. Four syntheses of this compound have been reported, which are either low yielding or long (13 or more steps). We report a 6-step synthesis of 2,3,4-trideoxy-2,3,4-trifluoroglucose starting from levoglucosan. The solution-phase structure of an intermediate, 1,6-anhydro-2,4-dideoxy-2,4-difluoroallose, features a rare example of a bifurcated F center dot center dot center dot H(O)center dot center dot center dot F hydrogen bond and is compared to its crystal structure.

An in-depth analysis of the electro-optical and light emissive properties was carried out with a new fused heteroacene, the bis [(1,2)(5,6)] indoloanthracene. The compound was synthesized in a straightforward bidirectional manner from 1,4-dibromo-2,5-diodobenzene utilizing a reaction cascade of isomerisation and cyclisation sequences. Bis-[(1,2)(5,6)] indoloanthracene exhibits bright luminescence with high quantum yield in solution as well as in the solid state. By using this novel semiconductor as active layer, an efficient OLED has been fabricated for which its emission pattern resembles at least two emitters in a single emissive region originated from the same molecule. One has its origin from the single molecule and is similar to the luminescence spectra in solution, whereas the other functions through the formation of aggregates being similar with the emission pattern found with crystals of bis-[(1,2)(5,6)]indoloanthracene. As a result bright sky-blue OLEDs with very high luminance exceeding 10000 cd/m2 were obtained. Such color pattern and performance has not previously been observed with low molecular weight, electron-rich fused polycyclic aromatic compounds and indicate a promising new class of materials for development.

The design of molecule-based systems combining magnetic, chiroptical and second-order optical nonlinear properties is still very rare. We report an unusually unsymmetric diiron(III) complex 1, in which three bulky chiral carboranylpyridinealkoxide ligands (oCBhmp-) bridge both metal ions and the complex shows the above-mentioned properties. The introduction of o-carborane into the 2-(hydroxymethyl)pyridine (hmpH) architecture significantly alters the coordination of the simple or aryl-substituted 2-hmpH. The unusual architecture observed in 1 seems to be triggered by the poor nucleophilicity of our alkoxide ligand (oCBhmp-). A very rare case of spontaneous resolution takes place on precipitation or exposure to solvent vapor for the bulk compound, as confirmed by a combination of single-crystal and powder X-ray diffraction, second-harmonic generation, and circular dichroism. The corresponding enantiopure complexes (+)1 and (-)1 have also been synthesized and fully characterized. This research provides a new building block with unique geometry and electronics to construct coordination complexes with multifunctional properties. Fil: Di Salvo, Florencia. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina Fil: Tsang, Min Ying. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España Fil: Teixidor, Francesc. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España Fil: Viñas, Clara. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España Fil: Planas, José Giner. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España Fil: Crassous, Jeanne. Universite de Rennes I; Francia Fil: Vanthuyne, Nicolas. Aix Marseille Université; Francia Fil: Aliaga Alcalde, Núria. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Los Materiales de Barcelona; España Fil: Ruiz, Eliseo. Universidad Central de Barcelona; España Fil: Coquerel, Gerard. Universite de Rouen; Francia Fil: Clevers, Simon. Universite de Rouen; Francia Fil: Dupray, Valerie. Universite de Rouen; Francia Fil: Choquesillo Lazarte, Duane. Consejo Superior de Investigaciones Científicas; España Fil: Light, Mark E.. University of Southampton; Reino Unido Fil: Hursthouse, Michael B.. University of Southampton; Reino Unido

The Reformatsky reaction of ethyl bromodifluoroacetate to ?-oxygenated sulfinylimines is described. Using Honda–Reformatsky conditions, the reaction proceeds with double diastereodifferentiation, with the configuration of the sulfinyl group determining the stereochemical course of the reaction. Excellent diastereoselectivities (>94:6) are obtained for the matched cases. In contrast, reaction with sulfinylimines derived from unsubstituted alkanals proceeded with virtually no diastereoselectivity

International audience; A series of carbazolylurea and carbazolylthiourea-based receptors have been synthesized and their anion complexation and fluorescence properties studied. The urea compounds show selectivity for oxoanion complexation over chloride and the fluorescence of compound 1 is selectively quenched by benzoate anions in DMSO/0.5% water. However the thiourea compounds show reduced anion affinities compared to the urea analogues.

The syntheses of new o-carboranyl alcohols 1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = 9-anthracenyl 2, 4-pyridyl 4), 1-[R(hydroxy)methyl]-2-phenyl-1,2-dicarba-closo-dodecaborane (R = 3-phenyl-2-propen-1-ol 6, 2-furanyl 7) are reported. Their crystal structures, along with those for the related 1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = phenyl 1, 2-pyridyl 3) and 1-[phenyl(hydroxy)methyl]-2-phenyl-1,2-dicarba-closo-dodecaborane (5) derivatives are reported. We provide an analysis of these compounds by means of X-ray crystallography, NMR/IR spectroscopies, thermal analyses and gas phase calculations in the context of crystal engineering. The results show that the crystal packing for these alcohols can be described in terms of three major supramolecular synthons based on hydrogen bonding of OH groups with themselves (O–H⋯O homosynthons: 1, 6 and 7), with the pyridine nitrogen atom (O–H⋯N heterosynthons: 3 and 4) or with aromatic rings (O–H⋯π: 2). The latter shows an unusual combination of O–H⋯π and π–π interactions. The supramolecular heterosynthons are clearly favoured over their respective supramolecular homosynthons. In the absence of a nitrogen atom, the bulkiness around the OH groups seems to play a key role in the formation or not of full O–H⋯O hydrogen bonding. The supramolecular arrays are finally supported by both, weak dihydrogen or hydrophobic interactions, due to the presence of o-carboranyl fragments in these molecules. These compounds display good thermal stabilities, with compound 4 showing an unexpectedly high melting temperature of 256 °C probably arising from an infinite O–H⋯N hydrogen bonding network. Gas phase calculations demonstrate that O–H⋯N hydrogen bonded dimers are 3.5 kcal mol−1 more stable than analogous for O–H⋯O hydrogen bonded ones.

The convenient synthesis of original aminobenzyl-o-carboranes, which represent a new class of nitrogenated carborane derivatives, is described. These novel compounds have been efficiently prepared starting from commercially available aromatic aldehydes and monosubstituted o-carboranes via carboranyl alcohols and chlorides as intermediates. The key step of this methodology is a selective nucleophilic amination under mild conditions that allows the formation of the expected amines while limiting the partial deboronation of the carborane cluster. This general strategy has been applied to the preparation of a wide variety of aminobenzyl-o-carboranes. The extension of this pathway to the synthesis of enantiopure carborane-amine combinations is also described.

International audience; Four receptors containing either 2-amidoindole or 7-nitro-2-amidoindole groups have been synthesized and shown to complex oxo-anions in DMSO-d6/0.5% water solution. X-ray crystal structure elucidation reveals that receptor 1 complexes dihydrogen phosphate ion pairs in the solid state that are part of a continuous chain. Whilst this receptor binds dihydrogen phosphate in a 1:1 stoichiometry in solution, compound 4, which contains 7-nitroindole groups, does form 1:2 receptor:dihydrogen phosphate complexes in DMSO-d6/0.5% water.

International audience; Proton NMR titrations have been performed with meso-octacalix[4]pyrrole and a variety of organic chloride and bromide salts in dichloromethane-d2. The results show apparently increasing chloride stability constants within each set of anion salts (tetrabutylammonium < imidazolium < pyridinium). Addition of 1-ethyl-3-methylimidaolium (EMIM) nitrate to dichloromethane-d2 solutions of calix[4]pyrrole caused significantly larger downfield shifts of the pyrrole NH protons of calix[4]pyrrole than addition of equimolar quantities of tetrabutylammonium nitrate. The first crystal structure of a nitrate complex of a calix[4]pyrrole is also presented.

International audience; Two new ortho-phenylenediamine based bis-urea compounds have been synthesised with pendant amide groups. The stability constants of the new compounds with a variety of anionic guests have been measured by 1H NMR titration techniques and compared to the parent bis-urea. The X-ray crystal structure of the acetate and benzoate complexes of a bis-amide functionalised system have been solved and reveal the receptor forming a dimer with two anions bound at the termini of the hydrogen bonded assembly.