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International audience; After extensive studies of 1D and 2D skeletal carbo‐mers based on C8π‐conjugatingdialkynylbutatriene units(DABs: ~C≡C–(R)C=C=C=C(R)–C≡C~) bridging spor sp2centers in carbo‐butene, ‐xylylene or ‐benzene derivatives, 3D versions are envisaged through carbo‐barrelenes and partially reduced derivatives thereofwhere two or three DAB blades span a bridge between sp3carbinol vertices or ether thereof. For R = Ph, stable representatives were synthesized through a pivotal [6]pericyclynedione, and extensively characterized by spectroscopic, electrochemical and crystallographic methods. Density functional theory calculations allow detailed analysis of structural and electronic features of the 7 Å high barrel‐shaped molecules, and show that they can behave as cages for ionic species. Beyond aesthetical concerns, the results could open prospects of applications in host‐guest supramolecular chemistry and single molecule charge transport.

International audience; A pharmacophore design approach, based on the coordination chemistry of an intimate molecular hybrid of active metabolites of pro-drugs, known to release active species upon enzymatic oxidative activation, is devised. This is exemplified by combining two anti-mycobacterial drugs: pyrazinamide (first line) and delamanid (third line) whose active metabolites are pyrazinoic acid (PyzCOOH) and likely nitroxyl (HNO (or NO.)), respectively. Aiming to generate those active species, a hybrid compound was envisaged by coordination of pyrazine-2-hydroxamic acid (PyzCONHOH) with a Na3[FeII(CN)5] moiety. The corresponding pentacyanoferrate(II) complex Na4[FeII(CN)5(PyzCONHO−)] was synthesized and characterized by several spectroscopic techniques, cyclic voltammetry, and DFT calculations. Chemical oxidation of this complex with H2O2 was shown to induce the release of the metabolite PyzCOOH, without the need of the Mycobacterium tuberculosis (Mtb) pyrazinamidase enzyme (PncA). Control experiments show that both H2O2- and N-coordinated pyrazine FeII species are required, ruling out a direct hydrolysis of the hydroxamic acid or an alternative oxidative route through chelation of a metal center by a hydroxamic group. The release of HNO was observed using EPR spectroscopy in the presence of a spin trapping agent. The devised iron metal complex of pyrazine-2-hydroxamic acid was found inactive against an actively growing/non-resistant Mtb strain; however, it showed a strong dose-dependent and reversible vasodilatory activity with mostly lesser toxic effects than the reference drug sodium nitroprussiate, unveiling thus a potential indication for acute or chronic cardiovascular pathology. This is a priori a further indirect evidence of HNO release from this metal complex, standing as a possible pharmacophore model for an alternative vasodilator drug.

Hexa-tert-butyl-carbo-benzene (C18 tBu6 ) and three phenylated counterparts (C18 tBum Ph6-m ; m=4, 2) have been synthesized. The peralkylated version (m=6) provides experimental access to intrinsic features of the insulated C18 core independently from the influence of π-conjugated substituent. Over the series, structural, spectroscopic, and electrochemical properties are compared with those of the hexaphenylated reference (m=0). Anchoring tBu substituents at the C18 macrocycle is shown to enhance stability and solubility, and to dramatically modify UV/Vis absorption and redox properties. Whereas all carbo-benzenes reported previously were obtained as dark-reddish/greenish solids, crystals and solutions of C18 tBu6 happen to be yellow (λmax =379 vs. 472 nm for C18 Ph6 ). In comparison to C18 Ph6 , the reduction of C18 tBu6 remains reversible, but occurs at twice as high an absolute potential (E1/2 =-1.36 vs. -0.72 V). Systematic XRD analyses and DFT calculations show that the C18 ring symmetry is the nearest to D6h for m=6, which indicates a maximum geometric aromaticity. According to calculated nucleus-independent chemical shifts (NICS), the macrocyclic magnetic aromaticity is also maximum for C18 tBu6 : NICS(0)=-17.2 ppm versus (-18.0±0.1) ppm for the theoretical references C18 H6 and C18 F6 , and -13.5 ppm for C18 Ph6 . Accurate correlations of NICS(0) with experimentally recorded or calculated maximum UV/Vis absorption wavelengths, λmax , and chemical hardness, η=ELUMO -EHOMO , are evidenced.

International audience; An improved 12-step synthetic route and full characterization of hexaphenyl-carbo-benzene (4, 8%) and the p-bis-3,5-di-tert-butylphenyl homologue (11, 4%), are described. The carbo-benzene reference 4 is now accurately described in the crystal state by X-ray diffraction analysis in the chiral space group P2(1)2(1)2(1), and in comparison to the less symmetric derivative 11 exhibiting a centro-symmetric packing. According to cyclic voltammetry, both hexaaryl-carbo-benzenes 4 and 11 can behave as both reversible potent electron acceptors and standard electron donors, with respective potentials of -0.73 +/- 1 V and +1.17 +/- 2 V/SCE, respectively. Due to their extremely low solubility, solid films of 11 fabricated using the "wet method", with the initial view of studying charge transport properties, were found to display high roughness.

International audience; The carbo-mer of the para-quinodimethane core is stable within in a bis(9-fluorenylidene) derivative. Oxidation of this carbo-quinoid with MnO2 in the presence of SnCl2 and ethanol affords the corresponding p-bis(9-ethoxy-fluoren-9-yl)-carbo-benzene. The latter can be in turn converted back into the carbo-quinoid by reduction with SnCl2, thus evidencing a chemical reversibility of the interconversion between a pro-aromatic carbo-quinoid and an aromatic carbo-benzene, and is reminiscent of the behavior of the benzoquinone/hydroquinone redox couple (in the red-ox opposite sense).

International audience; Ideally Cs-/C2v-symmetric chromophores, constituted by two electro-active groups conjugated through the carbo-mer of the cyclohexa-1,3-diene core, are selectively prepared by the SnCl2-mediated reduction of tailored hexaoxy-[6]pericyclynes: in the latter substrates, one of the 1,4-dioxybut-2-yne edges is "chemically locked" by two CF3 substituents preventing complete reduction to the corresponding aromatic carbo-benzenic core, which is expected to be more "[small pi]-insulating" between the electro-active ends. The bis-trifluoromethylated carbo-cyclohexadiene products are also shown to be significantly stabilized with respect to their bis-phenylated analogues. Their structural (crystal X-ray diffraction analyses), spectroscopical (NMR and UV-vis spectra), physio-optical (dichromism in solution) and electrochemical (cyclic voltammograms) properties are compared on the basis of the electron-donating/electron-withdrawing nature of the substituents. These properties are also compared with those of their aromatic carbo-benzene and flexible carbo-n-butadiene counterparts.

Diethylamino-substituted oligophenylenevinylene (OPV) building blocks have been prepared and used for the synthesis of two [60]fullerene- OPV dyads, F-D1 and F-D2, which exhibit different conjugation length of the OPV fragments. The electrochemical properties of these acceptor-donor dyads have been studied by cyclic voltammetry. The first reduction is always assigned to the fullerene moiety and the first oxidation centered on the diethylaniline groups of the OPV rods, thus making these systems suitable candidates for photoinduced electron transfer. Both the OPV and the fullerene- centered fluorescence bands are quenched in toluene and benzonitrile, which suggests the occurrence of photoinduced electron transfer from the amino-substituted OPVs to the carbon sphere in the dyads in both solvents. By means of bimolecular quenching experiments, transient absorption spectral fingerprints of the radical cationic species are detected in the visible (670 nm) and near-IR (1300-1500 nm) regions, along with the much weaker fullerene anion band at lmax=1030 nm. Definitive evidence for photoinduced electron transfer in F-D1 and F-D2 comes from transient absorption measurements. A charge-separated state is formed within 100 ps and decays in less than 5 ns.