Anion-encapsulating, discrete prism and extended frusta, from trimetallated triangular macrocycles and linkers.

Reaction of a trinuclear triangular macrocyclic complex Pb3L(CF3SO3)6 with bidentate linkers in a ratio of 3 equiv. of linker per 2 equiv. of complex, produces a prismatic structure with 4,4'-dipyridyl, and two unprecedented, extended 3D frustum-like structures with 1,2-di(4-pyridyl)ethylene and 1,4-di(4-pyridyl)benzene. The cavities of these structures encapsulate triflate anions.

Electrophilic Si-H Activation by Acetonitrilo Benzo[h]quinoline Iridacycles: Influence of Electronic Effects in Catalysis.

The performance of six newly synthesized benzo[h]quinoline-derived acetonitrilo pentamethylcyclopentadienyl iridium(III) tetrakis(3,5-bis-trifluoromethylphenyl)borate salts bearing different substituents -X (-OMe, -H, -Cl, -Br, -NO2 and -(NO2 )2 ) on the heterochelating ligand were evaluated in the dehydro-O-silylation of benzyl alcohol and the monohydrosilylation of 4-methoxybenzonitrile by Et3 SiH, two reactions involving the electrophilic activation of the Si-H bond. The benchmark shows a direct dependence of the catalytic efficiency with the electronic effect of -X, which is confirmed by theoretical assessment of the intrinsic silylicities Π of hydridoiridium(III)-silylium adducts and by the theoretical evaluation of the propensity of hydridospecies to transfer the hydrido ligand to the activated substrate. The revisited analysis of the Ir-Si-H interactions shows that the most cohesive bond in hydridoiridium(III)-silylium adducts is the Ir-H one, while the Ir-Si is a weak donor-acceptor dative bond. The Si…H interaction in all the cases is noncovalent in nature and dominated by electrostatics confirming the heterolytic cleavage of the hydrosilane's Si-H bond in this key catalytically relevant species.

(NHC-olefin)-nickel(0) nanoparticles as catalysts for the (Z)-selective semi-hydrogenation of alkynes and ynamides.

Nickel(0) nanoparticles coordinated to NHC ligands bearing N-coordinated cinnamyl moieties were readily prepared by reduction of a [NiCpBr(NHC-cinnamyl)] complex with methyl magnesium bromide. The combination of a strong σ-donor NHC ligand with a π-coordinating appended cinnamyl moiety likely prevents nickel(0) nanoparticle aggregation to larger inactive species, and allows the effective and (Z)-selective semi-hydrogenation of alkynes and ynamides.

Synthesis of a helicene-fused porphyrin leading to a π-extended chiral chromophore.

The preparation of several covalently linked [6]-helicene-porphyrins is reported. A fused [6]-helicene-porphyrin π-extended aromatic system was isolated, the enantiomers separated and the chiroptical properties determined. The oxidative cyclodehydrogenation proved to be very effective for six-membered fused helical systems, but not suited for the formation of five-membered fused systems.

Rational engineering of an erythropoietin fusion protein to treat hypoxia.

Erythropoietin enhances oxygen delivery and reduces hypoxia-induced cell death, but its pro-thrombotic activity is problematic for use of erythropoietin in treating hypoxia. We constructed a fusion protein that stimulates red blood cell production and neuroprotection without triggering platelet production, a marker for thrombosis. The protein consists of an anti-glycophorin A nanobody and an erythropoietin mutant (L108A). The mutation reduces activation of erythropoietin receptor homodimers that induce erythropoiesis and thrombosis, but maintains the tissue-protective signaling. The binding of the nanobody element to glycophorin A rescues homodimeric erythropoietin receptor activation on red blood cell precursors. In a cell proliferation assay, the fusion protein is active at 10-14 M, allowing an estimate of the number of receptor-ligand complexes needed for signaling. This fusion protein stimulates erythroid cell proliferation in vitro and in mice, and shows neuroprotective activity in vitro. Our erythropoietin fusion protein presents a novel molecule for treating hypoxia.

Molecular tectonics: formation and structural studies on a 2-D directional coordination network based on a non-centric metacyclophane based tecton and zinc cation.

The combination of tectons based on the [1111]metacyclophane backbone blocked the 1,3-alternate conformation bearing two imidazoly or pyrazolyl groups located on the same side with metal halide complexes leads to the formation of either discrete metallmacrobicycles or infinite 1-D coordination networks. The same backbone bearing two sets of two different coordinating poles composed of two pyridyl and two pyrazolyl units, owing to its non-centrosymmetric nature, forms a directional 2-D network packed in an anti-parallel fashion.

Molecular tectonics: generation and structural studies on 1- and 2D coordination networks based on a meta-cyclophane in 1,3-alternate conformation bearing four pyrazolyl units and cobalt, zinc and copper cations.

The combination of a [1111] metacyclophane blocked in 1,3-alternate conformation and bearing four pyrazolyl coordinating units with MX(2) (M = Co, Zn and X = Cl or Br) leads to the formation of crystals formed by packing of 2D coordination networks. In the case of CuBr(2), the formation of a 1D network was observed. Structural studies by X-ray diffraction methods on single crystals were performed on all cases reported.

Synthesis and properties of oligo[n]cruciforms: nanosized sterically encumbered tetraethynylphenyl-homologated fluorophores.

A series of nanosized phenyleneethynylenes have been prepared which are sterically insulated from the surrounding environment by multiple functionalization with triisopropylsilyl (TIPS) substituents. The phenyleneethynylenes comprise oligo[n]cruciforms 1-4 (n = 3-5) and a dehydrotribenzo[12]annulene 5, the former of which possess para-acyclic and the latter ortho-cyclic electronic conjugation pathways. All compounds were characterized by (1)H and (13)C NMR, IR, and mass spectroscopic techniques. The X-ray crystal structure of 1 confirmed the sterically isolating properties of the TIPS substituents. A comparison of the physical properties of these electronically differing systems revealed that they were all luminescent upon UV irradiation displayed negligible aggregation in dilute solution and that particular members of the series studied were electrochemically active, undergoing facile reversible reductions. The phenyleneethynylenes also exhibited significantly enhanced thermal stability by virtue of the presence of the TIPS substituents. The properties of 1-5 suggest that they are promising building blocks for the construction of materials for novel molecular electronics applications.

Synthesis and structural studies of metallamacrotricycles based on a metacyclophane in 1,3-alternate conformation bearing four imidazolyl units.

The combination of a [1111]metacyclophane blocked in 1,3-alternate conformation and bearing four imidazole units with MX2 (M = Co, Cu, Zn and Hg; X = Cl or Br) complexes leads to the formation of a series of analogous neutral metallamacrotricycles. In all cases, the structure of the binuclear complexes has been studied by X-ray diffraction methods on single crystals.

Direct synthesis and structural characterisation of tri- and tetra-nuclear silver metallaknotanes by self-assembly approach.

The combination of ligands based on two quinoline units acting as primary coordinating sites connected by tetra- or penta-ethyleneoxy fragments behaving as secondary interaction sites leads spontaneously in a one-pot reaction to the formation of tri- and terta-nuclear metalla-organic knots in the presence of silver cation.

Direct orthoruthenation of planar prochiral pyridine derivatives by C-H bond activation with [Ru(CO)2Cl2]n and its unexpected stereoselectivity.

The treatment of planar prochiral pyridine derivatives with d6 [Ru(CO)2Cl2]n stereoselectively and efficiently produces new dimeric ortho-ruthenated complexes.

New manganese-scaffolded organic triple-deckers based on quinoxaline, pyrazine and pyrimidine cores.

The thermolytic coupling of Ph(2)CN(2) and (t-Bu)(Ph)CN(2) with doubly cyclomanganated 2,5-diphenylpyrazine and 4,6-diphenylpyrimidine afforded substantial amounts of new triple decker compounds of either C(i) and C(2) symmetry respectively containing, in both series, two eta(3)-bonded Mn(CO)(3) fragments which intervene as scaffolds sustaining the helical non-conjugated triaryl backbone. The molecular structures of two pyrazine derivatives show a typical non-parallel stacking of the aromatic rings and the encapsulation of the central pyrazyl fragment with interplanar centroid-to-centroid distances of ca. 3.5 A. The stacking of the aromatics in the triple-decker pyrimidine derivatives has been assessed by (1)H NMR experiments at low temperature. All the triple-decker-type compounds are electroactive. Pyrimidine triple-deckers can reversibly be electrochemically reduced to the corresponding anions.

Towards a better understanding of magnetic interactions within m-phenylene alpha-nitronyl nitroxide and imino nitroxide based radicals, part III: Magnetic exchange in a series of triradicals and tetraradicals based on the phenyl acetylene and biphenyl coupling units.

The present work completes and extends our previous reports on the determination of the magnetic ground state and on the strength of the through bond exchange coupling within series of biradicals. This knowledge was subsequently exploited for the analysis of the magnetic interactions in their crystals. We report here the studies of series of triradicals incorporating alpha-nitronyl nitroxides (NN) or alpha-imino nitroxides (IN) as terminal radical fragments connected through a m-phenylene coupling unit in one case and a phenyl acetylene unit in other case. Tetraradical derivatives have also been studied. The studies of isolated molecules (EPR in solution and DFT calculations) allow the assessment of the magnetic interactions through the magnetic coupling unit. All triradical derivatives are found to exhibit a quartet ground state, whereas a singlet ground state is determined for the tetraradical. This last result reinforces previous findings that the singlet ground state is favoured in related biradicals involving similar m-phenylene couplers. Moreover, the through bond magnetic exchange coupling for the ortho-meta connectivity could be demonstrated as being ferromagnetic, thus ascertaining our previous hypotheses. The magnetic properties of the triradicals and tetraradicals in their solid state have been rationalized by using a previously proposed methodology, allowing to identify the most relevant magnetic pathways.

Novel heteroleptic cis-(C--N)2Pd(II) chelates for the preparation of enantiopure planar chiral cyclopalladated 2-[tricarbonyl(eta6-phenyl)chromium]pyridine.

In the presence of large amounts of [Me4N]Cl, the reaction of ortho-chloromercurated 2-[(eta6-phenyl)tricarbonylchromium]pyridine with mu-chloro cyclopalladated aromatic compounds yields a series of new heteroleptic heterodinuclear cis-(C--N)2Pd(II) complexes, which are valuable precursors of planar chiral cyclopalladated (eta6-arene)Cr(CO)3 complexes.

Photochemical and thermal ligand exchange in a ruthenium(II) complex based on a scorpionate terpyridine ligand.

A ruthenium(II) complex containing a 1,10-phenanthroline unit and a terpyridine fragment covalently linked to a benzonitrile group has been synthesised; coordination and decoordination of the benzonitrile group can be induced thermally and photochemically respectively, in an acetone-water mixture.