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A new ligand, namely, 2-(5-(pyren-1-yl)pentyl)-9-methyl-1,10-phenanthroline, as well as new bis(2,9-dialkyl-1,10-phenanthroline)copper(II) complexes were designed, which were immobilized on multiwalled carbon nanotube (MWCNT) electrodes. These complexes show a high tendency of autoreduction into their copper(I) form according to electrochemical and EPR experiments. These complexes exhibit strong interactions with MWCNT sidewalls either with or without anchor functions such as the pyrene moiety. The pyrene-modified derivative can be electropolymerized on glassy carbon and MWCNT electrodes to form a poly-[bis(2-(5-(pyren-1-yl)pentyl)-9-methyl-1,10-phenanthroline)copper(II)] metallopolymer film. Furthermore, these MWCNT-supported bis(2,9-dialkyl-1,10-phenanthroline)copper complexes demonstrate a low overpotential for a 4H+/4e–oxygen reduction reaction at pH 5 with an onset potential of 0.86 V versus RHE. Integration of these functionalized MWCNTs at gas-diffusion electrodes of H2/air fuel cells led to a high open-circuit voltage of 0.84 V and a maximum current density of 1.77 mW cm–2using a Pt/C anode.

This work is focused on the structural and physical properties of CePt2Al2, an intermetallic compound. At room temperature, the modulated orthorhombic structure Cmme(a00)000, with q→= (0.481, 0, 0) has been determined by single-crystal X-ray diffraction supplemented by dependence of lattice parameters above room temperature for which the X-ray powder diffraction was used. The compound undergoes a structural transition to a tetragonal structure above room temperature. This transition exhibits 50 °C hysteresis and creates a domain structure in the sample. The magnetic behavior has been studied by specific heat, magnetization, and transport measurements in the temperature range between 0.5 and 300 K. Specific heat and susceptibility shows an antiferromagnetic order below 2 K. On the basis of electrical resistivity and other bulk measurements, CePt2Al2can be considered a Kondo lattice material. The presence of a modulated crystal structure opens the possibility of a charge density wave state in CePt2Al2as observed for (Re)Pt2Si2.

The dependence of nonlinear optical properties upon the spin state in molecular switches is still an unexplored area. Chiral [Fe(phen)3]2+complexes are excellent candidates for those studies because they are expected to show nonlinear optical properties of interest and at the same time show photoconversion to a short-lived metastable high-Spin state by ultrafast optical pumping. Herein, we present the synthesis, crystallographic, and spectroscopic comparison of chiral [Fe(phen)3]2+complexes obtained with chiral anions, a new lipophilic derivative of the D2-symmetric (As2(tartrate)2)2–, and D3-symmetric tris(catechol)phosphate(V) (TRISCAT), tris(catechol)arsenate(V) (TRISCAS), and 3,4,5,6-tetrachlorocatechol phosphate(V) (TRISPHAT). Complexes [Fe(phen)3](rac-TRISCAT)2(2) and [Fe(phen)3](X-TRISCAS)2(X = rac(3), Δ (4), Λ (5)) were found to be isomorphous in the R32 Sohncke space group with twinning by inversion correlated with the starting chiral anion optical purity. The structures show the [Fe(phen)3]2+complex interacting strongly along its 3-fold axis with two anions. Only the structure of a [Fe(phen)3](rac-TRISPHAT)2solvate (6) could be obtained, which showed no particular anion/cation interaction contrary to what was observed previously in solution. The [Fe(phen)3](X-As2(tartrate)2) (X = Δ (7), Λ (8), and racemic mixture (9)) crystallizes in enantiomorphic space groups P3121/P3221 with the same solid-state packing. Dichroic electronic absorption studies evidenced racemization for all chiral complexes in solution due to ion pair dissociation, whereas the asymmetric induction is conserved in the solid state in KBr pellets. We evidenced on chiral complexes 4and 5strong nonlinear second harmonic generation, the intensity of which could be correlated with the complex electronic absorption.

Networked chemical transformations are key features of biological systems, in which complex multicomponent interactions enable the emergence of sophisticated functions. Being interested in chirality induction phenomena with dynamic Möbius π-systems, we have designed a pair of Möbius [28]hexaphyrin ligands in order to investigate mixtures rather than isolated molecules. Thus, a hexaphyrin bearing a chiral amino arm was first optimized and found to bind a ZnOAc moiety, triggering an impressive quasi-quantitative chirality induction over the Möbius π-system. Second, this amino-type hexaphyrin was mixed with a second hexaphyrin bearing a chiral carboxylate arm, affording at first ill-defined coordination assemblies in the presence of zinc. In contrast, a social self-sorting behavior occurred upon the addition of two exogenous achiral effectors (AcO–and BuNH2), leading to a well-defined 1:1 mixture of two Möbius complexes featuring a sole Möbius twist configuration (parallel chirality inductions). We next successfully achieved compartmentalized switching, i.e., a single-component transformation from such a complex mixture. The BuNH2effector was selectively protected with Boc2O, owing to a lower reactivity of the arm’s NH2function intramolecularly bound to zinc, and subsequent addition of BuNH2restored the initial mixture, retaining parallel chirality inductions (five cycles). By changing the nature and twist configuration of only one of the two complexes, at initial state or by switching, this approach enables a “two-channel” tuning of the chiroptical properties of the ensemble. Such multiple dynamic chirality inductions, controlled by selective metal–ligand recognition and chemical reactivity, set down the basis for Möbius-type stereoselective transformation networks with new functions.

Thin metallic Pd films (100 Å) were submitted to irradiation with 100 KeV Xe ions. After an initial increase of the atomic disorder, a decrease of the metallic coverage occurs as holes are created due to sputtering. This leads to a percolating transition. The modifications of the electronic mean free path, film thickness and metallic surface coverage were measured in situup to the percolation threshold by means of resistive measurements, Rutherford Backscattering and Transmission Electron Microscopy experiments. The resistance at 300 K is found to diverge near the percolation threshold with the typical 2D exponent value. A phenomenological model accounts for the evolution of the topological parameters as the fluence (number of incoming ions per unit surface) increases. We present low temperature electrical measurements on films irradiated at different fluences, thus lying at different distances from the percolation threshold. Our results show a strong interaction between the microscopic and the macroscopic disorder near the percolation threshold : the conductance temperature dependence crosses over from a logarithmic shape (i.e. characteristic of weak localization in 2D metallic films) to a power lam dependence, due to the non-Euclidean (fractal) dimensionality of the percolating metallic structure. Moreover, very close to the threshold but always above it, the conductance varies exponentially with temperature, revealing the appearance of an Anderson insulator, although a continuous metallic path exists across the samples. At 4.2 K, the resistance approaches the percolation threshold with exponent 2, (different from the classical percolation value 1.3 observed at 300 K). This new exponent must contain information on the observed Metal-Insulator Transition.

Metastable MgHxhydride was prepared by H ion implantation into Mg films at 5 K. The resistivity and magnetoresistance temperature dependence reveal weak localization effects due to atomic disorder. At low hydrogen concentrations, x ≤0.3, the conductivity varies as σ∼log (T), typical of two-dimensional weak localization behaviour. The resistivity is also very sensitive to the sample inhomogeneity, due to H diffusion, which can be modelled by introducing a temperature-dependent geometrical percolating factor G. At higher H concentrations, 0.7 ≤x ≤3, after annealing at 20 K, 50 K and 110 K, the samples also exhibit weak localization but with three-dimensional behaviour i.e. a $\sigma \sim \sqrt{T}$. Our analysis is consistent with the existence of an inhomogeneous system formed by a mixture of two phases with contrasted conduction properties, one of which is a well-behaved metal, while the other displays the localization properties. The results lead us to identify the former phase to a non percolating superconducting phase at low temperature.

PMP1, a regulatory subunit of the yeast plasma membrane H+-ATPase, is a single transmembrane helix protein. Its cytoplasmic C-terminus possesses several positively charged residues and interacts with phosphatidylserine lipids as shown through both 1H- and 2H-NMR experiments. We used all-atom molecular dynamics simulations to obtain atomic-scale data on the effects of membrane interface lipid composition on PMP1 structure and tilt. PMP1 was embedded in two hydrated bilayers, differing in the composition of the interfacial region. The neutral bilayer is composed of POPC (1-palmitoyl-2-oleoyl-3-glycero-phosphatidylcholine) lipids and the negatively charged bilayer is composed of POPC and anionic POPS (1-palmitoyl-2-oleoyl-3-glycero-phosphatidylserine) lipids. Our results were consistent with NMR data obtained previously, such as a lipid sn-2 chain lying on the W28 aromatic ring and in the groove formed on one side of the PMP1 helix. In pure POPC, the transmembrane helix is two residues longer than the initial structure and the helix tilt remains constant at 6 ± 3°. By contrast, in mixed POPC-POPS, the initial helical structure of PMP1 is stable throughout the simulation time even though the C-terminal residues interact strongly with POPS headgroups, leading to a significant increase of the helix tilt within the membrane to 20 ± 5°.

The Heck reaction of alkylated 2-(trimethylsilyl)ethanesulfonyl (SES)-protected β-amino esters provides benzazepines in good yields. Good selectivity towards cyclisation was obtained when the reaction was performed in PEG 3400 as the solvent under microwave activation. Cleavage of the SES group with HF provides the corresponding free benzazepine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Murine coronaviruses such as mouse hepatitis virus (MHV) infect mouse cells via cellular receptors that are isoforms of biliary glycoprotein (Bgp) of the carcinoembryonic antigen gene family (G. S. Dveksler, C. W. Dieffenbach, C. B. Cardellichio, K. McCuaig, M. N. Pensiero, G.-S. Jiang, N. Beauchemin, and K. V. Holmes, J. Virol. 67:1-8, 1993). The Bgp isoforms are generated through alternative splicing of the mouse Bgp1 gene that has two allelic forms called MHVR (or mmCGM1), expressed in MHV-susceptible mouse strains, and mmCGM2, expressed in SJL/J mice, which are resistant to MHV. We here report the cloning and characterization of a new Bgp-related gene designated Bgp2. The Bgp2 cDNA allowed the prediction of a 271-amino-acid glycoprotein with two immunoglobulin domains, a transmembrane, and a putative cytoplasmic tail. There is considerable divergence in the amino acid sequences of the N-terminal domains of the proteins coded by the Bgp1 gene from that of the Bgp2-encoded protein. RNase protection assays and RNA PCR showed that Bgp2 was expressed in BALB/c kidney, colon, and brain tissue, in SJL/J colon and liver tissue, in BALB/c and CD1 spleen tissue, in C3H macrophages, and in mouse rectal carcinoma CMT-93 cells. When Bgp2-transfected hamster cells were challenged with MHV-A59, MHV-JHM, or MHV-3, the Bgp2-encoded protein served as a functional MHV receptor, although with a lower efficiency than that of the MHVR glycoprotein. The Bgp2-mediated virus infection could not be inhibited by monoclonal antibody CC1 that is specific for the N-terminal domain of MHVR. Although CMT-93 cells express both MHVR and Bgp2, infection with the three strains of MHV was blocked by pretreatment with monoclonal antibody CC1, suggesting that MHVR was the only functional receptor in these cells. Thus, a novel murine Bgp gene has been identified that can be coexpressed in inbred mice with the Bgp1 glycoproteins and that can serve as a receptor for MHV strains when expressed in transfected hamster cells.

Tunneling conductance measurements (dI/dV)(V) on thick and clean super-conducting films (S1) backed by normal metals (M2) show geometrical resonance effects, which have been associated with the variation d?(x) of the pair potential near the interface. We analyze both theoretically and experimentally the three factors involved in the resonance effect on S1/M1 sandwiches where one of the films is superconducting. The first factor, period, has already received considerable attention and is connected with the ratioVF*/d1 of the renormalized Fermi velocity and the thicknessd1 of the film S1. We show that generally subharmonic effects, related to multiple interference effects, are expected. This result is demonstrated experimentally on Pb/M2 sandwiches. The phase depends on the sign of d?(x), the detailed shape of its variation, and on the nature of the tunneling process. Unfortunately the interplay among these parameters is difficult to analyze, although directive tunneling is found to fit better with experiments than the generally assumed diffuse tunneling. The amplitude of the resonance should be proportional to the change of d?(x). The ambiguity in the experimental results is pointed out and an experiment that shows clearly the role of the superconducting proximity mechanisms is described where the proximity on several simultaneously prepared Pb/Al films is controlled by deposition of various third upper layers. The theoretical discussion is an extension of the Ishii matrix formulation, itself based on an application of the Andreev scattering process.

Theiler's murine encephalomyelitis virus is a neurotropic murine picornavirus which replicates permissively and causes a cytopathic effect in the BHK-21 cell line. We examined the interactions between the GDVII and DA strains of Theiler's virus and BHK-21 host cell proteins in a virus overlay assay. We observed binding of the virions to two proteins of approximately 60 kDa. These proteins were microsequenced and identified as desmin and vimentin, two main components of the intermediate filament network. The association between desmin or vimentin and virions was demonstrated by immunoprecipitation. Anti-desmin and anti-vimentin monoclonal antibodies precipitated GDVII or DA virions from extracts of infected BHK-21 cells. The intracellular distributions of virions and of the desmin and vimentin intermediate filaments of BHK-21 cells were investigated by two-color immunofluorescence confocal microscopy. Following infection, the intermediate filament network was rearranged into a shell-like structure which surrounded a viral inclusion. Finally, close contact between GDVII virus particles and 10-nm intermediate filaments was observed by electron microscopy.

We have studied by electron tunneling the subcritical gapless behavior of superconductingIn Bi thin films in a perpendicular magnetic field. The variation of the initial slope of the tunneling characteristics with field gives quantitative information on the variation of the pair potential and allows a comparison with the various existing models. We confirmed the important contribution of the macroscopic screening currents in the films due to the large demagnetizing effects for this geometry. We also found that the effect of the decrease of the microscopic screening currents of the vortex structure for very thin film was largely compensated by the increasing role of the inhomogeneous field distribution outside the sample.