Functionalization of polyoxotungstates with organoarsonate coligands enabling surface decoration was explored for the triangular cluster architectures of the composition [CoII9(H2O)6(OH)3(p-RC6H4AsVO3)2(α-PV2WVI15O56)3]25– ({Co9(P2W15)3}, R = H or NH2), isolated as Na25[Co9(OH)3(H2O)6(C6H5AsO3)2(P2W15O56)3]·86H2O (Na-1; triclinic, P1̅, a = 25.8088(3) Å, b = 25.8336(3) Å, c = 27.1598(3) Å, α = 78.1282(11)°, β = 61.7276(14)°, γ = 60.6220(14)°, V = 13888.9(3) Å3, Z = 2) and Na25[Co9(OH)3(H2O)6(H2NC6H4AsO3)2(P2W15O56)3]·86H2O (Na-2; triclinic, P1̅, a = 14.2262(2) Å, b = 24.8597(4) Å, c = 37.9388(4) Å, α = 81.9672(10)°, β = 87.8161(10)°, γ = 76.5409(12)°, V = 12920.6(3) Å3, Z = 2). The axially oriented para-aminophenyl groups in 2 facilitate the formation of self-assembled monolayers on gold surfaces and thus provide a viable molecular platform for charge transport studies of magnetically functionalized polyoxometalates. The title systems were isolated and characterized in the solid state, in aqueous solutions, and on metal surfaces. Using conducting tip atomic force microscopy, the energies of {Co9(P2W15)3} frontier molecular orbitals in the surface-bound state were found to directly correlate with cyclic voltammetry data in aqueous solution.

We report the formation of self-assembled monolayers of a molecular photoswitch (azobenzene-bithiophene derivative, AzBT) on cobalt via a thiol covalent bond. We study the electrical properties of the molecular junctions...

We report on the phosphonic acid route for the grafting of functional molecules, optical switch (dithienylethene diphosphonic acid, DDA), on La 0.7 Sr 0.3 MnO 3 (LSMO). Compact self-assembled monolayers (SAMs) of DDA are formed on LSMO as studied by topographic atomic force microscopy (AFM), ellipsometry, water contact angle and X-ray photoemission spectroscopy (XPS). The conducting AFM measurements show that the electrical conductance of LSMO/ DDA is about 3 decades below that of the bare LSMO substrate. Moreover, the presence of the DDA SAM suppresses the known conductance switching of the LSMO substrate that is induced by mechanical and/or bias constraints during C-AFM measurements. A partial light-induced conductance switching between the open and closed forms of the DDA is observed for the LSMO/DDA/C-AFM tip molecular junctions (closed/open conductance ratio of about 8). We show that, in the case of long-time exposition to UV light, this feature can be masked by a non-reversible decrease (a factor of about 15) of the conductance of the LSMO electrode. Paris-Saclay, ANR-11-IDEX-0003-02. We thank C. van Dyck (U. of Alberta, Canada), V. Diez Cabanes and J. Cornil (LCNM, U. Mons, Belgium) for theoretical discussions on the electronic properties of diarylethene derivatives. We thank S. Godey and D. Deresmes (IEMN-CNRS) for advises and collaborations with the UHV C-AFM experiments, and J.L. Caudron (IEMN-CNRS) for XPS measurements.

We investigated the near-field distribution associated to the photonic mode of terahertz photonic micro-resonators by scattering scanning near-field optical microscopy. Probing individual THz microresonators concentrating electric field is important for high-sensitivity chemical and biochemical sensing and fundamental light-matter interactions studies at nanoscale. We imaged both electric field concentration predicted by numerical simulations and unexpected patterns that deviate from intuitive assumptions. We propose a scenario based on the multiplication of the near-field with the far-field pattern of the probe / resonator ensemble that is in excellent agreement with the experimental data and propose an image analysis procedure to recover the near-field of such structures.

Reactions between η3‐allylpalladium chloride dimer, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and 1‐amino‐2‐fluoro‐1‐perfluoroethyl‐3‐phenylprop‐1‐en‐3‐one or 1,12‐diamino2,11‐difluoro‐1,12‐bis(perfluorobutyl)dodeca‐1,11‐diene3,10‐dione simultaneously provided two types of PdII complexes. One is an anionic η3‐allylpalladium complex with protonated DBU as counterion while the other is a neutral η3‐allyl(β‐ketoiminato)palladium complex. A mechanism involving the amidine function of DBU in the formation of the two complexes is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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We report on the imaging by THz s-SNOM of the field concentration associated to the photonic mode of a split-ring resonator with a 2 µm small gap. The ability to concentrate and probe THz radiations at this scale is of interest for studies on micro and nano objects. Our results are interpreted with numerical calculations as an interplay between the confined near-field and the directional far-field emission of the system.