Frédéric Chérioux

Complete Supramolecular Self-Assembled Adlayer on a Silicon Surface at Room Temperature

The engineering of a complete adlayer of organic nanolines by supramolecular self-assembly has been achieved for the first time on a silicon-based surface at room temperature and has been studied by scanning tunneling microscopy. This complete adlayer has been successfully obtained thanks to the combination of a specific Si(111)-B square root 3x square root 3R30 degrees semiconductive surface and of strong hydrogen bonds between a pair of dipolar molecules.

Synthesis and characterisation of an octupolar polymer and new molecular octupoles with off-resonant third order optical nonlinearities

The first synthesis and Z-scan measurements of an octupolar polymer with off-resonant third order nonlinear optical properties are discussed; two other new molecular thiophene-based octupoles with similar nonlinearities are also reported.

Reversible Photoswitching of Azobenzene-Based Monolayers Physisorbed on a Mica Surface

The formation of compact and large-scale self-assembled monolayers (SAMs) adsorbed on a mica surface has been achieved by insertion of alkyl chains on azobenzene derivatives, leading to strong intermolecular van der Waals interactions and hydrogen bonding. The reversible photoswitching of monolayers was investigated by monitoring the variation of the thickness of the SAMs during the cis-trans isomerization of the azobenzene cores with an atomic force microscope (AFM). The absence of covalent bonds between molecules and substrate induces a molecular diffusion which leads to the complete isomerization of the molecules constituting the SAMs.

Detection and High-Precision Positioning of Liquid Droplets Using SAW Systems

The capability to accurately handle liquids in small volumes is a key point for the development of lab-on-chip devices. In this paper, we investigate an application of surface acoustic waves (SAW) for positioning micro-droplets. A SAW device based on a 2 times 2 matrix of inter-digital transducers (IDTs) has been fabricated on a (YXl)/128deg LiNbO3 substrate, which implies displacement and detection in two dimensions of droplets atop a flat surface. Each IDT operates at a given frequency, allowing for an easy addressing of the active channel. Furthermore, very low cross-talk effects were observed as no frequency mixing arose in our device. Continuous as well as pulsed excitations of the IDTs have been studied, yielding, respectively, continuous and step-by-step droplet displacement modes. In addition, we also have used these two excitation types to control the velocity and the position of the droplets. We also have developed a theoretical analysis of the detection mode, which has been validated by experimental assessment.

Dendritic Systems Based on Dinuclear Ruthenium or Rhodium Units Generating Peripheral Catalytic Sites

A series of dendritic cations 1-4 containing Ru(2)S(3) or Rh(2)S(3) units, either in the core or in the dendrons, has been synthesized and characterized. The X-ray crystal structure analysis of 2-Cl shows a trigonal bipyramidal Rh(2)S(3) core with propeller-like para-hydroxyphenyl substituents at the sulfur atoms. Reaction of the peripheral OH groups with diphenylphosphino benzoic acid results in the formation of phosphine-functionalized dendritic cations 5-8. The ruthenium-containing cation 5, with three PPh(2) functions at the periphery, acts as ligand for rhodium(I) and enhances significantly the catalytic activity of [[Rh(CO)(2)Cl](2)] for the carbonylation of methanol.

Room‐Temperature Electronic Template Effect of the SmSi(111)‐8×2 Interface for Self‐Alignment of Organic Molecules

This work describes an innovative concept for the development of organized molecular systems based on the template effect of the pre-structured semi-conductive SmSi(111) interface. This substrate is selected because Sm deposition in the submonolayer range leads to a 8x2-reconstruction, which is a well-defined one-dimensional semi-metallic structure. Adsorption of aromatic molecules [1,4-di-(9-ethynyltriptycenyl)-benzene] on SmSi(111)- 8x2 and Si(111)-7x7 interfaces is investigated by scanning tunneling microscopy (STM) at room temperature. Density functional theory (DFT) and semi-empirical (ASED+) calculations define the nature of the molecular adsorption sites of the target molecule on SmSi as well as their self-alignment on this interface. Experimental data and theoretical results are in good agreement.

Synthesis and electrochemical properties of new star-shaped thiophene oligomers and their polymers

The efficient synthesis of some 2,4,6-tris[5-(2,2′-bithienyl)]-1,3,5-triazines and 1,3,5-tris[5-(2,2′-bithienyl)]benzenes and their electrochemical properties are discussed.

Dipole-driven self-organization of zwitterionic molecules on alkali halide surfaces.

Summary We investigated the adsorption of 4-methoxy-4′-(3-sulfonatopropyl)stilbazolium (MSPS) on different ionic (001) crystal surfaces by means of noncontact atomic force microscopy. MSPS is a zwitterionic molecule with a strong electric dipole moment. When deposited onto the substrates at room temperature, MSPS diffuses to step edges and defect sites and forms disordered assemblies of molecules. Subsequent annealing induces two different processes: First, at high coverage, the molecules assemble into a well-organized quadratic lattice, which is perfectly aligned with the <110> directions of the substrate surface (i.e., rows of equal charges) and which produces a Moiré pattern due to coincidences with the substrate lattice constant. Second, at low coverage, we observe step edges decorated with MSPS molecules that run along the <110> direction. These polar steps most probably minimize the surface energy as they counterbalance the molecular dipole by presenting oppositely charged ions on the rearranged step edge.

Specific reactivity of SH versus OH functions towards dinuclear arene ruthenium units: synthesis of cationic complexes of the type [(arene)2Ru2(SR)3]+

Abstract The reaction of [(arene)RuCl 2 ] 2 (arene=C 6 H 6 , p -MeC 6 H 4  i Pr, C 6 Me 6 ) with p -thiocresol, 2-mercaptoethanol and p -mercaptophenol in refluxing ethanol gives the tris-thiolato complexes [(arene) 2 Ru 2 (SR) 3 ] + (R= p -C 6 H 4 Me, CH 2 CH 2 OH, p -C 6 H 4 OH) which can be isolated as the chloride salts. The remarkable selectivity of (arene)ruthenium units for SH versus OH functions reflects the affinity of ruthenium towards sulfur.

Large-Scale Patterning of Zwitterionic Molecules on a Si(111)-7 7 Surface

The formation of a large scale pattern on Si(111)-7 × 7 reconstruction is still a challenge. We report herein a new solution to achieve this type of nanostructuration by using of zwitterionic molecules. The formation of a large-scale pattern is successfully obtained due to the perfect match between the molecular geometry and the surface topology and to electrostatic interactions between molecules and surface. The adsorption is described by high-resolution scanning tunneling microscopy (STM) images and supported by density functional theory and STM calculations.