Jérôme Husson

Combination of Cobalt and Iron Polypyridine Complexes for Improving the Charge Separation and Collection in Ru(terpyridine)2‐Sensitised Solar Cells

Mixtures of polypyridine Fe(II) and Co(II) complexes are used as electron mediators in Ru-thienyltpy-sensitised solar cells (tpy=terpyridine). The use of the metalorganic redox couples allows for improved charge-collection efficiency with respect to the classical iodide/iodine couple which, when associated to Ru-tpy(2) dyes, usually produces poor performance. The improved charge collection is explained by a combination of effective dye regeneration and decreased recombination with the oxidised electrolyte on the basis of data obtained by transient spectroscopy and photoelectrochemical measurements. The efficiency of the regeneration cascade is also critically dependent upon the ability of the Co(II) complex to intercept Fe(III) centres, as clearly indicated by chronocoulometry experiments.

Adsorption of Ni(II) ions on colloidal hybrid organic-inorganic silica composites.

Two new silica-based composites were prepared as adsorbents for the capture of Ni(II) ions. The first strategy consists in coating chitosan on colloidal fumed silica after acidic treatment yielding the composite SiO(2)+CS. The second route involves in a first step surface condensation of triethoxysilylbutyronitrile, followed by acidic hydrolysis of the surface-bound nitrile groups affording silica particles covered by carboxylic group. In a third step, chitosan has been grafted on the surface-bound C(=O)OH groups yielding the composite SiO(2)(CO(2)H)+CS. The novel hybrid materials were characterized by IR spectroscopy, scanning electron and AFM microscopy, and zeta potential measurements. Batch experiments were conducted to study the sorption performance of these composites for Ni(II) removal from aqueous NiCl(2) solution at different pH. Both Langmuir, Freundlich, and Temkin isotherm models provide good fits with the experimental data. It was shown that these low-cost materials present a promising capacity to adsorb Ni(II) ions. At pH 7, the maximum adsorption capacity q(max)of Ni(II) on the adsorbent, is found to be 182 mg g(-1) for SiO(2)+CS, and 210 mg g(-1) for SiO(2)(CO(2)H)+CS.

A more efficient synthesis of 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine

We report in this paper a new route for the synthesis of 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine. This synthetic pathway has a lower ecological impact with respect to yield, atom economy, solvent and chemicals used and wastes generated when compared to a previously reported method. In addition it uses furfural, which can be obtained from renewable sources. The title compound can be used to prepare complexes that are valuable for applications in Dye Sensitized Solar Cells.

Preparation of Silica-Supported Biosorbents for Copper(II) Removal

The objective of this study is the preparation of various types of functionalized silica particles for the capture of Cu(II) ions. Amino-functionalized silica and hybrid chitosan/silica particles have been prepared by grafting silica with amino groups and/or adsorption of chitosan on the surface of silica to develop efficient adsorbents for heavy metals ions in water. The adsorption of Cu(II) on these materials was carried out at pH 5 at 298 K. The kinetics were evaluated utilizing pseudo-first-order and pseudo-second-order models. The best interpretation for equilibrium data was given by both Langmuir and Freundlich isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied. This study demonstrates that the adsorption capacities for Cu(II) ions are more efficient for the bio-hybrid material compared to amino-functionalized silica.

Preparation of carboxylate derivatives of terpyridine via the furan pathway

This protocol describes a practical procedure for the preparation of terpyridine carboxy derivatives, which have numerous applications, including being photoactive components of functional materials, and which can be used in medicinal chemistry or in catalysis. This protocol relies on the permanganate-mediated oxidation of a furan ring on the polypyridine system. The procedure involves three stages. First, a furan-functionalized terpyridine is synthesized from furfuraldehyde and a 2-acetylpyridine derivative. Second, the furan ring is oxidized thus providing a carboxylic acid. Finally, esters are prepared by reaction of the acids in refluxing alcohols. The procedure is simple, uses a reagent available from renewable resources (furfural) and avoids the use of noxious reagents or solvents, thus making it more environmentally friendly when compared with previously described methods. The whole protocol can be conducted in ∼10 d, including isolation and drying of intermediates and products.

Evaluation of Adhesion Forces for the Manipulation of Micro-Objects in Submerged Environment through Deposition of pH Responsive Polyelectrolyte Layers

Optimization of surface treatment for reversible adhesion of micro-objects in liquid environment for the need in microassembly processes is presented. A spherical borosilicate probe and planar oxidized silicon wafer substrates were modified by deposition of pH sensitive polyelectrolyte films through layer-by-layer technique. Branched polyethylenimine (b-PEI) and poly(sodium styrenesulfonate) (PSS) were deposited in alternating manner on surfaces, and the influence of polyelectrolyte concentration, pH of deposition, and number of layers on the adhesion were successively examined. The multilayer buildup was followed by optical reflectometry (OR) and dissipative quartz crystal microbalance (QCM-D). The adhesion forces were monitored in aqueous environment at variable pH values by colloidal probe AFM microscopy. The thermodynamic work of adhesion was derived from the pull-off forces by using the Johnson-Kendall-Roberts (JKR) model and compared to the work of adhesion determined from contact angle measurements. It was found out that they correlate well, however, the values accessed from JKR model were underestimated, which was attributed mainly to the effect of surface roughness. Obtained results have demonstrated that it is possible to achieve repeatable reversible adhesion with the change of pH of submerged environment by appropriately tailoring the surface properties and therefore the prevailing surface forces.

Synthesis of new 4′-(N-alkylpyrrol-2-yl)-2,2′: 6′,2″-terpyridines via N-alkylation of a pyrrole moiety

Abstract New 4′-(N-alkylpyrrol-2-yl)-2,2′:6′,2″-terpyridines were synthesized by N-alkylation of a pyrrole substituent with alkyl halides in dimethyl sulfoxide.

1-{4-[(Hexyloxy)methyl]pyridin-2-yl}ethanone

A new member of the 2-acetylpyridine family has been prepared and characterized. Its synthesis is a two-step process starting from a pyridyl-alcohol in which the ketone moiety is protected as a cyclic acetal. Alkylation of the alcohol followed by hydrolysis of the acetal afforded the title compound in 52% overall yield.

A new and facile method for the functionalization of a Merrifield resin with terpyridines: application as a heterogeneous catalyst for the synthesis of biaryls in environmentally friendly solvents

Abstract A classical Merrifield resin was modified with pendant terpyridine heterocycles in order to develop a new material for heterogeneous catalysis. The protocol relies on the reaction of a pyrrolyl anion with chloromethyl groups present on the resin. The modified polymer was then reacted with a Pd salt to afford a catalyst that was tested in the Suzuki cross-coupling reaction in environmentally friendly solvents.

Diethyl 2,2′-(1,4-phenyl­enedi­oxy)­diacetate

In the title compound, C14H18O6, a crystallographic center at the centroid of the aromatic ring generates the complete molecule which is planar within 0.085 (1) Å for the non-H atoms. In the crystal, weak C—H⋯O and C—H⋯π interactions link the molecules.