Electronic, steric and catalytic properties of N-heterocyclic carbene rhodium(I) complexes linked to (metallo)porphyrins.

Electronic and steric properties of NHC ligands functionalized with porphyrins were investigated. When porphyrins are used as NHC-wingtips, nickel(II) in the macrocyle significantly improves the catalytic activity of the neighbouring NHC-Rh(I) complex in the conjugate addition of phenylboronic acid to cyclohexen-2-one.

Transition metal silicide surface grafting by multiple functional groups and green optimization by mechanochemistry.

Chromium disilicide (CrSi2) particles were synthesized by using an arc melting furnace followed by mechanical milling. XRD and DLS analyses show that aggregates of around 3 µm containing about 10 nm sized crystallites were obtained. These aggregates were functionalized in solution by coupling agents with different anchoring groups (silane, phosphonic acid, alkene and thiol) in order to disperse them into an organic polymer. Dodecene was used to modify the CrSi2 surface during mechano-synthesis in a grinding bowl with quite little solvent quantity and the optimization step allowed the aggregate size to be reduced to 500 nm. A thermoelectric composite was then made of alkene CrSi2 grafted samples and poly(p-phénylène-2,6-benzobisoxazole). This study opens the route for new surface grafting of intermetallic silicides for applications linked to electronics and/or energy.

Phosphonate coupling molecules for the control of surface/interface properties and the synthesis of nanomaterials.

Phosphonic acids are increasingly being used for controlling surface and interface properties in hybrid or composite materials, (opto)electronic devices and in the synthesis of nanomaterials. In this perspective article, a concise survey of phosphonate coupling molecules is first presented, including details on their coordination chemistry, their use in the surface modification of inorganic substrates with self-assembled monolayers, and the analytical techniques available to characterize their environment in nanomaterials. Then, some of their recent applications in the development of organic electronic devices, photovoltaic cells, biomaterials, biosensors, supported catalysts and sorbents, corrosion inhibitors, and nanostructured composite materials, are presented. In the last part of the article, a brief overview of recent progress in the use of phosphonate ligands for the preparation of molecular nanomaterials like metal organic frameworks and functionalized polyoxometalates is given.

Anchoring of phosphorus-containing cobaltabisdicarbollide derivatives to titania surface.

Cobaltabisdicarbollide derivatives have been anchored for the first time to the surface of TiO(2) particles using two phosphorus-containing cobaltabisdicarbollide derivatives: Cs[1,1'-mu-(HO)(O)P-3,3'-Co(1,2-C(2)B(9)H(10))(2)], Cs[1], and Cs[8,8'-mu-(OH)(O)-P(O)(2)-3,3'-Co(1,2-C(2)B(9)H(10))(2)], Cs[2]. Grafting of cobaltabisdicarbollide anions to the TiO(2) particle surface through phosphinate or phosphate anchors has been achieved by using standard conditions. Characterization of the modified titanium dioxide surfaces by FTIR, (11)B and (31)P NMR, DRUV-vis spectroscopy, and transmission electron microscopy (TEM) indicates an efficient functionalization on the particle surface.

Functional organotrimethoxysilane derivative with strong intermolecular pi-pi interaction: one-pot grafting reaction on oxidized silicon substrates.

Although the fabrication of self-assembled monolayers (SAMs) on an oxidized silicon substrate with special functionality is an important topic for various applications, it is still very difficult to obtain a densely grafted monolayer. With a newly synthesized organotrimethoxysilane containing a 1-cyano-1,2-bisbiphenyl-ethylene (CNMBE) moiety which provides a strong pi-pi intermolecular interaction, an SAM of well-ordered structure is readily obtained by a one-pot grafting reaction under mild conditions. The aggregation process of the CNMBE moiety, which induced a close packing of organosilane on the substrate, was visually monitored by the fluorescence of the monolayer grafted on quartz.

Trichlorosilane isocyanate as coupling agent for mild conditions functionalization of silica-coated surfaces.

Despite the importance of the isocyanate group in chemistry, very few examples of isocyanate-modified silicas have been reported, and all of the strategies described so far led to partial or total hydrolysis or condensation of the isocyanate group. By synthesizing trichlorosilane isocyanate as the coupling reagent, we show that oxidized silicon wafers are successfully modified with the isocyanate group. Our method is achieved in mild conditions, at low temperature, without side-reactions and allows the formation of a self-assembled monolayer (SAM) of isocyanates. The isocyanate group then offers a flexible way to further functionalize silica substrates with different nucleophiles, due to its high and specific reactivity.

Organized self-assembled monolayers from organosilanes containing rigid pi-conjugated aromatic segments.

The morphology of surfaces modified by pi-conjugated arylsilanes depends on various parameters such as the nature and the number of the hydrolyzable functions or the length of the aromatic segment. The grafting of phenyltrichlorosilane and phenyltrimethoxysilane leads to multilayers even when the reactions are carried out at 0 degrees C, the films obtained from phenyltrichlorosilane being much thicker than the one obtained from phenyltrimethoxysilane. A submonolayer is obtained using phenyltriethoxysilane. Whereas the trifunctional phenyltrichlorosilane forms an inhomogeneous multilayer, the difunctional phenyldichlorosilane (PhSiHCl2) and the monofunctional phenylchlorosilane (PhSiH2Cl) (the SiH bond is not reactive under these experimental conditions) deposit as dense homogeneous monolayers. For these two phenylchlorosilanes, the surface analytical data are similar except for contact angle measurements, which can be explained by a different orientation of the phenyl group at the surface. Concerning the influence of the length of the aromatic segment on the quality of the film, styryltrimethoxysilane and methylstilbenyltrimethoxysilane lead to dense monolayers indicating that adding a short group such as the vinyl group is sufficient to induce an organization between aromatic groups and to achieve a dense monolayer.

Studies of the functionalisation of organic-inorganic hybrid materials by using the Heck reaction.

Cogelation of 4-styryltrimethoxysilane was performed using NH4F as catalyst. The functionalisation of the styryl group was then studied by using Heck's reaction with ethyl 4-bromobenzyl- or 4-bromoarylvinylbenzyl-phosphonates. The efficiency of the solid-phase reaction was highly dependent on the texture of the solids.