Valeria La Parola

Fullerene-ionic-liquid conjugates: a new class of hybrid materials with unprecedented properties.

A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity.

An Atom‐Economical Approach to Functionalized Single‐Walled Carbon Nanotubes: Reaction with Disulfides

Owing to their unique structure, thermal stability, and mechanical and electronic properties, single-walled carbon nanotubes (SWCNTs) have been a subject of continuous and intense interest. However, various applications in many fields, such as molecular electronics, solar cells, and nanomedicine, often require the development of reproducible protocols for the chemical modification of SWCNTs. In fact, one of the main drawbacks of the use of SWCNTs is their tendency to aggregate and intrinsic poor solubility, which prevent their manipulation and limit their potential. To date, several methods have been described for the chemical functionalization of SWCNTs; however, new versatile and reliable methods are still needed.We focused our attention on disulfides, which are a very useful family of compounds owing to the presence of the flexible S S bond. Disulfides can be prepared readily from the corresponding thiols; thus, a wide range of substrates are accessible. In this study, we used very mild and reproducible conditions for the production of a wide variety of functionalized SWCNTs (f-SWCNT). Pristine HiPco SWCNTs (p-SWCNTs, prepared with high-pressure carbon monoxide, HiPco) were treated with disulfides in deoxygenated toluene at reflux (Scheme 1). The reaction with diphenyl disulfide was monitored for 48 h by

Supported C60-IL-PdNPs as extremely active nanocatalysts for C–C cross-coupling reactions

A C60-ionic liquid hybrid has been covalently linked to three different solid supports, namely amorphous silica, SBA-15 and Fe2O3@SiO2, and the resulting materials have been employed as covalently supported ionic liquid phases (cSILP) in order to immobilize and stabilize palladium nanoparticles (PdNPs). These novel hybrid materials are based on a sort of “matryoshka” system (PdNPs@imidazolium-salt@C60@support) in which the imidazolium-based moieties have not been directly linked to the surface of the support, but they are present in an octopus-like spatial arrangement on the uniformly surface-distributed fullerenes. These materials have been fully characterized and successfully employed as catalysts in C–C bond forming reactions showing, in the case of Suzuki cross-coupling, an outstanding catalytic activity both under classical heating and by irradiating with microwaves. Turn-over frequencies (TOFs) of up to 3 640 000 h−1 have been achieved and the silica-based catalyst showed full recyclability even after 10 cycles.

Hybrid paper–TiO2 coupled with a Cu2O heterojunction: an efficient photocatalyst under sun-light irradiation

Hybrid paper–TiO2, paper–Cu2O–TiO2 and paper–TiO2–Cu2O photocatalysts were prepared via a non-hydrolytic sol–gel process followed by mild hydrothermal treatment to generate the TiO2 layer, and a reduction process to form the Cu2O nanoparticles. The hybrid photocatalysts have been characterized by Raman, TGA, FE-SEM, UV-Vis and XPS. The immobilized TiO2 was found to form a homogeneous thin layer composed of nanoparticles with a size smaller than 10 nm. The Cu2O nanoparticles with sizes of 30–100 nm were generated either on the top of the TiO2 layer or by reduction of Cu2+ ions. All the prepared hybrid catalysts showed efficient photocatalytic properties for the degradation of toluidine when exposed to simulant solar light. A strong enhancement in the photocatalytic activity was observed when TiO2 was coupled with the Cu2O heterojunction, with the highest effect being observed when the Cu2O NPs were present on top of the TiO2 layer. The hybrid photocatalyst can be reused for at least four consecutive cycles without a significant decrease in the degradation efficiency. The preparation technique of the hybrid catalyst is reliable, economic, easy to implement and may be scaled to prepare paper–TiO2 hybrid photocatalysts active under sun-light exposure.

Correction: Supported C60-IL-PdNPs as extremely active nanocatalysts for C–C cross-coupling reactions

Correction for ‘Supported C60-IL-PdNPs as extremely active nanocatalysts for C–C cross-coupling reactions’ by Francesco Giacalone et al., J. Mater. Chem. A, 2016, 4, 17193–17206.

Influence of Doping on the Structural Transformations of the Proton Conducting Perovskite BaCe1xYxO3-D

From neutron diffraction it is known that the BaCeO3 perovskite undergoes a sequence of phase transformations from high temperature cubic C to rhombohedral R, to orthorhombic O1 (Imma) and to orthorhombic O2 (Pnma). Doping Y3+ on the Ce4+ site introduces charge compensating O vacancies (VO) that may be partially filled with OH complexes with exposition to H2O, so making the material an ionic conductor. Anelastic relaxation experiments have been carried out on samples doped with 2%Y and 10%Y; the real part s’(T) of the complex elastic compliance presents softenings at the transitions, and the loss s’’/s’ curves allow the content of VO and H to be monitored. Doping has a strong effect on the temperature of the Pnma/R transition: with 10%Y in the fully hydrated state TO1-R increases up to 750 K while after full outgassing falls to 500 K, meaning that the introduction of ~5% VO shifts the transition of 250 K. While the effect of cation substitution on the transitions temperature is easily explained in terms of simple arguments usually valid for perovskites based on bond length considerations, the remarkable stabilization of the R phase by VO requires to take into account the anomalous sequence of phase transitions of undoped BaCeO3, where the R structure transforms into orthorhombic Pnma on cooling with the loss of an octahedral tilt system.