Bimetallic nanoparticles represent attractive catalytic systems thanks to the synergy between both partners at the atomic level, mainly induced by electronic effects which in turn are associated with the corresponding structures (alloy, core-shell, hetero-dimer). This type of engineered material can trigger changes in the kinetics of catalyzed processes by variations on the electrophilicity/nucleophilicity of the metal centers involved and also promote cooperative effects to foster organic transformations, including multi-component and multi-step processes. Solvents become a crucial factor in the conception of catalytic processes, not only due to their environmental impact, but also because they can preserve the bimetallic structure during the catalytic reaction and therefore increase the catalyst lifetime. In this frame, the present review focuses on the recent works described in the literature concerning the synthesis of bimetallic nanoparticles in non-conventional solvents, i.e., other than common volatile compounds, for catalytic applications.

Dedicatedt ot he Laboratoire HØtØrochimieF ondamentale et AppliquØeo nt he occasiono fi ts 50 th anniversary.Supporting information for this article is availableunder https://doi.org/10.1002/adsc.201700535.Abstract: Small zero-valent copper nanoparticles (CuNPs) have been straightforwardly preparedf rom Cu(I) andC u(II) precursors in glycerol andi nt he presence of polyvinylpyrrolidone as stabilizer. Thanks to the negligible vaporp ressure of the solvent, these original nano-systems could be directly characterized in glycerol as well as in the solids tate, exhibiting relevantly homogeneous colloidal dispersions,a lso evena fter catalysis. CuNPs coming from the well-defined coordinationc omplex di-m-hydroxobis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride {[Cu(k 2 -N,N-TMEDA)(m-OH)] 2 Cl 2 } have been highly efficient in C-C andC -heteroatom bond formation processes. This newc atalytic system has proved its performance in C-Nc ouplings and in the synthesis of differently substitutedp ropargylic amines throughc ross-dehydrogenative couplings, multi-component reactions such as A 3 (aldehydealkyne-amine) and KA 2 (ketone-alkyne-amine) couplings,a sw ell as in the formationo fh eterocycles such as benzofurans,i ndolizines,a nd quinolines under smoothc onditions.N os ignificant copper amount was detected in the extracted organic compounds from the catalytic phase by inductively coupled plasma-atomic emission spectroscopic (ICP-AES)analyses,p roving ah ighly efficient immobilization of copper nanoparticles in glycerol. From am echanisticp oint of view,s pectroscopic data (infrareda nd ultraviolet-visible spectra) agreew ith asurface-like catalytic reactivity.

Small and well-dispersed zerovalent PdCu-A and PdCu-B bimetallic nanoparticles (mean diameter, ca. 3–4 nm) stabilized by polyvinylpyrrolidone (PVP) were synthesized by a coreduction process in neat glycerol under hydrogen pressure from Cu­(II) and Pd­(II) precursors. These BMNPs were fully characterized both at solid state and in glycerol solutions by different techniques (PXRD, FT-IR, XPS, cyclic voltammetry, HR­(TEM), HAADF-STEM, EDX), thanks to the negligible vapor pressure of glycerol. Depending on the Pd:Cu ratio, different structures were observed. Thus, using a Pd:Cu ratio of 1:1, PdNPs coated by a nonuniform Cu-shell were formed, while for Pd:Cu = 1:2, a disordered alloy was obtained; Pd:Cu = 2:1 ratio mainly led to monometallic species. The as-prepared BMNPs were tested in catalytic semihydrogenation of alkynes and azide–alkyne cycloaddition (CuAAC) with the aim of establishing a correlation between structure and reactivity. Moreover, PdCu-A nanoparticles were applied in one-pot tandem processes involving AAC and C–C cross coupling reactions.

We report aR h-catalyzedh ydroaminomethylation reaction of terminal alkenes in glycerolt hat proceeds efficiently under mild conditions to produce the corresponding amines in relatively high selectivity towards linear amines, moderate to excellent yields by using al ow catalyst loading (1 mol %[ Rh],2mol %p hosphine) and relative low pressure (H 2 /CO, 1:1, total pressure 10 bar). This work sheds light on the importance of glycerol in enabling enamine reduction via hydrogen transfer.M oreover,e vidence for the crucial role of Rh as chemoselective catalyst in the condensation step has been obtained for the first time in the frame of the hydroaminomethylation reaction by precluding deleterious aldol condensation reactions. The hydroaminomethylation proceeds under am olecular regime;t he outcomeo f catalytically actives peciesi nto metal-based nanoparticles renderst he catalytic system inactive.

In this work, a series of cobalt-doped ceria nanorods have been synthesized coming from two cobalt precursors by the impregnation method, based on ceria nanorods pre-formed by the hydrothermal method. The properties of obtained catalysts were investigated by various techniques, including Brunauer-Emmett-Teller nitrogen physisorption measurements (BET), X-ray powder diffraction (XRD), hydrogen temperature-programmed reduction (H 2 -TPR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The catalytic activities of as-prepared samples were studied in the deep oxidation of p-xylene at low temperatures (225300°C). The catalyst characterizations evidenced the crystalline phase formations of CeO 2 and Co 3 O 4 with the average crystallite sizes of 17.545.8 nm and 11.123.4 nm, respectively. The cobalt addition by cobalt nitrate into CeO 2 decreased the surface area of CeO 2 nanorods (67.9 m 2 .g ¹1 ), in contrast to the increase using cobalt acetate (76.082.5 m 2 .g ¹1 ). Co 3 O 4 /CeO 2 catalysts showed reduction peaks at much lower temperatures than that of pure nanorod ceria. 7.5 mass% Co 3 O 4 supported on nanorod CeO 2 catalyst synthesized from cobalt acetate as a type of cobalt precursor with the smallest nanoparticle size and high BET surface area was the most efficient for p-xylene deep oxidation, achieving more than 95% of p-xylene conversion to CO 2 at 275°C, and its performance was stabilized for more than 100 hours tested.

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Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogenous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.

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