The wet synthesis and quantification of ligand-free sub-nanometric Au clusters in solid matrices.

© The Royal Society of Chemistry. The synthesis of ligand-free sub-nanometric metal clusters on a large scale suffers typically from very low yields (15% yields, as unambiguously determined using a very simple and extremely sensitive analytical reaction test.

Incorporation of Mn12single molecule magnets into mesoporous silica

The incorporation of four Mn12 derivatives, namely [Mn12O12(O2CR)16(H2O)4] (R = CH3 (1), CH3CH2 (2), C6H5 (3), C6F5 (4)), into the hexagonal channels of the MCM-41 mesoporous silica has been studied. Only the smallest clusters 1 and 2, i.e. those with compatible size with the pores of MCM-41, could enter into the mesoporous silica. Powder X-ray diffraction analysis, HRTEM images and N2 adsorption–desorption isotherm experiments show that the well-ordered hexagonal structure of MCM-41 is preserved and that the Mn12 clusters are inside the pores. The magnetic properties of the MCM-41/2b nanocomposite material obtained in CH2Cl2 indicate that the structure of the cluster is maintained after in…

Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxide catalysts

Abstract MoVTeNbO catalysts, prepared by hydrothermal synthesis, are active and highly selective in the ODH of ethane, especially those with a MoVTeNb molar ratio of 1–0.15–0.16–0.17 and heat-treated at 600–650 °C. On the best catalyst, selectivities higher than 80% at ethane conversion levels higher than 80% have been obtained operating at relatively low reaction temperatures (340–400 °C). Thus, yields of ethylene of ca. 75% have been obtained, which exceeds the best yield reported in the literature. Te 2 M 20 O 57 ( M =Mo, V, Nb) and (V,Nb)-substituted θ -Mo 5 O 14 , in addition to small amounts of the Te 0.33 M O 3.33 ( M =Mo, V, Nb) phase, can be proposed in the most selective cataly…

Corrigendum to “Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxides catalysts” [J. Catal. 225 (2) (2004) 428–438]

Mo-containing tetragonal tungsten bronzes. The influence of tellurium on catalytic behaviour in selective oxidation of propene

Abstract Te-free and Te-containing multicomponent Mo-based catalysts presenting tetragonal tungsten bronze (TTB) structure have been prepared, characterized and tested for the selective oxidation of propene. The catalysts were prepared hydrothermally and heat treated at 700 °C. The structural characterization performed by means of XRD, FTIR, SAED and HRTEM confirms the incorporation of tellurium to the TTB structural framework and shows that its presence does not modify in essence the crystalline structure. However, the incorporation of Te strongly modifies the catalytic performance, and the highest yield to acrolein has been achieved on catalysts with Te/Mo atomic ratios in bulk of 0.03. T…

A new family of "clicked" estradiol-based low-molecular-weight gelators having highly symmetry-dependent gelation ability.

Reported herein is the discovery of a novel family of "clicked" estradiol-based LMWGs whose gelation ability highly depends on the gelator symmetry. These LMWGs that gel different organic solvents in the presence of H(2)O even at concentrations as low as 0.04 wt% are readily accessible using "click" chemistry.