resumo
Iron oxide magnetic nanoparticles were synthesized with different sizes (11 and 30 nm). Subsequently they were shelled with a silica layer allowing grafting of an organic phosphine ligand that coordinated to the [MoI2(CO)(3)] organometallic core. The silica layer was prepared by the Stober method using either mechanical (both 11 and 30 nm nanoparticles) or ultrasound (30 nm only) stirring. The latter nanoparticles once coated with silica were obtained with less aggregation, which was beneficial for the final material holding the organometallic moiety. The Mo loadings were found to be 0.20, 0.18, and 0.34 mmol(Mo)center dot g(-1) for MNP30-Si-phos-Mo, MNP11-Si-phos-Mo, and MNP30-Si-us-phos-Mo, respectively, with the ligand-to-metal ratio reaching 4.6, 4.8, and 3.2, by the same order, confirming coordination of the Mo moieties to two phos ligands. Structural characterization obtained from powder X-ray diffraction (XRD), scanning electron microscopy (SEM)/ transmission electron microscopy (TEM) analysis, and Fourier-transform infrared (FTIR) spectroscopy data confirmed the successful synthesis of all nanomaterials. Olefin epoxidation of several substrates catalyzed by these organometallic nano-hybrid materials using tert-butyl hydroperoxide (tbhp) as oxidant, achieved very good results. Extensive testing of the catalysts showed that they are highly active, selective, recyclable, and efficient concerning oxidant consumption.
categoria
Chemistry, Physical
autores
Fernandes, CI; Vaz, PD; Nunes, CD
nossos autores
Pedro Miguel Duarte Vaz
Colaboradoragradecimentos
This research was funded by Fundacao para a Ciencia e Tecnologia (FCT), Portugal, is acknowledged for financial support to Centro de Quimica Estrutural through grants UIDB/00100/2020 and UIDP/00100/2020.