resumo
A Zn,Al layered double hydroxide (LDH) with [Cp*MoO3](-) (Cp* = eta(5)-C5Me5) anions in the interlayer has been prepared by a direct coprecipitation method. The intercalated LDH and the mixed metal oxide (MMO) obtained after its calcination were characterized by elemental and thermogravimetric analyses, powder X-ray diffraction (PXRD), FT-IR and FT-Raman spectroscopy, C-13 and Al-27 MAS NMR, and scanning electron microscopy. The observed basal spacing of 17.1 angstrom for the LDH Zn,Al-Cp*MoO3 (corresponding to a gallery height of 12.3 angstrom) suggests that the guest anions self-assemble into dimers via offset face-to-face Cp*center dot center dot center dot Cp* interactions, which facilitates hydrogen-bonding interactions between the oxido ligands of the complexes and the layer hydroxyl groups, while positioning the hydrophobic aromatic rings towards the center of the galleries. Calcination of Zn,Al-Cp*MoO3 at 550 degrees C under air gave an MMO comprising well-dispersed ZnO, alpha-ZnMoO4 and ZnAl2O4 (spinel) oxides in a molar of ca. 1.4:1.6:1. The MMO exhibited catalytic activity for the epoxidation of cis-cyclooctene with tert-butylhydroperoxide (TBHP) as terminal oxidant, with quantitative yield of the epoxide being achieved within 24 h at 85 degrees C.
palavras-chave
OLEFIN EPOXIDATION; MOLYBDENUM; FERROCENE; COMPLEX
categoria
Chemistry
autores
Gomes, AC; Neves, P; Gago, S; Valente, AA; Goncalves, IS; Pillinger, M
nossos autores
Ana Catarina Costa Gomes Alves
Investigador Auxiliar
Anabela Tavares Aguiar Valente
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Martyn Pillinger
Investigador Principal
Patrícia dos Santos Neves
Investigador AuxiliarProjectos
Sistemas ativados por estímulos para a terapia com monóxido de carbono (SASCOT)
Conversao catalitica de olefinas derivadas da biomassa (BiOle_AcidOxCat)
agradecimentos
We acknowledge funding provided within the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, the CENTRO 2020 Regional Operational Programme (project references CENTRO-01-0145-FEDER-028031 and PTDC/QUI-QOR/28031/2017), and the Operational Programme for Competitiveness and Internationalization (project reference POCI-01-0145-FEDER-030075), financed by national funds (OE) through the FCT (Fundacao para a Ciencia e a Tecnologia)/MEC (Ministerio da Ciencia, Tecnologia e Ensino Superior) and when appropriate co-financed by the European Union through the European Regional Development Fund under the Portugal 2020 Partnership Agreement. The position held by P. N. was funded by national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in numbers 4, 5 and 6 of article 23 of the Decree-Law 57/2016 of 29 August, changed by Law 57/2017 of 19 July.