abstract
The reaction of MoO3, 2,2'-bipyridine-5,5-dicarboxylic acid (H(2)bpdc), water, and dimethylformamide in the mole ratio 1:1:1730:130 at 150 degrees C for 3 days in a rotating Teflon-lined digestion bomb leads to the isolation of the molybdenum oxide/bipyridinedicarboxylate hybrid material (DMA)[MoO3(Hbpdc)]center dot nH(2)O (1) (DMA = dimethylammonium). Compound 1 was characterized by scanning electron microscopy, FT-IR and C-13{H-1} CP MAS NMR spectroscopies, and elemental and thermogravimetric analyses. The solid state structure of 1 was solved and refined through Rietveld analysis of high resolution synchrotron X-ray powder diffraction data in conjunction with information derived from the above techniques. The material, crystallizing in the noncentrosymmetric monoclinic space group Pc, is composed of an anionic one-dimensional organic-inorganic hybrid polymer, (1)(infinity)[MoO3(Hbpdc)](-), formed by corner-sharing distorted {MoO4N2} octahedra, which cocrystallizes with charge-balancing DMA(+) cations and one water molecule per metal center. In the crystal structure of 1, the close packing of individual anionic polymers, DMA(+) cations, and water molecules is mediated by a series of supramolecular contacts, namely strong (O-H center dot center dot center dot O, N+-H center dot center dot center dot O-) and weak (C-H center dot center dot center dot O) hydrogen bonding interactions, and pi-pi contacts involving adjacent coordinated Hbpdc(-) ligands. The catalytic potential of 1 was investigated in the epoxidation reactions of the bioderived olefins methyl oleate (Ole) and DL-limonene (Lim) using tert-butylhydroperoxide (TBHP) as the oxygen donor and 1,2-dichloroethane (DCE) or (trifluoromethyl)benzene (BTF) as cosolvent, at 55 or 75 degrees C. Under these conditions, 1 acts as a source of active soluble species, leading to epoxide yields of up to 98% for methyl 9,10-epoxystearate (BTF, 75 degrees C, 100% conversion of Ole) and 89% for 1,2-epoxy-p-menth-8-ene (DCE, 55 degrees C, 95% conversion of Lim). Catalytic systems employing the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as solvent could be effectively recycled.
keywords
METAL-ORGANIC FRAMEWORK; STATE COORDINATION CHEMISTRY; TEMPERATURE IONIC LIQUIDS; OLEFIN EPOXIDATION; DIOXOMOLYBDENUM(VI) COMPLEXES; POLYOXOMOLYBDATE CLUSTERS; OCTAMOLYBDATE CLUSTERS; CARBON-DIOXIDE; METHYL OLEATE; ACTIVE-SITES
subject category
Chemistry
authors
Amarante, TR; Neves, P; Valente, AA; Paz, FAA; Fitch, AN; Pillinger, M; Goncalves, IS
our authors
Anabela Tavares Aguiar Valente
Principal Researcher
Filipe Alexandre Almeida Paz
Principal Researcher
Isabel Maria de Sousa Gonçalves
Associate Professor
Martyn Pillinger
Principal Researcher
Patrícia dos Santos Neves
Assistant Researcher
Tatiana Ribau Amarante
Junior Researcheracknowledgements
We are grateful to the Fundacao para a Ciencia e a Tecnologia (FCT), QREN, Fundo Europeu de Desenvolvimento Regional (FEDER), COMPETE, and the European Union for funding (R&D Project No. PDTC/QUI-QUI/098098/2008, FCOMP-01-0124-FEDER-010785). The Associate Laboratory CICECO (Pest-C/CTM/LA0011/2011) is acknowledged for continued support and funding. We thank the FCT and the European Union for a postdoctoral grant to P.N. (SFRH/BPD/73540/2010), cofunded by MCTES and the European Social Fund through the program POPH of QREN, and for a Ph.D. grant to T.R.A. (SFRH/BD/64224/2009). We further wish to acknowledge the European Synchrotron Radiation Facility (Grenoble, France) for granting access time to the ID31 beamline under the CH-3692 and CH-3702 research proposals.