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ABSTRACT: The reaction of MoO3, 2,2'-bipyridine-5,5-dicarboxylic acid (H2bpdc), water, and dimethylformamide in the mole ratio 1:1:1730:130 at 150 °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)]·nH2O (1) (DMA = dimethylammonium). Compound 1 was characterized by scanning electron microscopy, FT-IR and (13)C{(1)H} 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)[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···O, N(+)-H···O(-)) and weak (C-H···O) hydrogen bonding interactions, and π-π 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 °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 °C, 100% conversion of Ole) and 89% for 1,2-epoxy-p-menth-8-ene (DCE, 55 °C, 95% conversion of Lim). Catalytic systems employing the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as solvent could be effectively recycled.
Inorganic Chemistry 03/2013; · 4.60 Impact Factor
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ABSTRACT: Solid 1:1 inclusion compounds of triclosan with native and permethylated β-cyclodextrin (β-CD and TRIMEB) were prepared by co-crystallisation and co-evaporation, respectively, and studied by FT-IR and (13)C{(1)H} CP/MAS NMR spectroscopies, thermogravimetric analysis, X-ray diffraction and theoretical calculations. Results showed that triclosan inclusion into TRIMEB afforded an amorphous solid, whilst β-CD·triclosan is composed of microcrystals belonging to two different phases. In the phase featuring larger crystals, X-ray diffraction was carried out and the β-CD host units, packing head-to-head in infinite channels, were refined; the geometry for the included but highly disordered triclosan molecules was assessed by theoretical calculations. The bacterial growth inhibitory action of the inclusion compounds was studied in comparison to that of pure triclosan on Gram-negative (Salmonella, Escherichia) and Gram-positive strains (Bacillus, Listeria, Enterococcus and Staphylococcus) typically associated with human pathologies, and also on environmental bacteria isolated from different soil and water sources. The antimicrobial activities obtained in the present work showed that, of the two CD hosts, TRIMEB brings the most favourable carrier effect: it reduced the toxicity of triclosan against some of the environmental strains and afforded slightly higher action against virulent strains.
Journal of pharmaceutical and biomedical analysis 02/2013; 80C:34-43. · 2.45 Impact Factor
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ABSTRACT: A convenient diastereoselective rearrangement of the racemic (R/S)-spiro[chroman-2,4′-imidazolidine]-2′,4,5′-triones 3a–c into (2′R,5S)- and (2′S,5R)-5-(3-oxo-2,3-dihydrobenzofuran-2-yl)imidazolidine-2,4-diones 4a–c under alkali conditions is described. The obtained σ bridged benzofuran-3(2H)-one-hydantoin dyads 4a–c are subsequently transformed into π conjugated benzofuran-3(2H)-one-hydantoin dyads 5a–c by a diastereoselective dehydrogenation using I2 (catalytic)/DMSO system to predominantly yield the (Z)-isomer. The novel single and double bonded benzofuran-3(2H)-one-hydantoin conjugate structures 4a–c and 5a–c were unambiguously elucidated by single-crystal X-ray diffraction and 2D NMR techniques allowing an in-depth stereochemical and mechanistic discussions.
Tetrahedron 01/2013; 69:5413-5420. · 3.03 Impact Factor
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CrystEngComm 01/2013; 15(15):2822-2834. · 3.84 Impact Factor
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Materials Science Forum 01/2013;
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ABSTRACT: Bis(pyrazolyl)methanetetracarbonyl-molybdenum(0), cis-[Mo(CO)4(BPM)] (1), was prepared from Mo(CO)6 and the ligand bis(pyrazolyl)methane (BPM), and examined as a catalyst precursor for the epoxidation of olefins using tert-butylhydroperoxide (TBHP) as oxidant. Catalytic activities followed the sequence 1-octene < trans-2-octene < α-pinene < (R)-(+)-limonene < cis-cyclooctene, and, with the exception of α-pinene and limonene, the corresponding epoxide was always the only reaction product. Turnover frequencies for the epoxidation of cyclooctene were 580 mol molMo−1 h−1 at 55 °C and 1175 mol molMo−1 h−1 at 75 °C, which compare favourably with those found for other molybdenum carbonyl complexes used as catalyst precursors for the same reaction under similar conditions. Catalytic activities were lower in the presence of organic co-solvents, decreasing in the sequence 1,2-dichloroethane > nitromethane > ethanol > hexane > acetonitrile. It is proposed that the oxodiperoxo complex [MoO(O2)2(BPM)] (2) may be the active catalyst formed in situ by oxidative decarbonylation of 1, since crystals of 2 suitable for structure determination by X-ray diffraction were obtained from the reaction solution recovered after a catalytic run at 55 °C with cis-cyclooctene as substrate. In support of this hypothesis, the catalytic performance of 2 for the epoxidation of cyclooctene at 55 °C is very similar to that for 1.
Journal of Organometallic Chemistry 01/2013; 723:56-64. · 2.38 Impact Factor
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ABSTRACT: The title compound, C(15)H(22)N(2)O(3), was obtained as a by-product of oxidative cleavage of 1,3-dicyclo-hexyl-(3-oxo-2,3-dihydro-benzofuran-2-yl)imidazolidine-2,4-dione. Herein, we report the crystal structure of a second polymorph, which was obtained by crystallization from an ethanol solution at 253 K, instead of slow evaporation of the same solvent at room temperature. While the first polymorph [Talhi et al. (2011). Acta Cryst. E67, o3243] crystallized in the non-centrosymmetric space group P2(1)2(1)2(1), this second polymorph crystallizes in the centrosymmetric space group P2(1)/n. Compared to the first polymorph, in the crystal no C=O⋯C=O inter-actions were found (C⋯O inter-molecular distance longer than 3.15 Å) and instead, close packing of individual mol-ecular units is mediated by C-H⋯π and weak C-H⋯O inter-actions.
Acta Crystallographica Section E Structure Reports Online 11/2012; 68(Pt 11):o3233-4. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(23)H(19)N, was obtained unexpectedly from the reaction of [Eu(nta)(3)(PzPy)] {Hnta = 1-(2-naphtho-yl)-3,3,3-trifluoro-acetone and PzPy = 2-[3(5)-pyrazol-yl]pyridine} with 1-naphthyl-methyl-amine. The 1- and 2-naphthyl groups are essentially planar [r.m.s. deviations of 0.007 and 0.011 Å, respectively] and subtend angles of 38.69 (11) and 16.50 (11)°, respectively, with the central CH(3)-C=N-CH(2) unit, which is also almost planar [r.m.s. deviation = 0.002 Å]. In the crystal, the mol-ecules are disposed in zigzag-type fashion, forming layers perpendicular to [100]. Weak supra-molecular C-H⋯π inter-actions contribute to the packing forces.
Acta Crystallographica Section E Structure Reports Online 11/2012; 68(Pt 11):o3143. · 0.35 Impact Factor
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Acta Crystallographica Section E Structure Reports Online 11/2012; 68(11):o3143. · 0.35 Impact Factor
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ABSTRACT: A new heterodinuclear [Zn(L)Dy](3+) complex, with L being a compartmental Schiff base ligand, exhibits the characteristic Dy(3+) luminescence associated with a single-ion field induced slow relaxation of the magnetisation. This complex may be considered as one of the rare examples of a bifunctional luminescent single-ion magnet.
Chemical Communications 09/2012; 48(80):9974-6. · 6.17 Impact Factor
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ABSTRACT: The asymmetric unit of the title compound, C(4)H(5)N(7), comprises two independent but virtually superimposable mol-ecules. Each mol-ecule is planar with the dihedral angles between the five-membered rings being 2.8 (3) and 2.1 (3)°. The crystal structure is formed by an extensive network of relatively strong N-H⋯N hydrogen-bond inter-actions. Individual mol-ecules are arranged into supra-molecular zigzag chains running parallel to [001] by way of the strongest N-H⋯N inter-actions. Adjacent chains are inter-connected by rather long (D⋯A distances range from ca 3.00 to 3.03 Å) but highly directional (inter-action angles above ca 173°) hydrogen bonds forming a supra-molecular layer in the bc plane.
Acta Crystallographica Section E Structure Reports Online 09/2012; 68(Pt 9):o2700-1. · 0.35 Impact Factor
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The Journal of Physical Chemistry C 08/2012; 116:19951-19957. · 4.80 Impact Factor
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ABSTRACT: A new family of mixed-lanthanide cyano-bridged coordination polymers Ln(0.5)Ln'(0.5)(H(2)O)(5)[W(CN)(8)] (where Ln/Ln' = Eu(3+)/Tb(3+), Eu(3+)/Gd(3+), and Tb(3+)/Sm(3+)) containing two lanthanide and one transition metal ions were obtained and characterized by X-ray diffraction, photoluminescence spectroscopy, magnetic analyses, and theoretical computation. These compounds are isotypical and crystallize in the tetragonal system P4/nmm forming two-dimensional grid-like networks. They present a magnetic ordering at low temperature and display the red Eu(3+) ((5)D(0) → (7)F(0-4)) and green Tb(3+) ((5)D(4) → (7)F(6-2)) characteristic photoluminescence. The Tb(0.5)Eu(0.5)(H(2)O)(5)[W(CN)(8)] compound presents therefore green and red emission and shows Tb(3+)-to-Eu(3+) energy transfer.
Inorganic Chemistry 08/2012; 51(16):9005-16. · 4.60 Impact Factor
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ABSTRACT: The reaction of [MoO(2)Cl(2)(pypzEA)] (1) (pypzEA = ethyl[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate) with water in a Teflon-lined stainless steel autoclave (100 °C) or in an open reflux system leads to the isolation of the molybdenum oxide/pyrazolylpyridine composite material [Mo(2)O(6)(HpypzA)] (2; HpypzA = [3-(pyridinium-2-yl)-1H-pyrazol-1-yl]acetate). The solid state structure of 2 was solved through single crystal and powder X-ray diffraction analyses in conjunction with information derived from FT-IR and (13)C CP MAS NMR spectroscopies and elemental analyses. In the asymmetric unit of 2, two crystallographically distinct Mo(6+) centers are bridged by a syn,syn-carboxylate group of HpypzA. The periodic repetition of these units along the a axis of the unit cell leads to the formation of a one-dimensional composite polymer, (∞)(1)[Mo(2)O(6)(HpypzA)]. The outstretched pyrazolylpyridine groups of adjacent polymers interdigitate to form a zipper-like motif, generating strong onset π-π contacts between adjacent rings of coordinated HpypzA molecules. The composite oxide 2 is a stable heterogeneous catalyst for liquid-phase olefin epoxidation.
Inorganic Chemistry 07/2012; 51(15):8629-35. · 4.60 Impact Factor
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ABSTRACT: The two-dimensional cyano-bridged coordination polymer Er(H(2)O)(4)[W(CN)(8)] exhibits a magnetic transition at 12 K and an unusual field-dependent transition from short-range to ferromagnetic ordering.
Inorganic Chemistry 05/2012; 51(12):6425-7. · 4.60 Impact Factor
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ABSTRACT: The reaction of 2-formyl-5,10,15,20-tetraphenylporphyrin with aryl methyl ketones and ammonium acetate, in the presence of La(OTf)(3), affords benzoporphyrins and 2-(2,6-diarylpyridin-4-yl)porphyrins. This methodology was used to prepare, for the first time, a 2-(2,2':6',2''-terpyridin-4'-yl)porphyrin. The structures of two 2-(2,6-diarylpyridin-4-yl)porphyrins were confirmed by single-crystal X-ray diffraction.
Chemical Communications 05/2012; 48(49):6142-4. · 6.17 Impact Factor
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ABSTRACT: The oxidative decarbonylation of the η(3)-allyl dicarbonyl complexes [Mo(η(3)-C(3)H(5))Cl(CO)(2)(L)] (L = 2,2'-bipyridine (bipy) (1), 4,4'-di-tert-butyl-2,2'-bipyridine (di-tBu-bipy) (2)) by reaction with aqueous tert-butylhydroperoxide (TBHP) or H(2)O(2) gave the following compounds in good to excellent yields: the oxo-bridged dimers [MoO(2)Cl(L)](2)O (L = bipy (3), di-tBu-bipy (6)) using TBHP(10 equiv.)/CH(3)CN/r.t.; the molybdenum oxide/bipyridine hybrid material {[MoO(3)(bipy)][MoO(3)(H(2)O)]}(n) (4) and the octanuclear complex [Mo(8)O(24)(di-tBu-bipy)(4)] (7) using TBHP(50 equiv.)/H(2)O/70 °C; the oxodiperoxo complexes MoO(O(2))(2)(L) (L = bipy (5), di-tBu-bipy (8)) using H(2)O(2)(10 equiv.)/CH(3)CN/r.t. The structure of 7·x(solvent) (where solvent = CH(2)Cl(2) and/or diethyl ether) was determined by single crystal X-ray diffraction. Despite possessing the same windmill-type complex as that described previously for 7·10CH(2)Cl(2), the crystal structure of 7·x(solvent) is unique due to differences in the crystal packing. Compounds 1-8 were examined as catalysts or catalyst precursors for the epoxidation of cyclooctene using aqueous TBHP or H(2)O(2) as oxidant at 55 or 70 °C. Reactions were performed without co-solvent or with the addition of water, ethanol or acetonitrile. Cyclooctene oxide was always the only reaction product. Solids recovered after 24 h reaction at 70 °C were identified by FT-IR spectroscopy as the hybrid 4 from (1,3-5)/TBHP, complex 5 from (1,3-5)/H(2)O(2), and complex 8 from (2,6-8)/H(2)O(2). With TBHP as oxidant, the highest epoxide yields (for 24 h reaction at 70 °C) were obtained using excess H(2)O as solvent (28-38% for 1,3-5; 87-98% for 2,6-8), while with H(2)O(2) as oxidant, the highest epoxide yields were obtained using CH(3)CN as solvent (54-81% for 3-8).
Dalton Transactions 03/2012; 41(12):3474-84. · 3.84 Impact Factor
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ABSTRACT: The asymmetric unit of the title compound, poly[(μ(4)-{[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}phospho-nato)lanthanum(III)], [La(C(3)H(9)NO(9)P(3))](n), comprises an La(3+) center and a H(3)nmp(3-) anion (where H(3)nmp(3-) is a residue of partially deprotonated nitrilo-tris-(methyl-ene-phospho-nic acid), namely {[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}-phos-pho-nate). This study concerns a structural redetermination using single-crystal X-ray diffraction data, collected at the low temperature of 180 K, of a recently investigated material whose structural details have been proposed from powder X-ray diffraction studies [Silva et al. (2011 ▶). J. Am. Chem. Soc.133, 15120-15138]. The main difference between the two models rests on the position of the H atoms. While two H atoms were modeled as attached to the same phospho-nate group in the powder determination, in the current model, the same H atoms are instead distributed among two of these groups. The sample studied was an inversion twin.
Acta Crystallographica Section E Structure Reports Online 03/2012; 68(Pt 3):m294-5. · 0.35 Impact Factor
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ABSTRACT: The title compound, C(48)H(20)F(19)N(4)O(3)P, prepared by the nucleophilic attack of triethyl phosphite on one of the 4-fluoro atoms of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, contains a single molecule in the asymmetric unit. The porphyrin unit is almost planar [largest non-H atom deviation = 0.174 (6) Å], and has the planes of the neighbouring benzene rings oriented at angles ranging from 64.3 (2) to 89.6 (3)° relative to the porphyrin core. The P=O group is almost coplanar with the attached benzene ring, subtending an angle of 4.0 (3)°. Several weak supramolecular interactions, namely C-H...π, C-F...π, P=O...π, C-H...(O,F) and F...F contacts, contribute to the crystal packing.
Acta crystallographica. Section C, Crystal structure communications 03/2012; 68(Pt 3):o104-7. · 0.78 Impact Factor
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ABSTRACT: Recrystallization of [MoO(2)Cl{HC(3,5-Me(2)pz)(3)}]Cl [where HC(3,5-Me(2)pz)(3) is tris(3,5-dimethyl-1H-pyrazol-1-yl)methane] led to the isolation of large quantities of the dinuclear complex dichlorido-2κ(2)Cl-μ-oxido-κ(2)O:O-tetraoxido-1κ(2)O,2κ(2)O-[tris(3,5-dimethyl-1H-pyrazol-1-yl-1κN(2))methane]dimolybdenum(IV) acetonitrile monosolvate, [Mo(2)Cl(2)O(4)(C(16)H(22)N(6))]·CH(3)CN or [{MoO(2)Cl(2)}(μ(2)-O){MoO(2)[HC(3,5-Me(2)pz)(3)]}]·CH(3)CN. At 150 K, this complex cocrystallizes in the orthorhombic space group Pbcm with an acetonitrile molecule. The complex has mirror symmetry: only half of the complex constitutes the asymmetric unit and all the heavy elements (namely Mo and Cl) are located on the mirror plane. The acetonitrile molecule also lies on a mirror plane. The two crystallographically independent Mo(6+) centres have drastically different coordination environments: while one Mo atom is hexacoordinated and chelated to HC(3,5-Me(2)pz)(3) (which occupies one face of the octahedron), the other Mo atom is instead pentacoordinated, having two chloride anions in the apical positions of the distorted trigonal bipyramid. This latter coordination mode of Mo(VI) was found to be unprecedented. Individual complexes and solvent molecules are close-packed in the solid state, mediated by various supramolecular contacts.
Acta crystallographica. Section C, Crystal structure communications 03/2012; 68(Pt 3):m73-5. · 0.78 Impact Factor
