- Ionic nanoparticle networks as solid state catalysts
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We report on the catalytic activity for the cycloaddition of CO2 to cyclic organic carbonates of recently developed ionic nanoparticle networks (INN). The combination of high imidazolium content and ability to coordinate to CO2 molecules within the 3D network makes the hybrid INN materials highly promising heterogeneous catalysts for CO2 activation reactions. The catalytic activity of INN powders and gels was investigated with various starting epoxides. Quantitative conversion was reached with epichlorohydrin. The influence of mono or bis(imidazolium) bridging ligands and methylation at the C2 position in the aromatic ring of the organic cation could be highlighted by evaluation of the activity with the less reactive propylene oxide as the starting epoxide. Finally, the influence of the type of inorganic nanoparticle support was also studied by preparing heterobimetallic silica-zinc oxide nanoparticle networks. Promising results were obtained with various epoxides. Conversion or selectivity up to 100 % could be obtained. The catalyst could be reused owing to the good thermal stability of the hybrid inorganic-organic INN. After four reaction runs the catalyst still proved to be active. The catalytic activity of imidazolium-based nanoparticle networks was demonstrated for CO2 cycloaddition reactions to various epoxides. The hybrid solid-state material can be easily separated and reused after the reaction. Conversion or selectivity up to 100 % could be obtained under mild conditions and in a short reaction time. Copyright
- Roeser, Jerome,Kronstein, Martin,Litschauer, Marco,Thomas, Arne,Neouze, Marie-Alexandra
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- Palladium-quaternary phosphonium phase transfer catalyst brush assembly as reusable and environmentally benign catalyst for coupling of aryl halides and sodium tetraphenylborate in neat water
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A first example of simultaneous covalent anchoring of a palladate anion-phosphonium cation matrix on the surface of silica nanoparticles and application in the Suzuki coupling reaction of a variety of different haloarenes and sodium tetraphenylborate in neat aqueous media without the addition of any organic co-solvent are described.
- Hajipour, Abdol R.,Azizi, Ghobad
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- Insoluble ligands and their applications. IV. Polysiloxane-bis(2-aminoethyl)amine ligands and some derivatives
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Methods have been developed for the preparation of insoluble polysiloxane ligands containing pendant - N(CH2CH2NH2)2 groups and their salicylaldimine Schiff-base and cyclised derivatives.The ability of these materials to take up metal ions from aqueous so
- Ahmed, I.,Parish, R.V.
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- Tailoring photoluminescence properties in ionic nanoparticle networks
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To investigate the original and promising luminescence properties of ionic nanoparticle networks (INN), various material compositions were investigated. In this work, the linker used to network the silica nanoparticles was varied; numerous substituted or non-substituted imidazolium, pyrazolium and pyridinium linkers are presented. Photoluminescence experiments on the INN hybrid materials revealed strong emission bands over a broad range in the visible region of the light spectrum. Varying the aromatic linker between the imidazolium units induced clear shifts of the emission maxima up to 100 nm, as a consequence of π-π stacking interactions. Steric hindrance and inductive effects of the substituents, introduced on the aromatic units, also strongly influenced the luminescence properties of the materials by modifying the π-π stacking between the imidazolium rings. Small and wide-angle X-ray scattering (SAXS, WAXS) experiments revealed a clear trend between the obtained structural parameters (short-range order parameter and distance of the aromatic units within the hybrid material) and the luminescence quantum yields of the INN materials. Inducing luminescence: Interesting luminescence properties were observed in ionic nanoparticle networks containing no luminophore. "Playing" with the nanoparticle linker allowed tailoring of the excitation and emission wavelength over a broad range. A clear trend between the obtained structural parameters (obtained from small-angle X-ray scattering experiments) and the luminescence quantum yields of the ionic nanoparticle network materials could be evidenced (see figure).
- Kronstein, Martin,Akbarzadeh, Johanna,Drechsel, Christina,Peterlik, Herwig,Neouze, Marie-Alexandra
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- Nanoparticles connected through an ionic liquid-like network
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Silica nanoparticles linked through ionic liquid-like molecules are synthesized by two routes. The first approach utilized a bis(trialkoxysilyl)- substituted imidazolium iodide to link the silica nanoparticles. In the second approach, the silica nanoparticles were first modified by 3- chloropropyltrimethoxysilane and N-(3-trimethoxysilylpropyl)imidazole and then coupled through nucleophilic substitution. A comparison of both approaches shows that the second approach results in a more efficient interfacing of nanoparticles. The Royal Society of Chemistry 2008.
- Litschauer, Marco,Neouze, Marie-Alexandra
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- A novel strategy to synthesize well-defined PS brushes on silica particles by combination of lithium-iodine exchange (LIE) and surface-initiated living anionic polymerization (SI-LAP)
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Core-shell hybrid particles, possessing a hard core of silica particles (SiPs) and a soft shell of brushlike polystyrene (PS), were successfully prepared by the combination of lithium-iodine exchange (LIE) and surface-initiated living anionic polymerization (SI-LAP). The molecular weight, graft density and brush thicknesses of the PS brushes were controllable. This journal is
- Min, Jiakang,Lin, Yichao,Zheng, Jun,Tang, Tao
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- Sustainable parts-per-million level catalysis with FeIII: One-pot cascade synthesis of 2,3-dihydroquinazolin-4(1H)-ones in water
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A silica-supported iron complex has been identified as a highly active and reusable catalyst for the synthesis of medicinally important 2,3-dihydroquinazolin-4(1H)-ones. The catalyst was fully characterized by various spectroscopic analyses such as Fourie
- Dutta, Apurba,Trivedi, Priyanka,Kulshrestha, Akshay,Kumar, Arvind,Chaturvedi, Vinita,Sarma, Diganta
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- Palladium nanoparticles supported on cysteine-functionalized MNPs as robust recyclable catalysts for fast O- and N-arylation reactions in green media
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A magnetically robust recyclable nanocatalyst was fabricated by immobilizing of Pd onto the surface of cysteine-functionalized magnetic nanoparticles (MNPs?Cys-Pd). This nanocatalyst was characterized using various techniques such as FT-IR, XRD, TEM, SEM, EDX, VSM, and ICP. The application of catalyst (MNPs?Cys-Pd) was investigated for O-arylation and N-arylation reactions. This phosphine-free complex was found as highly efficient heterogeneous catalyst in green media and mild reaction conditions. In addition, it gave excellent recyclability without significant deactivation after ten cycles.
- Hajipour, Abdol R.,Khorsandi, Zahra,Fatemeh Mohammadi Metkazini
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- Recyclable and eco-friendly Pd-complexed graphene oxide/N-heterocyclic carbene catalyst for various coupling reactions in aqueous phase
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In this study, we report recyclable Pd-complexed graphene oxide (GO) catalysts with a bulky N-heterocyclic carbene (NHC) ligand (GO/NHC-Pd) for various cross-coupling reactions in the aqueous phase. To prepare GO/NHC-Pd, the NHC precursor and a trimethoxy-silane linker were combined on the GO surface via condensation, followed by the Pd chelation over GO/NHC. The GO-based catalysts were applied to three types of C–C cross-coupling reactions including Suzuki, Heck and Sonogashira reactions in the aqueous phase, to evaluate their catalytic performance. The reusability of the catalysts was tested by performing five consequent cross-coupling reactions.
- Kim, Seongsoo,Cho, Hong-Jun,Shin, Dong-Sik,Lee, Sang-Myung
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supporting information
p. 2421 - 2425
(2017/05/31)
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- Preparation of choline chloride–urea deep eutectic solvent-modified magnetic nanoparticles for synthesis of various 2-amino-4H-pyran derivatives in water solution
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A novel hybrid magnetic nanocatalyst was synthesized by covalent coating of Fe3O4 magnetic nanoparticles with choline chloride–urea deep eutectic solvent using 3-iodopropyltrimethoxysilane as a linker. The structure of this new catal
- Tavakol, Hossein,Keshavarzipour, Fariba
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p. 2372 - 2380
(2017/09/30)
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- Temperature-dependent immobilization of a tungsten peroxo complex that catalyzes the hydroxymethoxylation of olefins
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Abstract A tungsten peroxo complex stabilized by the bidentate picolinato ligand has been synthesized and then immobilized successfully on imidazole-functionalized silica. The immobilized tungsten-based catalyst was employed as an efficient catalyst for the one-pot synthesis of β-alkoxy alcohols from olefins and methanol with H2O2. Regarding the catalyst evaluation and the results of characterization by the various methods, it was demonstrated that the immobilization of tungsten peroxo complex was highly temperature-dependent. The tungsten peroxo complex can dissociate and diffuse into the liquid phase at reaction temperature, resulting in a homogeneous reaction. Nevertheless, the catalytically active species was anchored on the imidazole-functionalized silica by hydrogen bonding as the temperature was lowered to 0°C after the reaction, which thus offered a highly effective approach for recycling the catalyst for consecutive cycles. In addition, various olefins can be converted to the corresponding β-alkoxy alcohols with good conversion and selectivity under relative mild conditions by H2O2. Running hot and cold: A tungsten peroxo complex (see picture) can dissociate and diffuse into the liquid phase at the reaction temperature, resulting in a homogeneous reaction. After reaction, the catalytically active species was anchored on the functionalized silica by hydrogen-bonding as the temperature was lowered to 0°C. This offers an effective approach for catalyst recovery and recycling.
- Chen, Jizhong,Hua, Li,Chen, Chen,Guo, Li,Zhang, Ran,Chen, Angjun,Xiu, Yuhe,Liu, Xuerui,Hou, Zhenshan
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p. 1029 - 1037
(2015/06/08)
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- Heterogenised N-heterocyclic carbene complexes: Synthesis, characterisation and application for hydroformylation and C-C bond formation reactions
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The imidazolium salts: 1-mesityl-3-(3-trimethoxysilylpropyl)imidazolium iodide and 1-tert-butyl-3-(3-trimethoxysilylpropyl)imidazolium iodide, abbreviated as (tmpMes)HI (3a) and (tmptBu)HI (3b), respectively, have been synthesised. The palladium(ii) complexes (η3-C 3H5) (tmpMes)PdCl (5a) and (η3-C 3H5)(tmptBu)PdCl (5b), rhodium(i) and iridium(i) complexes (η4-1,5-COD) (tmpMes)MCl, M = Rh (6a), Ir (7a) and (η4-1,5-COD)(tmptBu)MCl, where M = Rh (6b), Ir (7b), were synthesised by silver transmetallation reactions using the silver(i) complexes (tmpMes)AgI (4a) and (tmptBu)AgI (4b). The iridium complex 7b has been structurally characterised. The Pd(ii) and Rh(i) complexes have been immobilised by attachment to chemically modified MCM-41. The immobilised palladium(ii) materials have been tested as recyclable catalysts for Suzuki type C-C bond formation reactions in water and the immobilised rhodium(i) materials have been examined for their catalytic ability for the hydroformylation of 1-octene.
- Dastgir, Sarim,Coleman, Karl S.,Green, Malcolm L. H.
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supporting information; experimental part
p. 661 - 672
(2011/02/28)
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- Reaction of metal alkoxides with 3-alkyl-substituted acetylacetone derivatives - Coordination vs. hydrodeacylation
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Reaction of Ti(OiPr)4 or Zr(OPr)4 with 1 or 2 molar equiv of the 3-alkyl-substituted acetylacetone derivatives 3-acetyl-6-trimethoxysilylhexane-2-one or 3-acetylpentane-2-one not only gives the corresponding β-diketonate complexes but also results in about 15% hydrodeacylation of the β-diketone. With the stronger Lewis acid Al(O sBu)3 hydrodeacylation prevails. Hydrodeacylation is suppressed when a 1:5 ratio of metal alkoxide and β-diketone is reacted.
- Puchberger, Michael,Rupp, Wolfgang,Bauer, Ulrike,Schubert, Ulrich
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p. 1289 - 1294
(2007/10/03)
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- Silica-Supported Cyclopentadienyl-Rhodium(I),-Cobalt(I), and-Titanium(IV) Complexes
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The silylated cyclopentadiene derivative, (MeO)3Si(CH2)3C5H5, synthesised from commercially-available (MeO)3Si(CH2)3Cl, has been used to prepare the complexes 5-(MeO)3Si(CH2)3C5H4>Rh(CO)2, 5(MeO)3Si(CH2)3C5H4>Rh(COD)(COD= cyclo-octa-1,5-diene), and 5-(MeO)3Si(CH2)3C5H4>2TiCl2.The complexes 5(MeO)3Si(CH2)3C5H4>TiCl3, prepared by reaction of NaC5H4(CH2)3Si(OMe)3 with TiCl4 (1/1 molar ratio) and also by reaction of 5-(MeO)3Si(CH2)3C5H4>Ti(OEt)3 with CH3COCl, proved to be very unstable.Attempts to synthesise the complex 5-(MeO)3Si(CH2)3C5H4>(η5-C5H5)TiCl2, either by reaction of 5-(MeO)3Si(CH2)3C5H4>TiCl3 with NaC5H4 or reaction of (η5-C5H5)TiCl3 with NaC5H4(CH2)3Si(OMe)3, gave none of the expected product and only (η5-C5H5)TiCl2 could be isolated from these reactions.The cyclo-octadiene rhodium complex supported on silica has been shown to be an efficient cyclotrimerization catalyst, and the silica-supported titanium complex SIL-(CH2)3C5H4)TiCl2 is, after reduction with butyllithium, an efficient and selective catalyst for the hydrogenation of alk-1-enes.
- Booth, B. L.,Ofunne, G. C.,Stacey, C.,Tait, P. J. T.
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p. 143 - 156
(2007/10/02)
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