Search results for "Ethylene"
showing 10 items of 2589 documents
CCDC 705803: Experimental Crystal Structure Determination
2010
Related Article: G.Dupouy, S.Triki, M.Marchivie, N.Cosquer, C.J.Gomez-Garcia, S.Pillet, E.-E.Bendeif, C.Lecomte, S.Asthana, J.-F.Letard|2010|Inorg.Chem.|49|9358|doi:10.1021/ic101038z
CCDC 705804: Experimental Crystal Structure Determination
2010
Related Article: G.Dupouy, S.Triki, M.Marchivie, N.Cosquer, C.J.Gomez-Garcia, S.Pillet, E.-E.Bendeif, C.Lecomte, S.Asthana, J.-F.Letard|2010|Inorg.Chem.|49|9358|doi:10.1021/ic101038z
CCDC 1547125: Experimental Crystal Structure Determination
2017
Related Article: Alokesh Hazari, Carlos J. Gómez-García, Michael G.B. Drew, Ashutosh Ghosh|2017|Polyhedron|138|145|doi:10.1016/j.poly.2017.09.012
CCDC 1440482: Experimental Crystal Structure Determination
2016
Related Article: Néstor Calvo Galve, Mónica Giménez-Marqués, Miguel Palomino, Susana Valencia, Fernando Rey, Guillermo Mínguez Espallargas, Eugenio Coronado|2016|Inorg.Chem.Front.|3|808|doi:10.1039/C5QI00277J
Effect of hydrogen on the ethylene polymerization process over Ziegler–Natta catalysts supported on MgCl2(THF)2. I. Studies of the chain‐transfer rea…
2001
The effect of hydrogen on the molecular weight of polyethylene obtained over vanadium catalysts (based on VCl4 and VOCl3) supported on MgCl2(THF)2 was studied and the results were compared to those obtained for similar titanium catalysts. It was confirmed that the dependencies of the transfer reaction on the hydrogen concentration are a half‐order in all investigated systems. However, the transition metal of the catalytic site affects the ratio of the transfer rate with hydrogen to the propagation rate (ktr,H/kp) and the results showed that hydrogen is a more effective agent of polyethylene molecular weight control in vanadium‐based systems as compared to the titanium catalyst.
Quadruply-bonded dimolybdenum compounds: Reactivity towards TCNE. Structural evidences for the 1-D polymer [Mo2(O2 CCF3)4(TCNE)]∞
2005
cited By 3; International audience; Reaction of [Mo2(O2CR)4] (R = CF 3, 1) with TCNE in toluene affords the new compound [Mo2(O2CCF3)4 (TCNE)·6H5CH3 (2). The structure of 2 is built on [Mo2(O2 CCF3)4] fragments having the usual paddlewheel structure of 1 (Mo-Mo 2.1117(8) Å) and TCNE units. Each polynitrile moiety acts as a bridging ligand between two Mo2 fragments (Mo-N 2.875(4) Å) affording 1-D polymeric chains crossing in the crystal; the toluene molecules occupy the cavities between the chains. 13C NMR, IR and electrochemical data clearly show that formation of 2 does not involve electron density transfer from dimolybdenum fragment to the TCNE unit, which remains in 2 in its neutral stat…
Synthesis of Optically Active Hydroxyalkyl Cycloheptatrienes: A Key Step in the Total Synthesis of 6,11-Methylene-LXB4
2020
AbstractStarting from methyl cycloheptatrienyl-1-carboxylate, 6-acylation was successfully achieved employing glutaryl chloride in the presence of AlCl3 under controlled reaction conditions to furnish keto carboxylic acid product. After protection of this keto carboxylic acid as tert-butyl ester, reagent-controlled enantioselective reductions delivered configuration-defined methyl-6-hydroxylalkyl cycloheptatriene-1-carboxylates with up to 80% ee. Whereas simple NaBH4 reduction of the keto carboxylic acid and subsequent lactonization afforded a methyl-6-tetrahydropyranonyl cycloheptatriene-1-carboxylate. Resolution using chiral HPLC delivered the product enantiomers with up to >99% ee Fin…
Biologically-induced transition of bio-silica sol to mesoscopic gelatinous flocs: a biomimetic approach to a controlled fabrication of bio-silica str…
2012
Siliceous sponges form their skeletal elements, the spicules, enzymatically via the sponge-specific enzyme silicatein. The enzymatic product of silicatein in vitro is a bio-silica polymer that is not processed/hardened by phase separation. In the present study we applied a two-phase system to investigate the transition of bio-silica, formed by silicatein, from the lucid state to the opaque/turbid state. We report for the first time that the polyether polyethylene glycol [PEG] causes a rapid transition of the lucid bio-silica to the opaque/turbid state. For the experiments the recombinant silicatein from the demosponge Suberites domuncula had been used. This process is rapid (1 h) and procee…
Cell adhesion on UV-crosslinked polyurethane gels with adjustable mechanical strength and thermoresponsiveness
2021
Temperature-responsive polyurethane (PU) hydrogels represent a versatile material platform for modern tissue engineering and biomedical applications. However, besides intrinsic advantages such as high mechanical strength and a hydrolysable backbone composition, plain PU materials are generally lacking bio-adhesive properties. To overcome this shortcoming, the authors focus on the synthesis of thermoresponsive PU hydrogels with variable mechanical and cell adhesive properties obtained from linear precursor PUs based on poly(ethylene glycol)s (pEG) with different molar masses, isophorone diisocyanate, and a dimerizable dimethylmaleimide (DMMI)-diol. The cloud point temperatures of the dilute,…
Odd-even chain length-dependent order in pH-switchable self-assembled layers.
2004
The reversible self-assembly of a series of bipolar amphiphiles, alpha,omega-bis(3- or 4-amidinophenoxy)alkanes (chain length n = 5-12), on mercaptoalkanoic acid-functionalized gold surfaces (chain length n = 10, 11, 14, 15) has been studied by in-situ ellipsometry, IR reflection absorption spectroscopy (IRAS), and atomic force microscopy (AFM). The layer order, amphiphile orientation, and tendency to form bilayers depends on the position of the amidine substituent, the alkyl chain length of both the amidine amphiphile and the underlying acid self-assembled monolayer (SAM), and whether the amidine alkyl chain contained an even or odd number of methylene groups. Thus, para-substituted bisben…