14296-16-3Relevant articles and documents
Decreasing the alkyl branch frequency in precision polyethylene: Effect of alkyl branch size on nanoscale morphology
Inci, Bora,Lieberwirth, Ingo,Steffen, Werner,Mezger, Markus,Graf, Robert,Landfester, Katharina,Wagener, Kenneth B.
, p. 3367 - 3376 (2012)
Synthesis and morphological characterization are reported for a series of 13 precision branched polyethylene structures, the branch being placed on every 39th carbon and varying in size from methyl to pentadecyl group. A recently established synthetic scheme for preparation of the symmetrical α,ω-diene monomer was employed to increase the number of methylene carbons between the branch points from 20 to 38, yielding polymers with 5.26 mol % α-olefin incorporation. The morphology of these polymers was investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). Methyl branching significantly reduces the melting point and single crystal lamellae thickness of unbranched polyethylene. On the other hand, all further branches from ethyl to pentadecyl produce polymers that have similar melting points and single crystal lamellae thicknesses. A clear change in the morphology of both solution and melt-grown crystals of these polymers was observed from a situation where the methyl branch is incorporated in the polymer's unit cell to one where branches of greater mass are mostly expelled from the unit cell.
The Micellar Properties of Ionic Surfactants Consisting of the α,ω-Type Surfactant Ion and the Same Type Counter Ion
Satake, Iwao,Morita, Tadakazu,Maeda, Tamaki,Hayakawa, Katumitu
, p. 761 - 765 (1997)
The micellar properties of N, N, N, N', N', N'-hexamethyl-1, 20-icosanediyldiammonium, or the corresponding di(1-pyridinium)alkanedioates -OOC(CH2)nCOO- (n = 2 - 10), were studied by conductivity and pyrene fluorescence measurements. In both systems, the critical micelle concentration (cmc) varied little up to n = 4, but decreased rapidly with a further increase in n. The binding degree (β) of the alkanedioate counter ion was virtually independent of the type of surfactant ion head group and gradually increased from 0.69 at n = 2 to 0.91 at n= 10. The observed n dependences of cmc and β were similar to those of the conventional ionic surfactants with an α,ω-type counter ion, indicating the importance of the hydrophobic interaction between the hydrocarbon part of the counter ion and the micellar core. On the basis of a phase-separation model, the transfer free energy per methylene group of the counter ion from aqueous-to-micellar environments was estimated to be about - 1.0 RT. The fluorescence measurements suggest that the surface layer of the micelle becomes progressively loose as n decreases. The micelle aggregation numbers of the bis (trimethylammonium) salts are of the order of 50.
Preparation and characterization of crosslinked poly(vinylimidazolium) anion exchange membranes for artificial photosynthesis
Carter, Blaine M.,Keller, Laura,Wessling, Matthias,Miller, Daniel J.
, p. 23818 - 23829 (2019)
The interrelated nature of material properties in ion exchange membranes, such as ion exchange capacity and water uptake, frustrates the systematic study of how membrane chemistry and structure affect the transport of water, ions, and uncharged solutes in the membrane. Herein, we describe the preparation of a series of crosslinked poly(vinylimidazolium) anion exchange membranes by UV-photopolymerization of difunctional (i.e., crosslinking) and monofunctional (i.e., non-crosslinking) monomers, in which the ion exchange capacity and crosslink density may be independently controlled. Ion exchange membranes used in artificial photosynthesis (solar-driven CO2 reduction) devices must permit the transport of electrolyte ions and minimize the crossover of CO2 reduction products (e.g., alcohols) between electrodes. The water content, methanol (CO2 reduction product) permeability, and ionic conductivity of the membranes were evaluated. Ionic conductivity and methanol permeability were increased by reducing crosslink density or increasing solvent content in the prepolymerization solvent mixture. For all prepared membranes, methanol permeability was directly correlated with water volume fraction in the membrane. Minimizing the water volume fraction is critical to the design of membranes with low permeability to CO2 reduction products.
On-Nanoparticle Gating Units Render an Ordinary Catalyst Substrate- And Site-Selective
Kim, Minju,Dygas, Miroslaw,Sobolev, Yaroslav I.,Beker, Wiktor,Zhuang, Qiang,Klucznik, Tomasz,Ahumada, Guillermo,Ahumada, Juan Carlos,Grzybowski, Bartosz A.
, p. 1807 - 1815 (2021)
When an organometallic catalyst is tethered onto a nanoparticle and is embedded in a monolayer of longer ligands terminated in "gating"end-groups, these groups can control the access and orientation of the incoming substrates. In this way, a nonspecific catalyst can become enzyme-like: it can select only certain substrates from substrate mixtures and, quite remarkably, can also preorganize these substrates such that only some of their otherwise equivalent sites react. For a simple, copper-based click reaction catalyst and for gating ligands terminated in charged groups, both substrate- and site-selectivities are on the order of 100, which is all the more notable given the relative simplicity of the on-particle monolayers compared to the intricacy of enzymes' active sites. The strategy of self-assembling macromolecular, on-nanoparticle environments to enhance selectivities of "ordinary"catalysts presented here is extendable to other types of catalysts and gating based on electrostatics, hydrophobicity, and chirality, or the combinations of these effects. Rational design of such systems should be guided by theoretical models we also describe.
Synthesis of 13C-labelled ω-hydroxy carboxylic acids of the general formula HO213C-(CH2)n-CH2OH or HO2C-(CH2)n-13CH2OH (n = 12, 16, 20, 28)
Schink, Carina,Spielvogel, Sandra,Imhof, Wolfgang
, p. 385 - 402 (2021/07/10)
13C-labelled ω-hydroxy-carboxylic acids HO213C-(CH2)n-CH2OH or HO2C-(CH2)n-13CH2OH (n = 12, 16, 20, 28) with 13C labels selectively introduced either at the carboxy group or at the primary alcohol function at the end of the hydrocarbon chain have been synthesized. Different synthetic strategies had to be applied depending on the position of the label, the chain length of the respective synthetic target and due to economic considerations. 13C labels in general were introduced by nucleophilic substitution of a suitable leaving group with labelled potassium cyanide and subsequent hydrolysis of the nitriles to produce the corresponding labelled carboxy functions, which may also be reduced to give the labelled primary alcohol group. All new compounds are characterized by GC/MS, IR and NMR methods as well as by elemental analysis.
Cysteine-Targeted Insecticides against A. gambiae Acetylcholinesterase Are Neither Selective nor Reversible Inhibitors
Gorecki, Lukas,Andrys, Rudolf,Schmidt, Monika,Kucera, Tomas,Psotka, Miroslav,Svobodova, Barbora,Hrabcova, Veronika,Hepnarova, Vendula,Bzonek, Petr,Jun, Daniel,Kuca, Kamil,Korabecny, Jan,Musilek, Kamil
supporting information, p. 65 - 71 (2019/12/25)
Acetylcholinesterase cysteine-targeted insecticides against malaria vector Anopheles gambia and other mosquitos have already been introduced. We have applied the olefin metathesis for the preparation of cysteine-targeted insecticides in high yields. The prepared compounds with either a succinimide or maleimide moiety were evaluated on Anopheles gambiae and human acetylcholinesterase with relatively high irreversible inhibition of both enzymes but poor selectivity. The concept of cysteine binding was not proved by several methods, and poor stability was observed of the chosen most potent/selective compounds in a water/buffer environment. Thus, our findings do not support the proposed concept of cysteine-targeted selective insecticides for the prepared series of succinimide or maleimide compounds.
Cycloalkane-based thermomorphic systems for organic electrochemistry: An application to Kolbe-coupling
Okada, Yohei,Kamimura, Kazuya,Chiba, Kazuhiro
supporting information; experimental part, p. 5857 - 5862 (2012/09/08)
The discovery that cycloalkanes can form thermomorphic systems with typical polar organic solvents has led to the development of less-polar electrolyte solutions. Their mixing and separation can be regulated reversibly at a moderate temperature range. The phase switching temperature can be controlled by changing the solvent compositions. While biphasic conditions are maintained below the phase switching temperature, conductive monophasic conditions as less-polar electrolyte solutions are obtained above the phase switching temperature. After the electrochemical transformations, biphasic conditions are reconstructed below the phase switching temperature, facilitating the separation of cycloalkane where hydrophobic products or designed hydrophobic platforms are selectively partitioned. Several polar organic solvents, including acetonitrile, methanol, and pyridine, can be used in this system according to the requirement of the reactions.
Decreasing the alkyl branch frequency in precision polyethylene: Pushing the limits toward longer run lengths
Inci, Bora,Wagener, Kenneth B.
, p. 11872 - 11875 (2011/10/04)
A symmetrical α,ω-diene monomer with a 36 methylene run length was synthesized and polymerized, and the unsaturated polymer was hydrogenated to generate precision polyethylene possessing a butyl branch on every 75th carbon (74 methylenes between branch points). The precision polymer sharply melts at 104 °C and exhibits the typical orthorhombic unit cell structure with two characteristic wide-angle X-ray diffraction (WAXD) crystalline peaks observed at 21.5° and 24.0°, corresponding to reflection planes (110) and (200), respectively.
Synthesis of alkylene-bridged diphenyl-oligoynes
Klinger, Christian,Vostrowsky, Otto,Hirsch, Andreas
, p. 1508 - 1524 (2007/10/03)
A general synthesis route for the preparation of oligoynes stabilized by alkylene bridges is reported. The corresponding macrocycles contain oligoynes with up to eight conjugated triple bonds. The stabilization of the conjugated sp-oligoyne rods was achieved by bulky terminal phenylic endcaps spanning the alkylene chain to isolate the individual acetylenic rods and to avoid polymerization. Alkylene chains with up to 40 methylene groups were employed. The two terminal acetylene functions were introduced prior to the oligoyne elongation by twofold introduction of additional C2-acetylene or C4-butadiyne building blocks. The final step was the intramolecular acetylene coupling upon which very large macrocycles with up to 62 ring members containing segregated sp-, sp2- and sp3-segments were formed. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Dynamic assessment of bilayer thickness by varying phospholipid and hydraphile synthetic channel chain lengths
Weber, Michelle E.,Schlesinger, Paul H.,Gokel, George W.
, p. 636 - 642 (2007/10/03)
A library of "hydraphile" synthetic ion channel analogues that differ in overall length from ～28-58 A has been prepared. A new and convenient ion-selective electrode (ISE) method was used to assay Na+ release. Liposomes were formed from three d
