Search results for "Mono"
showing 10 items of 6843 documents
Adsorption-induced polymer translocation through a nanopore: a Monte Carlo investigation
2005
Abstract We study the translocation of a coarse-grained flexible polymer through a nanopore in a membrane induced by its adsorption on the trans side of the membrane. Dramatic differences in the threading behavior are observed if the adhesion to the membrane wall, e w , is below or above the adsorption threshold e c r . For e w e c r (weak adsorption) the activation barrier for translocation is at c cis 0 ≈ N / 2 (in terms of the fraction of chain c cis = N cis / N before the pore), independent of chain length N. For e w > e c r this barrier is at a constant (vanishing) number of passed trans monomers for all N. The mean time of chain passage τ trans ∝ c cis 1.3 when c cis c cis 0 . It scal…
Electrochemical study on (NN)Fe3 (CO)9 ((NN) = 2,3-diazanorbornene) and related compounds. A new example of activation of carbon monoxide replaceme…
1985
Abstract The compound (NN)Fe 3 (CO) 9 ( 1 ) in tetrahydrofuran undergoes two reversible one-electron reduction processes in cyclic voltammetry at the platinum electrode. A rapid electron transfer-catalyzed reaction occurs when 1 is reduced in the presence of L (L = P(OMe) 3 ) and this gives (NN)Fe 3 (CO) 8 L ( 2 ), quantitatively. Only an electron-induced nucleophilic substitution is observed for compound 2 under the same conditions, yielding (NN)Fe 3 (CO) 7 L 2 , which undergoes a similar reaction but with much lower efficiency, to give (NN)Fe 3 (CO) 6 L 3 .
Conformational polymorphism and amphiphilic properties of resorcinarene octapodands
2010
o-Nitroaniline functionalized resorcinarene octapodands 1-5 with pendant methyl, ethyl, pentyl, nonyl or 1-decenyl groups, respectively, were synthesized and their structural properties investigated using X-ray crystallography and NMR spectroscopy. The upper rim of each podand is identical containing flexible side arms, in which rotation around the -OCH(2)CH(2)N- linkers create excellent possibilities for polymorphism. Two conformational polymorphs of acetone solvate of 2 were identified containing different side arm orientation and crystal packing. Compound 1 crystallized from acetone and nitromethane yielding two pseudopolymorphs with different packing motifs. The longer alkyl chains of 3…
Buildup of ultrathin multilayer films by a self-assembly process: III. Consecutively alternating adsorption of anionic and cationic polyelectrolytes …
1992
A solid substrate with a positively charged planar surface is immersed in a solution containing an anionic polyelectrolyte and a monolayer of the polyanion is adsorbed. Since the adsorption is carried out at relatively high concentrations of polyelectrolyte, a large number of ionic residues remain exposed to the interface with the solution and thus the surface charge is effectively reversed. After rinsing in pure water the substrate is immersed in the solution containing a cationic polyelectrolyte. Again a monolayer is adsorbed but now the original surface charge is restored. By repeating both steps in a cyclic fashion, alternating multilayer assemblies of both polymers are obtained. The bu…
Physico-chemical investigation of nanostructures in liquid phases: Nickel chloride ionic clusters confined in sodium bis(2-ethylhexyl) sulfosuccinate…
2009
The confinement of finite amounts of nickel chloride in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in n-heptane has been investigated by FT-IR, UV-vis-NIR and fluorescence spectroscopies. The analysis of experimental data consistently leads to hypothesize that NiCl(2) forms small size ionic clusters stabilized by a monolayer of oriented surfactant molecules. Due to confinement and interfacial effects, these ionic clusters show peculiar photophysical properties, which are different from those possessed by the bulk material. From NiCl(2)/AOT/n-heptane solutions, by evaporation of the organic solvent, interesting salt/surfactant nanocomposi…
Stereochemistry of terpene derivatives. Part 7: Novel rigidified amino acids from (+)-3-carene designed as chiral GABA analogues
2010
Abstract Several novel cyclopropyl-rigidified γ- and δ-amino acids 3 – 4 have been prepared starting from monoterpene (+)-3-carene 2 . These compounds are proposed as chiral analogues of γ-aminobutyric acid (GABA) 1 and are expected to be of interest as potential inhibitors of GABA receptors.
Bis(triorganometal) and diorganometal 1,3-dithiolates (R3M)2(C6H3XS2) and R2M(C6H3XS2) (M = Sn, Pb; X= H, Cl)
1984
Abstract Bis(triorganometal) and diorganometal 1,3-dithiolates (R3M)2(C6H3XS2) (C6H5XS2 1,3-dithiobenzene (for X = H) or 1,3-dithio-4-chlorobenzene (for X = Cl); M = Sn, X = Cl, R = CH3, C6H5; M = Pb, X = H, Cl, R = CH3, C2H5) and R2M(C6H3XS2) (R = CH3, C2H5, C6H5; M = Sn, X = Cl; M = Pb, X = H, Cl) have been prepared as the first organometal IVB derivatives of 1,3-dithiols, and investigated by vibrational, 1H NMR, and (in the case of organotin compounds) Mossbauer spectroscopy. The triorganometal derivatives are monomeric and the diorganometal derivatives dimeric in solution (37° C). For the latter a twelve-membered ring structure is proposed for both solution and the solid state.
Metallic Charge‐Transfer Salts of Bis(ethylenedithio)tetrathiafulvalene with Paramagnetic Tetrachloro(oxalato)rhenate(IV) and Tris(chloranilato)ferra…
2014
The synthesis, crystal structure and physical characterization of three radical salts of the donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) and tetrachloro(oxalato)rhenate(IV) {[ReCl4(C2O4)]2–} or tris(chloranilato)ferrate(III) {[Fe(C6O4Cl2)3]3–} anions are reported. The isolated salts with ReIV are (ET)[ReCl4(C2O4)] [1, monoclinic, space group C2/c with a = 18.3409(3) A, b = 10.8414(2) A, c = 11.1285(3) A, β = 99.9714(7)°, V = 2179.38(8) A3, Z = 4] and (ET)4[ReCl4(C2O4)]·C6H5CN [2, monoclinic, space group P21/c with a = 11.8549(2) A, b = 32.9079(5) A, c = 36.4154(5) A, β = 96.742(2)°, V = 14108.1(4) A3, Z = 8]. The salt with FeIII is (ET)6[Fe(C6O4Cl2)3]·(H2O)1.5·(CH2Cl2)0.5 […
Stabilization of polynuclear plutonium(IV) species by humic acid
2014
Abstract Although the formation of tetravalent plutonium (Pu(IV)) polymers with natural organic matter was previously observed by spectroscopy, there is no quantitative evidence of such reaction in batch experiments. In the present study, Pu(IV) interaction with humic acid (HA) was investigated at pH 1.8, 2.5 and 3, as a function of HA concentration and for Pu total concentration equal to 6 × 10−8 M. The finally measured Pu(IV) concentrations ([Pu(IV)]eq) are below Pu(IV) solubility limit. Pu(IV)–HA interaction can be explained by the complexation of Pu(IV) monomers by HA up to [Pu(IV)]eq ∼ 10−8 M. However, the slope of the log–log Pu(IV)–HA binding isotherm changes from ∼0.7 to ∼3.5 for hi…
Sensory and Chemical Analysis of Fractions Obtained by Gel Permeation of Water-Soluble Comte Cheese Extracts
1995
The pure water extraction of Comte cheese solubles and their chromatographic separation facilitate sensory analysis experiments with the fractions directly collected from the column. Two extracts, one obtained after ultrafiltration, the other after chromatography on Sephadex G25, have been separated on Toyopearl HW-40S. The sensory evaluation of the obtained fractions shows in the two cases that some fractions have interesting flavors. However, physicochemical analysis shows that organoleptic characteristics are linked more to the presence of amino acids and salts than to the presence of peptides. Apart from monosodium glutamate, most of the amino acids are present in the fractions at conce…