@article {2615, title = {Orientational order of near D-3h solutes in nematic liquid crystals. II. Description via Gay-Berne model with embedded quadrupoles}, journal = {Journal of Chemical Physics}, volume = {130}, number = {15}, year = {2009}, note = {ISI Document Delivery No.: 437KLTimes Cited: 3Cited Reference Count: 19Sokolovskii, R. O. Burnell, E. Elliott}, month = {Apr}, pages = {6}, type = {Article}, abstract = {We perform Monte Carlo simulations of a mixture of soft ellipsoids with embedded quadrupoles as a model of various chloro- and methyl-substituted benzenes dissolved in nematic liquid crystals. We find that oblate Gay-Berne ellipsoids with multiple embedded quadrupoles qualitatively reproduce the trend in the order parameter asymmetry experimentally observed in NMR spectra. The trend is opposite to what is expected on the basis of the interaction of the solute{\textquoteright}s quadrupole with the solvent{\textquoteright}s average electric field gradient "felt" by dissolved dihydrogen molecules. We identify the specific minimum of the solute-solvent interaction energy landscape that may produce the unexpected sign of the order parameter asymmetry that is seen in the experiment and the simulation.}, keywords = {COMPOUNDS, deuterium, dissolving, ELECTRIC-DIPOLE INTERACTIONS, LIQUID MIXTURES, liquid theory, METHODS, Monte Carlo, MONTE-CARLO SIMULATIONS, nematic liquid crystals, nuclear magnetic resonance, ORGANIC, POTENTIALS, SHAPE, SOLVENTS}, isbn = {0021-9606}, url = {://000265486300033}, author = {Sokolovskii, R. O. and Burnell, E. E.} } @article {2048, title = {Reactive uptake of N2O5 on aqueous H2SO4 solutions coated with 1-component and 2-component monolayers}, journal = {Journal of Physical Chemistry A}, volume = {112}, number = {20}, year = {2008}, note = {ISI Document Delivery No.: 301OHTimes Cited: 16Cited Reference Count: 90Cosman, L. M. Bertram, A. K.}, month = {May}, pages = {4625-4635}, type = {Article}, abstract = {Reactive uptake of N2O5 on aqueous sulfuric acid solutions was studied in the presence of 1-component (octadecanol) and 2-component (octadecanol + phytanic acid) monolayers. In the 1-component monolayer experiments, the reactive uptake coefficient depended strongly on the molecular surface area of the surfactant. Also, the 1-component monolayer showed significant resistance to mass transfer even when the fractional surface coverage of the surfactant was less than 1. For example, a monolayer of I-octadecanol with a fractional surface coverage of 0.75 decreased the reactive uptake coefficient by a factor of 10. This is consistent with previous studies. In the 2-component monolayer experiments, the reactive uptake coefficient depended strongly on the composition of the monolayer. When the monolayer contained only straight-chain molecules (1-octadecanol), the reactive uptake coefficient decreased by a factor of 42 due to the presence of the monolayer. However, when the monolayer contained 0.20 mole fraction of a branched surfactant (phytanic acid) the reactive uptake coefficient only decreased by a factor of 2. Hence, a small amount of branched surfactant drastically changes the overall resistance to reactive uptake. Also, our results show that the overall resistance to reactive uptake of 2-component monolayers can be predicted reasonably accurately by a model that assumes the resistances to mass transfer can be combined in parallel.}, keywords = {AIR-WATER-INTERFACE, ATMOSPHERIC AEROSOL, EVAPORATION RESISTANCES, FILMS, HETEROGENEOUS HYDROLYSIS, MIXED MONOLAYERS, ORGANIC, REACTION PROBABILITIES, SEA-SALT, SULFURIC-ACID PARTICLES, TRANSPORT PROPERTIES}, isbn = {1089-5639}, url = {://000255905000015}, author = {Cosman, L. M. and Bertram, A. K.} } @article {4921, title = {Characterization of dissolved tannins and their metal-ion complexes by electrospray ionization mass spectrometry}, journal = {Analytica Chimica Acta}, volume = {411}, number = {1-2}, year = {2000}, note = {ISI Document Delivery No.: 305EYTimes Cited: 25Cited Reference Count: 51}, month = {May}, pages = {91-102}, type = {Article}, abstract = {Electrospray mass spectrometry was used to characterize metal-complexing ligands derived from tannic acid, a component of natural dissolved organic matter. Complexes formed by tannin ligands with copper and other biogeochemically important metals were identified from the mass-to-charge ratios of the corresponding deprotonated molecular ions, allowing stoichiometry and metal oxidation state to be determined. Ligand ion intensities were proportional to tannic acid concentration, with detection limits on the order of 5 nM for individual compounds in 50:50 water/acetonitrile. The relative abundance of free ligand and complex ions indicated the degree of complexation under different solution conditions (metal concentration, pH, ionic strength). Using tandem mass spectrometry, the structure and principal copper binding site for one of the tannins were also determined, providing unique information with regard to metal complexation by these polyfunctional ligands. The technique can be combined with high performance liquid chromatography for on-line separation of dissolved organic compounds. Results demonstrate the potential of this approach for characterizing the different classes of metal-complexing ligands found in natural waters. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {AFFINITY-CHROMATOGRAPHY, CHROMATOGRAPHY, COMPLEXATION, copper, electrospray ionization, high performance liquid, iron, LIGANDS, MASS SPECTROMETRY, metal-ion complexes, NATURAL ORGANIC-LIGANDS, ORGANIC, PERFORMANCE, PROTEINS, REGIOSELECTIVE MONO-OXIDATION, SPECIATION, STOICHIOMETRY, tannins, TOXICITY, trace metals}, isbn = {0003-2670}, url = {://000086527500011}, author = {Ross, A. R. S. and Ikonomou, M. G. and Orians, K. J.} } @article {3264, title = {THE ONE-STEP SYNTHESIS OF CHIRAL AMINO PHOSPHINO FERROCENES}, journal = {Journal of Organometallic Chemistry}, volume = {492}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QV350Times Cited: 10Cited Reference Count: 24}, month = {May}, pages = {157-164}, type = {Article}, abstract = {Reaction of the chiral lithium reagent-2-lithio-(alpha-N,N-dimethyl)aminoethylbenzene with 1,1{\textquoteright}-ferrocenediylphenylphosphine gives chiral aminophosphinoferrocenes that contain both chiral carbon and phosphorus centres. Treatment of the ferroceno-phane with 2-lithio-N,N-dimethylaminomethylferrocene followed by hydrolysis gives the product ferrocenyl 2-(dimethylaminomethylferrocenyl) phenylphosphine as a pair of diastereomers. The single crystal structures of compound 3a PdCl2 and compound 4. PdCl2.2CH(2)Cl(2) have been determined. The compounds, 2-(ferrocenylphenylphosphino)-1-(alpha-N, N{\textquoteright}-dimethylaminoethylbenzene)ferrocene, 5 and 1-[2-(alpha-N,N{\textquoteright}-dimethyraminoethylbenzene)phenylphospphino]-1{\textquoteright}-diphenyl phosphinoferrocene, 6a, have also been prepared by minor modifications of the methodology developed.}, keywords = {<1>FERROCENOPHANES, ASYMMETRIC-SYNTHESIS, CATALYST, chirality, crystal structure, FERROCENE, GRIGNARD, HALIDES, HYDROGENATION, iron, METAL-COMPLEXES, ORGANIC, palladium, PHOSPHORUS, PLANAR CHIRALITY, REAGENTS, SECONDARY}, isbn = {0022-328X}, url = {://A1995QV35000005}, author = {Butler, I. R. and Cullen, W. R. and Rettig, S. J. and White, A. S. C.} } @article {7151, title = {EVIDENCE FOR NUCLEOPHILIC-ADDITION BY MUONIUM TO PYRAZINE IN WATER - CONTRAST WITH ORDINARY HYDROGEN}, journal = {Journal of the American Chemical Society}, volume = {113}, number = {24}, year = {1991}, note = {ISI Document Delivery No.: GQ931Times Cited: 15Cited Reference Count: 24}, month = {Nov}, pages = {9096-9099}, type = {Article}, abstract = {The presence of heterocyclic N atoms in an aromatic solute enhance its rate of reaction toward muonium, and the free radicals formed are seen to have muonium attached to a C atom of the ring. This contrasts the behavior of H-1 in water, where addition to N-heterocyclic rings occurs an order of magnitude slower and with H attaching to N, at least in acid solution. Muonium evidently shows nucleophilic character while ordinary hydrogen atoms are electrophilic. Pyrazine (1,4-diazine) was used for this comparison with benzene because it has the advantage over pyridine of forming only two possible radicals.}, keywords = {1-HYDROPYRIDINYL RADICALS, ATOMS, ELECTRON-SPIN RESONANCE, FREE-RADICALS, LEVEL-CROSSING-RESONANCE, LIQUIDS, ORGANIC, ROTATION, SPECTROSCOPY}, isbn = {0002-7863}, url = {://A1991GQ93100010}, author = {Wu, Z. and Barnabas, M. V. and Stadlbauer, J. M. and Venkateswaran, K. and Porter, G. B. and Walker, D. C.} }