Construction of a new multi-turn time-of-flight mass spectrometer

A new type of multi-turn time-of-flight mass spectrometer was constructed, consisting of four cylindrical electric sectors and 28 electric quadrupole lenses, the size of the vacuum chamber being 60 x 70 x 20 cm. It was demonstrated that the mass resolution can be increased according to the number of cycles of the ions through the ion optical system.     

Evaluation of different tubing geometries for high-speed counter-current chromatography

Different tubing geometries were evaluated for use in high-speed counter-current chromatography. Standard round tubing was compared to rectangular and twisted rectangular tubing. The number of theoretical plates for a standard anthocyanin mixture from black currant was determined for each experiment. The results of twisted rectangular tubing were superior to a standard setup.     

Mixed-Valent Heptairon Complex with a Ground-State Spin Value of S=12/2 Constructed from a Triiron Cluster Ligand

The anionic triiron(III) cluster ligand [Fe(III)(3)(μ(3)-O)(bpca)(2)Cl(4)(EtO)(2)](-) (1; Hbpca=bis(2-pyridylcarbonyl)amine) was prepared as a building block for constructing larger metal assemblies. This "metal cluster complex ligand" was used in the synthesis of the mixed-valent heptairon complex [Fe(II)(1)(2)(EtOH)(2)], which has a ground-state spin value of S=12/2.     

Understanding the Hofmeister effect in interactions between chaotropic anions and lipid bilayers: molecular dynamics simulations

A set of all-atom molecular dynamics simulations have been performed to better understand critical phenomena regarding a Hofmeister series of anions and lipid bilayers. The simulations isolate the effect of anion size and show clear differences in the interactions with the dipolar phoshpatidylcholine headgroup. Cl- anions penetrate into the headgroup region of the bilayer, but the simulations confirm theories which predict that larger anions penetrate more deeply, into a more heterogeneous and hydrophobic molecular region. That anion size leads to such differences in partitioning in the bilayer provides atomic-level support to hypotheses inspired by several experimental studies. The ability of larger anions to bury deep within the bilayer is correlated with a less well-structured hydration shell, shedding of which upon penetration incurs a smaller penalty for the larger anions than for Cl-.     

Tris(1‐ethyl‐3‐methyl­imidazolium) hexa­chloro­lanthanate

In the title complex, (C₆H₁₁N₂)₃[LaCl₆], centrosymmetric octahedral hexa­chloro­lanthanate anions are located at the corners and face‐centers of the monoclinic unit cell. The ring H atoms of the cations interact with the Cl atoms of the anions via hydrogen bonding, and bifurcation of the hydrogen bonding is observed. Cation–cation interactions via hydrogen bonding between the ring H atoms and π‐electrons of aromatic rings are also observed as in other imidazolium salts.     

Diffusion in organic solvents: Interdiffusion coefficient of 1,1,2,2-tetrabromoethane

Interdiffusion coefficient have been measured for 1,1,2,2-tetrabromoethane in 21 organic solvents in order to ascertain the influence of shape, size, viscosity, nature and degree of branching, of the solvent molecules on transport properties. None of the existing correlations for diffusion in binary liquid systems appear to fit all the experimental data. Steric effects due to the solvent molecules are shown to be very important in the interpretation of the diffusion process.     

OXYGEN QUENCHING IN MICELLAR SOLUTION AND ITS EFFECT ON THE PHOTOCYCLIZATION OF N-METHYLDIPHENYLAMINE

Abstract— Oxygen effects on the photocyclization of N-methyldiphenylamine to N-methylcarbazole were investigated in n-hexane, water, and aqueous surfactant solutions by steady state irradiations and flash photolysis measurements. The reaction sequence in micelles was found to involve the same intermediate steps as in homogeneous solutions. In aerated micellar solutions, the quantum yield of N-methylcarbazole is significantly higher than in n-hexane, while the rate constants of the unimolecular reaction steps show no solvent dependence. The bimolecular dehydrogenation of the intermediate 4a, 4b-dihydro-N-methylcarbazole by oxygen is enhanced in aqueous and micellar solutions, whereas the quenching rate of triplet intermediates by oxygen was not affected. The lesuhs are interpreted using a dispersed phase model of micellar solutions. Special 'micellar effects' need not be invoked since the dependence of the quantum yield on the solvent is shown to be due to the difference in the overall oxygen concentration.