Indirect laser photoacoustic detection for trace samples on membranes

An indirect laser photoacoustic technique is described. The basic principle, the experimental set-up and the influencing factors are discussed in detail. This method was used to quantify phenylamine, arginine and methylene blue on membranes. The linear ranges of the calibration curve are up to two orders of magnitude. With 1 microliter of sample solution, the detection limits are 0.25, 1.52 and 0.14 pmol for phenylamine, arginine and methylene blue, respectively.     

A facile entry to l-aryl-4,5-dihydro[1,4]oxazepino-[5,4-a]isoindole-2,7-diones

The titled compounds were prepared by reacting N-(2-bromoethyl)phthalimide with enolates of phenylacetic acid esters. 2,3-Dihydrooxazolo[2,3-a]isoindolones are believed to be intermediates in the process. An X-ray crystallographic analysis was conducted on one of the compounds.     

Asymmetry and magnetism in bis(oximato)-bridged heterobimetallic compounds: a computational approach

A density functional study of exchange coupling was carried out for a series of heterobinuclear oximato-bridged transition metal complexes. Model calculations were used to examine the influence of the electronic configuration of the metal atoms on the coupling constants. This analysis was complemented by a study of the variation of the coupling constant with the most usual structural distortions within this family of compounds. The influence of the nature of the terminal ligands as well as that of the symmetry on the bridge were also investigated.     

Reversible temperature-induced transformations of poly(N-ethyl-4-vinylpyridinium) complexes with dodecyl sulfate in aqueous salt solutions

Supramolecular organization of complexes formed by poly(N-ethyl-4-vinylpyridinium bromide) and sodium dodecylsulfate in aqueous salt solutions was studied as a function of temperature and concentration of the complexes. It was shown that a decrease in temperature and/or concentration of complexes led to their reversible disaggregation into a molecularly dispersed (“unipolymer”) state. The ratio between the components in complex particles remained unchanged in this case. It was first found that phase separation in aqueous solutions of the complexes upon temperature elevation is accompanied by the precipitation of a nonstoichiometric complex.