No abstract

Premicellar aggregation processes were investigated in a wide range of concentrations and temperatures of cetyltrimethylammonium bromide (CTAB) aqueous solutions. Two independent techniques were involved to study adsorption and aggregation of CTAB molecules at the glass/solution interface. Electronic spin resonance (ESR) was used to estimate microviscosity properties through the reorientation correlation time τ c of (2,2,6,6-tetramethylpiperidin-1-oxyl), while atomic force microscopy (AFM) was involved to evaluate the CTAB molecule morphology at the glass/solution interface. In the dependence of τ c vs the CTAB concentration three discontinuities were revealed within 0.2–0.5, 0.5–1.02, and 1.02–1.1 mM narrow concentration ranges, which are probably connected with the formation of bilayer and hemispherical, hemicylindrical, cylindrical, and spherical admicelles. The images of some of them at the glass surface have been independently obtained by AFM. One-dimensional thin layer (2 nm) of Pt parallel strips on a glass surface have been synthesized by chemical vapor deposition of the Pt on the surface micellar CTAB linear templates followed by washing of the latter.

The aggregation in aqueous solutions of alkylated 1,4 diazabicyclo[2.2.2]octanes of various hydrophobicity and their adsorption at the water-air interface were studied by tensiometry, conductometry, potentiometry, viscosimetry, and ESR spectroscopy. The parameters of ad sorption, critical micelle concentrations, concentrations of free counterions (bromide ions), and degree of binding of the counterions with micelles were determined. The intensification of the micelle formation ability of the surfactants with an elongation of the alkyl fragment was shown. The effective radii of ensembles of the hexadecyl and octadecyl derivatives were deter mined by the dynamic light scattering method. A relationship between the concentration de pendences of the size of micelles and their shape was established.

NMR and IR spectroscopy and X-ray diffraction were used to show that the reaction of 2,2,2-trichloro-and 2,2,2-tribromo-5-methylbenzo[d] [1,3,2]dioxaphospholes with para-substituted arylacetylenes proceeds with regioselective formation of 4-aryl-2-halo-7-methyl-2-oxobenzo[e][1,2]oxaphosphorines. With the trichlorophosphole, selective chlorination of the phenylene fragment in the para position to the endocyclic oxygen atom occurs. With the tribromophosphole, 6-bromo-and unsubstituted benzo[e][1,2]oxaphosphorines are formed as major products. The molecular and supramolecular structure of some of the obtained oxaphosphorines was studied by X-ray diffraction.We recently showed [2] that the reaction of 2,2,2-trichlorobenzo[d][1,3,2]dioxaphosphole (I) with arylacetylenes unexpectedly provides 4-aryl-2,6-dichlorobenzo[e][1,2l 5 ]oxaphosphorine 2-oxides. This mechanistically rather complex reaction involves facile formation of the phosphoryl group and carbon3phos-phorus bond, ipso substitution of the oxygen atom, and regioselective chlorination of the phenylene substituent in the para position to the oxygen atom of the foming benzo[e][1,2]oxaphosphorine ring. Introduction of one, two, or four halogen atoms in the ophenylene fragment of starting phosphole I does not alter the reaction pathway [335], but the regioselective chlorination of the benzo fragment to form 4-aryl-2,6,7-trihalobenzo[e][1,2]oxaphosphorines takes place only if it bears only one halogen substituent.In this work we present the results of investigation of the effect of the electron-donor methyl substituent in the phenylene fragment of 2,2,2-trichloro-and 2,2,2-tribromo-5-methylbenzo[d][1,3,2]dioxophospholes (II, III) on the synthetic result of their reaction with arylacetylenes. It was found that the reaction of compound II with arylacetylenes proceeds with a high degree of regioselectivity and leads mainly (or exclu-ÄÄÄÄÄÄÄÄÄÄÄÄ 1 For communication V, see [1].