Preparation and Characteristics of a Cation Exchanger Based on Oxidized Anthracite

The features of anthracite oxidation as influenced by temperature and time were determined. Physicochemical and sorption characteristics of the resulting cation exchanger were studied.     

Condensed heterocycles with a thiazole ring. 14 Nature of the electronic spectra of symmetrical polymethine dyes of the thiazolo[3,4-b][1,2,4]triazine series

Symmetrical mono-, tri-, and pentamethinecyanine dyes with a thiazolo[3,4-b][1,2,4]triazine ring were synthesized. The electron-density distributions in the dye molecules in the ground and first and second excited states were obtained by quantum-chemical calculations. It was established that the first two electron transitions are localized on the same atoms and that charge transfer to the triazine fragment of the molecule is realized in the case of excitation. The degree of participation of the heterocyclic ring in the first electron transition, which is responsible for the color of the dye, decreases with lengthening of the polymethine chain.See [1] for communication 13.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 24, No. 3, pp. 418–423, March, 1988.     

Solid‐State Active Elements Based on Dyes and Prepared by a Sol‐Gel Method

A new method is suggested for producing the solgel matrices with the molecules of laser dyes introduced into them. The curves of tuning lasing in Rhodamine 6G, Rhodamine 4S, Rhodamine 101, and phenylamine 430 in these matrices are obtained. The total range of tuning is 550–650 nm at a pumping energy of 4 mJ. The halfwidth of the generation spectrum is independent of the pumping energy to 4 mJ and comprises 0.3 ± 0.1 nm. The main factors forming the generation spectrum are noted.     

The role of chelate substituent steric effects in reactions between hydroperoxyl radicals and copper bis(salicylalalkyliminates)

Rate constants for the reactions between HOO radicals and [2-(R-N= CH)C₆H₄O]₂Cu decreased according to the nature of the R substituent in the order (70°C): CH₃ > n-C₄H₉ > iso-C₃H₇ > cyclo-C₆H₁₁ > tert-C₄H₉; this followed the same sequence as the Charton steric constants of the R substituents.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 1, pp. 70–73, January–February, 1993.The authors would like to express their gratitude to the Ukrainian Basic Reaearch Fund for financing the current work.     

Sorption Properties of Bulk and Deposited Ammonium Molibdophosphate with Respect to Cs+, Sr2+, and UO 2 2 + $$ {\mathrm{UO}}_2^{2+} $$ Ions

Theoretical and Experimental Chemistry - The sorption of Cs+, Sr2+, and $$ {\mathrm{UO}}_2^{2+} $$ ions on bulk ammonium molibdophosphate (AMP) and also on compositions obtained by its deposition...     

Synthesis of monodisperse polymer suspensions with a narrow particle size distribution in the presence of water-insoluble triple block copolymers of polypropylene oxide and polyethylene oxide (pluronics)

The colloidal chemical properties of triple block copolymers of polypropylene oxide and polyethylene oxide (pluronics of various structures) were studied in comparison. All of them are shown to be surfactants but differ in interfacial tension, surface activity, surface area occupied in the adsorption layer, and adsorption layer thickness. The kinetic regularities of polymerization of styrene and methyl methacrylate were studied. The particle diameters and their size distribution were determined. Distinctions in the kinetic regularities of polymerization are shown: the shape of the conversion—time curves (for the duration of the initial and stationary stages of polymerization) and the dependences of the diameter on the surfactant concentration and monomer to water volume ratio. In the presence of the water-insoluble pluronics, the mechanism of formation of polymer—monomer particles and interfacial layer on the surface differs from that when using water-soluble surfactants, which makes it possible to distinguish these processes into an independent type of heterophase polymerization.