Luminescence of Pr,Nd and Yb ions implanted in GaAs and GaP

New experimental data on luminescence spectra of Pr and Nd ions implanted into GaAs and GaP crystals and the results on luminescence kinetics of Nd doped GaP are presented. The results show that RE ions form different complexes in measured samples.     

DBU as a scaffold for the synthesis of [1,3]oxazolo[2’,3’ : 2,3]pyrimido-[1,2-a]azepines: annulation with aromatic cyanopropargylic alcohols

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Chloro(bromo)vinyl ketones and 2,2-Dichloroacrolein in Reactions with Hydrazines

Reactions of 2,2-dichlorovinyl and 2,2-dibromovinyl ketones with alkylhydrazines afford respectively 1-R-3-alkyl(aryl)-5-chloro- or 5-bromopyrazoles in preparative yields. The dichloroacrolein forms with alkylhydrazines and dimethylhydrazine only the corresponding hydrazones. Quantum-chemical calculations were performed characterizing the structure of the obtained ketones and dichloroacrolein alkylhydrazones, of dichloroacrolein dimethylhydrazone, of 1-alkyl-5-chloropyrazolinium halides, and 1-alkyl-5-chloropyrazoles.     

Effect of the nature of titania on the activity of Cu?Ti?O catalysts for selective catalytic reduction of nitrogen oxides with ammonia

The activity of Cu–Ti oxide catalysts has been studied in the selective catalytic reduction of NO with ammonia. We have elucidated how the nature ofstarting titania affects the catalyst activity in this reaction.     

Crown-containing styryl dyes

Complexation of styryl dyes containing theN-phenylaza-15-crown-5 fragment (trans-2a,b) with Ca²⁺ ions in MeCN was studied. Unlike cationic dyetrans-2a, betainetrans-2b forms both complexes of 1∶1 stoichiometry and aggregates consisting of four dye molecules and one Ca²⁺ ion. Cation-induced aggregation was observed also for the analog of dyetrans-2b, which contains a dimethylamino group instead of an azacrown ether fragment (trans-3). Apparently, the interaction between a metal cation and sulfo groups of moleculestrans-2b ortrans-3 makes the main contribution to the stability of aggregates. The dependence of the stability of aggregates on the nature of the metal cation was studied.     

Impulsive-discharge formation in water

This paper reports on research on an impulsive electrical discharge in deionized water (=2 × 10⁴ · m) in the voltage range 17–50 kV. The research showed that the discharge proceeds through the development of subsonic (U=17–22 kV) or supersonic (U=25–50 kV) streamers, depending on the electric-field strength at the surface of the tip. When voltage impulses having an amplitude of 20–25 kV are unleashed, the development of both types of streamers is observed in the discharge gap. The experiments carried out by the authors do not confirm the hydrodynamic origin of the disturbances at the initiating electrode that give rise to the discharge's development. The authors hypothesize that streamer development is due to the ionization of water molecules. The energy expenditures to ionize the molecules in the streamer channel are estimated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 88–92, January, 1989.     

The exchange reaction H2 (ν = 1) + H = H + H2

The classical trajectory method is applied to calculate the total cross section for the exchange reaction H₂(ν = 1) + H = H + H₂. The vibrational excitation is shown to influence efficiently the threshold value. Partial reaction rate-constants calculated on the basis of the cross sections obtained are in good agreement with those measured in H-maser experiments.     

Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide

Cross coupling of 2-arylpyrrole with benzoylbromoacetylene over aluminum oxide at room temperature gave 45–94% of 2-(benzoylethynyl)-5-arylpyrroles. Intermediate 2-(2-benzoyl-1-bromoethenyl)-5-arylpyrroles were isolated in up to 19% yield. The reaction was accompanied by formation of less than 5% of adducts of the initial pyrroles with the cross-coupling products, 2-benzoyl-1,1-bis(5-arylpyrrol-2-yl)ethenes.     

Synthesis of the complex of chlorodiphenylborane with dimethylformamide

Summary A complex compound between chlorodiphenylborane and dimethylformamide was prepared by reaction in solvent, nonsolvent, and excess of dimethylformamide; it has the composition (C₆H₅)₂BC1 ·HCON(CH₃)₂. Some of its properties were examined.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seria Khimicheskaya, No. 10, pp. 1838–1843, October, 1964     

Synthesis of Functionally-substituted Pyrrolothiazolidines from Pyrrole-2-carbodithioates, CH-acids, and Haloacetylenes

Functionally substituted pyrrolothiazolidines have been synthesized by the sequential treatment of pyrrole-2-carbodithioates with methylene-reactive nitriles and haloacetylenes in a KOH-DMSO system.