Condensed imidazo-1,2,4-azines. 12. Synthesis and structure of substituted 5-H-imidazo[1,2-b]-1,2,4-triazepin-4-ones (-thiones)

The synthesis has been effected of new representatives of the imidazo[1,2-b]-1,2,4-triazepin-4-ones (-thiones). It has been shown with the aid of IR and UV spectroscopic and mass spectrometric methods that the lactam (thione) form is the predominant one for the compounds synthesized.For Communication 11, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 694–699, May, 1985.     

Diffractive proteon fragmentation in 16, 32, and 110 GeV/cK − p interactions and the diffractive production of heavy quarks(s\bar s,c\bar c)

The inclusive proton diffraction dissociation cross sections in 16, 32, and 110 GeV/cK ^? p interactions are determined from the spike nearx=1 in the inclusive negative particle spectra and are compared to those obtained inK?p interactions using other selection methods at various energies. The same procedure is applied to events containing aV ⁰ in order to obtain the cross section for diffractive \(s\bar s\) production. While the total cross section for proton diffraction is found to be approximately constant in the energy range studied here, proton diffraction yielding an \(s\bar s - pair\) is found to increase significantly. In particular it is almost constant at 85 μb forΛ ⁰ and Σ production but for \(NK\bar K\) it rises from zero at 16 GeV.c to about 200 μb at 110 GeV/c. From the result for \(s\bar s\) diffractive production an estimate for the \(c\bar c\) diffractive production cross section of approximately 1–10 μb at 110 GeV/c is obtained.     

Measurement of Cross Sections for Inclusive Forward Charged Hadron Production in Carbon–Carbon Collisions at Beam Energy of 19.6 GeV per Nucleon

Physics of Atomic Nuclei - The invariant cross sections for forward charged-hadron production at zero angle in carbon–carbon collisions at a beam kinetic energy of 19.6 GeV per nucleon were...     

Luminescence-spectral and acid-base characteristics of 3-aryl-7-diethylaminocoumarins

The absorption and fluorescence spectra and the acid-base characteristics of 7-diethylaminocoumarins containing an aromatic substituent at position 3 and H, Cl, CH ₃ ,CF ₃ ,and N(CH ₂ CH ₂ ) ₂ O at position 4 were studied. For the para-substituted derivatives a linear correlation was obtained between the pK _a values and the Hammett _p constants. On the basis of the obtained data, and also of an x-ray crystallographic investigation of 3-phenyl-4-methyl-7-diethylaminocoumarin it was concluded that there is weak -conjugation between the 3-aryl groups and the coumarin fragment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 40–46, January, 1991.     

Spectral-luminescence properties and acid-base properties of luminophores obtained from 3-iodo-7-dialkylaminocoumarins

The absorption and fluorescence spectra of the conjugate acids of 7-dialkylaminocoumarins were studied, and their pK_a ^I, pK_a ^II, and pK_a ^* values were determined. It was established with the aid of PMR data that the primary protonation generally involves the nitrogen-containing substituent in the 3 or 4 position, while the secondary protonation involves the nitrogen atom in the 7 position.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1170–1175, September, 1991.     

Search for Θ+(1540) in exclusive proton-induced reaction p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N) at the energy of 70 GeV

A search for narrow Θ⁺(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction $p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)$ on carbon nuclei or quasifree nucleons at $E_{beam} = 70GeV(\sqrt s = 11.5GeV)$ studying nK ⁺, pK _S ⁰ , and pK _L ⁰ decay channels of Θ⁺(1540) in four different final states of the $\Theta ^ + \bar K^0 $ system. In order to assess the quality of the identification of the final states with neutron or K _L ⁰ , we reconstructed Λ(1520) → nK _S ⁰ and ? → K _L ⁰ K _S ⁰ decays in the calibration reactions p + C(N) → Λ (1520)K ⁺+C(N) and p+C(N) → p?+C(N). We found no evidence for a narrow pentaquark peak in any of the studied final states and decay channels. Assuming that the production characteristics of the $\Theta ^ + \bar K^0 $ system are not drastically different from those of the Λ(1520)K ⁺ and p? systems, we established upper limits on the cross-section ratios $\sigma (\Theta ^ + \bar K^0 )/\sigma (\Lambda (1520)K^ + ) < 0.02$ and $\sigma (\Theta ^ + \bar K^0 )/\sigma (p\phi ) < 0.15$ at 90% C.L. and a preliminary upper limit for the forward-hemisphere cross section $\sigma (\Theta ^ + \bar K^0 )$ nb/nucleon.     

Synthesis,spectral-luminescence,and acid-base properties of 3-halo-7-aminocoumarins

The reactions of substituted coumarins with a variety of halogenating agents, leading to the formation of the corresponding 3-chloro-, 3-bromo-, and 3-iodo-7-aminocoumarins, have been studied. It has also been shown, based on the results of studies of the spectral-luminescence and acid-base characteristics of these 3-halo-7-aminocoumarins, that their basicity increases as the electron-donating nature of the substituent in the 4-position increases, and is also greater, as expected, for 3-iodo- and 3-chloro derivatives than for 3-bromo derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1609, December, 1990.     

Mass Number Dependence of the Forward Production of Charged Hadrons and Nuclear Fragments in Carbon–Lead and Carbon–Carbon Interaction at a Beam Energy of 19.6 GeV per Nucleon

Physics of Atomic Nuclei - The inclusive differential cross sections for the production of $$\pi^{\pm}$$ and $$k^{-}$$ mesons, protons, and antiprotons with momenta between 6 and 50 GeV/c and...