384 research outputs found
Synthesis of Heteroannulated Indolopyrazines through Domino N-H Palladium-Catalyzed/Metal-Free Oxidative C-H Bond Activation
A convenient approach to [1,2,5]oxadiazolo[3′,4′:5,6]pyrazino[2,3-b]indoles and their heteroannulated analogues bearing various aryl substituents in the backbone has been developed. This synthetic protocol is based on Pd-catalyzed Buchwald-Hartwig and subsequent annulation by intramolecular oxidative cyclodehydrogenation. The photophysical properties for new polycycles have been measured. © 2020 American Chemical Society.Russian Foundation for Basic Research, RFBR: 18-29-23045, 18-33-00103-mol_aThis work was supported by the Russian Foundation for Basic Research (research project no. 18-29-23045 mk). Y.A.K. would like to acknowledge the financial support for the part of the synthetic section from the Russian Foundation for Basic Research (research project no. 18-33-00103-mol_a)
Dibenzo[ f,h]furazano[3,4- b]quinoxalines: Synthesis by Intramolecular Cyclization through Direct Transition Metal-Free C-H Functionalization and Electrochemical, Photophysical, and Charge Mobility Characterization
Herein, we describe the synthesis of unsymmetrically substituted dibenzo[f,h]furazano[3,4-b]quinoxalines by intramolecular cyclization through direct transition metal-free C-H functionalization. The electrochemical and photophysical properties for several polycycles have been measured. In thin films of the dibenzo[f,h]furazano[3,4-b]quinoxalines, hole mobility is in the order of 10-4 cm2 V-1 s-1. The results show that the HOMO and LUMO energy levels are appropriate for using the compounds as hole-transport materials in thin-film devices, in particular, organic and perovskite solar cells. Copyright © 2020 American Chemical Society.Russian Foundation for Basic Research, RFBR: 18-33-00103-mol_aRussian Science Foundation, RSF: 18-13-00409The research was financially supported by the Russian Science Foundation (project no. 18-13-00409). Y.A.K would like to acknowledge the financial support for the part of the synthetic section from the Russian Foundation for Basic Research (research project no. 18-33-00103-mol_a). The authors are grateful to Grigory A. Kim for carrying out the DFT calculations, which were performed by using “Uran” supercomputer of the Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences. NMR experiments were carried out by using equipment of the Center for Joint Use “Spectroscopy and Analysis of Organic Compounds” at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences
New Approach to Unsymmetrical 1,3- and 1,4-Diazatriphenylene Derivatives Through Intramolecular Oxidative Cyclodehydrogenation
The research was financially supported by the Russian Science Foundation (Project № 16-13-10435). NMR spectra and elemental analyses were covered by Program of the Ural Branch of the Russian Academy of Sciences (Рroject № 18-3-3-12)
Time dependence of the proton flux measured by PAMELA during the July 2006 - December 2009 solar minimum
The energy spectra of galactic cosmic rays carry fundamental information
regarding their origin and propagation. These spectra, when measured near
Earth, are significantly affected by the solar magnetic field. A comprehensive
description of the cosmic radiation must therefore include the transport and
modulation of cosmic rays inside the heliosphere. During the end of the last
decade the Sun underwent a peculiarly long quiet phase well suited to study
modulation processes. In this paper we present proton spectra measured from
July 2006 to December 2009 by PAMELA. The large collected statistics of protons
allowed the time variation to be followed on a nearly monthly basis down to 400
MV. Data are compared with a state-of-the-art three-dimensional model of solar
modulation.Comment: 17 pages, 5 figures, 1 table, to appear in Astrophysical Journal.
Corrected two elements of Table
Measurement of the isotopic composition of hydrogen and helium nuclei in cosmic rays with the PAMELA experiment
The satellite-borne experiment PAMELA has been used to make new measurements
of cosmic ray H and He isotopes. The isotopic composition was measured between
100 and 600 MeV/n for hydrogen and between 100 and 900 MeV/n for helium
isotopes over the 23rd solar minimum from July 2006 to December 2007. The
energy spectrum of these components carries fundamental information regarding
the propagation of cosmic rays in the galaxy which are competitive with those
obtained from other secondary to primary measurements such as B/C.Comment: 11 pages, 11 figures, 5 tables. To appear in Astrophysical Journa
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