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Tolkunov A.S.,L M Litvinenko Institute Of Physical Organic Chemistry And Coal Chemistry | Mazepa A.V.,Av Bogatsky Physico Chemical Institute | Palamarchuk G.V.,University of Kharkiv | Shishkin O.V.,University of Kharkiv | And 3 more authors.
Monatshefte fur Chemie | Year: 2017

Abstract: New derivatives of 11,12-dihydroquinazolino[3,2-c][2,3]benzodiazepin-14(6H)-one have been synthesized. 11-(2-Thienyl)- and 11-(5-R-2-furyl)-substituted compounds were prepared by the Pictet–Spengler reaction of 3-amino-2-(3,4-dimethoxybenzyl)quinazolin-4(3H)-one with heterocyclic aldehydes in aprotic media. Their chemical structures were confirmed by 1H and 13C NMR spectroscopy and mass spectrometry. We observed the opening of diazepine ring in 8,9-dimethoxy-11-(5-chloro-2-furyl)-11,12-dihydroquinazolino[3,2-c][2,3]benzodiazepin-14(6H)-one when treated with trifluoroacetic acid, and the structure of the product was determined by NMR (1H, 13C, HSQC, HMBC experiments) and mass spectrometry data. The crystal structure of 3-amino-2-[4,5-dimethoxy-2-[(5-oxofuran-2(5H)-yliden)methyl]benzyl]quinazolin-4(3H)-one was confirmed by single-crystal X-ray analysis. Graphical abstract: [Figure not available: see fulltext.] © 2017, Springer-Verlag Wien.

Gektin A.,Institute for Scintillation Materials of Ukraine | Shiran N.,Institute for Scintillation Materials of Ukraine | Vasyukov S.,Institute for Scintillation Materials of Ukraine | Belsky A.,University Claude Bernard Lyon 1 | Sofronov D.,SSI Institute for Single Crystals
Optical Materials | Year: 2013

Absorption, excitation and luminescence spectra of pure and Eu doped CsI crystals were studied depending on the activator content, excitation energy, heat treatment and X-ray irradiation. Several types of Eu2+ related centers were found. It is shown that complex centers are stable at room temperature but their structure and concentration changes at heat treatment and under irradiation. The increased content of oxygen-containing radicals was determined by IR spectroscopy in Eu-containing crystals as opposed to pure one. It is supposed that some of emission centers in CsI:Eu are caused by the presence of intrinsic (vacancy type) and extrinsic (oxygen or hydroxyl ions) defects located in the nearest environment of Eu2+ ions. © 2013 Elsevier B.V. All rights reserved.

Kononets V.,Institute for Scintillation Materials of Ukraine | Kononets V.,University Claude Bernard Lyon 1 | Benamara O.,University Claude Bernard Lyon 1 | Patton G.,University Claude Bernard Lyon 1 | And 11 more authors.
Journal of Crystal Growth | Year: 2015

Ce-doped Lu2xGd2-2xSiO5 (LGSO:Ce) fiber-shaped crystals (x = 0.5) were grown by the micro-pulling down (m-PD) technique. To optimize the activator concentration for achieving the best scintillation parameters, the cerium concentration in the melt was varied in the range from 0.01 to 1.5 at.%. Distributions of Gd3+ and Ce3+ in LGSO:Ce crystals grown by the μ-PD and Czochralski (Cz) techniques were compared. The spatial distribution of cations across the LGSO:Ce scintillation crystals grown by the μ-PD technique is studied using wide-field microscopy under simultaneous excitation of two types of Cerelated centers and confocal microscopy under the selective excitation of Ce3+ in CeO6 crystallographic sites. It is revealed that the fiber-shaped crystals contain a single crystal core surrounded by crystalline material with a higher density of inclusions and cracks that are predominantly directed along the crystal axis. The formation of inclusions and cracks is interpreted by a nonuniform radial distribution of LGSO: CE cations. © 2014 Elsevier B.V. All rights reserved.

Sidletskiy O.,Institute for Scintillation Materials of Ukraine | Belsky A.,University Claude Bernard Lyon 1 | Gektin A.,Institute for Scintillation Materials of Ukraine | Neicheva S.,Institute for Scintillation Materials of Ukraine | And 9 more authors.
Crystal Growth and Design | Year: 2012

A full concentration range of Lu 2xGd 2-2xSiO 5 (LGSO:Ce) crystals was grown by the Czochralski method. Dependence of the scintillation properties on composition (x) in the range of solid solutions is established. It was determined that the LGSO:Ce scintillation yield increases in the range 0.3 < x < 0.8 and reaches 29000 phot/MeV at 60% of Lu in the host (x = 0.6), and energy resolution improves up to 6.7% at 662 KeV. The observed light yield increase, surprisingly high Ce 3+ segregation coefficients, improvement of energy resolution, and suppression of afterglow can be attributed to modification of both hot and thermalized diffusion of secondary electrons and holes induced by short-range separation in solid solution. The proposed approach can be valid for a wide range of mixed scintillation crystals and provides room for further improvement of their characteristics by isovalent substitution of host atoms. © 2012 American Chemical Society.

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