Evgeni M. Glebov
Novosibirsk State University
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Featured researches published by Evgeni M. Glebov.
Journal of Photochemistry and Photobiology A-chemistry | 2000
K.L Ivanov; Evgeni M. Glebov; Victor F. Plyusnin; Yu.V. Ivanov; Vjacheslav P. Grivin; N.M Bazhin
Abstract The method of laser flash photolysis with excitation at 308xa0nm was used to study the photochemistry of persulfate-ion in aqueous solutions with additions of N,N-dimethylformamide (DMF). The photolysis of S2O82− in water gives rise to SO4 − radical anions with a 0.55 quantum yield. The rate constant of SO4 − recombination was measured (2k=(2.7±0.2)×109xa0M−1xa0s−1 at ionic strength μ=0.9xa0M). In the presence of DMF the additional intermediate absorption band appears with a maximum at 380xa0nm, belonging to radical CH2(CH3)NCHO. Its extinction coefficient was determined (e380=1700±200xa0M−1xa0cm−1). The rate constants of reactions SO 4 − +DMF((4.3±0.2) × 10 8 M −1 s −1 ) and CH 2 (CH 3 )NCHO+O 2 ((1.3±0.1) × 10 9 M −1 s − 1 ) were measured. Thus, DMF is a good acceptor of active radicals (e.g., OH radical) which have absorption in the far UV region and which are impossible to detect directly in pulse photochemical experiments.
Photochemical and Photobiological Sciences | 2005
Irene V. Znakovskaya; Yulia A. Sosedova; Evgeni M. Glebov; Vjacheslav P. Grivin; Victor F. Plyusnin
The stationary photolysis of [PtCl(6)](2-) in aqueous solutions (10(-5)-10(-4) M) at the region of 313 nm leads to its photoaquation with a quantum yield of 0.19. Laser flash photolysis experiments (308 nm) provided evidence of the formation of Pt(iii) intermediates, namely [PtCl(4)(OH)(H(2)O)](2-) and [PtCl(4)](-), and Cl(2) (-) radical anions. The Pt(iii) complexes formed as a result of an intrasphere electron transfer from Cl(-) ligands to the excited Pt(iv) ion. However, the main ( approximately 90%) photolysis channel was not accompanied by the transfer of Cl atoms to the solvent bulk. The photoaquation of [PtCl(6)](2-) results from the back electron transfer in the secondary geminate pair, [PtCl(5)(H(2)O)](2-)-Cl. The relative yield of Pt(iii) intermediates, recorded after the completion of all processes in the geminate pair, was less than 10% of the number of disappearing initial [PtCl(6)](2-) complexes.
RSC Advances | 2012
Evgeni M. Glebov; Aleksandr V. Kolomeets; Ivan P. Pozdnyakov; Victor F. Plyusnin; Vjacheslav P. Grivin; Helge Lemmetyinen
Ultrafast pump–probe spectroscopy (λpump = 405 nm) was applied to study the primary photochemical processes for PtCl62− and PtBr62− complexes in aqueous and alcohol solutions. For PtCl62−, an intermediate with a lifetime of ca. 200 ps was registered and identified as an Adamson radical pair [PtIIICl52−⋯Cl˙]. The transformations of the primary intermediate give rise to successive formation of different Pt(III) species. The reactions of Pt(III) results in chain photoaquation in aqueous solutions and reduction of Pt(IV) to Pt(II) in alcohol solutions. For PtBr62− complex, the previously reported (I. L. Zheldakov, M. N. Ryazantsev and A. N. Tarnovsky, J. Phys. Chem. Lett., 2011, 2, 1540; I. L. Zheldakov, PhD thesis, Bowling Green State University, 2010) formation of active 3PtBr5− intermediate is followed by very fast (15 ps) aquation of Pt(IV) in aqueous solutions and parallel reactions of solvation and reduction of Pt(IV) to Pt(II) in alcohol solutions. All the processes in alcohols are finished within 0.5 ns. The data of ultrafast experiments are supported by nanosecond laser flash photolysis and stationary photolysis.
Journal of Photochemistry and Photobiology A-chemistry | 1995
Evgeni M. Glebov; Victor F. Plyusnin; N.I. Sorokin; Vjacheslav P. Grivin; A. B. Venediktov; Helge Lemmetyinen
Abstract Both stationary and laser flash photolysis were used to study the photochemistry of IrCl 6 2− in alcohol solutions. The primary photochemical photolysis process at 308 nm was demonstrated to involve electron transfer from the solvent to the excited complex. When the photolysis was performed at 248 nm, the photodissociation of the excited complex, with the elimination of a chlorine atom from the coordination sphere of iridium, was accompanied by electron transfer. At room temperature, the rate constants of the reaction between the primary alcohol radicals and the IrCl 6 2− complex were determined to be (3.2±0.1) × 10 9 M −1 s −1 for hydroxymethyl and (2.3±0.1) × 10 9 M −1 s −1 for α-hydroxyethyl radicals. The dark reactions of the IrCl 6 2− complex arising from photolysis are discussed.
Photochemical and Photobiological Sciences | 2011
Evgeni M. Glebov; Aleksandr V. Kolomeets; Ivan P. Pozdnyakov; Victor F. Plyusnin; Helge Lemmetyinen
Ultrafast pump-probe spectroscopy (λ(pump) = 400 nm) was applied to study the primary photophysical processes for the IrCl(6)(2-) complex in methanol and ethanol solutions. The excitation to the LMCT 2U(u) state was followed by formation of an intermediate absorption completely decaying with three characteristic times of 300 fs, ca. 2.5 ps, and 30 ps. The corresponding processes were interpreted as the 2U(u)*→1U(g)* electronic transition, vibrational relaxation, and internal conversion to the ground state. Complete recovery of the ground state is consistent with the absence of the photochemical activity of the IrCl(6)(2-) visible LMCT bands.
Journal of Photochemistry and Photobiology A-chemistry | 1998
Evgeni M. Glebov; Victor F. Plyusnin; Vjacheslav P. Grivin; Yu.V. Ivanov; Helge Lemmetyinen
Abstract Laser flash photolysis has been used to study the formation of X 2 ·− radical ions (X = Br and Cl) upon photoreduction of IrCl 6 2− complex in methanol solutions, containing free X − ions. It has been shown that two channels of halogen atom formation are possible. These are the reactions Of X − ions with either the primary radical cation CH 3 OH ·+ which results from single electron transfer from a methanol molecule to the excited complex or the intermediate, arising from transformation of primary light-excited IrCl 6 2− complex.
Journal of Coordination Chemistry | 2007
Yong Chen; Feng Wu; Xu Zhang; Nansheng Deng; Nikolai Bazhin; Evgeni M. Glebov
The photolysis of Fe(III)-pyruvate and Fe(III)-citrate complexes in water produces hydroxyl radicals in the presence of dissolved oxygen, and can promote the oxidation of organic compounds. The photodegradation of glyphosate with Fe(III)-pyruvate and Fe(III)-citrate complexes was investigated under irradiation at λu2009≥u2009365u2009nm. The effect of initial concentration of glyphosate, the initial pH value, and the Fe(III)/carboxylate ratio were examined. Upon irradiation of glyphosate aqueous solution with the complexes in the acidic range of natural waters, the bioavailable orthophosphate could be released from degradation of glyphosate. The amount of orthophosphate increased with increasing Fe(III)/carboxylate ratio.
International Journal of Chemical Kinetics | 1998
Evgeni M. Glebov; Victor F. Plyusnin; Vjacheslav P. Grivin; Yu. V. Ivanov; Helge Lemmetyinen
The photochemistry of IrCl62− complex in simple alcohols have been studied using laser-flash photolysis. Single electron transfer from the solvent molecule to the light-excited complex has been shown to be the primary photochemical process. Quantum yields of the photoreduction of IrCl62− complex and the rate constants of its reaction with hydroxyalkyl radicals were determined at 200–330 K. Deviations of the rate constants from Debye–Smoluchowski equation for diffusion-controlled reactions are discussed.
Journal of Photochemistry and Photobiology A-chemistry | 1997
Evgeni M. Glebov; Victor F. Plyusnin; V.L. Vyazovkin; A. B. Venediktov
Abstract Low-temperature spectrophotometry and electron spin resonance (ESR) were used to study the IrC 2− 6 photochemistry in methanol matrices frozen at 77 K. Photoreaction gives rise to the absorption band of an IrCl 3− 6 complex with a maximum at 215 nm and to a new band with a maximum at 287 nm that is unobservable during IrCl 2− 6 photolysis in solutions at room temperature. The appearance of this new band is assigned to the formation of a weak complex between the . CH 2 OH radical and IrCl 3− 6 ion (i.e. a IrCl 3− 6 … . CH 2 OH radical complex). The irradiation of methanol matrix with IrCl 2− 6 gives rise to the . CH 2 OH radical signal in the ESR spectrum with additional splitting which can be attributed to the partial delocalization of spin density from radical to the IrCl 3− 6 complex and the appearance of hyperfine splitting (HFS) on the iridium nucleus. When the matrix is heated to 115 K the IrCl 3− 6 … . CH 2 OH complex disappears.
Journal of Photochemistry and Photobiology A-chemistry | 2001
Victor F. Plyusnin; Evgeni M. Glebov; Vjacheslav P. Grivin; Yuri V. Ivanov; A. B. Venediktov; Helge Lemmetyinen
Abstract The photochemical transformation of fac-Pt(NO2)3Cl32− complex in water solutions and frozen matrices has been studied by laser flash photolysis, optical, ESR, and NMR spectroscopies. Upon steady-state photolysis of liquid water solutions, the fac-Pt(NO2)3Cl32− absorption bands disappear in the optical spectrum with both the preservation of isosbestic point at 43xa0620xa0cm−1 and the appearance of a new absorption band with a maximum at 48xa0000xa0cm−1, belonging to Pt(II) complexes. Applying the NMR method to nuclei 195 Pt and 14 N , we have shown that the final photolysis products are mainly complexes [PtCl3(NO2)]2−, Pt(NO2)2(H2O)2, and [Pt(NO2)6]2−. The photolysis of frozen (H2O+LiCl or H2O+MgClO4) matrices containing the fac-Pt(NO2)3Cl32− complex yields a new wide absorption band with a maximum in a region of 30xa0000xa0cm−1 which belongs to the [PtCl3(NO2)2(ONO)]2− nitrito-isomer of the initial complex. A longer irradiation causes photodissociation of nitrito-isomer into a complex of trivalent platinum [PtCl3(NO2)2]2− and free NO2 radical whose characteristic lines are manifested in the ESR spectrum. The laser flash photolysis shows that in solution at room temperature, the [PtCl3(NO2)2(ONO)]2− nitrito-isomer thermally dissociates in about 300xa0ns with an activation energy of 48.6±1.7xa0kJxa0mol−1. The [PtCl3(NO2)2]2− complex dissociates in about 7xa0μs giving the second free NO2 radical and a [PtCl3(NO2)]2− complex. This reaction has an activation energy of 37.6±1.5xa0kJxa0mol−1. It is shown that dissociation of the [PtCl3(NO2)2]2− complex is reversible and the NO2 radical coordinates again with the [PtCl3(NO2)]2− ion with a rate constant 4.2×109xa0M−1xa0s−1. In addition to the repeated coordination, the NO2 radical also disappears in a reversible reaction of recombination (2krec=1.8×109xa0M−1xa0s−1) to give N2O4 molecule.