Valeri P. Kazakov

Singlet-oxygen generation in the catalytic reaction of dioxiranes with nucleophilic anions

Nucleophilic anions such as Cl(-), I(-), Br(-), t-BuO(-), O(2)(-) and OH(-) efficiently catalyze the decomposition of dimethyldioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFD). Singlet oxygen ((1)O(2)) is formed in these catalytic reactions, as demonstrated by the characteristic infrared chemiluminescence (IR-CL) at 1268 nm. The yield of (1)O(2) generation, measured by the IR-CL method, lies in the range between 2 and 98%, which depends on the particular anion employed. For the bromide ion, the catalytic decomposition of the dioxirane is in competition with the oxidation of Br(-) to elemental bromine.

Chemiluminescence in the thermal decomposition of di(tert-butyl) trioxide

Intense chemiluminescence (CL) in the visible and IR regions arising during the thermal decomposition of di(tert-butyl) trioxide has been observed. The decomposition rate constants have been determined. The emitter of CL in the IR region is singlet oxygen, that of CL in the visible region is triplet excited acetone. Kinetic and spectral data and thermochemical and MNDO calculations point to a homolytic mechanism of decomposition. The formation of the CL emitters occurs in the reactions of radicals that arise upon the decay of di(tert-butyl) trioxide.

Deuteration effect in auto-oscillation chemiluminescence of the Belousov-Zhabotinskii reaction

It has been established that substitution of H2O by D2O in the auto-oscillation system of malonic acid+bromate+catalyst (Ce3+ 4+, Ru(bipy)32+, 3+) not only changes the parameters of oscillations recorded according to the chemiluminescence intensity, but can also lead to their complete disappearance. The step that is responsible for the D2O effect on chemiluminescent oscillation reactions is the deuteration of the methylene group of malonic acid.AbstractОбнаружено, что замена H2O на D2O в автоколебательной системе малоновая кислота — бромат — катализатор (Ce3+,4+, Mn2+,3+, Ru(bipy)32+,3+) не только изменяет параметрю колебателЫного режима, регистрируемото по интенсивности шемилюминесценции, но может приводитв вообще к исчезновению колебаний. Стадией, определяющей влияние D2O на шемилюминесцентную колебателыную реакцию, является стадия дейтерирования метиленовой группы малоновой кислоты.

New autooscillation chemiluminescence reaction of 4-oxyquinoline oxidation by bromate ions

A new autooscillation chemiluminescence reaction of 4-oxyquinoline oxidation by bromate ions, catalyzed by cerium ions and tris-(2,2′-dipyridine) ruthenium complexes, has been discovered.AbstractОбнаружена новая автоколебательная хемилюминесцентная реакция окисления 4-оксихинолина ионами бромата, катализируемая ионами церия, и трис-2,2′-дипиридильными комплексами рутения.

Abnormal fluctuations of chemiluminescence intensities (“chaos”) in the malonic acid-bromate-tris (2,21-dipyridine) ruthenium complex system

Abnormal fluctuations of chemiluminescence intensities have been observed in the CH2(COOH)2−BrO3−Ru(bipy)32+,3+ system, when catalyst concentrations are insufficient for stable self-oscillations to be generated. Amplitude distribution of these fluctuations (reaction “noise”) are of the “bell” shape, which is typical for the normal Gaussian distribution. Their nature is similar to the large-scale fluctuations that are the “nuclei” for dissipative structures.AbstractОбнаружены аномально большие флуктуации интенсивности хемилюминесценции в системе CH2(COOH)2−BrO3−−Ru(bipy)32+,3+ при концентрациях катализатора, недостаточных для возникновения устойчивых автоколебаний. Распределение амплитуды этих флуктуаций (“шума” реакции) имеет колоколообразный вид, характерный для нормального гауссовского распределения. Вероятно, по своей природе они близки к тем крупномасштабным флуктуациям, которые являются “зародышами” диссипативных структур.

A novel chemiluminescence from the reaction of dioxiranes with alkanes. Proposed mechanism of oxygen-transfer chemiluminescence

Oxidation of adamantane and 2,3-dimethylbutane by nmethyl(trifluoromethyl)dioxirane is accompanied by chemiluminescence (CL); nformation of the emitter of CL, triplet excited trifluoropropanone, is nproposed to occur via a concerted oxenoid mechanism of oxygen ninsertion into C–H bond of the hydrocarbons.

Chemiluminescent studies for the kinetics of decomposition of Di-(tert-butyl)-trioxide

Thermolysis of di-(tert-butyl)-trioxide produces IR and visible chemiluminescence (CL) which may be ascribed to emission by singlet oxygen (IR-CL) and triplet acetone (vis. CL).

Decomposition of dioxetane induced by electron transfer from a photoexcited lanthanide ion

The photodecomposition of adamantylideneadamantane-1,2-dioxetane (1) in the presence of Ce3+ is discovered. Electron transfer plays a dominant role in the reaction mechanism. The photoirradiation of solutions of1 and CeCl3 within the absorption region of the latter leads to the decomposition of1 with the initial quantum yield φ=0.29±0.03. The reaction is caused by the dynamic extinction of the photoluminescence of*Ce3+ ions by dioxetane1. Adamantanone is the main product of the photocatalytic reaction. However, side products of the interaction of the intermediate 1,4-dioxyradical anion with the solvent are also formed.

Chemihiminescence by the interaction of XeO3 and the products of photolysis of uranyl solutions in sulfuric acid

Using the chemiluminescence oxidation of U(IV) and H2O2 with xenon trioxide as a model, it has been found that during the photolysis of solutions of UO2SO4 in sulfuric acid in the absence of any organic compounds, the accumulation of U(SO4)2 and H2O2 takes place as a result of the reaction of the primary products of the photoreduction of uranyl ion,i.e., UO2+ and the OH radical.

Degradation of the holmium—barium—copper oxide superconductor, HoBa2Cu3O6.92, under the action of H2O and D2O: a study by the radiothermoluminescence method

Information about the existence of impurities and defects on the surfaces of high-T{sub c} superconductors (HTSC) can be obtained by radiothermoluminescence (RTL). The degradation of HTSC materials results from their interaction with water and CO{sub 2}. It has been established that the intensity of RTL is very insignificant for freshly prepared HTSC or for samples stored in a dry atmosphere. However, a large increase in RTL intensity occurs if specimens are in contact with water. Barium hydroxide, carbonate, and oxides make the largest contribution to RTL of superconducting ceramics with degraded surfaces. The RTL curves for Ba(OH){sub 2} and BaCO{sub 3} differ slightly from each other, which makes it difficult to estimate the contribution of each of them to the luminescence observed.