Electrogenerated chemiluminescence (ECL) of luminol at a boron-doped diamond electrode has been used for hypochlorite determination. The presence of H2O2 induces the generation of the ECL signals of luminol. In contrast, the presence of hypochlorite oxidizes luminol directly to decrease the ECL signals of luminol. Accordingly, a decrease of the ECL signals of luminol in the presence of H2O2 was used as the signal response for hypochlorite detection. A linear decrease of ECL signals with the NaClO concentration in the range from 0 to 20 μM was observed with a sensitivity of 18.56 a.u. μM-1 cm-2. An estimated detection limit of 0.88 μM was achieved, which is around one order lower than the detection limit obtained using the normal electrochemical method with the same electrode. The system also provides a good selectivity towards Cu2+ and Na+. A reproducibility of 3.40%RSD was noted for 15 repetitive measurements. The analytical performance was found to be favourable in comparison to those of other typical electrochemical and electrochemiluminescence methods, indicating that it is applicable for real sample detection.

Electrogenerated chemiluminescence of luminol at a boron-doped diamond electrode for the detection of hypochlorite.

The effect of the electronic and steric characteristics of phosphine ligands on the catalytic properties of palladium catalysts in the allylation of norbornadiene with allyl formate has been investigated. The activity and selectivity of catalysts formed in situ from palladium acetate and phosphines depend on the nature of the ligand. A certain lability of phosphine is required to achieve a high activity and the desired selectivity of the reaction. In addition, not more than one position in the coordination sphere of palladium can be occupied by the phophine-ligand. The key role of the ligand becomes evident at the β-hydride elimination step. The conditions for the selective production of 5-methylene-6-vinylnorbornene were determined.

The influence of the phosphine ligand nature on palladium catalysts in the norbornadiene allylation with allyl formate

Allylation of norbornadiene in the presence of Pd0 phosphine complexes: a DFT modeling

The chemiluminescent reaction of luminol is widely used for analytical purposes. Surface-active components of biological membranes are often present in biochemical studies and in many real objects of analysis. Their influence on the chemiluminescent reaction of luminol has not been systematically studied. Therefore, it is necessary to investigate this chemiluminescent reaction in organized molecular systems - micellar, vesicular and other systems simulating biological membranes. Micellar medium may also provide an additional opportunity to control chemiluminescent reactions, primarily with the aim of increasing their efficiency. The kinetics of the chemiluminescent oxidation of luminol and its hydrophobic analogue N-octylluminol with a hypochlorite ion in aqueous solutions and micellar solutions of non-ionic surfactant Triton X-100 was studied in the present work. It was shown that the growth and fading of the luminol and N-octylluminol chemiluminescence is adequately described by a two-exponential dependence, and the effective rate of increase in the intensity of chemiluminescence is directly proportional to the concentration of the hypochlorite ion. The dependences of the rate of accumulation and consumption of the intermediate product on the presence and concentration of surfactants in the reaction mixture are determined. The results are discussed in terms of the effect of localization of the reagents and intermediate reaction products.

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Хемилюминесцентные реакции люминола и n-октиллюминола с гипохлоритом в растворах неионогенных поверхностно-активных веществ

For the model chemiluminescent reaction of N-octylluminol, a hydrophobic analogue of luminol and a surfactant, a scheme was established and parameters of the formal kinetic equation were calculated. The formation of intrinsic micelles of the substrate promotes a triple increaese in the rate of the first step of the luminogenous reaction and a multiple increase in the detected maximum and integrated signal intensities compared to results obtained in the classical chemiluminescent system based on luminol. The reversible conversion of N-octylluminol to a non-luminescent form was revealed, and the equilibrium is strongly shifted to the latter, which distorts the shape of the detected kinetic curve and decreases the analytical signal with time. This shift can be prevented by using the systems with controlled mixing of reagents.

Kinetic features of the chemiluminescent oxidation of N-octylluminol by the hypochlorite ion in a self-organized micellar medium

The palladium-catalyzed allylation of norbornadiene is a unique method for the C-C bond formation involving allyl derivatives. This reaction proceeds in solution. However, the selection of the solvent is so far an empirical procedure, and the role of the solvent in this process is poorly understood. The effect of the solvent on the reaction pattern is considered in terms of polarity, polarizability, and coordinating ability of the solvent. These properties were shown to be the key factors in selecting the proper solvent. Based on investigation of the mechanism of individual catalytic cycle stages, the features of the interaction between the solvent, the catalyst, and reagents were analyzed.

Solvent effect in palladium-catalyzed allylation of norbornadiene

A comparative study of the kinetics of the chemiluminescent reaction of luminol, localized in the aqueous phase, and its hydrophobic analogue, N-octyl luminol, localized in the micellar phase, with the hypochlorite ion in anionic sodium dodecyl sulfate micelles at various surfactant concentrations is carried out. The dependence of the rate constant of the accumulation and decay of the intermediate product on the presence and concentration of the surfactant in the reaction mixture is determined.

Chemiluminescence Reactions of Luminol and N -Octyl Luminol with Hypochlorite in Anionic Surfactants

We study the effect of surfactants having a different charge and length of the hydrocarbon radical on the intensity and kinetic laws of the model chemiluminescent reaction of a hydrophobic analogue of luminol, N-octyl luminol. The effect of the solution pH and the charge, structure, and concentration of surfactants on the intensity of the chemiluminescence is assessed, and the kinetic laws of the chemiluminescent reaction are determined.

P. V. Melnikov

Papers

Solvent effect in palladium-catalyzed allylation of norbornadiene

Chemiluminescence Reactions of Luminol and N -Octyl Luminol with Hypochlorite in Anionic Surfactants

Kinetic features of the chemiluminescent oxidation of N-octylluminol by the hypochlorite ion in a self-organized micellar medium

Chemiluminescent Reaction of N -Octyl Luminol with a Hypochlorite Ion in a Micellar Medium