Solvent effects on chemiluminescence from the hydrogen peroxide-lucigenin reaction: Kinetics of light emission in mixed polar solvents

Summary The effect of reaction media composition on reaction kinetics was studied for the reaction of lucigenin (10,10-dimethyl-9,9-biacridinium nitrate) with hydrogen peroxide and alkali. Chemiluminescent emission as well as lucigenin disappearance were recorded in mixtures of water with the co-solvents methanol, ethanol, 1-propanol, dimethylsulfoxide, and dimethylformamide. The kinetic results (base and peroxide concentration influence on the reaction rate and the relative chemiluminescence yield) are very similar in all the reaction media, suggesting that the fundamental step in the disappearance of lucigenin and in light emission decay is HO ₂ ^– addition to lucigenin. Lucigenin can also disappear through dark reactions with OH^– or H₂O₂. The co-solvent acts as a catalyst for the reaction with HO ₂ ^– and increases both the initial chemiluminescence intensity and the decay rate constant.

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Lösungsmitteleffekte bei der Chemilumineszenz der Wasserstoffperoxid-Lucigenin Reaktion. Kinetik der Lichtemission in gemischten polaren Lösungsmitteln

Zusammenfassung Es wurde der Einfluß der Zusammensetzung des Reaktionsmediums auf die Kinetik der Reaktion von Lucigenin (10,10-dimethyl-9,9-biacridiniumnitrat) mit Wasserstoffperoxid und Alkali untersucht. Die Emission der Chemilumineszenz und das Verschwinden von Lucigenin wurde in Mischungen von Wasser mit den Kosolventien Methanol, Ethanol, 1-Propanol, Dimethylsufoxid und Dimethylformamid gemessen. Die kinetischen Resultate (Einfluß der Basen- und Peroxid-Konzentration auf die Reaktionsgeschwindigkeit und die relative Chemilumineszenzausbeute) sind für alle Reaktionsmedien sehr ähnlich; das legt den Schluß nahe, daß der grundlegende Schritt im Verbrauch des Lucigenin unter Lichtemission die Addition von HO ₂ ^– an Lucigenin ist. Lucigenin kann auch über Dunkelreaktionen mit OH^– oder H₂O₂ verschwinden. Das Kosolvens agiert als Katalysator für die Rekation mit HO ₂ ^– und erhöht sowohl die anfängliche Chemilumineszenzintensität als auch die Zerfallsgeschwindigkeitskonstante.

     

Chemiluminescence in model membrane structures. Chemiluminescence of lucigenin in the presence of Mg(OH)2 and benzyl alcohol. Temperature effects

The quantum yields of the lucigenin light reaction in didodecyldimethylammonium bromide (DDAB) are affected by the presence of Mg(OH)₂; a 35% increase is observed in lamellar and a 65% increase in vesicular aggregates. The system is insensitive to benzyl alcohol. The quantum yields inDDAB versus those in water, as a function of temperature show a slope change in the region of the phase transition in lamelar aggregates. This effect is far less pronounced in vesicular aggregates. In contrast to theDDAB aggregates, anionic sodium dimethyldidodecylphosphate (SDDP) sonicated aggregates are associated with lower quantum yields and no apparent slope change in the region of the phase transition.

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Chemilumineszenz in Modell-Membranstrukturen. Die Chemilumineszenz von Lucigenin in der Gegenwart von Mg(OH)₂ und Benzylalkohol. Temperatureffekte

Zusammenfassung Die Quantenausbeuten der Lichtreaktion von Lucigenin in Didodecyldimethylammoniumbromid (DDAB) werden durch die Gegenwart von Mg(OH)₂ beeinflußt. Es wird 35% Verstärkung in lamellaren und 65% Verstärkung in vesicularen Aggregaten beobachtet. Das System ist Benzylalkohol gegenüber unempflindlich. Eine Gegenüberstellung der Quantenausbeuten inDDAB bzw. in Wasser als eine Funktion der Temperatur zeigt eine Änderung des Anstiegs im Bereich des Phasenüberganges bei lamellaren Aggregaten. Dieser Effekt ist in vesicularen Aggregaten nicht so ausgeprägt. Im Gegensatz zu denDDAB-Aggregaten sind die beschallten anionischen Natriumdimethyldodecylphosphat (SDDP)-Aggregate durch geringere Quantenausbeuten und keine offensichtlichen Anstiegsänderungen im Bereich des Phasenüberganges gekennzeichnet.

     

Chemiluminescence in model membrane structures chemiluminescence of lucigenin in the presence of estrogens

The chemiluminescence quantum yields of the lucigenin light reaction in 10^–2 M didodecyldimethylammonium bromide (DDAB) lamelar aggregates are affected by the presence of estrone and 17 -ethynylestradiol. A rise in quantum yields is observed at ca. 1·10^–4 M estrogen concentration as compared with the homogeneous (aqueous) medium, followed by a dramatic drop as the estrogen concentration increases. Unexpectedly, the smecticity of the lamelar aggregate is destroyed by estrone concentration as low as 10^–3 M and 17 -ethynylestradiol concentrations as low as 2·10^–4 M.

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Chemilumineszenz in Modell-Membranstrukturen Die Chemilumineszenz von Lucigenin in Gegenwart von Estrogenen

Zusammenfassung Die Chemilumineszenzquantenausbeuten der Lucigenin-Lichtreaktion in 10^–2 M Didodecyldimethylammoniumbromid (DDAB)-Lamellaraggregaten wird bei Gegenwart von Estron und 17 -Ethinylestradiol beeinflußt. Es wird eine Erhöhung der Quantenausbeuten bei ca. 1·10^–4 M Estrogengehalt gegenüber einem homogenen (wäßrigen) Medium beobachtet, bei Erhöhung der Estrogenkonzentration erfolgt jedoch eine drastische Erniedrigung der Quantenausbeuten. Die Smektizität der Lamellaraggregate wird bei Estronkonzentrationen von etwa 10^–3 M und 17 -Ethinylestradiolkonzentrationen von etwa 2·10^–4 M unerwarteterweise zerstört.

     

Effect of nicotine on the chemiluminescence of lucigenin in model membrane structures

The chemiluminescence of the classical lucigenin light reaction is adversely affected by nicotine in didodecyldimethylammonium bromide bilayer lamelar aggregates. The ratio of chemiluminescence quantum yields in the oriented medium, with and without nicotine, is equal to e^{–0.571[Nicotine]} whereas in the homogenous medium, the same ratio is equal to e^{–0.214[Nicotine]}. Furthermore, the appearance of the primary emitter's (N-methylacridone) emission in the chemiluminescence spectrum, already observed in oriented systems, is strongly supressed by nicotine.

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Der Effekt von Nikotin auf die Chemilumineszenz von Lucigenin in Modellmembranen

Zusammenfassung Die Chemilumineszenz der klassischen Lucigenin-Lichtreaktion wird von Nikotin in Didodecyldimethylammoniumbromid-Lamellaraggregaten geschwächt. Das Verhältnis der Chemilumineszenzquantenausbeuten ist in orientiertem Medium — mit oder ohne Nikotin — e^{–0,571[Nikotin]}, in homogenem Medium jedoch e^{–0,214[Nikotin]}. Außerdem wird die Emission des Primäremitters (N-Methylacridon) im Chemilumineszenzspektrum von Nikotin stark unterdrückt.

     

CdTe纳米棒-过氧化氢化学发光体系的研究

在水相中合成了以巯基乙酸和L-半胱氨酸为稳定剂的CdTe纳米棒。研究发现在碱性溶液中H2O2能直接氧化CdTe纳米棒产生强烈的化学发光,化学发光的强度与CdTe纳米棒尺寸大小相关,且一些表面活性剂能强烈敏化该反应。     

测定化探样品中痕量钒的流动注射光泽精化学发光法

用配有Jones还原器的流动注射系统,研究了光泽精与钒(Ⅱ)的化学发光反应,并建立了钒的流动注射化学发光分析法。该法线性范围为1×10-6～1×10-2 g/L ,检出限为3×10-7 g/L,相对标准偏差为2.0 %(1×10-4 g/L,n=11),相关系数在0.9988以上。已用于化探样品中痕量钒的测定,结果令人满意。     

Solvent effect on the absorption spectra ofN-2,6-trichlorobenzoquinonimine

The absorption spectra of solutions ofN-2,6-trichlorobenzoquinonimine in organic solvents of varying polarities are investigated. The ability of the compound to form molecular complexes in ethanol is discussed. The stability constants of the molecular complexes are determined from the spectra in mixed solvents. The equilibrium constant of the reaction involving the acquisition of a proton by the solute is calculated in water and in water—acetone mixtures.

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Lösungsmitteleffekte auf das Absorptionsspektrum vonN-2,6-trichlorbenzochinonimin

Zusammenfassung Die Absorptionsspektren wurden in Lösungsmitteln verschiedener Polarität untersucht und die Fähigkeit zur Bildung von Molekülkomplexen des Substrats in Ethanol diskutiert, wobei die Stabilitäskonstanten aus Messungen in Lösungsmittelgemischen errechnet wurden. Die Gleichgewichtskonstanten der Protonierung in Wasser und Wasser—Aceton wurden ebenfalls bestimmt.

     

光泽精与钨（Ⅲ）的流动注射－胶束增敏化学发光反应

采用了Jones柱在线还原钨（Ⅵ）为钨（Ⅲ），详细研究了钨（Ⅲ）与光泽精的化学发光反应，加入乳化剂OP能明显提高发光的信噪比，基于此建立了痕量钨的流动注射化学发光分析法。该法线性范围为1×10－6～1×10－2 g·L－1, 检出限为5×10－7 g·L－1 , 相对标准偏差为2.0％（5×10－5 g·L－1, n=11）。文中还探讨了反应机理。     

Chemiluminescence behavior of sodium hydrogen carbonate in the potassium permanganate-hydrogen peroxide reaction

Chemiluminescence (CL) phenomenon of hydrogen peroxide with potassium permanganate in the presence of sodium hydrogen carbonate was reported. Effects of the surfactant on the CL system were investigated. Nonionic surfactants could effectively increase the CL signal. Radical scavengers and organic reagents such as nitro blue tetrazolium chloride (NBT), cytochrome c, sodium azide, ascorbic acid, thiourea, tert-butanol and dimethyl sulphoxide were used to study the emitting species. CL emission spectrum was recorded and the results showed that the maximal emission wavelengths of NaHCO₃-H₂O₂-KMnO₄ system were 440 and 634 nm. The mechanism was discussed based on electron spin resonance (ESR) spectra, fluorescence spectra and UV-vis absorption spectra. The addition of rhodamine B or uranine into this CL system enhanced the CL signal. It was due to part of the energy transfer from singlet oxygen and excited triplet dimers of two CO₂ molecules to rhodamine B or uranine. The CL could be induced by excited rhodamine B or uranine.     

Solvent effects on the acid-catalyzed hydrolysis of tetramethylurea

Tetramethylurea was hydrolyzed in aqueous hydrochloric acid at temperatures of 80, 90, and 100°C. All reactions were carried out in an excess of both tetramethylurea and water, with first-order dependence on acid concentration being observed. As the concentration of water was increased, the rate of hydrolysis decreased until equimolar amounts of water and tetramethylurea were present. Subsequent addition of water had no effect on the observed rate.     

Solvent effects on acid-base behavior: Five uncharged acids in water-sulfolane solvents

An electrometric titration method utilizing glass electrodes and silver-silver bromide electrodes in a cell without liquid junction has been applied to a determination of the dissociation constants of five uncharged weak acids (HA) in four mixtures of water and sulfolane (tetramethylene sulfone) at 25°C. The acids studied were monochloroacetic, formic, benzoic, and acetic acids andp-nitrophenol, and the mole fractions (x ₂) of sulfolane in the mixed solvents were 0.2, 0.4, 0.6, and 0.8. All measurements were made at a constant ionic strength of 0.02 mole-kg^–1 in a solution containing NaBr at a molality of 0.01 mole-kg^–1. The cell was standardized by measurements of HClO₄ at molalities from 0.002 to 0.01 mole-kg^–1 and, in subsequent measurements, a solution of NaA was titrated with HClO₄. To obtain the thermodynamic pK, an activity correction derived from the Debye-Hückel theory was applied. The pK of all five acids was found to vary linearly withx ₂ in the range 0 to 0.8. By comparison of data for acetic acid in water-methanol, water-dioxane, and water-sulfolane solvents, it was shown that the results are consistent with the known properties of sulfolane (low acidity, basicity, and solvating power), but the linear variation of pK with solvent composition remains unexplained.On leave 1973–1975 from the University of Gdansk, Poland.     

Solvent effects on infrared spectra of 2-acetylthiophene in organic solvents

Infrared spectroscopy studies of 2-acetylthiophene (ACTH) in 18 different organic solvents, both polar and non-polar, were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration upsilon(C=O) of ACTH were correlated with the properties such as the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with the LSER than the AN. A six-membered ring-like hydrogen bonding structure was presented and the solvent effects of ACTH in alcohol solvents were investigated in detail.     

Solvent effects on the absorption spectra of merocyanine dyes

Solvent effects on the lowest-energy electronic transitions of two merocyanines derived from quinoline have been studied using nine different solvent parameters reported in the literature. Relative merits and deficiencies of different parameters have been assessed. From the correlation results, attempts have been made to propose a solute-solvent interaction mechanism. For an assorted set of 19 solvents, as well as for a set of nine hydroxylic solvents, excellent results are obtained with correlation equation involving E_T(30) and Hilderbrand's solubility parameter _H.     

Decomposition of hydrogen peroxide in protic and polar aprotic solvents on TS-1 heterogeneous catalyst

Kinetic parameters of H₂O₂ decomposition in methanol, propanol-1, propanol-2, acetone, and acetonitrile at 30–55°C on a TS-1 heterogeneous catalyst were determined. Recommendations are given on choice of solvents in oxidation of organic compounds with hydrogen peroxide.     

Solvent effects on tautomerism equilibria in heterocycles

. High-level ab initio quantum mechanical methods have been used to analyze the tautomeric preferences in the gas phase and in aqueous solution of three important five-member heterocycles: 4-(5-)methylimidazole, 5-hydroxyisoxazole, and 3-hydroxypyrazole. Solvent effects have been introduced by means of self-consistent reaction field (SCRF) calculations at the ab initio level using our parametrized version of the polarizable continuum model developed by Miertus, Scrocco and Tomasi (MST), including geometry relaxation upon solvation. The extent to which the MST model, and SCRF methods in general, are suitable for the study of processes of this type is discussed.     

Influence of solvents on the properties of chemical compounds

Based on Sinanolu's solvent theory in connection with a method for the calculation of the molecular volume given by Beveridge a modified continuum model is suggested. The model is tested by the determination of the conformational structure of the title compounds. The predictions obtained by this model are in good agreement with the experimentally determined data.