Synthesis and Verification of 9,10-Diphenylanthracene and Its Utility as a Fluorescer in a Peroxyoxalate Chemiluminescence System. An Organic Laboratory Project Integrating Synthesis with Fluorescence and Chemiluminescence

A project for the organic laboratory integrating the organic synthesis of 9,10-diphenylanthracene with fluorescence and chemiluminescence is described. The fluorescent compound is synthesized from anthraquinone by reaction with phenyllithium and subsequent hydrolysis and reduction with KI and NaH₂PO₂ in acetic acid. The structure of the product is verified by its melting point and by IR, ¹H NMR, and fluorescence spectroscopy. A peroxyoxalate chemiluminescent reaction using bis(2-butoxycarbonyl-3,4,6-trichlorophenyl) oxalate and hydrogen peroxide as the energy source is tested. The chemiluminescence emittance spectrum of the prepared diphenylanthracene is found to be essentially identical to that of the fluorescence spectrum of the same compound. Finally, the kinetics of the chemiluminescent reactions using different intensity-modifiers are monitored by measuring intensity-versus-time decay curves.     

Flow injection determination of hydrogen peroxide by means of a solid-state-peroxyoxalate chemiluminescence reactor

A solid-state reactor for detection of hydrogen peroxide in aqueous samples by peroxyoxalate chemiluminescence is described. Bis(2,4,6-trichlorophenyl)oxalate in solid form is packed into a bed reactor, which eliminates mixing problems and facilitates the instrumental development. Perylene is added as a sensitizer to a water/acetonitrile (20:80) carrier stream into which the samples (200–600 μl) are injected. Detection limits of 6 × 10^?9 M H₂O₂ (0.2 μg l^?1) are obtained with both a commercial and a home-made luminescence detector. Calibration graphs are linear up to 10^?5 M. The r.s.d. for 2 × 10^?7 M (6.7 μg^?1) hydrogen peroxide (n = 10) is 2.8%. Sample throughput is ca. 120 h^?1.     

Determination of Hydrogen Peroxide Concentrations By Flow Injection Analysis Based On the Enhanced Chemiluminescent Reaction Using Peroxidase

Abstract

The technique of flow injection analysis was employed in the determination of hydrogen peroxide. the method was based on the chemiluminescence reaction of luminol with H₂O₂ which is catalyzed by horseradish peroxidase and enhanced by p-iodophenol. Hydrogen peroxide was linearly detected in the range 10^?6M-10^?4M by measuring the maximum intensity of light emitted. the detection limit is about 1 · 10^?6M hydrogen peroxide. Transition metal cations at millimolar concentrations do not have any interference on the determination of hydrogen peroxide by FIA based on the enhanced chemiluminescent reaction. This technique is relatively rapid and simple, and permits measurement of up to 80 samples/hr using generally available equipment.     

Sensing and catalytic decomposition of hydrogen peroxide by silicon carbide nanotubes: A DFT study

In this study, by carrying out detailed density functional theory calculations, we investigate the adsorption and stepwise decomposition of hydrogen peroxide (H₂O₂) over (6,0) and (7,0) zigzag silicon carbide nanotubes (SiCNTs). The results indicate that the H₂O₂ can be adsorbed on the exterior surface of the SiCNTs with noticeable adsorption energies and charge transfers. To gain insight into the catalytic activity of the surface, the interaction between the H₂O₂ and SiCNT is analyzed by detailed electronic analysis such as adsorption energy, charge density difference and activation barrier. The decomposition of H₂O₂ into O₂ and H₂ species can be viewed as the kinetically preferred reaction pathway for dehydrogenation of hydrogen peroxide over SiCNTs. There is also a curvature effect on the dehydrogenation kinetics of hydrogen peroxide, that small diameter SiCNTs with large curvature would be beneficial for decomposition of H₂O₂. © 2015 Wiley Periodicals, Inc.     

Peroxyoxalate chemiluminescence of 1,4-dihydroxy-3-methyl-thioxanthone and quenching effect of β-cyclodextrin

The chemiluminescence generated from the reaction of bis(2,4,6-trichlorophenyl) oxalate (TCPO), hydrogen peroxide and 1,4-dihydroxy-3-methyl-thioxanthone (DMT) was investigated. Effects of reacting components, solvent and concentrations of TCPO, sodium salicylate, hydrogen peroxide and DMT were studied and their optimal values were determined. In addition, the influences of β-Cyclodextrin (β-CD) on the peroxyoxalate chemiluminescence (PO-CL) system of DMT were examined at optimized condition. The results showed that the presence of β-CD causes both enhancing and quenching effects on PO-CL system of DMT based upon its concentration. The Stern–Volmer quenching constant (K _q) was evaluated as 2.32?×?10⁴?M^?1 (R ^2?= 0.991) by creating a linear regression plot on experimentally obtained data. This study resulted in satisfactorily determination of β-CD in the range 5.0?×?10^?6 to 1.0?×?10^?4?M.     

A Multicommuted Flow‐based System for Hydrogen Peroxide Determination by Chemiluminescence Detection Using a Photodiode

Abstract

A simple, rapid, and automated assay for hydrogen peroxide in pharmaceutical samples was developed by combining the multicommutation system with a chemiluminescence (CL) detector. The detection was performed using a spiral flow‐cell reactor made from polyethylene tubing that was positioned in front of a photodiode. It allows the rapid mixing of CL reagent and analyte and simultaneous detection of the emitted light. The chemiluminescence was based on the reaction of luminol with hydrogen peroxide catalyzed by hexacyanoferrate(III).

The feasibility of the flow system was ascertained by analyzing a set of pharmaceutical samples. A linear response within the range of 2.2–210 µmol l^?1 H₂O₂ with a LD of 1.8 µmol l^?1 H₂O₂ and coefficient of variations smaller than 0.8% for 1.0×10^?5 mol l^?1 and 6.8×10^?5 mol l^?1 hydrogen peroxide solutions (n=10) were obtained. Reagents consumption of 90 µg of luminol and 0.7 mg of hexacyanoferrate(III) per determination and sampling rate of 200 samples per hour were also achieved.     

Chemiluminescence of Electrochemically Oxidized 9‐(Phenylthiophosphoryloxymethylidene)‐10‐methylacridan Derivatives

The electrochemistry and electrochemiluminescence (ECL) properties of acridan phosphate ester are reported. Electrochemical oxidation of 9‐(phenylthiophosphoryloxymethylidene)‐10‐methylacridan disodium salt (Compound 1) yields the corresponding acridinium ester. The latter undergoes a fast reaction with hydrogen peroxide forming an intermediate, which produces electronically excited 9‐methyl acridone and emits blue light after relaxation to the ground state. The electrochemical oxidation of this compound appears to occur in two one‐electron steps and light emission is observed for both steps. The chemiluminescence reaction could also be triggered by electrochemical oxidation of Compound 1 in the absence of H₂O₂ when the solution was saturated with O₂. Mechanisms for these reactions based on ECL, voltammetry and in situ UV‐vis identification of the oxidation products are proposed. Due to the low electrode potential required to achieve ECL emission and the occurrence of light emission in the absence of hydrogen peroxide, this compound is proposed as a label for rapid and sensitive determination of biomolecules in automated analysis.     

Selective Oxidations Using a Cytochrome P450 Enzyme Variant Driven with Surrogate Oxygen Donors and Light

Cytochrome P450 monooxygenase enzymes are versatile catalysts, which have been adapted for multiple applications in chemical synthesis. Mutation of a highly conserved active site threonine to a glutamate can convert these enzymes into peroxygenases that utilise hydrogen peroxide (H₂O₂). Here, we use the T252E-CYP199A4 variant to study peroxide-driven oxidation activity by using H₂O₂ and urea-hydrogen peroxide (UHP). We demonstrate that the T252E variant has a higher stability to H₂O₂ in the presence of substrate that can undergo carbon-hydrogen abstraction. This peroxygenase variant could efficiently catalyse O-demethylation and an enantioselective epoxidation reaction (94 % ee). Neither the monooxygenase nor peroxygenase pathways of the P450 demonstrated a significant kinetic isotope effect (KIE) for the oxidation of deuterated substrates. These new peroxygenase variants offer the possibility of simpler cytochrome P450 systems for selective oxidations. To demonstrate this, a light driven H₂O₂ generating system was used to support efficient product formation with this peroxygenase enzyme.     

Synthesis of Hydrogen Peroxide Using Dielectric Barrier Discharge Associated with Fibrous Materials

A new synthesis pathway toward hydrogen peroxide has been investigated using non-thermal plasma. This work is aimed at studying the activation of oxygen/hydrogen mixtures by a cylindrical dielectric barrier discharge. An experimental device has been especially developed for this application, it mainly differs from other cylindrical discharges in that the liquid ground electrode, and subsequently the reactor, can be regulated in temperature. The formation of hydrogen peroxide is reported (1) in a gas phase discharge and (2) in surface discharge. The gas phase discharge, characterized by an empty discharge gap, lead to a low activation of O₂ into O₂/H₂ mixtures and poor selectivity toward H₂O₂. The modification of the discharge into a surface discharge, by introducing in the gap fibrous materials, considerably improves the efficiency of the process. The influence of the temperature on H₂O₂ formation is discussed and correlated to the formation of a water layer on fibre surface. This layer appears to be a crucial point into H₂O₂ plasma synthesis. The presence of TiO₂ on the fibre surface is reported as improving the stabilisation of hydrogen peroxide. The formation of a complex between H₂O₂ and TiO₂ is suggested and discussed. The formation of H₂O₂ in the gas phase or in the aqueous condensed phase is finally discussed. The investigation of the influence of the reactant gas composition and the presence or not of water, lead to the conclusion that (1) both H₂ and O₂ are required to achieve the synthesis reaction; (2) H₂O₂ is formed in the gas phase and then solubilised and/or stabilised in the water layer. A global reaction pathway is finally proposed to summarize the synthesis reaction.     

The Crystal Structures of Peroxonium Hexafluoroantimonate H3O2SbF6 and Bis(dihydrogenperoxo)hydrogen Hexafluoroantimonate H5O4SbF6

Protonated hydrogen peroxide is produced from the reaction of antimony pentafluoride with bis(trimethylsilyl)peroxide in the presence of hydrogen fluoride. Depending on the stoichiometry of the reaction mixture, the compounds H₃O₂SbF₆ and H₅O₄SbF₆ are formed, which are stable up to room temperature and have been characterized by X-ray crystallography. The structure of the H₃O₂⁺ ion is shown on the right.     

A Highly Selective and Sensitive Chemiluminescent Probe for Real-Time Monitoring of Hydrogen Peroxide in Cells and Animals

Selective and sensitive molecular probes for hydrogen peroxide (H₂O₂), which plays diverse roles in oxidative stress and redox signaling, are urgently needed to investigate the physiological and pathological effects of H₂O₂. A lack of reliable tools for in vivo imaging has hampered the development of H₂O₂ mediated therapeutics. By combining a specific tandem Payne/Dakin reaction with a chemiluminescent scaffold, H₂O₂-CL-510 was developed as a highly selective and sensitive probe for detection of H₂O₂ both in vitro and in vivo. A rapid 430-fold enhancement of chemiluminescence was triggered directly by H₂O₂ without any laser excitation. Arsenic trioxide induced oxidative damage in leukemia was successfully detected. In particular, cerebral ischemia-reperfusion injury-induced H₂O₂ fluxes were visualized in rat brains using H₂O₂-CL-510 , providing a new chemical tool for real-time monitoring of H₂O₂ dynamics in living animals.     

A Chemiluminescence Microarray Based on Catalysis by CeO2 Nanoparticles and Its Application to Determine the Rate of Removal of Hydrogen Peroxide by Human Erythrocytes

In this work, cerium oxide nanoparticles are capable of strongly enhancing the chemiluminescence (CL) of the luminol–hydrogen peroxide (H₂O₂) system. Based on this, a microarray CL method for the determination of the removal rate constant of H₂O₂ by human erythrocytes has been developed. It is providing direct evidence for a H₂O₂-removing enzyme in human erythrocytes that acts as the predominant catalyst. A reaction mechanism is discussed. The proposed microarray CL method is sensitive, selective, simple and time-saving, and has good reproducibility and high throughput. Relative CL intensity is linearly related to the concentration of H₂O₂ in the range from 0.01 to 50 μM. The limit of detection is as low as 6.5?×?10^?11 M (3σ), and the relative standard deviation is 2. 1 % at 1 μM levels of H₂O₂ (for n?=?11).     

Pre-Chemiluminescent biexponential degradation of bis(2,4-dinitrophenyl) oxalate in hydrogen peroxide-acetonitrile

The pre-chemiluminescent hydrogen peroxide-bis(2,4-dinitrophenyl) oxalate reaction has been studied in order to understand better its role in peroxyoxalate chemiluminescence. The reaction is shown to be first order in each reactant. An unusual biexponential degradation of the oxalate occurs which suggests that it exists in solution as two conformations that react with hydrogen peroxide at different rates. Inclusion of the fluorophor 9,10-diphenylanthracene does not affect the reaction rate.     

Pd(111), Pd(100)及Pd(110)表面H2和O2直接合成H2O2的密度泛函理论研究

采用周期性密度泛函理论研究了H₂和O₂在Pd(111),Pd(100)及Pd(110)表面上直接合成H₂O₂的反应机理,对反应的主要基元步骤进行了计算和分析.结果表明,Pd(111)表面对H₂O₂直接合成的催化选择性最好,表面原子密度较低的Pd(100)表面和Pd(110)表面上含有O-O键的表面物种解离严重,不利于H₂O₂的生成.H₂O₂的选择性与含有O-O键表面物种的O-O键能和表面物种的结合能有关.含有O-O键的表面物种在表面的结合能越大,越容易发生解离,不利于形成H₂O₂.     

Peroxidase-dependent fluorescence decrease of carboxyfluorescein and its enhancement by liposome encapsulation

The fluorescence intensity of 5(6)-carboxyfluorescein (CF) was decreased by addition of horseradish peroxidase (HRP) and hydrogen peroxide (H₂O₂). The reaction inside a liposome containing CF and HRP on addition of H₂O₂ was measured fluorometrically after destruction of the liposome with Triton X-100. The reaction efficiency was higher than that without liposome because CF and HRP were concentrated inside the latter. The determination of H₂O₂ can be performed with a smaller amount of HRP by liposome encapsulation.     

Direct synthesis of hydrogen peroxide from H2/O2 using Pd/Al2O3 catalysts

Pd/Al₂O₃ catalysts were prepared by the impregnation method and were used for the direct formation of hydrogen peroxide from H₂ and O₂. The H₂O₂ concentration and selectivity were strongly dependent on the solubility of hydrogen in the reaction medium. The modification of the support by halogenate has a beneficial effect on the selectivity. The state of the active Pd on Pd/Al₂O₃ catalysts was studied using X-ray photoelectron spectroscopy, and Pd(0) was found to be active.     

Oxidant Effect of H2O2 for the Syntheses of Quinoline Derivatives via One-Pot Reaction of Aniline and Aldehyde

A convenient one-pot method for the synthesis of substituted quinolines via the reaction of aniline and aldehyde in the presence of a Lewis acid (AlCl₃) and an oxidant (H₂O₂) has been developed. Hydrogen peroxide was found to promote the reaction by its function as a hydrogen hunter, hindering the formation of by-product N-alkylaniline. The effect of the oxidant on the yield and selectivity was studied. When the molar ratio of aniline, n-butyraldehyde, and H₂O₂ was 1:3:0.5 at 25 °C, the yield of 3-ethyl-2-propylquinoline was improved from 64% (reaction without H₂O₂) to 84% (with H₂O₂), and the quinoline selectivity was improved to almost 100%. Moreover, the reaction time was obviously reduced. The substituent effect was also investigated in this work.     

Determination of carbonyl compounds in air by HPLC using on-line analyzed microcartridges,fluorescence and chemiluminescence detection

Summary Sensitive and selective detection of dansylhydrazones of atmospheric carbonyl compounds (aldehydes and ketones) can be achieved using high performance liquid chromatography (HPLC) with fluorescence or chemiluminescence detection. The carbonyl compounds are derivatized by drawing air through small glass cartridges packed with porous glass particles impregnated with dansylhydrazine. After sampling, the contents of the cartridges are analyzed on-line by using a small plug of water (200 L) to transfer and focus the hydrazone derivatives at the head of a HPLC column. Greatly increased sensitivity over traditional methods derives from 1) analysis of the entire contents of the sampling cartridge, and 2) detection by fluoresence or peroxyoxalate chemilum-inescence. Results are compared for photo-initiated and H₂O₂-initiated peroxyoxalate chemiluminescence. This novel and practical system enables the detection of sub-ppbv concentrations of formaldehyde, acetaldehyde, acetone and higher carbonyls in air using relatively short sampling times.     

A Highly Selective and Sensitive Chemiluminescent Probe for Real‐Time Monitoring of Hydrogen Peroxide in Cells and Animals

Selective and sensitive molecular probes for hydrogen peroxide (H₂O₂), which plays diverse roles in oxidative stress and redox signaling, are urgently needed to investigate the physiological and pathological effects of H₂O₂. A lack of reliable tools for in vivo imaging has hampered the development of H₂O₂ mediated therapeutics. By combining a specific tandem Payne/Dakin reaction with a chemiluminescent scaffold, H₂O₂‐CL‐510 was developed as a highly selective and sensitive probe for detection of H₂O₂ both in vitro and in vivo. A rapid 430‐fold enhancement of chemiluminescence was triggered directly by H₂O₂ without any laser excitation. Arsenic trioxide induced oxidative damage in leukemia was successfully detected. In particular, cerebral ischemia‐reperfusion injury‐induced H₂O₂ fluxes were visualized in rat brains using H₂O₂‐CL‐510 , providing a new chemical tool for real‐time monitoring of H₂O₂ dynamics in living animals.