Reactive Intermediate Species Research Articles

Controllable synthesis of MnO2/iron mesh monolithic catalyst and its significant enhancement for toluene oxidation

A series of monolithic MnO2/iron mesh (IM) catalysts for oxidation of toluene were successfully prepared by using in situ hydrothermal growth. MnO2 can grow firmly on the IM substrates surface with a shedding rate of only 0.14%. Due to the highest Oads and high-valent Mn4+ and Fe3+ elements, the temperature at 50% and 90% toluene conversion (T50% and T90%) was 252 and 265 °C, respectively for the best performance catalyst (hydrothermal temperature of 80 °C, hydrothermal time of 12 h, and precursor manganese ion concentration of 0.03 mol/L). The catalysts also presented good water resistance and cycle performance. In-situ DRIFTS results suggesting that toluene was first rapid transformed into the reaction intermediate species (benzoate species) and then converted to CO2 and H2O. Therefore, this work provides a new direction for the research and application of IM-based monolithic catalysts.

Astrochemical significance and spectroscopy of tetratomic [H, P, S, O

Context. Phosphorus is integral to life on Earth, and its role in the chemistry of the interstellar medium is highly debated and unknown. Only a handful of phosphorus-bearing species have been detected thus far, with the most recent confirmed detection taking place in 2014. The simultaneous detection of molecules such as PO, SH, and OH indicate the possibility of reactive intermediate species existing in the interstellar medium and circumstellar envelopes of evolved stars. To explore this possibility, the [H, P, S, O] tetratomic isomer family was characterized using high level ab initio methods. Aims. The aim of this study is to provide rotational, vibrational, and electronic spectroscopic data to drive experimental and observational detection of new phosphorus and sulfur-bearing molecules. Additionally, chemical pathways are explored to explain possible reservoirs for the as of yet undetected PH and PS diatomic molecules. Methods. Coupled cluster quantum chemistry methods were used to calculate the equilibrium electronic structure followed by the anharmonic treatment of the cubic and quartic force fields to obtain accurate rotational and vibrational data. Møller–Plesset perturbation theory in conjunction with coupled cluster methods were used to explore bimolecular reaction pathways. Multi-reference methods were then used to characterize the photochemical pathways of the excited electronic states and simulate the electronic absorption spectrum. Results. The reaction between detected molecules SH and PO is highly exothermic and forms the HSPO isomer. Deeply submerged transition state barriers allow for facile isomerization to other isomers, especially HOPS. The dominant photochemical process predicted for HOPS is dissociation to form OH + PS, while that of HSPO is a combination of photodissociation to form H + SPO and SH + PO, depending on the wavelength of light absorbed. If PH and PS are formed in the early outflows from evolved stars, bimolecular reactions may act as a reservoir and partially account for their lack of detection to date. The electronic absorption spectrum is predicted to be congested in the 175–200 nm region for both HOPS and HSPO. Differentiating peaks exist >400 nm, which can be used for spectral assignment. Vibrationally corrected rotational constants and anharmonic vibrational frequencies were calculated to assist in the laboratory and observation identification of the most stable molecules. The PO stretch is predicted to be the most intense vibrational mode in both HOPS isomers, and a frequency difference of 20 cm−1 may prove to help differentiate the conformers in an experimental spectrum.

Tuning Tiδ+-Vo·-Ptδ+ interfaces over Pt/TiO2 catalysts for efficient photocatalytic oxidation of toluene

• Ti δ+ -Vo·-Pt δ+ is constructed in Pt/TiO 2 -C via reduction–oxidation treatment. • Ti δ+ -Vo·-Pt δ+ provides abundant intermediates for the photocatalysis reaction. • More reactive oxygen species can realize the direct opening of aromatic ring. • The mineralization rate of Pt/TiO 2 -C is improved by 15% compared with Pt/TiO 2 . Promoting the ring-opening process is vital to increase the mineralization of aromatic volatile organic compounds. Rational regulation of metal-support interaction is essential for the opening of the aromatic ring over Pt/TiO 2 catalysts. Herein, the Pt/TiO 2 -C catalyst with Ti δ+ -Vo·-Pt δ+ interface obtained by reverse electron transfer is successfully regulated via reduction–oxidation treatment for efficient photocatalytic degradation of toluene. This structure accelerates the pre-activation of toluene to generate abundant reactive intermediate species for the photocatalysis reaction. On the other hand, the special interface endows Pt/TiO 2 -C the ability to produce more reactive oxygen species under illumination, which can synergistically promote the direct opening of benzene ring. The Pt/TiO 2 -C shows a stronger oxidation capacity and a mineralization rate 15% higher than the traditional Pt/TiO 2 . This work proves that reduction–oxidation treatment is an effective approach to modify catalysts for air purification and provides a novel idea for the degradation of other aromatic volatile organic pollutants.

Development of a Deep-Sea Submersible Chemiluminescent Analyzer for Sensing Short-Lived Reactive Chemicals.

Based on knowledge of their production pathways, and limited discrete observations, a variety of short-lived chemical species are inferred to play active roles in chemical cycling in the sea. In some cases, these species may exert a disproportionate impact on marine biogeochemical cycles, affecting the redox state of metal and carbon, and influencing the interaction between organisms and their environment. One such short-lived chemical is superoxide, a reactive oxygen species (ROS), which undergoes a wide range of environmentally important reactions. Yet, due to its fleeting existence which precludes traditional shipboard analyses, superoxide concentrations have never been characterized in the deep sea. To this end, we have developed a submersible oceanic chemiluminescent analyzer of reactive intermediate species (SOLARIS) to enable continuous measurements of superoxide at depth. Fluidic pumps on SOLARIS combine seawater for analysis with reagents in a spiral mixing cell, initiating a chemiluminescent reaction that is monitored by a photomultiplier tube. The superoxide in seawater is then related to the quantity of light produced. Initial field deployments of SOLARIS have revealed high-resolution trends in superoxide throughout the water column. SOLARIS presents the opportunity to constrain the distributions of superoxide, and any number of chemiluminescent species in previously unexplored environments.

Highly Selective and Sensitive Detection of Breath Isoprene by Tailored Gas Reforming: A Synergistic Combination of Macroporous WO3 Spheres and Au Catalysts.

Precise detection of breath isoprene can provide valuable information for monitoring the physical and physiological status of human beings or for the early diagnosis of cardiovascular diseases. However, the extremely low concentration and low chemical reactivity of breath isoprene hamper the selective and sensitive detection of isoprene using oxide semiconductor chemiresistors. Herein, we report that macroporous WO3 microspheres whose inner macropores are surrounded by Au nanoparticles exhibit a high response (resistance ratio = 11.3) to 0.1 ppm isoprene under highly humid conditions at 275 °C and an extremely low detection limit (0.2 ppb). Furthermore, the sensor showed excellent selectivity to isoprene over five interferants that could be exhaled by humans. Notably, the selectivity to isoprene is critically dependent on the location of Au nanocatalysts and macroporosity. The mechanism underlying the selective isoprene detection is investigated in relation to the reforming of less reactive isoprene into more reactive intermediate species promoted by macroporous catalytic reactors, which is confirmed by the analysis using a proton transfer reaction quadrupole mass spectrometer. The sensor for breath analysis has high potential for simple physical and physiological monitoring as well as disease diagnosis.

First principles evaluation of the OER properties of TM−X (TM = Cr, Mn, Fe, Mo, Ru, W and Os, and X = F and S) doped IrO2 (110) surface

Using first-principles calculations, we investigated the energetics and structural properties of cation substitutional doping (TM = Cr, Mn, Fe, Mo, Ru, W, Os), anion substitutional doping (F and S), as well as a cation-anion dopant complexes (TM-X) incorporated in an IrO2 (110) surface slab. All the defect configurations resulting from substitutional doping and their complexes were found to be energetically favorable. Also, the various dopant atoms resulted in low lattice distortion on the IrO2 surface, with changes in the bond lengths. All the oxygen evolution reaction (OER) intermediate species (O, OH and OOH) were found to adsorb favorable on the various considered surface configurations. Considering the changes in bond lengths of the OH and OOH intermediate species, we found that the OOH adsorbate species disintegrated on the OsIr and WIr + FO configurations in the IrO2 surface slab to O and OH species. This implies that those configurations are unsuitable for the OER reaction. We found that the presence of the Mo, Os and W dopant atoms resulted in higher over-potential (ηOER) compared with the pristine IrO2. The electrochemical-step symmetry index (ESSI) versus ηOER showed that the MnIr + So, FeIr + Fo, CrIr + So and So dopant configurations resulted in the most improved OER activity. Thus, the consideration of the bond dissociation and free energies, the ηOER, and ESSI versus the ηOER provides significant insight towards assessing catalytic materials for the OER.

Real-time study of on-water chemistry: Surfactant monolayer-assisted growth of a crystalline quasi-2D polymer

<h2>Summary</h2> Unlike in the bulk, the hydrogen bond network of water is interrupted at water interfaces, and thus chemical reaction occurs at the water interface in a different manner than in the bulk, owning to, e.g., the possibility of templating molecules. On-water chemistry has generated highly crystalline, functional 2D materials through surfactant-monolayer-assisted interfacial synthesis (SMAIS). Yet, the details of the on-water reaction mechanism have remained unresolved. Here, by tracking the quasi-2D polyaniline film generation process using <i>in situ</i> surface-specific vibrational technique, we clarify how the polymerization reaction occurs at the water surfaces during SMAIS. We identify an aniline derivative with a positively charged terminal =NH₂ group as a key reaction intermediate species for highly crystalline film formation. A comparison of differently designed water interfaces reveals that intermediate species can be accumulated and ordered at the interface by the negatively charged surfactant headgroups, prompting highly crystalline, conductive polyaniline film formation. These results demonstrate the importance of interfacial electric fields and electrostatic interactions for controlled on-water chemistry.

Promotion effect of iron addition on the structure and CO2 hydrogenation performance of Attapulgite/Ce0.75Zr0.25O2 nanocomposite supported Cu-ZnO based catalyst

• Fe introduction improves the surface dispersion of metallic Cu on CZF x K/ATP-CZO catalysts. • Medium Fe addition enhances the formation of surface adsorbed and lattcie oxygen species and ZnO-CZO interfaces. • In-situ DRIFT is adopted to explore the CO 2 adsorption mode and reaction intermediate species. • Methanol is synthesized over CZF 0.5 K/ATP-CZO catalyst with the highest CO 2 conversion and space time yield. A series of CZF x K/ATP-CZO catalysts (x= 0, 0.3, 0.5, 1.0, 1.5 and 2.0) are applied to clarify the effects of the iron addition on the catalytic performance of CO 2 hydrogenation to CH 3 OH. The physicochemical properties and catalytic mechanism were investigated by N 2 adsorption/desorption, XRD, TEM, N 2 O chemisorption, XPS, H 2 -TPR, CO 2 -TPD and in-situ DRIFT techniques. The best catalytic performance is achieved over CZF 0.5 K/ATP-CZO catalyst, exhibiting X CO2 = 17.5%, STY CH3OH = 0.108 g/g cat. ∙h and STY CO = 0.146 g/g cat. ∙h (T = 320°C, P = 6 MPa). The formation of dispersed surface metallic Cu species and larger number of surface adsorbed and lattcie oxygen species and ZnO-CZO interfaces are detected over CZF 0.5 K/ATP-CZO due to stronger interaction between dispersed metallic Cu particles on ZnO-Fe nano-cluster and ATP-CZO composite, resulting in the superior activation ability for H 2 and CO 2 respectively. Additionally, the evidence is provided by in-situ DRIFTS under the activity test temperature (320°C) that HCOO∗ and CO* species are preferable for accumulating over CZK/ATP-CZO catalyst without Fe addition while medium Fe-modified CZF x K/ATP-CZO catalysts (CZF 0.3 K/ATP-CZO, CZF 0.5 K/ATP-CZO) catalysts are benefitial to promote the transformation of HCOO∗ species to CH 3 OH. These excessive Fe-modified CZF x K/ATP-CZO catalysts (CZF 1.0 K/ATP-CZO, CZF 2.0 K/ATP-CZO) are more easily to produce CH 4 via formate pathway (CO 2 * → HCOO* → HCO* → CH* → CH 4 *). The abundant population and high transformation activity of formate intermediate species over CZF 0.5 K/ATP-CZO give a strong positive effect on the CO 2 hydrogenation to methanol performance. The strong interactions between dispersed metallic Cu species and larger number of surface adsorbed and lattcie oxygen species and ZnO-CZO interfaces give rise to favorable methanol synthesis performances over CZF0.5K/ATP-CZO catalyst.

Ligand Radical Mediated Water Oxidation by a Family of Copper o-Phenylene Bis-oxamidate Complexes.

Understanding the reactivity landscape for the activation of water until the formation of the O-O bond and O2 release in molecular chemistry is a decisive step in guiding the elaboration of cost-effective catalysts for the oxygen-evolving reaction (OER). Copper(II) complexes have recently caught the attention of chemists as catalysts for the 4e-/4H+ water oxidation process. While a copper(IV) intermediate has been proposed as the reactive intermediate species, no spectroscopic signature has been reported so far. Copper(III) ligand radical species have also been formulated and supported by theoretical studies. We found, herein, that the reactivity sequence for the water oxidation with a family of Copper(II) o-phenylene bis-oxamidate complexes is a function of the substitution pattern on the periphery of the aromatic ring. In-situ EPR, FTIR, and rR spectroelectrochemical studies helped to sequence the elementary electrochemical and chemical events leading toward the O2 formation selectively at the copper center. EPR and FTIR spectroelectrochemistry suggests that ligand-centered oxidations are preferred over metal-centered oxidations. rR spectroelectrochemical study revealed the accumulation of a bis-imine bound copper(II) superoxide species, as the reactive intermediate, under catalytic turnover, which provides the evidence for the O-O bond formation during OER.

Chemical Forms of Mercury in Pilot Whales Determined from Species-Averaged Mercury Isotope Signatures

Marine mammals detoxify organic methylmercury (MeHg) as inorganic mercury selenide (HgSe), yet the nature of the reaction intermediate species and the tissue-specific redistribution of Hg species in the body are unknown. We report that the identity and proportion of the dominant Hg species in long-finned pilot whale (Globicephala melas) tissues can be obtained from the bulk variation of isotopic values of δ 202 Hg against the extent of demethylation (percentage of total Hg as MeHg, %MeHg) using an alternating regularized inversion method. Our analysis of isotope data from two previous studies supports that MeHg is demethylated as a tetraselenolate species (Hg(Sec)4), which further transforms into HgSe. Hg(Sec)4 occurs in the liver, kidneys, muscle, heart, and brain, whereas HgSe biomineralization occurs only in the liver and kidneys. This study provides a mathematical approach that facilitates probing the molecular-level chemistry of mercury in biological tissues using bulk isotopic data.

Insights into the Electron-Transfer Mechanism of Permanganate Activation by Graphite for Enhanced Oxidation of Sulfamethoxazole.

Many reagents as electron sacrificers have been recently investigated to induce decomposition of permanganate (KMnO4) to produce highly reactive intermediate Mn species toward oxidation of organic contaminants; however, this strategy meanwhile causes low KMnO4 utilization efficiency. This study surprisingly found that graphite can mediate direct electron transfer from organics (e.g., sulfamethoxazole (SMX)) to KMnO4, resulting in high KMnO4 utilization efficiency, rather than reductive sites of graphite-induced conversion of KMnO4 to highly reactive intermediate Mn species. The galvanic oxidation process (GOP) and comparative experiments of different organic contaminants prove that the KMnO4/graphite system mainly extracts electrons from organic contaminants via a one-electron pathway instead of a two-electron pathway. More importantly, the KMnO4/graphite system has superior reusability, graphite can keep a long-lasting reactivity, and the KMnO4 utilization efficiency elevates significantly after each cycle of graphite. The transformation of SMX in the KMnO4/graphite system mainly includes self-coupling, hydroxylation, oxidation, and hydrolytic reaction. The work will improve insights into the electron-transfer mechanism and unveil the advantages of efficient KMnO4 utilization in the KMnO4-based technologies in environmental remediation.

Electrochemical Generation and Use in Organic Synthesis of C-, O-, and N-Centered Radicals.

During the last decade several research groups have been developing electrochemical procedures to access highly functionalized organic molecules. Among the most exciting advances, the possibility of using free radical chemistry has attracted the attention of the most important synthetic groups. Nowadays, electrochemical strategies based on these species with a synthetic purpose are published continuously in scientific journals, increasing the alternatives for the synthetic organic chemistry laboratories. Free radicals can be obtained in organic electrochemical reactions; thus, this review reassembles the last decade's (2010-2020) efforts of the electrosynthetic community to generate and take advantage of the C-, O-, and N-centered radicals' reactivity. The electrochemical reactions that occur, as well as the proposed mechanism, are discussed, trying to give clear information about the used conditions and reactivity of these reactive intermediate species.

Amphiphilic catalyst for decomposition of unsaturated polyester resins to valuable chemicals with 100% atom utilization efficiency

Plastic waste is increasingly aggravating environmental pollution problems. Unsaturated polyester resin is one kind of thermoset resins. Its three-dimensional network endows it good mechanical and chemical properties, but made its degradation and recovery challenging. Here we report a novel and efficient reaction system consisting of amphiphilic p-toluenesulfonic acid/acetic acid aqueous solution for decomposition of unsaturated polyester resin by acyl exchange reaction. Amphiphilic p-toluenesulfonic acid facilitated the entrance of itself and solvent into the resin and consequently promoted catalytic cleavage of ester bonds in unsaturated polyester resin. Water, as a co-catalyst, stabilized the key reaction intermediate species, which reduced largely the overall reaction activation energy and thus accelerated the degradation of the resins. Unsaturated polyester resin was completely degraded and converted to the valuable chemicals at 180 °C, which can be then recycled by a new separation process. The degradation products were mainly ethylene glycol diacetate, phthalic acid, and copolymer products of styrene and maleic anhydride, with the mass ratio of 43.18%, 24.81% and 44.16% to raw unsaturated polyester resin waste, respectively. The atoms of unsaturated polyester resin were completely incorporated into the high-value degradation products with zero production of waste. Hence, this work provides a green, economical, practical strategy to degrade waste unsaturated polyester resin and recycle high-value chemicals with an 100% atom utilization efficiency.

Mechanistic study of efficient producing CO2 electroreduction via 2D metal-organic frameworks M3(2,3,6,7,10,11-hexaiminotriphenylene)2 surface

M3(HITP)2 prototype 2D MOFs compounds possess a high catalytic activity for CO2 electroreduction to hydrocarbon fuels at low overpotentials. However, the mechanism path selectivity is still a huge challenge during the production of final product species at low potentials. The transition metal coordinated nitrogen active center of M3(HITP)2 catalysts is identified to strong M-C bound coupling, leading to a high selectivity towards CH3OH, Cr3(HITP)2, and Mn3(HITP)2. Further, it also demonstrates a high efficiency catalytic performance for generating CH4. In addition, linear scaling relations and volcano plot of thermodynamic stability are also investigated and compared, suggesting that some M3(HITP)2 compounds have effective selectivity performance to CO2 reduction reaction (CO2RR). Furthermore, linear scaling relationships and volcano plots between different intermediate species are common descriptors used to identity an excellent catalyst for CO2 electroreduction. In order to get a further exploration of the reaction mechanism pathway and final products for the CO2RR, authors considered all the intermediates. It showed that the most favorable reaction pathway and intermediate species can be determined by the metal-carbon (M-C) or metal-oxygen (M-O) bounds. The reduction of CO2 into CH4 with a high overpotential depends on the thermodynamic rate-determining step (RDS) of the largest limiting potential along the minimum energy path, the electronic structure of these catalysts also plays an important role in the selective CO2RR.

The spatial distribution of hydrogen and oxygen atoms in a cold atmospheric pressure plasma jet

Cold atmospheric pressure plasma jets (CAPJs) are an emerging technology for the localised treatment of heat sensitive surfaces. Adding humidity to the CAPJ’s feed gas yields an effective production of highly reactive intermediate species, such as hydrogen atoms, oxygen atoms, and hydroxyl radicals, among others, which are key species for biomedical applications. This study focusses on the effluent of the CAPJ kINPen, which was operated with argon feed gas and a humidity admixture of 3000 ppm, while a gas curtain was used to limit the diffusion of ambient air into the effluent. The axial and radial density distribution of O and H atoms is measured by means of picosecond two-photon absorption laser induced fluorescence spectroscopy (ps-TALIF). A maximum O atom density of (3.8 ± 0.7) × 1015 cm−3 and a maximum H atom density of (3.5 ± 0.7) × 1015 cm−3 are found at the nozzle of the plasma jet. The experimental results are compared to a two-dimensional reacting flow model that is coupled with a local zero-dimensional plasma chemical model. With this model, the main H and O atom production mechanisms are determined to be the dissociation of H2O and O2 in the plasma zone of the plasma jet. The latter indicates, that a significant amount of oxygen (1%) was present inside the device. The reaction of OH with O atoms represents the main consumption pathway for O atoms and is at the same time a significant production pathway for H atoms. The main consumption of H atoms is through a three-body reaction including O2 to form HO2, which consumes more H and O atoms to form OH. It is pointed out, that most of the species are produced in the plasma zone, and that O and H atoms, OH and HO2 radicals, and O2 and H2O molecules are strongly connected.

USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTI-RADICAL (НО∙) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMOYL FRAGMENT II. DERIVATIVES OF 2’,4’-DIHYDROXYCHALCONE, FLAVANONE AND FLAVONE, CONTAINING A HYDROXY GROUP IN POSITION 7

42 derivatives of 2’,4’-dihydroxychalcone, flavanone and flavone, containing the hydroxy group in position 7 (ring "A"), as well as substituents in the ring "B", have been studied.The aim is to study the quantum-chemical parameters of 2',4'-dihydroxychalcone, flavanone and flavone derivatives containing a hydroxy group in position 7, in order to identify the effect of substituents on Mulliken charges (a.e) in the aromatic core "A", bond numbers (Nµ), the unsaturation index (IUA) and the electron density of the carbon atoms of the cinnamoyl fragment.Materials and methods. The listed above parameters have been calculated by the semi-empirical method PM7 (WinMopac 2016 program) on the workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM.Results. The analysis of the values of quantum-chemical parameters, as well as their comparison with the corresponding indicators presented in Report I, revealed a number of important features associated with the influence of the hydroxy group in position 7 (ring "A") on the studied quantum-chemical parameters of molecules. It has been established that the hydroxy group in the ring “A” does not significantly affect the Mulliken charge and the electron density of the carbon atoms of the propenone unit C-7→C-8→C-9. On atom C-9 (carbonyl carbon), the Mulliken charge always has a positive value, and the electron density is about 3.4670-3.4840 for all three groups of compounds. The transition from 2’,4’-dihydroxychalcone to flavanone and flavone by the formation of the pyrone heterocycle, is accompanied by an increase in the negative charge on C-8, which can be explained by the involvement of the oxygen heteroatom in the transmission of electronic effects. The hydroxy group in the ring “A”, has practically no effect on the charge and electron density of atoms. An analysis of the values of bond numbers and unsaturation indices suggests that atoms C-1 of 2’,4’-dihydroxychalcone and 7-hydroxyflavanone derivatives, are characterized by the lowest Nµ value; the lowest bond numbers are characteristic for atom C-8 derivatives of 7-hydroxyflavone. Consequently, the primary attack of the HO·radical will be directed at C-1 (in chalcones and flavanones) and at C-8 in flavones.Conclusion. The performed quantum-chemical calculations make it possible to analyze the effect on the main quantum-chemical parameters of the molecule, which can be useful in predicting the biological activity of flavanoid compounds due to their antiradical effect on reactive oxygen intermediate species (ROIs).

Anti-Opioid Antibodies in Individuals Using Chronic Opioid Therapy for Lower Back Pain.

In addition to the risk of developing opioid use disorder (OUD), known side-effects of long-term opioid use include chronic inflammation and hyperalgesia, which may arise from immune responses induced following chronic opioid use. To investigate this hypothesis, blood samples were obtained from individuals with chronic back pain who were either chronically taking prescription opioids or had minimal recent opioid exposure. Patient samples were analyzed using an enzyme-linked immunosorbent assay (ELISA) against hydrocodone- or oxycodone-hapten conjugates to assess the levels of antibodies present in the samples. While no specific response was seen in opioid-naïve subjects, we observed varying levels of anti-opioid IgM antibodies in the exposed subjects. In these subjects, antibody formation was found to be weakly correlated with current reported daily opioid dose. Other drugs of abuse found to elicit an immune response have been shown to generate advanced glycation end-products (AGEs) through reaction with glucose and subsequent modification of self-proteins. Investigations into this potential mechanism of anti-opioid antibody production identified reduced the formation of reactive intermediate species upon norhydrocodone reaction with glucose in comparison with nornicotine, thus identifying potentially important differences in hapten processing to yield the observed adaptive immune response.

Unraveling the reaction mechanism of co-reactant free in-situ cathodic solid state ECL of Ru(bpy)32+ molecule immobilized on Nafion coated nanoporous gold electrode

The electrochemiluminescence (ECL) of Ru(bpy)32+ molecule which is immobilized on Nafion coated nanoporous gold electrode (Ru(bpy)32+/Nafion/NPG) is investigated without involving any additional co-reactant in 0.1 M phosphate buffer solution (PBS) at pH 7.4 and the observed results are compared with Ru(bpy)32+ molecule immobilized on Nafion coated polycrystalline gold (Ru(bpy)32+/Nafion/pc-Au). Because of high surface area volume ratio and more active sites on NPG, the obtained co-reactant free unusual cathodic ECL signal at less cathodic potentials (0.1 V vs Ag/AgCl) showed 40 times higher intensity on Ru(bpy)32+/Nafion/NPG when compared with Ru(bpy)32+/Nafion/pc-Au in PBS (pH 7.4). Interestingly, this kind of ECL signal is not observed in the case of Ru(bpy)32+ molecule which is immobilized on Nafion coated glassy carbon (GC) and polycrystalline platinum (pc-Pt) electrodes. Based on the detailed experiments on effect of different pH, various direction of scanning potential and in-situ spectroelectrochemical studies, we proposed a new reaction mechanism for the unusual cathodic ECL on Ru(bpy)32+/Nafion/NPG. Upon electrochemical oxidation on Ru(bpy)32+/Nafion/NPG at higher potential, the stored Ru(bpy)32+ is converted into Ru(bpy)33+ at the same time generated reactive intermediate species like OH radical from the conversion of Au(OH)3 to Au0 during the reduction process leads energetic electron transfer reaction to proceed the excited state of Ru(bpy)32+ and then emits light. Unlike the conventional ECL system, this kind of co-reactant free in-situ generated solid state ECL approach offers to the scope in various bio analytical applications.

Reactivity of Cyanide and Thiocyanate Towards the Nitrosyl Carbonyl [Co(CO)3(NO)

The reaction of equimolar amounts of [Co(CO)3(NO)] and [PPN]CN, PPN+ = (PPh3)2N+, in THF at room temperature resulted in ligand substitution of a carbonyl towards the cyanido ligand presumably affording the complex salt PPN[Co(CO)2(NO)(CN)] as a reactive intermediate species which could not be isolated. Applying the synthetic protocol using the nitrosyl carbonyl in excess, the title reaction afforded unexpectedly the novel complex salt PPN[Co2(μ‐CN)(CO)4(NO)2] (1) in high yield. Because of many disorder phenomena in crystals of 1 the corresponding NBu4+ salt of 1 has been prepared and the molecular structure of the dinuclear metal core in NnBu4[Co2(μ‐CN)(CO)4(NO)2] (2) was determined by X‐ray crystal diffraction in a more satisfactory manner. In contrast to the former result, the reaction of [PPN]SCN with [Co(CO)3(NO)] yielded the mononuclear complex salt PPN[Co(CO)2(NO)(SCN‐κN)] (3) in good yield whose molecular structure in the solid was even determined and its composition additionally confirmed by spectroscopic means.

Simulation of the environmental degradation of diuron (herbicide) using electrochemistry coupled to high resolution mass spectrometry

The environmental degradation of contaminants such as pesticides can hinder the ability of analytical instruments, even high-performance system such as mass spectrometry, to detect and quantify contamination reliably. There is thus a need for developing synthetic approaches that allow the fast identification of contaminants markers that can be later support quantitative analysis. Combining electrochemical cell (EC), liquid chromatography (LC) and electrospray mass spectrometry (MS) (online EC-MS and offline EC-LC-MS) allows the rapid identification of some oxidation products of diuron (DIU) in the absence and in the presence of glutathione. The structural elucidation of DIU oxidation products was based on retention time, m/z ratio in positive mode and fragmentation pattern. Reactions such as hydrolytic dechlorination, hydroxylation, dehydrochlorination, dehydrogenation/hydrogenation, conjugation and dimerization have been successfully mimicked serving applications such as drug metabolism and environmental degradation simulation. The resort to electrochemistry to simulate naturally occurring reaction has been of particular interest for the production of reactive intermediate species. In this study, quinone imines, highly electrophilic chemical intermediates, have been identified as transformation products during the oxidative metabolism of diuron for the first time. The obtained results, supported by theoretical calculations, are useful for predicting and understanding the oxidative DIU degradation pathway.