Product P1 Research Articles

Experimental and theoretical insights into the influence of gamma irradiation degradation products of N,N,N′,N′-tetraoctyl diglycolamide on extraction efficiency toward trivalent f-elements

Understanding the effect of radiation rays on N,N,N′,N′-tetraoctyl diglycolamide (TODGA) based solvent extraction systems is an essential task for establishing and optimizing related extraction processes in nuclear industries. However, the influence of various radiolysis degradation products on extraction efficiency and the mechanism involved still remain elusive. In this work, the radiolysis degradation products of TODGA were analyzed with the aid of high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) technique and documented results, followed by the successful synthesis of ten radiolysis degradation products P1–P10. The extraction ability of each main degradation product towards Eu(III) and their effects on the extraction performance of TODGA system were systematically studied. These radiolysis degradation products with diverse chemical structures were found to reveal different roles in extraction such as serving as co-extractant and synergist, in which P2 resemblance in structure to TODGA offers the highest extraction ability among others, thus mitigating the decrease of extraction efficiency. Mechanism investigations including slope analysis and density functional theory (DFT) calculations reveal that P2 is involved as one of the extracted species in the complexation with Eu(III) in its first coordination sphere. These findings provide in-depth experimental and theoretical guidance on the molecular scale for designing TODGA-based metal separation processes.

Theoretical investigation on degradation of CH[triple bond, length as m-dash]CCH2OH by NO3 radicals in the atmosphere.

A detailed computational investigation is executed on the reaction between NO3 and CH[triple bond, length as m-dash]CCH2OH at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) level. Addition/elimination and H-abstraction mechanisms are found for the NO3 + CH[triple bond, length as m-dash]CCH2OH reaction, and they could compete with each other. The most feasible addition/elimination pathway through a series of central-C addition, 1,4-H migration to generate intermediates IM1 (CHCONO2CH2OH) and IM3 (CH2CONO2CH2O), and then IM3 directly decompose into product P2 (CH2CONO2CHO + H). The dominant H-abstraction pathway is abstracting the H atom of the -CH2- group to generate h-P1 (CHCCHOH + HNO3). RRKM-TST theory was used to compute the kinetics and product branching ratios of the NO3 + CH[triple bond, length as m-dash]CCH2OH reaction at 200-3000 K. The rate constants at 298 K are consistent with the experimental values. The lifetime of CH[triple bond, length as m-dash]CCH2OH is estimated to be 59.72 days at 298 K. The implicit solvent model was used to examine the solvent effect on the total reaction. Based on the quantitative structure-activity relationship (QSAR) model, the toxicity during the degradation process is increased towards fish, and decreased towards daphnia and green algae.

Mechanism and stereoselectivity of epoxidation reaction of a β-himachalene derivative: Insights from DFT, molecular docking, ADMET, and molecular dynamics investigations

Epoxidation of a β-himachalene derivative (A) can be carried out using meta-chloroperoxybenzoic acid (m-CPBA). An oxygen atom is added to the double bond C9C10, during the process, producing the epoxides P1 and P2. DFT calculations at the B3LYP/6-31G(d) level were used to study, Theoretically, the mechanism and stereoselectivity of the epoxidation reaction of compound A with m-CPBA. The calculation of activation energies associated with both possible reaction pathways, indicated that this epoxidation reaction is exothermic and highly stereoselective, favoring the formation of product P1 which is in agreement with the experimental results. Additionally, the IRC calculation shows that this reaction occurs via a one-step mechanism. The products P1, P2, and the starting compound A were evaluated for their antidiabetic activity and their potential to inhibit alpha-amylase and alpha-glucosidase through molecular docking, molecular dynamics, and ADMET studies. The evaluation of these three compounds aimed to study the effect of epoxidation and stereoselectivity on their inhibitory activity against the two enzymes.

Homogeneous oxidation of EE2 by ozone: Influencing factors, degradation pathway, and toxicity assessment

17α-Ethinylestradiol(EE2) is a common hormone drug that plays an essential role in endocrine and reproductive health. However, estrogens are degraded only to a limited extent by humans and livestock themselves, and most of them are excreted in undegraded or partially degraded form from human and livestock feces and urine into water bodies, posing a austere ecological risk. Of the known degradation processes in wastewater treatment plants, ozone-induced advanced oxidation shows tremendous potential. At the same time, the limitations of the test methodology makes it extremely difficult to do an in-depth investigation of the degradation mechanism. In this study, the influencing factors, including ozone dose, initial concentration, and pH were investigated. The degradation pathways of EE2 were analyzed by combing with quantum chemical calculations and high performance liquid chromatography coupled with quadrupole-time of flight tandem mass spectrometry (HPLC-Q-TOF-MS). Toxicity Estimation Software Tool (T.E.S.T) evaluated EE2 and its degradation intermediates for a variety of toxicities. And the results showed that reactions such as oxidative hydroxylation of the benzene ring and oxidative ring opening of the aliphatic ring mainly occurred during the degradation of estrogens, and the reaction was initially fast. The degradation effect is lower under neutral conditions, and the acidity and alkalinity of the solution are reduced with the reaction process under strong acid and alkaline conditions. The products of the experimental reactions reflect the active site, e.g., product P1 reflects C(5) as the site of easy reaction, which is consistent with previous theoretical predictions, suggesting that theoretical studies can provide complementary information on oxidation. The toxicity of intermediates obtained from partial ozone degradation improved compared to EE2, and the mutagenicity of EE2 was elevated greatly. However, single ozonation significantly diminished the developmental toxicity and bioaccumulation factor for a large proportion of intermediates. This work may contribute to the theoretical foundation for the practical application of ozone oxidation of environmental estrogens.

Theoretical insights into the HO●-induced oxidation of chlorpyrifos pesticide: Mechanism, kinetics, ecotoxicity, and cholinesterase inhibition of degradants

The oxidation of the common pesticide chlorpyrifos (CPF) initiated by HO● radical and the risks of its degradation products were studied in the gaseous and aqueous phases via computational approaches. Oxidation mechanisms were investigated, including H-, Cl-, CH3- abstraction, HO●-addition, and single electron transfer. In both phases, HO●-addition at the C of the pyridyl ring is the most energetically favorable and spontaneous reaction, followed by H-abstraction reactions at methylene groups (i.e., at H19/H21 in the gas phase and H22/H28 in water). In contrast, other abstractions and electron transfer reactions are unfavorable. However, regarding the kinetics, the significant contribution to the oxidation of CPF is made from H-abstraction channels, mostly at the hydrogens of the methylene groups. CPF can be decomposed in a short time (5–8 h) in the gas phase, and it is more persistent in natural water with a lifetime between 24 days and 66 years, depending on the temperature and HO● concentration. Subsequent oxidation of the essential radical products with other oxidizing reagents, i.e., HO●, NO2●, NO●, and 3O2, gave primary neutral products P1–P15. Acute and chronic toxicity calculations estimate very toxic levels for CPF and two degradation products, P7w and P12w, in aquatic systems. The neurotoxicity of these products was investigated by docking and molecular dynamics. P7w and P12w show the most significant binding scores with acetylcholinesterases, while P8w and P13w are with butyrylcholinesterase enzyme. Finally, molecular dynamics illustrate stable interactions between CPF degradants and cholinesterase enzyme over a 100 ns time frame and determine P7w as the riskiest degradant to the neural developmental system.

Chromatography Scrutiny, Molecular Docking, Clarifying the Selectivities and the Mechanism of [3 + 2] Cycloloaddition Reaction between Linallol and Chlorobenzene-Nitrile-oxide.

Employing the Molecular Electron Density Theory, [3 + 2] cycloaddition processes between 4-chlorobenzenenitrileoxide and linalool, have been applied using the DFT/B3LYP/6-311(d,p) method, activation, reaction energies and the reactivity indices are calculated. In an investigation of conceptual DFT indices, LIL-1 will contribute to this reaction as a nucleophile, whilst NOX-2 will participate as an electrophile. This cyclization is regio, chemo and stereospecific, as demonstrated by the reaction and activation energies, in clear agreement with the experiment's results, in addition, ELF analysis revealed that the mechanism for this cycloaddition occurs in two steps. Furthermore, a docking study was conducted on the products studied, and the interaction with the protein protease COVID-19 (PDB ID: 6LU7), our results indicate that the presence of the -OH group increases the affinity of these products, moreover, adsorption study by chromatography was made on silica gel as support; our outcome reveals that the -OH group creates an intramolecular hydrogen bond in the product P2, while in the product P3 will create a hydrogen bond with the silica gel which makes the two products P2 and P3 are very easy to separate by chromatography, this result is in excellent agreement with the Rf retention value. The study might provide a fundamental for developing natural anti-viral compound in promoting human health.

Sestec adhesive based on animal proteins for the production of particleboards

The development of a biodegradable adhesive that uses waste from industry will bring enormous economic, social, environmental, and health benefits. Many laboratories around the world conduct research on the development of natural adhesives that can replace those based on toxic formaldehyde. Works in this area are also carried out by Sestec Polska Sp. z o. o, an example of which is the Sestec B0021G adhesive. This product belongs to the family of animal protein-based adhesives and is dedicated to particle board (PB) production (classes P1–P5 according to EN 312). This work presents the results obtained during the preparation of boards based on Sestec B0021G protein adhesive, manufactured with the use of variable production parameters, and assesses the influence of these parameters on the properties of the obtained products. The emphasis was especially on presenting the impact of production parameters on the PB strength and water resistance. The tests were carried out using different densities (560–800 kg/m3), pressing temperatures (150–230 °C), amounts of adhesive (7–15% in the surface layer and 5–13% in the core layer) and specific press times (5–13 s/mm). The boards showed excellent mechanical properties and water resistance. Higher PB classes were obtained under standard production conditions. Eventually, the obtained results showed that the binder can be used to produce all classes of PB products P1 to P7, and not only P1-P5 as initially assumed.

Direct photolysis of diclofenac under simulated sunlight: Transformation pathway and biological concerns

Topical diclofenac gels are frequently applied on human skin and, consequently are exposed to sunlight during outdoor activities. The degradation of diclofenac (DCF) with sunlight exposure is known to occur but the detailed transformation characteristics and biological concerns have not been comprehensively investigated. In the present work, the transformation products during diclofenac photolysis were identified with the aid of ultra-performance liquid chromatography coupled with triple time-of-flight mass spectrometry (UPLC-TripleTOF). Biological concerns, including microtoxicity, genotoxicity, cytotoxicity and antiestrogenicity were examined with multiple in-vitro bioassays. Spearman correlation analysis was conducted to obtain further insight into the contributions of photolysis products to overall biological concerns. The results demonstrated that diclofenac was readily degraded under sunlight to form five main photolysis products via substitution, dechlorination, dehydroxylation, homodimerization and heterodimerization. Products P1, P2 and P5 were reported previously, while two dimer products (P3 and P4) are innovative products and have not been found in prior studies. A significant elevation in the microtoxicity was found during the photolysis of diclofenac, resulting mainly from the carbazole-containing photolysis products P2, P3, P4 and P5. Genotoxicity and antiestrogenicity declined along with the reduction of diclofenac, indicating that no photolysis products were genotoxic or anti-estrogenic. Modest cytotoxicity to the human skin epidermis cell line was observed and attributed to the formation of intermediate species. This outcome highlighted the biological concerns of diclofenac to human health when exposed to sunlight.

Enrichment of commercial feed with new formula products on the growth, yield, and mortality of the giant gourami Osphronemus goramy

Background and objective: The giant gurami (Osphronemus goramy) is considered the most desirable freshwater species in Indonesia, mainly for food security. This study evaluated the effectiveness of newly formulated products containing water, coconut, palm sap sugar, and fungus used for enriched commercial feed and their impact on gurami sago’s (local strain) growth performance, yield, and mortality. Methods: A total of 100 g of palm sugar are cooked with 1,000 ml of freshwater for fifteen minutes at a temperature of 60 °C. Furthermore was added 2,000 ml of mature coconut water. For every 1,000 ml of a mixture of mature coconut water and palm sap sugar solution was added 2 g of Aspergillus niger (called product P1), 2 g of Rhizopus oligosporus (product P2), and 2 g of Saccharomyces cerevisiae (product P3). Commercial fish feed pellets enriched with P1, P2, and P3 were designated as P1, P2, and P3 diets. At the same time, the commercial feed added with freshwater is called P4 feed (placebo). The dosage of each product is 300 ml/kg of feed. Juvenile sago gourami (initial weight 50±2.5 g and total length 13.2±0.4 cm) were stocked in triplicate (0.5x0.5x0.5 m) in a freshwater concrete pond with a stocking density of 30 individuals. /net, an initial feeding rate of 3% per day for 90 days of the experiment. Results: The weight gain ranged from 172.43 to 215.6%, the specific growth rate increased from 0.60 and 0.75%/day. The coefficient of thermal growth increased from 27.26 to 32.83. At the same time, yield ranging from 14.88 to 21.03 g/L and mortality for 90 days of the experiment decreased from 22.22% to 6.66%. The coefficient of variation in weight was between 0.68% and 1.30%. Conclusion: Giant gourami juvenile survived and grew well in diet P2, moderate growth in diet P3, and diet P1; the lowest growth was recorded in diet P4.

Experimental and Theoretical Study to Understand the Adsorption Process of p‐Anisidine and 4‐Nitroaniline for the Dissolution of C38 Carbon Steel in 1M HCl

AbstractIn this work, we investigated the addition effect of two organic compounds namely; p‐anisidine (P1) and 4‐nitroaniline (P2) against corrosion of C38 steel in an acidic medium HCl 1 M. We opted for these inhibitors belonging to the aniline family which is characterized by their solubility, their low cost, and their use as corrosion inhibitors in acidic environments. The concentration effect of the two products P1 and P2 either by stationary or by transiency measurements appears a significant decrease in the corrosion rate, and that the inhibition efficiency IE% reaches a value of 88.55 % and 84 % for a concentration of 1 mM respectively of P1 and P2. The thermodynamic parameters taken from the electrochemical impedance curves indicate that the tested inhibitors are adsorbed on the metal surface by a mixed mechanism (physical‐chemisorption), because the free adsorption energy of P1 and P2 is respectively equal to −38.02 Kj.mol−1 and −37.56 Kj.mol−1, and they are subjected to the Langmuir isotherm. The temperature effect lets to determine the activation energy (Ea) from the Arrhenius equation; however, the values of Ea indicate the adsorption of organic compounds on the metal surface. Scanning electron microscopy (SEM) suggested that the products tested could effectively block acid attack on metal surfaces. In parallel to experimental approach, theoretical one based on theoretical function density (DFT) calculation and Monte Carlo (MC) simulation is considered to investigate in depth the inhibition behavior of studied compounds.

Cyanomethylation of 2,3,4,9-tetrahydro-1H-carbazol-1-one based on using two different reagents: Antioxidant activity and DFT studies

C-2 and C-6 monoalkyl nitrile substituted reactant (1), which constitute the tricyclic framework of carbazole derivatives along with the substructure of the Strychnos alkaloids family, have been synthesized by using different bases to produce substitution reactions. In addition, the antioxidant capacity of the synthesized compound by the CUPRAC (cupric reducing antioxidant capacity) method was evaluated and the obtained TEAC (Trolox equivalent antioxidant capacity) coefficient implied that product (2) has antioxidant feature. The B3LYP/6-311G(d,p) level calculations were performed in the gas phase, and the optimized geometries obtained from these calculations were used for the solvation media calculations. The SMD variation of the IEFPCM (polarized continuum model) was used to conduct the quantum chemical calculations in the solvent environment such as CHCl3, CH3OH, and H2O (water, ε=78.4). Also, the NMR chemical shifts of the products were calculated using GIAO (Gauge-Independent Atomic Orbital) approach and compared with the corresponding experimental data. The TD-DFT calculations disclosed that the observed peaks for both products were attributed to the n→ π* and π→ π* excitations. Moreover, NBO analysis revealed that the n→ π* and π→ π* interactions have a great importance for lowering the stabilization energy for all compounds. Also, the FMO (Frontier Moleular Orbital) analyses implied that the product P2 would prefer the intermolecular interactions would rather than the intramolecular interactions.

The utilization of new products formulated from water coconut, palm sap sugar, and fungus to increase nutritional feed quality, feed efficiency, growth, and carcass of gurami sago (Osphronemus goramy Lacepède, 1801) juvenile

Background: Giant gourami (Osphronemus goramy Lacepede, 1801) has become popular aquaculture in Indonesia. However, information on the feed used is minimal. This study analyzed the change in feeding nutrition, fish growth, feed efficiency, and body-carcass using product formulated from water coconut, palm sap sugar, and fungus. Methods: A total of 2,000 ml coconut water and 1,000 ml of palm sap sugar solution were formulated. Each product formulated was added with 6 g of Aspergillus niger (called product P1), 6 g of Rhizopus oligosporus (called product P2), and 6 g of Saccharomyces cerevisiae (called product P3). Commercial feeds supplemented with P1, P2, and P3 products are designated P1, P2, and P3 diets. Commercial feed added to freshwater is called the P4 diet (placebo). Their dosage is 300 ml/kg of feed. Gurami sago juveniles (initial weight 50±2.5 g and length 13.2±0.4 cm) were stocked in triplicate nets (2×1×1 m) in a freshwater concrete pond with a stocking density of 30 fish/net, an initial feeding rate of 3% per day until study termination. Results: Our results support our hypothesis that different product formulations have a significant effect (p<0.05) on growth performance and feed efficiency. At the same time, supplementing commercial feed with varying formula products has a significant impact (p<0.05) on the fatty acid composition of the diets and carcass body of gurami sago. Conclusion: Diet P2 contains a higher concentration of fatty acids to increase body weight, feed efficiency, and the best carcass fatty acid composition than other experiments for sago gurami reared in freshwater concrete ponds.

Mechanism of secondary organic aerosol formation from the reaction of isoprene with sulfoxy radicals.

Isoprene can react with sulfoxy radicals (SO4•- and SO3•-) to form organosulfur compounds in aqueous phase, and the organosulfur compounds are important compositions of secondary organic aerosols (SOAs). To make sure the specific configurations of the products and the role of SO4•- and SO3•- in the formation of organosulfur compounds, the reaction mechanisms are studied by theoretical calculations. The lowest Gibbs free energy barrier of addition of SO3•- onto isoprene is 24.06kcalmol-1 at C4 site, and its rate constant is 1.30 × 10-11M-1s-1 at 298K and 1atm. And the Gibbs free energy barriers of addition of SO4•- onto isoprene at C1 and C4 sites are barrierless and 0.92kcalmol-1; the rate constants of these two addition processes are 6.85 × 109 and 1.17 × 105M-1s-1 at 298K and 1atm. It elucidates that organosulfates are easier to be formed. As for the products P1 (with alcohol group) and P2 (with aldehyde group), the lowest Gibbs free energy barrier of the formation of P1 is 3.17kcalmol-1, and that of the formation of P2 is 15.84kcalmol-1, which means that the product with alcohol group is easier to be formed than that with aldehyde group. This work provides a reference for the formation of organosulfur compounds in aqueous phase, and it may help to understand the SOA formation.

Solvothermal Alcoholysis Method for Recycling High-Consistency Silicone Rubber Waste

In this work, we investigated the potential use of high-consistency silicone rubber (SR), which is a synthetic solid material used in numerous industrial applications, to produce a range of liquid alkoxysiloxane derivatives R(OSiMe₂)ₓOR, with x = 1 (P₁), 2 (P₂), 3 (P₃), and 4 (P₄). We describe a simple and convenient solvothermal alcoholysis method for the chemical recycling of post-consumer SR in the presence of fatty alcohols under catalyst-free or catalytic conditions. This process proceeds easily both without and with a catalyst. Alkali-metal aryloxides supported by a methylsalicylato ligand (MesalO) gave the highest conversions of SR to products P₁–P₄. Magnesium and zinc aryloxides enabled efficient conversions of products P₂–P₄ to P₁. Binary metal catalysts of general formula [M₂M′₂(MesalO)₆] (M = Mg or Zn; M′ = Li, Na, or K), which had a combination of the catalytic properties shown by alkali-metal aryloxides and magnesium/zinc aryloxides, were produced and used to synthesize P₁–P₄. The results show that magnesium–sodium/potassium aryloxides had the best catalytic activities. Their use led to the formation of two dominant products, namely, P₁ and P₂, with conversion yields of 79 and 17%, respectively. Particular emphasis is placed on the operating conditions and high activity of the catalyst used. Key factors that affect the catalytic activity and reaction mechanism are also highlighted.

Theoretical studies on NH2 + NO2 reaction: Driven by reaction dynamics

Chemical dynamics simulations have been performed to study the NH2 + NO2 reaction on singlet potential energy surface at 298 K. To obtain more accurate potential energy surface, seven methods including MP2, B3LYP, OPBE, BhandH, HCTH407, M06 and M06–2X combined with aug-cc-pVDZ basis set were employed to calculate the properties of stationary points and the results are compared with the higher level CCSD(T) benchmark and the available theoretical and experimental values. The reaction reactivity, product branching ratio, and detailed microscopic reaction mechanisms are uncovered by direct dynamics simulations at the chosen B3LYP/aug-cc-pVDZ level of theory. The branching ratio between product P1 (N2O + H2O) : P2 (H2NO + NO) determined in current study is 0.22 : 0.78, which is in consistent with experimental observations. The study reveals a preference of P2 channel over P1 at 298 K, although the latter channel is more exothermic. This result indicates the dynamical factors govern the competition of two product channels. Three atomic mechanisms were determined and discussed in detail, in which the indirect reaction dominates. Interestingly, these indirect reactions follow the intrinsic reaction coordinate of the potential energy surface.

Mechanisms of Csp3-H functionalization of acetonitrile or acetone with coumarins: A DFT investigation

The mechanisms for the cross-dehydrogenative coupling (CDC) between coumarin and acetonitrile (or acetone) have been investigated with M06-L-D3 method, and 6−31+G(d,p) basis set for nonmetal elements and pseudopotential basis set of SDD for potassium atom. SMD model was applied to simulate the solvent effect. The computational results show that tert-Butyl peroxybenzoate (TBPB) is the best oxidant with the lowest bond dissociation Gibbs free energy (BDE=11.2 kcal/mol in the solvent of acetonitrile) and could be easily disintegrated into two radicals (PhCOO and t-BuO). In the first and second reactions, 2H-chromen-2-one reacted with acetontrile and acetone, respectively. Firstly, the Csp3-H activations of acetontrile and acetone could be achieved by PhCOO and t-BuO radicals; then cross-dehydrogenative coupling reactions converted 2H-chromen-2-one into final products P1 and P2; Gibbs free energy surfaces of these two reactions suggest that paths a4 and b4 would be the favorable paths with lower Gibbs energy barriers and releasing much energy. While in the third reaction, acetonitrile reacted with (E)-4-phenylbut-3-en-2-one via six possible paths, and path c4 could be the favorable one. When radical scavenger BHT (butylated hydroxytoluene) was added into the first reaction, only fourth product P4 can be yielded. The Gibbs free energy surface analysis of fourth reaction shows that BHT is much active than acetonitrile to go through the Csp3-H activation and path d2 is the favorable, which can agree with the experimental results. The BDE, localized orbital locator (LOL) isosurfaces, Laplacian bond order (LBO), electron density of bond critical point (ρBCP) and electron spin density isosurface graphs can be used to analyze the structure and reveal the reaction substances.

Quantum chemical study of the reaction of trichloroethylene with O(3P)

AbstractThe adiabatic mechanism of the reaction of trichloroethylene with O(3P), exploring the various O‐atom addition and H‐atom abstraction channels, is theoretically studied at the MP2/6‐311++G(2d, 2p), MP2/aug‐cc‐pVTZ, CCSD/6‐31G(d), G3, and CBS‐QB3 levels of theory. From a kinetic point of view, the addition to the less substituted carbon atom of the double bond is more favorable than the addition to the more substituted carbon. Such O‐atom addition reactions are favored over the one possible hydrogen‐abstraction reaction. Calculations of the present study showed that five products are obtained: HCCl + C(O)Cl2 (P1), Cl + ClC(O)CHCl (P2), H + ClC(O)CCl2 (P3), Cl + HC(O)CCl2 (P4), and CH(O)Cl + CCl2 (P5). The products P2 and P4 are found to be the most favored ones. The kinetic calculations of rate constant in the range of 285–395 K are performed at the CBS‐QB3 level of theory and are in conformity with the experimental outcomes.

A quantum chemical study on •Cl-initiated atmospheric degradation of CH2BrO2•

The singlet and triplet potential energy surfaces for the CH2BrO2• + •Cl reaction have been researched theoretically. All of the probable reaction routes were investigated by using B3LYP and G3(MP2) models. Addition/elimination and SN2 displacement exist on the singlet potential energy surfaces (PES), and the foremost approach process of CH2BrO2• + •Cl is generating IM1 (CH2BrOOCl) with no barrier, followed by the O-O bond breaking accompanied by an H-migrate resulting in the most abundant product P1 (CHBrO + HClO). One direct H-abstraction and three SN2 displacement reaction pathways exist on the triplet PES, and direct H-abstraction is the foremost pathway. RRKM-TST theory was employed to predict product distribution of the CH2BrO2• + •Cl reaction. At atmospheric pressure, the production of P1 (CHBrO + HClO) by addition/elimination dominants the reaction at T ≤ 800 K, while the direct H-abstraction takes over the reaction at T > 800 K. The total rate constants are insensitive to pressure, and the branching rate constants are just the opposite. The lifetime of CH2BrO2• in the presence of •Cl was predicted to 3.2 d. Moreover, time-dependent density functional theory (TDDFT) calculations suggest that IM1 (CH2BrOOCl), IM2 (CH2BrOClO) and IM3 (CH2(OBr)OCl) will photolyze under the sunlight.

Exploring the simultaneous biothiols-differentiating detecting feature of a BODIPY chemosensor with DFT/TDDFT

The simultaneous biothiols-differentiating fluorescence detecting feature of a boron dipyrromethene (BODIPY) derivative (Probe1) has been investigated through DFT/TDDFT calculations. Two decay pathways are revealed for the fluorescence sensing process, and the probe's ability to simultaneously and fluorescently differentiate cysteine (Cys), homocysteine (Hcy), sulfureted hydrogen (H2S), glutathione (GSH) is associated with the different excited-state properties of Probe1 and the biothiols-induced reaction products: the S1 state of Probe1 and the GSH/H2S-induced reaction product NBD-S-GSH/NBD-S is non-emissive, with complete/obvious charge separation; whereas, the S1 state of Cys/Hcy-induced reaction product NBD-S-Cys/NBD-S-Hcy as well as a common product P1 from all biothiols-induced reactions is a bright emissive state. The energetic and charge features of the excited states suggest a donor photoinduced electron transfer mechanism for the fluorescence quenching. It is also found that the intramolecular charge separation character of S1 state accounts for some of spectral behaviors, such as the signal intensity changes and the spectral shift, which can also be utilized in the simultaneously differentiating sensing of biothiols.

Theoretical investigations on mechanisms and pathways of CH2ClO2/CHCl2O2 with ClO reactions in the atmosphere.

A global and systematic theoretical research on the singlet and triplet potential energy surfaces (PESs) of the CH2ClO2/CHCl2O2 with ClO reactions are done at the CCSD(T)//B3LYP level and accompanied with RRKM computations to forecast the mechanism and distribution of products. The simulation results revealed that, on the singlet PES, products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) from IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are forecasted to the primary products of the CH2ClO2/CHCl2O2 + ClO reactions, which are initiated by the oxygen atom of ClO radical addition to the terminal-O atom of CH2ClO2/CHCl2O2 barrierlessly, while other product channels contribute less to the whole reactions owing to higher barriers. Two other isomers, including IM2 (CH2ClOOClO) and IM3 (CH2ClOClO2) for the CH2ClO2 + ClO reaction, and three other isomers, including IM2 (CHCl2OOClO), IM3 (CHCl2OClO2), and IM4 (CHCl2ClO3) for the CHCl2O2 + ClO reaction, could be produced as less significant products. RRKM calculations presented that the initial adducts IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are the primary products at T < 400K and T < 600K, respectively, and products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) are dominant the reactions at T ≥ 400K and T ≥ 600K, respectively. The atmospheric lifetime of CH2ClO2 and CHCl2O2 in ClO is around 4.61 and 3.24h, respectively.