Stereodynamics Study of Li+HF→LiF+H Reactions on X^2A’ Potential Energy Surface at Collision Energies below 5.00 kcal/mol

The product rotational polarizations of reaction Li-SHF→LiF-kH at different collision energies, as well as at the different vibrational states and rotational states, are calculated by using the quasi-classical trajectory method based on a new potential energy surface constructed by Aguado et al. [J. Chem. Phys. 119（2003） 10088]. We investigate the Mignment and the orientation of the product molecule by calculating the P（θr, φr） distribu- tions describing polar angle distribution, the P（θr） distributions describing the k-j＇ correlation and the P（φr） distributions describing the k-k＇-j＇ correlation. We also explore the dependence of reaction probabilities and cross sections on the rotational and vibrational quantum number of the title reaction. It is concluded that the vibrational state has more important impact on the angular distribution, reaction probability and cross section.

Investigation of isotope effects of dynamic properties for H(D) + OF reactions by the quasi-classical trajectory method

Quasi-classical trajectory （QCT） calculations are employed to study the dynamic properties for H（D）＋OF reactions on the adiabatic potential energy surface （PES） of the 1^3A″ triplet state. Obvious differences between the reaction probabilities for J=0, integral cross sections for J≠0, branch ratios of the product and internuclear distances as well as product rotational alignments between the title reactions axe found. These differences are attributed mainly to the different reduced masses of the reactants and the different zero-point energies （ZPEs） of the transition state.

CoxP@NiCo-LDH heteronanosheet arrays as efficient bifunctional electrocatalysts for co-generation of value-added formate and hydrogen with less-energy consumption

The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing robust bifunctional electrocatalysts are of great significance. Herein, a hierarchical heteronanostructure with Ni–Co layered double hydroxide(LDH) ultrathin nanosheets coated on cobalt phosphide nanosheets arrays(CoxP@NiCo-LDH) are fabricated and used for co-electrolysis of methanol/water to co-produce value-added formate and hydrogen with saving energy. Benefiting from the fast charge transfer introduced by phosphide nanoarrays, the synergy in nanosheets catalysts with hetero-interface,CoxP@NiCo-LDH/Ni foam(NF) exhibits superior electrocatalytic performance(10 mA cm-2@ 1.24 V and-0.10 V for methanol selective oxidation and hydrogen evolution reaction, respectively). Furthermore,CoxP@NiCo-LDH/NF-based symmetric two-electrode electrolyzer drives a current density of 10 m A cm-2 with a low cell voltage of only 1.43 V and the Faradaic efficiency towards the generation of formate and H2 are close to 100% in the tested range of current density(from 40 to 200 m A cm-2). This work highlights the positive effect of hetero-interaction in the design of more efficient eletrocatalysts and might guide the way towards facile upgrading of alcohols and energy-saving electrolytic H2 co-generation.

Detection and location of Helicobacter pylori in human gastric carcinomas

AIM: To define the infection status of Helicobacter pylori in 109 patients with gastric cancers and H pylori localization in gastric carcinoma tissues in South China. METHODS: The incidence of H pylori infection in gastric carcinomas was estimated by polymerase chain reaction (PCR), simultaneously; both morphological features and the localization of H pylori in gastric carcinomas were demonstrated by Warthin-Starry (WS) staining. The relationships between H pylori infection and the clinical-pathologic factors of gastric carcinomas were analyzed by software SPSS10.0. RESULTS: H pylori was found in 42 (39.03%) and 58 (53.21%) cases of 109 patients with gastric carcinomas by PCR and WS, respectively. H pylori infection rate detected in gastric carcinomas by WS was higher than that by PCR (X2=9.735, P<0.005<0.01). WS stain showed that H pylori existed in the gastric antrum mucus, mucosal gland of normal tissues adjacent to gastric carcinomas and the gland, mucus pool of cancer tissues. The positive rate of H pylori in normal tissues adjacent to carcinomas was higher than that in cancer tissues (X2=15.750, P<0.005 <0.01). No significant differences in age, sex, site, histological types and lymph node metastasis were found between H pylori-positive gastric carcinomas and H pylori-negative cases by both methods, but there were statistically significant differences of H pylori positive rate between early and advanced stage of gastric carcinomas (X2= 4.548 or 5.922, P= 0.033 or 0.015<0.05). CONCLUSION: These results suggested that H pylori infection might play a certain role in the early stage of carcinogenesis of human gastric mucosa epithelia.

NEW HETEROCYCLIC SYSTEM SYNTHESIS H THE REACTION OF 2,3-DIHYDRO-1,5-BENZOTHIAZEPINES WITH DICHLOROCARBENE

The reaction of two series of 2,3-dihydro-1,5-henzothiazepines Ⅰ with dichloro- carbene,gave azirino[2,1-d][1,5]benzothiazepines Ⅷ,azirino[2,1-e][1,6]benzothiazocines Ⅸ, pyrrolo[2,1-b][1,3]benzothiazoles Ⅹ,substituted-cyclopropanes Ⅺ and 2H-1,4-benzothiazin-2-ones Ⅻ.The structures of these products were confirmed by the analytical and spectral data.Compound Ⅷ and Ⅸ are two new ring systems.

Stereodynamics of O（^3P）＋H2 at Scattering Energies of 0.5, 0.75, and 1.0 eV

Quasiclassical trajectory calculation of the title reaction O（^3P）＋H2→OH＋H at three different scattering energies of 0.5, 0.75, and 1.0 eV on the lowest electronic potential energy surface 1^3A＂ has been done. Distribution P（θr） of polar angles between the relative velocityk of the reactant and rotational angular momentum vector j＇ of the product, distribution P（φr） of the azimuthal as well as dihedral angles correlating k-k＇-j＇, 3-dimensional distri-bution, and polarization-dependent differential cross sections （PDDCSs）dependent upon the scattering angle of the product molecule OH between the relative velocity k of the reactant and k＇ of the product at different scattering energies of 0.5, 0.75, and 1.0 eV are presented and discussed.

Synthesis, Structure and Catalytic Activity of a Manganese(Ⅲ) Complex Based on 2-(2-Hydroxyphenyl)-5,6-dichlorobenzimidazole Ligands

A new ligand, 2-（2-hydroxyphenyl）-5,6-dichlorobenzimidazole, H2pbmCl2（1）, and a novel MnIII complex, [MnIII（HpbmCl2）（pbmCl2）（DMF）2]（2）,（DMF = N,N-dimethylformamide）, have been synthesized and characterized. The crystal of compound 1（C13H8Cl2N2O, Mr = 279.12） belongs to the monoclinic system, space group P21 with a = 3.770（5）, b = 25.20（3）, c = 5.865（7） A, = 92.727（17）o, V = 556.6（12） A3, Z = 2, Dc = 1.665 g/cm^3, S = 1.137, μ= 0.568 mm^-1, F（000） = 284, the final R = 0.0876 and wR = 0.2334 for 1848 independent reflections. The molecule is planar due to the presence of a strong intramolecular hydrogen bond between O–H group of phenol and N atom of imidazole. H2pbmCl2（1） molecules are arranged into a one-dimensional linear chain through intermolecular hydrogen bonds（N–H…O and C–H…Cl）. The crystal of complex 2（C32H27Cl4MnN6O4, Mr = 756.34） belongs to the monoclinic system, space group P21/c with a = 19.043（10）, b = 10.808（5）, c = 18.704（11）A, β= 115.540（6）°, V = 3473（3） A3, Z = 4, Dc = 1.446 g/cm^3, S = 1.3, μ = 0.733 mm-1, F（000） = 1544, the final R = 0.1219 and wR = 0.2681 for 7811 independent reflections. The Mn ion adopts a distorted octahedral geometry coordinated by two deprotonated H2pbmCl2 ligands and two DMF molecules. The [MnIII（HpbmCl2）（pbmCl2）（DMF）2] molecules are arranged into a three-dimensional structure through hydrogen bonds（N–H…N, C–H…N and C–H…Cl） and weak π···πinteractions. The activity measurements suggest that complex 2 is able to serve as a catalyst for H2O2 disproportionation reaction to form O2 in neutral water solution.

Stereodynamics of the O(~3P) with H_2(D_2) (ν=0,j=0) reaction

Quasi-classical trajectory theory is used to study the reaction of O（3p） with H2 （D2） based on the ground 3A″ potential energy surface （PES）. The reaction cross section of the reaction O＋H2→＋OH＋H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters （P2（j′. k）） and several polarizeddependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.

Theoretical Study of the Isomerization Reaction of 1-3 H Transfer on Formamidine Substituted by Halogen

The ab initio method has been used to study the 1-3 H transfer reaction on formamidine substituted by halogen. The calculation results show that the substituted halogen has two effects on the 1-3 H transfer reaction: decreasing the activation energy and stabilizing the C=N double bond owing to the conjugative effect of p-π-p of products and transition states.

Kinetics and Dynamics of the H(^(2)S)+NO(X^(2)Π)→N(^(4)S)+OH(X^(2)Π) Reaction:A Quasi-classical Trajectory Study

A quasi-classical trajectory study of the H(^(2)S)+NO(X^(2)Π)→N(^(4)S)+OH(X^(2)Π) reaction kinetics and dynamics is reported on an accurate potential energy surface.The total integral cross sections of the reaction were calculated at the collision energy ranging from 2.00 e V to 2.80 e V.It was found that the total reaction integral cross section increases monotonically with the collision energy.Specifically at the collision energy range of 2.40-2.57 e V,our calculated results are in reasonably good agreement with the experimental data.The calculated thermal rate constants are in fairly good agreement with available experimental results.Through the trajectory analysis at the collision energy of 2.57 e V,it was found that the title reaction is dominated by the indirect trajectories(1.4 times more compared to the direct trajectories),which sheds light on the reaction dynamics of the title reaction in the high collision energy range.

Stereodynamics study of the H'(~2S)+NH(X^3Σ^-)→N(~4S)+H_2 reaction

The stereodynamics and reaction mechanism of the H′（^2S） ＋ NH （X^3∑^-） → N（^4S） ＋ H2 reaction are thoroughly studied at collision energies in the 0.1 eV-1.0 eV range using the quasiclassical trajectory （QCT） on the ground 4A″ potential energy surface （PES）. The distributions of vector correlations between products and reagents P（φr）, P（φr） and P（φr,φr） are presented and discussed. The results indicate that product rotational angular momentum j′ is not only aligned, but also oriented along the direction perpendicular to the scattering plane; further, the product H2 presents different rotational polarization behaviors for different collision energies. Furthermore, four polarization-dependent differential cross sections （PDDCSs） of the product He are also calculated at different collision energies. The reaction mechanism is analyzed based on the stereodynamics properties. It is found that the abstraction mechanism is appropriate for the title reaction.

Ten-Dimensional Quantum Dynamics Study of H+CH_(3)D→H_(2)+CH_(2)D Reaction

The mode selectivity of the H+CH_(3)D→H_(2)+CH_(2)D reaction was studied using a recently developed ten-dimensional time-dependent wave packet method.The reaction dynamics are studied for the reactant CH_(3)D initially from the ground state,the CH_(3) symmetry and asymmetry stretching excitation,the CD stretching excitation and the fundamental and the first overtone of the CH_(3) bending mode.The calculated reaction probabilities show that exciting either of the CH_(3) stretching modes enhances the reactivity in the collision energy range below 1.0 eV,while the CD stretching excitation does not obviously prompt the reaction.Fundamental CH_(3) bending excitation has nearly no effect on promoting reactivity.However,a significant enhancement is observed for the first overtone excitation of the CH_(3) bending mode,resulting from the Fermi resonance between the fundamental state of the CH_(3) symmetry stretching mode and the first overtone state of the CH_(3) bending mode.

Catalytic Hydrogen Transfer Reactions

Our recently studies on three types of reactions with hydrogen transfer as a key step,including catalytic asymmetric proton transfer reactions using"chiral proton transfer shuttle",catalytic B—H bond insertion containing a hydrogen atom transfer,and iron-catalyzed hydrosilylation reactions containing hydride transfer were briefly introduced.

Suzuki–Miyaura cross-coupling reactions in water using in situ generated palladium(II)–phosphazane complexes

The phosphazane derivatives （L1-3） were readily obtained by reaction of different ratios of PCI3 and PhNH2. The L1_3 derivatives were found to be efficient ligands in the palladium-catalyzed Suzuki C-C coupling reactions in water. It was determined that with the use of L1-3/Pd（OAc）2 system as a catalyst, aryl halides undergo Suzuki cross-couplings with arylboronic acids to give the desired products in moderate to excellent yields.

Mechanism and rate constants for complete series reactions of 19 fluorophenols with atomic H

Fluorine-containing halogenated fluorophenol may have effect as intermediate species involved in the formation of polyfluorinated dibenzo-p-dioxin/dibenzofurans （PFDDs/Fs）. The mechanism for the atomic H initiated reactions with complete series of nineteen fluorophenol congeners was studies using the density functional theory. At the MPWB1K,/6-31＋G（d,p） level, the geometries and frequencies of reactants, transition states, and products were obtained, and the accurate energetic values were acquired at the MPWB 1K/6-311 ＋G（3df,2p） level. The rate constants were evaluated by the canonical variational transition-state theory with the small curvature tunneling contribution over a wide temperature range of 600-1000 K. The study shows that the intramolecular hydrogen-bond in the ortho-substituted FPs as well as the inductive effect of the electron-withdrawing fluorine and steric repulsion of multiple substitutions may ultimately be responsible for the relative strength of the O-H bonds in FPs. The results can be used for further studies on PFDD/Fs formation mechanism.

The CO_2 laser-induced radical-chain reactions between CH_3CF_2H and chlorine-atom donors CF_2ClCFCl_2, CF_3CCl_3 CFCl_3 or CF_2Cl_2

The CO_2 laser induced room temperature reactions of CH_3CF_2H or another protium-donor CH_3CHClCH_3 with chlorine-atom donors (Z--Cl) CFCl_2CF_2Cl, CF_3CCl_3, CFCl_3 or CF_2Cl_2, have been investigated. Some of these reactions can yield two important monomers (CF_2=CH_2 and CF_2=CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experi- mental conditions has been studied. A laser-initiated chain process is supported by identifica- tion of Z--H intermediates in these reactions.

2020 Roadmap on gas-involved photo-and electro-catalysis

Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.

New efficient synthesis of 2,5,6-trisubstituted oxazolo[5,4-d]pyrimidi-7(6H)-ones via an oxazolyliminophosphorane

A new efficient synthesis of 2,5,6-trisubstituted oxazolo（5,4-d]pyrimidi-7（6H）-ones by consecutive azaWittig reaction was developed.The sequential three-component reaction of oxazolyliminophosphorane4,isocyanates and amines produced 2,5,6-trisubstituted oxazolo[5,4-d]pyrimidi-7（6H）-ones 7 in good overall yields in the presence of catalytic amount of EtONa.

Experimental evaluation of rate coefficients for Rb (5D_J)+H_2→RbH+H reaction

The Rb（5Dj）＋H2→RbH＋H photochemical reaction has been studied. Rb vapor mixed with H2 is irradiated in a glass cell with 778-nm pulses which populate one of the 52D states by two-photon absorption. Measurements for the relative intensities of the atomic fluorescence and the absorption of the RbH product near the axis of the cell yield the rate coefficients for the Rb（5D3/2）＋H2 and Rb（5D5/2）＋H2 reactions, which are （3.6±1.3） ×10^-11 and （1.7±0.6）×10^-11 cm^3/s, respectively. The relative reactivity with H2 for Rb（5D3/2） is higher than that for Rb（5D5/2）.

Competition of surface reactions of tritium release from irradiated Li_4SiO_4 pebbles

Out-of-pile tritium release experiments were performed on Li4 Si O4 pebbles produced from lithium hydroxide under various compositions of sweep gas(He, 1.1% H2/He) and environmental moisture conditions. The experimental results indicate that tritium gas can be released directly from "dry" Li4 Si O4 under pure He gas. This phenomenon did not happen on "wet" samples, which means that the chemical form of released tritium is sensitive to moisture. Adding H2 to sweep gas may increase the overall desorption rate of tritium gas through H2 isotope exchange reaction, which occurs at a lower temperature than those of directly released tritium gas. Yet, the threshold of the H2 isotope exchange reaction is higher than the desorption reaction of tritiated water. Consequently, the effect of H2 isotope exchange reaction would reduce significantly on water adsorbed Li4 Si O4 samples.