Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functio...Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functional groups and its electro-catalytic activity is still unclear. In this paper, we prepared different levels of oxidized carbons by a simple acid treatment and investigated the correlation between the surface oxygen functional groups of acid-treated carbon and electro-catalytic activity in an electrooxidation of L-ascorbic acid. Positively charged carbon was demonstrated by lone pair electron of oxygen from valence band spectra study. It was revealed that the positively charged carbon, especially involved in carbonyl, showed enhanced the electro-catalytic activity through both better adsorption of negatively charged reactants and lowered LUMO by electronegativity of oxygen.展开更多
This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied ...This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied a gap-free model using molecular dynamics. Physical quantities such as volume and pressure of the Na-O and Li-O systems exhibit similar behaviors around the thermodynamic ensembles NPT and NVE. However, for the Na2O system, at a minimum temperature value, we observe a range of total energy values;in contrast, for the Li2O system, a minimum energy corresponds to a range of temperatures. Finally, for physicochemical properties, we studied the diffusion coefficient and activation energy of lithium and potassium oxides around their melting temperatures. The order of magnitude of the diffusion coefficients is given by the relation Dli-O >DNa-O for the multiplicity 8*8*8, while for the activation energy, the order is well reversed EaNa-O > EaLi-O.展开更多
We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group e...We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.展开更多
Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water parti...Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water partition coefficient) of 96 aromatic sulfur-containing carboxylates, including phenylthio, phenylsulfinyl and phenylsulfonyl carboxylates. In comparison with TLSER models, the atomic charge models are more accurate and reliable to predict the partition properties of the kind of compounds. For the atomic charge models, the molecular descriptors are molecular surface area(S), molecular shape(O), weight(M W), net charges on carboxyl group(Q OC), net charges of nitrogen atoms(Q N), and the most negative atomic charge(q -) of the solute molecule. For water solubility(log S W) and octanol/water partition coefficient(log K OW), the correction coefficients r 2 adj(adjusted for degrees of freedom) are 0.936 and 0.938, and the standard deviations are 0.364 and 0.223, respectively.展开更多
Two 1,8-naphthalimide derivatives of 7H-benzimidazo[2,1,-a]benz[de] isoquino- lin-7-one（1） and 4-bromo-7H-benzimidazo[2,1,-a]benz[de]isoquinolin-7-one（2） have been synthesized and characterized by elemental analys...Two 1,8-naphthalimide derivatives of 7H-benzimidazo[2,1,-a]benz[de] isoquino- lin-7-one（1） and 4-bromo-7H-benzimidazo[2,1,-a]benz[de]isoquinolin-7-one（2） have been synthesized and characterized by elemental analysis, IR, 1H NMR, UV-Vis and fluorescence spectra. For the two compounds, density functional theory（DFT） calculations of the structures and natural population atomic charge analysis have been performed at the B3LYP/6-311G＊＊ level of theory. Based on Onsager reaction filed model and by using TD-DFT method at the B3LYP/6-311G＊＊ level, electron spectra of 1 and 2 with solvent effect in CHCl3 solvent have been predicted, which are in agreement with the experimental ones. Comparative studies on 1 and 2 indicate that introducing an electron-withdrawing group of Br into the 4-position of naphthalene ring in 2 does not significantly make the molecular geometry of 2 different from that of 1, but evidently changes the atomic charge redistribution, moves the positive-negative charges center and then changes the dipole moment in 2. Additionally, for compound 2, the existence of Br atom has also influenced the peak intensity and peak locations in both electron and fluorescence spectra.展开更多
The suitability of calculating atomic multipole moments from AM1 wave functions by cumulative potential-derived method has been investigated. It is shown that this method has a faster convergence of the fitting proces...The suitability of calculating atomic multipole moments from AM1 wave functions by cumulative potential-derived method has been investigated. It is shown that this method has a faster convergence of the fitting process and gives a better description of the charge distribution than the original PD method. Atomic charges obtained in this way are of comparable quality with 6-31G* data and the calculated dipole moments are closer to the experimental data than the values computed directly from the AM1 charges. The results demonstrate that the atomic multipole moments higher than monopole moment can be used to supplement the atomic charge to obtain a more accurate description of charge distribution. For the sake of comparison, both the Williams fitting potential surface and the Connolly one are used in the calculation.展开更多
Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （A...Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （Aphis craccivora） at 250 mg,L-1. The influence of N-oxide formation on the biological activity was elucidated by computational chemical study, and it indicated that the water bridge hydrogen bonding network was broken due to the influence of the O atom connected with the pyridine ring.展开更多
基金supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20153030031720)
文摘Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functional groups and its electro-catalytic activity is still unclear. In this paper, we prepared different levels of oxidized carbons by a simple acid treatment and investigated the correlation between the surface oxygen functional groups of acid-treated carbon and electro-catalytic activity in an electrooxidation of L-ascorbic acid. Positively charged carbon was demonstrated by lone pair electron of oxygen from valence band spectra study. It was revealed that the positively charged carbon, especially involved in carbonyl, showed enhanced the electro-catalytic activity through both better adsorption of negatively charged reactants and lowered LUMO by electronegativity of oxygen.
文摘This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied a gap-free model using molecular dynamics. Physical quantities such as volume and pressure of the Na-O and Li-O systems exhibit similar behaviors around the thermodynamic ensembles NPT and NVE. However, for the Na2O system, at a minimum temperature value, we observe a range of total energy values;in contrast, for the Li2O system, a minimum energy corresponds to a range of temperatures. Finally, for physicochemical properties, we studied the diffusion coefficient and activation energy of lithium and potassium oxides around their melting temperatures. The order of magnitude of the diffusion coefficients is given by the relation Dli-O >DNa-O for the multiplicity 8*8*8, while for the activation energy, the order is well reversed EaNa-O > EaLi-O.
文摘We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.
文摘Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water partition coefficient) of 96 aromatic sulfur-containing carboxylates, including phenylthio, phenylsulfinyl and phenylsulfonyl carboxylates. In comparison with TLSER models, the atomic charge models are more accurate and reliable to predict the partition properties of the kind of compounds. For the atomic charge models, the molecular descriptors are molecular surface area(S), molecular shape(O), weight(M W), net charges on carboxyl group(Q OC), net charges of nitrogen atoms(Q N), and the most negative atomic charge(q -) of the solute molecule. For water solubility(log S W) and octanol/water partition coefficient(log K OW), the correction coefficients r 2 adj(adjusted for degrees of freedom) are 0.936 and 0.938, and the standard deviations are 0.364 and 0.223, respectively.
基金Supported by Doctor Foundation of Shandong Province(No.BS2010CL021)Natural Science Foundation of Shandong Province(ZR2009AL020)Jiangsu Key Laboratory for Chemistry of Low-dimensional Materials P.R.China(JSKC12106 and JSKC12107)
文摘Two 1,8-naphthalimide derivatives of 7H-benzimidazo[2,1,-a]benz[de] isoquino- lin-7-one（1） and 4-bromo-7H-benzimidazo[2,1,-a]benz[de]isoquinolin-7-one（2） have been synthesized and characterized by elemental analysis, IR, 1H NMR, UV-Vis and fluorescence spectra. For the two compounds, density functional theory（DFT） calculations of the structures and natural population atomic charge analysis have been performed at the B3LYP/6-311G＊＊ level of theory. Based on Onsager reaction filed model and by using TD-DFT method at the B3LYP/6-311G＊＊ level, electron spectra of 1 and 2 with solvent effect in CHCl3 solvent have been predicted, which are in agreement with the experimental ones. Comparative studies on 1 and 2 indicate that introducing an electron-withdrawing group of Br into the 4-position of naphthalene ring in 2 does not significantly make the molecular geometry of 2 different from that of 1, but evidently changes the atomic charge redistribution, moves the positive-negative charges center and then changes the dipole moment in 2. Additionally, for compound 2, the existence of Br atom has also influenced the peak intensity and peak locations in both electron and fluorescence spectra.
文摘The suitability of calculating atomic multipole moments from AM1 wave functions by cumulative potential-derived method has been investigated. It is shown that this method has a faster convergence of the fitting process and gives a better description of the charge distribution than the original PD method. Atomic charges obtained in this way are of comparable quality with 6-31G* data and the calculated dipole moments are closer to the experimental data than the values computed directly from the AM1 charges. The results demonstrate that the atomic multipole moments higher than monopole moment can be used to supplement the atomic charge to obtain a more accurate description of charge distribution. For the sake of comparison, both the Williams fitting potential surface and the Connolly one are used in the calculation.
基金This work was financially supported by National Basic Research Program of China （973 Program, 2010CB126100）, National High Technology Research and Development Program of China （863 Program, 2011AA10A207）. This work was also partly supported by National Key Technology R＆D Program of China （2011BAE06B01）, National Natural Science Foundation of China （20802018）, Shanghai Foundation of Science and Technology （09391911800, 08391911600, 08ZR1406500）, Doctoral Program of Higher Education （200802511002）, Shanghai Leading Academic Discipline Project, Project Number： B507 and the Fundamental Research Funds for the Central Universities. This work was supported by ＂Special Fund for Agro-scientific Research in the Public Interest （201103007）＂.
文摘Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （Aphis craccivora） at 250 mg,L-1. The influence of N-oxide formation on the biological activity was elucidated by computational chemical study, and it indicated that the water bridge hydrogen bonding network was broken due to the influence of the O atom connected with the pyridine ring.
