The electronic and physical properties of PtmPdn (m+n≤5) metal clusters and their interactions with dioxygen have been studied by using hybrid density functional B3LYP method. The total energies, atomization energ...The electronic and physical properties of PtmPdn (m+n≤5) metal clusters and their interactions with dioxygen have been studied by using hybrid density functional B3LYP method. The total energies, atomization energies, vibration frequencies, and charge distributions were reported. The Pt-Pt bridge site modified by Pd atoms was found to be the most active site for the dissociation of dioxygen, which was mainly due to the change of electronic structures of the Pt atoms in bimetallic Pt-Pd clusters.展开更多
Optimized calculations of 209 polychlorinated diphenyl ethers (PCDEs) and diphenyl ethers were carried out at the B3LYP/6-31G^* level with the Gaussian 98 program. Based on the theoretical linear solvation energy r...Optimized calculations of 209 polychlorinated diphenyl ethers (PCDEs) and diphenyl ethers were carried out at the B3LYP/6-31G^* level with the Gaussian 98 program. Based on the theoretical linear solvation energy relationship (TLSER) model, the obtained structural parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting aqueous solubility (-lgSw) of PCDEs. The model obtained in this work contains two variables: mean molecular polarizability (a) and the most positive partial charge on a hydrogen atom (qH^+), of which RE = 0.9606 and SD = 0.32. And the results of cross-validation test also show that the model exhibits optimum stability and better predictive power. Moreover, the predictive power of the new model is better than that of MCIs method.展开更多
Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacin...Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.展开更多
Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alk...Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.展开更多
The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoreti...The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge transfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocalization, differentiated from that of planar p-system, is very interesting and is worthy for further investigation.展开更多
We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(lab...We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(labeled as:TM-sTCNQ,TM=3d,4d,5d series transition metals)by employing density functional theory method.Through highthroughput screenings and full reaction path researches,two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and MosTCNQ have been obtained.The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as−0.48 V.Furthermore,the Nb-sTCNQ catalyst can quickly desorb NH3 produced with a free energy of 0.65 eV,giving Nb-sTCNQ excellent catalytic cycle performance.The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N_(2),which enables the active center to adsorb and activate inert N_(2) molecules well,and the reduction processes require small energy input(i.e.,the maximum free energy changes are small).This work provides insights for finding highly efficient,stable,and low-cost nitrogen reduction reaction electrocatalysts.We hope our results can promote further experimental and theoretical research of this field.展开更多
A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theo...A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theoretical calculations obtained from four model clusters are carried out: (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">1</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">9</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">18</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">3</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">27</span></sub><span style="font-family:Verdana;"> and (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">4</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">36</span></sub><span style="font-family:Verdana;">, where there are interactions among 1, 2, 3 and 4 molecules of tryptophan. According to the literature, each interaction occurred with nine molecules of water to stabilize its expected zwitterionic form. In these models, the molecules of tryptophan appear at an adjacent distance among them to generate an analogous behavior when there is an experimental increase in the concentration. It is evident that </span><span style="font-family:Verdana;">the distance between adjacent molecules of tryptophan decreases as their concentration</span><span style="font-family:Verdana;"> increases. The optical properties of these clusters are obtained by studying the corresponding excited states and the molecular orbitals involved, showing charge transfers by using time-dependent density functional theory (TD-DFT) methods. The experimental spectroscopic data are obtained by using the clusters proposed, and good agreement is found by drawing a comparison with the theoretical data</span></span><span style="font-family:Verdana;">.展开更多
基金This work was partly supported by Innovation Foundation of the Chinese Academy of Sciences (K2003D2), National Natural Science Foundation of China (No. 20173060), Hi-tech Research and Development Program of China (2003AA517040) and Knowledge Innovation Program of the Chinese Academy of Sciences (KGCX2-SW-310)
文摘The electronic and physical properties of PtmPdn (m+n≤5) metal clusters and their interactions with dioxygen have been studied by using hybrid density functional B3LYP method. The total energies, atomization energies, vibration frequencies, and charge distributions were reported. The Pt-Pt bridge site modified by Pd atoms was found to be the most active site for the dissociation of dioxygen, which was mainly due to the change of electronic structures of the Pt atoms in bimetallic Pt-Pd clusters.
基金funded by the 973 National Basic Research Program of China (2003CB415002)China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimized calculations of 209 polychlorinated diphenyl ethers (PCDEs) and diphenyl ethers were carried out at the B3LYP/6-31G^* level with the Gaussian 98 program. Based on the theoretical linear solvation energy relationship (TLSER) model, the obtained structural parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting aqueous solubility (-lgSw) of PCDEs. The model obtained in this work contains two variables: mean molecular polarizability (a) and the most positive partial charge on a hydrogen atom (qH^+), of which RE = 0.9606 and SD = 0.32. And the results of cross-validation test also show that the model exhibits optimum stability and better predictive power. Moreover, the predictive power of the new model is better than that of MCIs method.
基金This work was supported by the Natural Science Foundation of Heilongjiang Province (No. B0313) and Research Foundation of China University of Mining and Technology
文摘Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.
基金This work was financially supported by the National Basic Research Program of China (2003CB415002), the China Postdoctoral Science Foundation (No. 2003033486) and the Natural Science Research Fund of University in Jiangsu (04KJB150149)
文摘Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.
基金supported by the National Natural Science Foundation of China(NSFC.69978021 and 20173064)FPNSFC(E9910030).
文摘The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge transfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocalization, differentiated from that of planar p-system, is very interesting and is worthy for further investigation.
基金support from the National Natural Science Foundation of China(22073033,21873032,21673087,21903032)startup fund(2006013118 and 3004013105)from Huazhong University of Science and Technology+5 种基金the Fundamental Research Funds for the Central Universities(2019kfyRCPY116)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)support from Guangdong Basic and Applied Basic Research Foundation(2021A1515010382)the computational resources from the computing cluster at the Key Laboratory of Theoretical Chemistry of Environment,Ministry of Education&School of Chemistry,South China Normal UniversityThe work was carried out at the LvLiang Cloud Computing Center of China,and the calculations were performed on TianHe-2The computing work in this paper is supported by the Public Service Platform of High Performance Computing by Network and Computing Center of HUST.
文摘We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(labeled as:TM-sTCNQ,TM=3d,4d,5d series transition metals)by employing density functional theory method.Through highthroughput screenings and full reaction path researches,two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and MosTCNQ have been obtained.The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as−0.48 V.Furthermore,the Nb-sTCNQ catalyst can quickly desorb NH3 produced with a free energy of 0.65 eV,giving Nb-sTCNQ excellent catalytic cycle performance.The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N_(2),which enables the active center to adsorb and activate inert N_(2) molecules well,and the reduction processes require small energy input(i.e.,the maximum free energy changes are small).This work provides insights for finding highly efficient,stable,and low-cost nitrogen reduction reaction electrocatalysts.We hope our results can promote further experimental and theoretical research of this field.
文摘A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theoretical calculations obtained from four model clusters are carried out: (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">1</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">9</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">18</span></sub><span style="font-family:Verdana;">, (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">3</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">27</span></sub><span style="font-family:Verdana;"> and (</span></span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">Trp</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">4</span></sub> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> (</span><span style="font-family:Verdana;"><i></span><i><span style="font-family:Verdana;">H</span></i><sub><span style="font-family:Verdana;">2</span></sub><i><span style="font-family:Verdana;">O</span></i><i><span style="font-family:Verdana;"></i></span></i><span style="font-family:""><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">36</span></sub><span style="font-family:Verdana;">, where there are interactions among 1, 2, 3 and 4 molecules of tryptophan. According to the literature, each interaction occurred with nine molecules of water to stabilize its expected zwitterionic form. In these models, the molecules of tryptophan appear at an adjacent distance among them to generate an analogous behavior when there is an experimental increase in the concentration. It is evident that </span><span style="font-family:Verdana;">the distance between adjacent molecules of tryptophan decreases as their concentration</span><span style="font-family:Verdana;"> increases. The optical properties of these clusters are obtained by studying the corresponding excited states and the molecular orbitals involved, showing charge transfers by using time-dependent density functional theory (TD-DFT) methods. The experimental spectroscopic data are obtained by using the clusters proposed, and good agreement is found by drawing a comparison with the theoretical data</span></span><span style="font-family:Verdana;">.