共查询到19条相似文献,搜索用时 15 毫秒
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氧电催化反应的活性与析氧反应和氧还原反应的热动力学驱动机制密切相关。从多自由度角度考虑,包括系统自由度和量子自由度两方面。系统自由度包括形貌工程、晶格工程和配位工程等,量子自由度包括电子自旋、轨道耦合和分子键自由度等,本质均是调节活性中心和中间体分子的轨道耦合强度。因此,突破中间体自身吸附自由能的线性关系,寻找新的氧耦联路径是提高氧电催化反应活性的一个关键方向。同时,控制活性中心和惰性中间体的分子轨道,实现质子化和脱质子化的过程也是提高反应活性的有效途径。这些新思路将有助于设计高效的催化剂,为能源领域的可持续发展做出贡献。 相似文献
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过渡金属化合物的CNDO计算(Ⅱ)——α-Fe吸附分子氮的活性中心模型 总被引:1,自引:1,他引:0
本文采用自旋非限制的CNDO-SCF方法研究了α-Fe吸附分子氮的活性中心模型,讨论了各种吸附模型的N_2活化程度,以及各种原子簇模型的费米能级、分子轨道系数等。 相似文献
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1-(2-羟乙基)-2-烷基-咪唑啉缓蚀剂缓蚀机理的理论研究 总被引:7,自引:1,他引:6
采用量子化学计算、分子动力学模拟和分子力学相结合的方法, 对6种不同烷基链长的1-(2-羟乙基)-2-烷基-咪唑啉缓蚀剂抑制H2S腐蚀的缓蚀机理进行研究, 并对其缓蚀性能进行评价. 前线轨道分布和Fukui指数表明, 6种缓蚀剂分子的反应活性区域均集中在分子的咪唑环上, 3个反应活性中心分别位于咪唑环上的N(4), N(7)和C(8)原子, 可使咪唑环在金属表面形成多中心吸附. 分子的反应活性及活性区域分布对烷基链长并不敏感. 单分子吸附能、膜的内聚能、吸附角和链间距的计算数据显示, 缓蚀剂膜的稳定性以及膜与金属基体的结合强度随链长的增加而增大; 当正构烷基碳链长度大于13时, 缓蚀剂可在金属表面形成一层高覆盖度、致密的疏水膜, 能有效阻碍溶液中的腐蚀介质向金属表面扩散, 从而达到阻碍或延缓腐蚀的目的. 相似文献
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在CCSD(T)-REL//B2GP-PLYP水平下构建[Au(CH_2)]~+与甲烷反应的可靠反应势能面,分析了C—H键活化过程中的几何结构变化情况;对反应IRC路径上关键点进行自然键轨道(NBO)电荷和分子轨道分析,从理论上推定该氢转移过程属于氢负离子(H~-)转移.对[M—X]+(M=Au,Ag,Cu;X=C,CH_2)与甲烷反应进行对比,分析了甲烷作为氢供体反应过程的内在影响因素.M—X键能和反应活性中心C上直接参与反应的低能轨道对反应活性均起重要作用,两者协同调控微观反应机制. 相似文献
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X. H. Liu M. Sun J. J. Yue Y. X. Yin X. L. Liu F. M. Miao 《Journal of Molecular Structure》2003,620(2-3):227-230
In this paper, we carried out a theoretical study on the active site structures of the Mn-SOD with ab initio Hartree–Fock SCF method, and analyzed the molecular orbital energies, charges and atomic orbital contribution to the frontier molecular orbital. 相似文献
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Amr Ali Attia Radu Silaghi‐Dumitrescu 《International journal of quantum chemistry》2014,114(10):652-665
A computational study based on density functional theory was undertaken to identify possible reaction pathways for the formation and decomposition of peroxynitrite at models of the active sites of the nonheme superoxide scavenging enzymes superoxide reductase (SOR) and iron superoxide dismutase (FeSOD). Two peroxynitrite isomers and their possible protonated states were investigated, namely Fe? OONO?, Fe? N(O)OO?, Fe? OONOH, and Fe? N(O)OOH. Peroxynitrite formation at the active sites was assumed by either the interaction of a peroxynitrite cis/trans anion with the pentacoordinated iron active site or the interaction between a nitric oxide bound adduct and superoxide; both scenarios were found to be facile for all models investigated. The ferrous adducts of the Fe? OONO?isomer were found to undergo instant heterolytic cleavage of the O? ONO bond to yield nitrite, whereas for the ferric adducts, the homolytic cleavage of the O? ONO bond to yield nitrogen dioxide was found to be energetically facile. For the Fe? N(O)OO? isomer, the active site models of FeSOD and SOR were only able to accommodate the cis isomer of peroxynitrite. Ferric adducts of the cis Fe? OONO? isomer were found to be energetically more stable than their trans counterparts and were also more stable than the cis adducts of the Fe? N(O)OO? isomer; conversely, the protonated forms of all adducts of the Fe? OONOH isomer were found to be lower in energy than their equivalent Fe? N(O)OOH adducts. Multiple reaction pathways for the decomposition of the formed peroxynitrite adducts (whether the anions or the protonated forms) were proposed and explored. The energy requirements for the decomposition processes ranged from exothermic to highly demanding depending on the peroxynitrite isomer, the type of model (whether an SOR or FeSOD active site), and the oxidation state of iron. © 2014 Wiley Periodicals, Inc. 相似文献
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1 INTRODUCTION AIDS, in other words, Acquired Immunodefici-encysyndrome, is a viral contagious disease withhigh death rate. However, effective treatment againstit has not appeared so far. At present, about 100kinds of natural compounds that could be extractedfrom natural products or artificially synthesized havebeen found to have anti-HIV activities to some ex-tent. They belong to flavonoid, terpenoid, steroid, cou-marin, peptide, alkaloid etc., respectively. Previousstudies show that… 相似文献
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A computer adapted vector method and Euler angle transformation procedures are used to generate the relationship between the atomic orbitals of icosahedral C60 Buckminsterfullerene cluster and to produce symmetry adapted molecular orbitals and vibrational species. The atomic overlaps based on the orientational relationship of the orbitals are used to compute the approximate molecular orbital energies and normalization constants. One of the vibrations of Au, symmetry is used to interpret the isomeric (dyotropic) rearrangement that breaks and forms two bonds to change two pentagons to two hexagons and vice versa. 相似文献
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Mattia Falconi Ruggero Gallimbeni Emanuele Paci 《Journal of computer-aided molecular design》1996,10(5):490-498
Summary Molecular dynamics (MD) simulations of 100 ps have been carried out to study the active-site behaviour of the Cu,Zn superoxide dismutase dimer (SOD) in water. The active site of each subunit was monitored during the whole simulation by calculating the distances between functional residues and the catalytic copper. The results indicate that charge orientation is maintained at each active site but the solvent accessibility varies. Analysis of the MD simulation, carried out by using the atomic displacement covariance matrix, has shown a different intra-subunit correlation pattern for the two monomers and the presence of inter-subunit correlations. The MD simulation presented here indicates an asymmetry in the two active sites and different dynamic behaviour of the two SOD subunits. 相似文献
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The structure-activity relationship of °uoroquinolones, which show anti-K. pneumoniae activity, was studied by using principal component analysis (PCA) and hierarchical cluster analysis (HCA). The PCA results showed that the lowest unoccupied molecular orbital energy, energy difference between the highest occupied and the lowest unoccupied molecular orbital, dipole moment, net atomic charge on atom I, molecular polarizability, partition coe±cient and molecular refractivity of these compounds are responsible for the separation between high-activity and low-activity groups. The HCA results were similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA, and three of them are proposed as active molecules against K. pneumoniae which is consistent with the results of clinical experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new °uoroquinolones with anti-K. pneumoniae activity. 相似文献
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Shinichi Katsuki 《Chemical physics letters》1986,130(6):511-514
The modified atomic orbital basis set determined for molecular orbital calculations on a given molecule is shown to be transferable to other molecules. This transferability is examined using the modified atomic orbital basis set determined for the carbon atom in methane for calculations on ethane, propane, butane, cyclohexane, acetylene, ethylene and benzene. 相似文献
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Employing hot tungsten filament to thermal dissociate molecular hydrogen,we generated gas phase atomic hydrogen under ultra-high vacuum(UHV)conditions and investigated its interaction with Pt(111) surface.Thermal desorption spectroscopy(TDS)results demonstrate that adsorption of molecular hy- drogen on Pt(111)forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species.Bulk Had species is more thermal-unstable than surface Had species on Pt(111),suggesting that bulk Had species is more energetic.This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions. 相似文献