微原子簇的奇异性质研究

本文系统地介绍了迄今实验所发现的微原子簇的奇异性质，概述了十多年来该领域的重要进展，并分析了理论研究现状。     

铝原子簇上化学吸附的尺度效应及其理论模型

对铝原子簇Al_n(n=1～10,12,13)已报导过的理论预测几何构型进行合理选择, 用量子化学CNDO/2法研究了单分子一氧化碳在这些簇上取不同吸附位形时的吸附作用。结果表明吸附强度随簇尺度的变化呈“幻数”特性: Al_2、Al_6、Al_(12)簇具有特别高的吸附能, 与实验观测结果相符。采用作者建议的推广电子壳模型可合理解释这一尺度效应。对Al_(12)和Al_(13)簇电子结构的分析进一步支持了壳模型的观点。随着簇的增大, 尺度效应逐步减弱并趋向于体相铝的性质。     

气相微原子簇化学研究进展

本文概述了气相微原子簇的制备及其反应性质研究的方法,对其奇并的吸附和反应特性进行了讨论,同时分析了相应的理论计算方法和结果,并对该领域的潜在应用前景进行了展望.     

“惰性电子对效应”本质的相对论分析

“惰性电子对效应”是英国化学家 N.V.Sidgwick 在总结大量有关ⅢA、ⅣA、ⅤA 族元素的族数氧化态稳定性的基础上提出的用于分析其化合物不同氧化态表观稳定性的一种原     

用相对论效应解释第二周期性

本文介绍了相对论效应的主要定性结论，并用以解释“第二周期性”     

相对论效应在结构化学中的作用

相对论发表已100周年,但是相对论效应在化学中的重要性却是在近20年来才被人们所了解。这是由于这些年计算化学蓬勃地发展,揭示出来许多有关化学中电子的、结构的和化学键的新信息;另外,无机化学,特别是含有重元素的无机化学的发展,也揭示出许多新的规律和实验测定出来的数据。这些只能在考虑到相对论效应后,才能合理地、完整地加以解释和描述[1~5]。有关相对论效应在量子化学和光谱性质中作用的进展。可参看有关文献[6~9]。本文主要介绍相对论效应在结构化学中的作用,并以此纪念相对论发表100周年。1相对论效应简介相对论推得物质质量m的表…     

相对论量子化学的新进展

本文概括介绍了相对论量子化学的新进展，详细讨论了相对论效应的本质，介绍了相对论计算的基本原理和计算方法的新发展，指出相对主化ＤＶ－Ｘａ法笔有效势法是计算含重元素化合物的最有效方法。     

原子簇化合物的结构规则与化学键性质

本文从形成双中心键,三中心键和四中心键时,成键与相应的反键之间数目关系的三个基本假定出发,推导出封闭型、巢型和网型硼烷的Wade规则及其分子中双中心键、三中心键和四中心键的具体数目。进而将Wade规则推广,使之适用于包括具有戴帽结构的杂硼烷和推广到用B原子稠合成的稠合型硼烷。最后用于讨论过渡金属羰基化合物和具有密堆积型过渡金属羰基化合物的结构规则。     

碱金属原子簇的结构和稳定性

基于从体心立方碱金属晶体优化确立的多体展开势能函数，本文通过坐标优化研究了碱金属原子簇Ｘｎ（Ｘ＝Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ）的结构和稳定性。发现：（１）Ｘｎ原子簇（ｎ＝４－２１）倾向于形成畸变四面体结构单元，（Ｔｄ）的密堆积，分子表面被三元环（Ｄ３ｈ）所覆盖，其中Ｘ７－Ｘ１５最优化结构中包含五角双锥Ｘ７（Ｄ５ｈ）结构单元，具有区域五重对称轴；（２）“微观晶体碎片”的分层优化结果表明，体心立方、面心     

计算机模拟铌原子簇的稳定构型和能量性质

采用密度泛函(DFT)方法结合全局优化"Basin-Hopping"算法研究了铌原子簇: 对于Nb小簇n＝2～6我们用密度泛函方法计算了它们的稳定几何构型和电子结构, 通过拟合计算结果构造铌原子簇势能函数, 并利用该函数和全局优化"Basin-Hopping"算法得到较大铌原子簇(n＝7～20)能量极小的结构. 计算结果表明与实验及其它计算结果相一致.     

Relativistic Coupled-Cluster Calculations of Spectroscopic Properties of Copernicium and Flerovium Monoxides

Calculations of spectroscopic properties of the CnO and FlO molecules are performed using ab initio all-electron 4c- and 2c-relativistic coupled-cluster approaches with single, double, and perturbative triple excitations. The corresponding calculation for HgO is also accomplished for comparison with the published data. The dependence of the results on the parameters of the basis set and approximations used is investigated in detail. The overall relative uncertainties of the recommended values on the level of 1–2 % are reached. The calculated spectroscopic constants are indicative of the following trend in the reactivity of the oxides HgO>FlO>CnO. This is confirmed by the trend in the adsorption energies, E_ads, of these molecules on the surfaces of gold, quartz, and Teflon. The predicted rather low E_ads values for the latter case should guarantee their delivery from the recoil chamber to the chemistry set up in gas-phase experiments.     

Spectroscopic and Chemical Properties of Ionic Liquids: Computational Study

A brief account is given of highlights of our computational efforts – often in collaboration with experimental groups – to understand spectroscopic and chemical properties of ionic liquids (ILs). Molecular dynamics, including their inhomogeneous character, responsible for key spectral features observed in dielectric absorption, infra-red (IR) and fluorescence correlation spectroscopy (FCS) measurements are elucidated. Mechanisms of chemical processes involving imidazolium-based ILs are illustrated for CO₂ capture and related reactions, transesterification of cellulose, and Au nanocluster-catalyzed Suzuki cross-coupling reaction with attention paid to differing roles of IL ions. A comparison with experiments is also made.     

Spectroscopic Properties of Lumiflavin: A Quantum Chemical Study

In this work, the electronic structure and spectroscopic properties of lumiflavin are calculated using various quantum chemical methods. The excitation energies for ten singlet and triplet states as well as the analysis of the electron density difference are assessed using various wave function‐based methods and density functionals. The relative order of singlet and triplet excited states is established on the basis of the coupled cluster method CC2. We find that at least seven singlet excited states are required to assign all peaks in the UV/Vis spectrum. In addition, we have studied the solvatochromic effect on the excitation energies and found differential effects except for the first bright excited state. Vibrational frequencies as well as IR, Raman and resonance Raman intensities are simulated and compared to their experimental counterparts. We have assigned peaks, assessed the effect of anharmonicity, and confirmed the previous assignments in case of the most intense transitions. Finally, we have studied the NMR shieldings and established the effect of the solvent polarity. The present study provides data for lumiflavin in the gas phase and in implicit solvent model that can be used as a reference for the protein‐embedded flavin simulations and assignment of experimental spectra.     

Physical and Chemical Properties of Large Metal and Semiconductor Clusters in View of Future Applications

Metal and semiconductor clusters in the nanometer size regime exhibit quantum size behavior which is demonstrated by means of scanning tunneling spectroscopy and scanning capacitance microscopy on single clusters. Cluster monolayers can be prepared by self-assembly processes on modified surfaces of substrates. Clusters in the channels of nanoporous alumina are promising candidates not only for a novel kind of cluster arrangement for future electronic applications but also for the easy generation of light emitting diodes.     

Exploring the Interactions of Atomic Oxygen on Silver Clusters with Hydrogen

The interactions between Ag_nO^-(n=1-8) and H₂ (or D₂) were explored by combination of the mass spectroscopy experiments and density function theory (DFT) calculations. The experiments found that all oxygen atoms in Ag_nO^-(n=1-8) are inert in the interactions with H₂ or D₂ at the low temperature of 150 K, which is in contrast to their high reactivity with CO under the same condition. These observations are parallel with the preferential oxidation (PROX) of CO in excess hydrogen catalyzed by dispersed silver species in the condensed phase. Possible reaction paths between Ag_nO^-(n=1-8) and H₂ were explored using DFT calculations. The results indicated that adsorption of H₂ on any site of Ag_nO^-(n=1-8) is extremely weak, and oxidation of H₂ by any kind of oxygen in Ag_nO^-(n=1-8) has an apparent barrier strongly dependent on the adsorption style of the "O". These experiments and theoretical results about cluster reactions provided molecule-level insights into the activity of atomic oxygen on real silver catalysts.     

Spectroscopic Properties of Methyl Ketone Bridged Electrochromic Materials: a Quantum Chemical and Experimental Study

Tuning accurately the color of electrochromic materials has been considered as a crucial step to achieve successful electrochromic display. In this paper, the effect of substitution on the color of methyl ketone bridged electrochromic materials has been investigated systematically by experimental and TDDFT methods. By screening 15 functional and 11 basis sets, a statistical method based on M052 X data is developed to estimate the maximum absorption wavelengths(λ_(max)) of electrochromic materials, based on analyzing λ_(max) of 18 molecules. For methyl ketone bridged electrochromic materials, the color from yellow to green and λ_(max) from 400 to 690 nm can be adjusted by electron-withdrawing functional group on Ar2 and electron-donating functional group on Ar1. This work not only exhibits the suitable method to predict the maximum absorption wavelength and color of electrochromic materials, but also inspires and accelerates further development of electrochromic materials for future displays.     

6-氯-2-氨基嘌呤核苷酸的合成、光谱性质及生化评价的研究

经过4步合成了一个嘌呤核苷酸衍生物6-氯-2-氨基嘌呤核苷三磷酸盐,使用1H NMR、13C NMR、31P NMR、IR和元素分析表征了它的化学结构。在不同pH值的溶液中研究了它的紫外和荧光光谱性质,并通过pH光度微量滴定法测定了一个质子化产物的pKa值为1.44。最后,在马铃薯三磷酸腺苷双磷酸酶的催化下研究了此化合物的水解特性,这个核苷衍生物三磷酸盐与ATP竞争马铃薯三磷酸腺苷双磷酸酶的活性位点的机理被证明是一个混合型抑制机理。     

银团簇的形成及性质研究*

本文综述了在固相、液相和气相中形成银团簇的方法, 银团簇的主要性质如吸收光谱、ESR、氧还电位、电子亲和势与电离能, 以及银团簇在光解水和照相显影过程中的催化作用。总结了银团簇的理论计算方法及计算得到的主要性质如稳定几何结构、电子亲和势与电离能。最后展望了今后的发展趋势。