过渡金属双核化合物Cr_2(O_2CH)_4、Mo_2(O_2CH)_4及CrMo(O_2CH)_4的从头计算研究

用从头计算方法研究双核过渡金属化合物Cr_2(O_2CH)_4、MO_2(O_2CH)_4及CrMo(O_2CH)_4的金属—金属多重键性质,计算优化键长与实验值符合很好,原子布居表明Mo_2(O_2CH)_4和CrMo(O_2CH)_4中Mo—Mo、Cr—Mo键分别为σ~2π~4δ~2与σ~2δ~2π~4四重键,同时金属-d与氧和碳-p电子间的电荷重叠对分子稳定有相当贡献。对Cr_2(O_2CH)_4在优化键长下3种组态σ~2δ~2δ~(*2)σ~(*2)、π~4π~(*4)及σ~2δ~2π~4的电子结构、原子布居、总能量及电离能的计算进行比较,讨论了Cr—Cr的成键性质,指出描述Cr—Cr间金属多重键本质必须考虑电子相关效应的影响。     

钼原子间多重键的杂化轨道研究

本文对一些含Mo-Mo原子间多重键的分子或离子进行了研究,分析了它们的电子结构和化学键提出其原子杂化轨道的形式,揭示了过渡金属原子间多重键的结构特征。     

含有金属-金属键的双核原子簇离子体系[Mo~2Sn]^2-(n=6~9)的电子结构与电子光谱

使用SCF-CI方法研究了含有Mo—Mo单键的原子簇离子体系[Mo_2Sn]~(2-)(n=6～9)的电子结构及电子光谱。讨论了随n增加,配体S,S_2,S_4对Mo—Mo键序、原子电荷的影响及其变化规律。分析了原子簇离子中的d-d相互作用能级次序及Mo—Mo,Mo—S′_t等键的性质,CI计算得到的谱带波数及强度次序与实验符合。指认分析表明,谱带的跃迁性质是有趣的,如第一吸收带为成键轨道之间的跃迁σ_(x~2-y~2)→π_(xz)(n=6～8),同时,对电子跃迁的性质进行了分类,对谱带的电荷转移性质也进行了讨论。     

混合价化合物的研究(Ⅱ)─—电化学及现场光谱电化学方法研究非质子介质中Dawson结构杂多阴离子[HAs_2Mo_(18)O_(62)]~(n-)的电还原性质

以电化学和现场紫外－可见－近红外及现场FTIR光谱电化学方法对Dawson结构杂多阴离子［HAS2Mo18O62］5－在非质子介质（CH3CN）中的电还原过程进行了研究．结果表明，该杂多阴离子在非质子介质中经历4步单电子还原反应，所产生的杂多蓝阴离子在近红外区出现宽广的价间电荷转移吸收带，而红外区Mo＝O端键及Mo—O—Mo桥键的特征吸收峰在还原后均有不同程度的红移．     

ClnAlNHn和HnAlNHn(n=1～3)的振动光谱与化学键性质的研究

用从头计算分子轨道法和密度泛函理论，在ＨＦ／６－３１Ｇ＊和Ｂ３ＬＹＰ／６－３１Ｇ＊水平上对ＣｌｎＡｌＮＨｎ和ＨａＡｌＮＨｎ（ｎ＝１～３）及其碎片分子的几何构型、电子结构、振动光谱和化学热力学性质进行了理论研究。结果表明，优化几何参数与实验值相。ＣｌＡｌＮＨ２和Ｈ２ＡｌＮＨ２分子中，Ａｌ－Ｎ键为由一个σ键和一个π键组成的双重键，旋转势垒分别为３４．１０和５４．３５ＫＪ．ｍｏｌ＾－１，而Ｃｌ３ＡｌＮＨ     

基于三脚架配体构筑的锕系-配体多重键的研究进展

非水溶液体系的锕系元素化学是一个极具挑战性的前沿研究领域, 近年来在分子磁性、多重键以及小分子活化等方面获得了迅速发展. 化学键是化学科学中最重要的基本概念之一, 而金属-配体多重键是该领域重要的研究内容. 多重键的形成与锕系元素的电子结构密切相关, 相对论效应使得锕系元素的s轨道和p轨道收缩, 轨道能量降低, 收缩的s和p轨道增加了对核电荷的屏蔽效应, 从而使d和f轨道具有一定的延展性和不稳定性. 这种不稳定性降低了5f电子的结合能, 电子更容易离去, 可使锕系元素具有丰富的氧化态. 由于较高的主量子数和相对论效应, 锕系元素的5f轨道具有更大的径向延展, 在锕系元素中5f轨道的电子行为影响较大. 目前, 锕系金属-配体多重键因其独特的成键方式和电子结构特征而受到科学家的广泛关注, 在合成和分离方面存在极大的挑战, 研究锕系-配体多重键将有助于我们了解它们的电子结构和反应性. 基于口袋型拓扑结构的三脚架配体被广泛地应用于锕系-配体多重键的研究, 这为探索锕系元素的5f电子结构和锕系多重键丰富的化学行为提供了重要支撑. 本综述总结了近年来基于三脚架配体构筑的锕系-配体多重键的研究进展, 并对未来进行了展望.     

Cr3+离子配合物电子结构和d-d 跃迁谱的研究

建议了一种采用考虑重叠修正项的多重散射Ｘα自治场方法，结合不可约张量方法求解过渡金属配合物价电子体系多电子Ｓｃｈｒｏｄｉｎｇｅｒ方程的方法，并将其应用到Ｃｒ＾３＋配合物光谱的计算，其计算结果与实验结果的方均根偏差仅１．５ｋｃｍ＾－１，同时分析了Ｘα方法中重叠修正项对配合物电子结构以及光谱计算结果的影响，以及选用的组态对计算结果的影响。     

过渡金属羰基簇的成键规则

原子簇化合物在性质、结构和成键方式等方面的特殊性,引起了合成化学、结构化学、催化化学及理论化学界的浓厚兴趣,且具有日益广阔的应用前景。对于其成键规律的研究,继Wade等提出的多面体骨架电子对理论之后,已有不少工作。本文系统研究了过渡金属羰基型原子簇化合物的结构特点,提出了确定9N-μ规则中μ值的四项条款,并用以解释了许多种过渡金属羰基簇化合物。讨论了它们的电子结构、反应性、成键特点等性质。由此还可     

助剂Mo对Ni基催化剂加氢脱氧催化作用机理的影响

制备了一系列Ni-Mo/γ-Al2O3催化剂,并采用X射线衍射、乙酸程序升温表面反应、NO-红外漫反射光谱、乙酸(或乙醇)-红外漫反射光谱等表征手段系统研究了助剂Mo的加入对Ni基催化剂的物化性质、乙酸加氢脱氧(HDO)产物、HDO活性位及乙酸(或乙醇)吸附形态的影响.结果表明,Mo的加入可提高活性组分NiO的分散度,且能抑制乙酸C-C键的断裂;Mo的加入可提供氧空穴,以促进乙酸C-O键及中间产物乙醇C-O键的断裂,显著提高了Ni基催化剂的HDO活性和产物C2H6的选择性.表明Mo的加入改变了Ni催化剂HDO的催化作用机理.     

锕系多重键金属有机化合物研究进展

多重键金属有机化合物在多种催化反应中已经得到广泛的应用, 并取得了很好的研究成果. 目前, 多重键金属有机化合物的研究已成为催化化学领域中一个引人注目的研究热点. 综述了锕系多重键金属有机化合物的研究进展. 根据化合物多重键的不同, 分别讨论了它们的合成及反应性能, 并定性讨论了多重键的性质.     

HEPT类化合物的QSAR研究

为定量结构／活性相关性研究提取了量子化学参数,拓扑指数Am,分子连接性指数^mxt及疏水性常数,同时应用正交变换和最佳变量子集算法（Leaps-and-Bonds)进行了变量压缩和选择,进而实施了多元回归分析,并由此结果进行了HEPT类化合物（1－[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine derivatives)的结构／活性关系的理论解释,进行了人工神经网络法对于该类化合物的活性预测,其结构明显好于多元回归法。     

From the Micro- to the Macro-: Managing the Conservation of the Warship,Vasa

Sweden's famous warship, Vasa, sank on her maiden voyage in August 1628, and remained on the bottom of Stockholm harbour for 333 years. Raised in 1961, she became the first large-scale wooden object to be treated with polyethylene glycol (PEG). In the summer of 2000 a number of acidic salt precipitations were noticed on the surface of the ship and on wooden artefacts in the storerooms. An international research project has been established to look into the causes of this problem and suggest possible re-treatments. Meanwhile projects are underway to monitor movements in the ship, to build a better support system, and to replace the thousands of iron bolts holding the structure together, while a sophisticated new climate system has recently been installed in the museum.     

液滴荧光传感与计算机联用技术在微量分析中的应用

通过在LS55型荧光-磷光-发光分光光度计上加装液滴产生及调节附件,采用计算机采集与分析处理数据,成功地研制了双通道液滴光化学传感装置.利用葡聚糖凝胶对复合维生素B中不同组分的选择性吸附来达到分离与同时检测的目的,并将其用于复合维生素B药片的分析,取得了满意的结果.     

明朝迁都北京与多民族国家治理

明朝建立后,面对多民族国家治理的新格局,定都问题一直是困扰朱元璋君臣的一大难题。终洪武之世,朱元璋也未能解决迁都的问题。燕王朱棣称帝后,将北平改为北京,条件具备后迅速将京师从南京迁到北京。成祖去世之后,虽有短暂的反复,但英宗即位不久,宣布定都北京,从此北京成为明朝永久的都城。迁都北京是明朝主动适应唐以后多民族交融局面的具体表现,一方面可以有效应对元朝残余的侵扰,另一方面能够整合农耕和游牧两大区域,为中国多民族国家治理做出了积极的贡献,意义重大。     

Using of the Agglomeration-in-liquid for the Technology of the Fine Materials

The content of the fine and ultrafine particles in the raw material results in difficulty of the separation, the loss of the valuable components and ecological contamination. Secondary using of the fine particles is impossible without their granulation. This problem has been solved by the agglomeration-in-liquid method.An agglomeration-in-liquid method is a process to produce agglomerates in a liquid phase from solid particles suspended in the liquid. The surface of solid particles and the binding liquid must be of identical polarity, but the continuous phase must be of the opposite polarity. The water solutions of the surfactant are the binding liquids or the organic liquids.     

On the scaling of the interface energy of the liquid clusters in the disordered nanoporous medium

Similarity of the extrusion curves of non-wetting liquid in a nanoporous medium with different initial fill volume fractions is observed experimentally. The similarity can be explained by the scaling of the interface energy and the self-similarity of the infinite percolation cluster of fluid-filled pores. Understanding the physical processes leading to the observed phenomena is a foundation for the development of high-performance devices for damping and energy storage on the basis of such heterogeneous systems.     

Copper-containing dendromesogens: the influence of the metal on the mesomorphism

The synthesis and liquid crystalline behaviour of the first and second generations of a dendrimeric structure based on poly(propyleneimine)(DAB-dendr(NH₂)_x) are reported. 4-(4-n-Alkoxybenzoyloxy)salicylaldehydes are used as mesogenic moieties attached at the peripheral amino groups of the dendrimers giving rise to dendromesogens with four and eight mesogenic branches. From these dendromesogens, considered as organic ligands, were prepared six metal-containing dendrimers which incorporate two or four copper atoms in their structures. All the dendrimeric ligands and three of the metal-containing dendrimers exhibit liquid crystalline properties which were studied by optical microscopy, DSC, X-ray diffraction and EPR spectroscopy.     

On the quality of the hardness kernel and the Fukui function to evaluate the global hardness

An approximated hardness kernel, which includes the second derivative with respect to the density of the kinetic energy, the electron-electron coulomb repulsion, and the exchange density functionals, has been tested for the calculation of the global hardness. The results obtained for a series of 40 cations and neutral systems and 16 anions represent in most cases an improvement of the results obtained using the HOMO-LUMO gap approach and indicate the viability of this approach to evaluate global hardness. In addition, the relevance of the Fukui function approximation and the role of the three components of the hardness kernel in the evaluation of the global hardness have been analyzed.     

Influence of the Position of the Connecting Spacer of the Chromophore on the Nonlinear Optical Response

A new chromophore, C1 , based on a similar DπA‐structure as in the FTC ‐chromophore but with a hydroxyalkyl spacer perpendicular to the direction of the dipole moment was synthesized. Both chromophores and the CLD ‐chromophore were used to prepare high T_g nonlinear optical vinyl polymers. The influence of the position of the spacer on the DπA‐system on the NLO response of the resulting polymers was investigated.