三甲基镓与氨基亚甲基酚配合物的合成与表征

八十年代以来,由于发现铝、镓、铟的金属有机化合物在制备半导体材料、特种陶瓷和电致发光材料等方面具有重要的应用价值 [1],因此,对此类化合物的研究报道也逐渐增多。 IIIA族金属有机配合物由于成键结构复杂,可以调节的结构点多,具有丰富的化学内含,而又具有相对稳定的化学性质 [2],所以,通过对 IIIA族金属有机配合物的研究,可以寻找到更稳定的、性能更佳的 MO(Metal Organic)新源,对于 MOCVD(Metal Organic Compound Vapor Deposit)技术的发展有着重要的意义 [3]。氨基亚甲基酚或萘酚由于其作为染料 [4]、杀虫剂 [5]、…     

N,N''''-双(3-羧基水杨醛叉缩胺乙基)草酰胺均双核铜(Ⅱ)的密度泛函研究

草酰胺及其衍生物过渡金属原子配合物是近年来在实验和理论上[1～5]研究都十分活跃的领域,其原因是这些配合物具有良好的磁性质,对磁功能分子设计和磁性材料合成有着十分重要的意义.     

我国盐湖粘土矿物及其意义的初步研究

本文论述了我国盐湖粘土矿物,它以伊利石-绿泥石为特征,含少量蒙脱石和高岭石等。不同地区盐湖和盐湖不同沉积阶段中某些粘土矿物组合、相对含量和粘土中化学成分等存在明显差异。盐湖粘土矿物基本上是他生的,同时也存在转交这种成因类型。盐湖粘土矿物基本特征是受我国干旱气候带和盐湖的不同物质来源所控制。     

利用压电频移分析法测定硫

1　引言硫是人体必需的元素之一,也是蛋白质等许多具有生物活性物质的重要组成元素。硫与人体健康的关系十分密切,硫的医疗价值越来越引起人们的重视,因此硫的测定具有重要意义。对于硫离子的测定,提出了包括极谱分析法[1]、电位分析法[2]、分光光度法[3]等多种分析方法。...     

N，N′-双(3-羧基水杨醛叉缩胺乙基)草酰胺均双核铜(II)的密度泛函研究

草酰胺及其衍生物过渡金属原子配合物是近年来在实验和理论上[1￣5]研究都十分活跃的领域,其原因是这些配合物具有良好的磁性质,对磁功能分子设计和磁性材料合成有着十分重要的意义。我们课题组合成了一种以N,N′-双(3-羧基水杨醛叉缩胺乙基)草酰胺为配体的Cu!-Cu!均双核配合物,由于该配合物的溶解性较差,难以培养出理想的单晶,因此一直未曾进行晶体结构解析。所以,该配合物分子的电子结构特征和几何构型,电子结构与配合物分子的稳定性及分子的磁性之间的构效关系等目前尚不清楚。因此,就该类磁功能配合物分子的上述问题进行理论研究,无疑…     

稀土硝酸盐与1,1,1-三(4′-二苯胺甲酰基-2′-氧杂丁基)丙烷配合物的合成及谱学性质

三角架型配体由于其独特的配位方式而具有许多优良的物理和化学性质 ,如能稳定高氧化态的过渡金属离子[1 3] ,用作优良的电极活性物质[4] ,具有生物活性[5] 等 .因此近十余年来对该类配合物的研究一直是配位化学研究领域的一个重要部分 .但到目前为止 ,对具有三角架结构的三酰胺型开链冠醚的研究却很少 ,且主要集中于研究它与过渡金属和碱金属离子的相互作用及其性质[4,5] ,有关该类配体与稀土离子的配位形式及性质的研究则更少[6] .为了进一步研究该类配体与稀土离子的配位能力及所形成配合物的性质 ,我们参照文献 [5]方法 ,合成出配体 1 ,…     

双核铜配合物{Cu[μ-S_2P(C_2H_5O)_2](C_(10)H_8N_2)}_2的合成和晶体结构

二烃基二硫代磷酸酯及其过渡金属配合物能阻止烃类自动氧化,是一种很重要的抗氧、抗磨和防腐蚀的添加剂[1] 。在生物学上也具有十分重要的地位,具有杀虫、抗菌、抗癌和抑制酶水解等特性[2] 。也广泛应用于钻镍、钻锰等金属的萃取分离[3] 。因此,对该领域的研究也十分活跃。对二烃基二硫代磷酸酯合过渡金属配合物及其加合物的研究,我们已作过多次报导 [4-7],但迄今为止,许多研究工作者希望得到二乙基二硫代磷酸酯合铜的晶体结构,均未获得成功。我们利用二乙基二硫代磷酸酯合钢与2 ,2 ’一联吡啶的加合反应,得到了标题配合物的晶体,…     

染料敏化太阳电池钌系敏化剂

钌系敏化剂是染料敏化太阳电池（DSSC）研究最早也最成功的敏化剂类型之一,最高光电转换效率已达到11%以上。研究总结钌系敏化剂的结构、谱学性质、电化学性质与其光电转换性能之间的构效关系,对于设计合成新的具有更高性能的敏化剂、推进DSSC的实用化进程具有十分重要的意义。本文综述了钌系敏化剂的研究进展,将这类敏化剂按结构和性质进行分类,讨论了其分子结构、电子结构、谱学性质、电化学性质对其光吸收能力、电子注入效能、电荷传输与复合等因素的影响,并对其光电转换性能进行了详细评述,总结了其结构与光电转换性能之间的构效关系,概括了高效钌系敏化剂的结构特征,为更高效敏化剂的设计合成提供了有价值的参考。     

两种芳香β-二酮化合物的合成及表征

β-二酮化合物是一类重要的有机合成中间体,β-二酮化合物分子内酮式-烯醇式之间的异构化转变赋予其许多独特的光化学和配位化学性质。关于酮式-烯醇式之间的互变关系有许多研究[1,2,3],借助于其光致互变异构的光化学性质,β-二酮化合物可广泛地用作光稳定等功能材料[4]。同时,     

氧和碳酸根桥联的双核铁(Ⅲ)配合物的合成、结构和光谱研究

氧桥联的双核铁配合物一直是无机化学工作者十分感兴趣的研究课题 .近年来 ,由于在生物体内发现多种金属蛋白和金属酶的活性中心存在氧和羧酸根桥联的双核铁结构单元 ,如蚯蚓血红蛋白 [1]、甲烷单加氧酶 [2 ]、核糖核酸还原酶 [3]、饱和脂肪酸还原酶 [4 ]和紫色酸性磷酸酶 [5]等 ,使得对氧桥联的双核铁配合物的研究成为当前生物无机化学研究中的热点之一[6] .为进一步了解氧桥联的双核铁配合物的物理化学性质 ,我们在系统研究的基础上 ,合成了一个新的氧和碳酸根桥联的双核铁配合物 ,测定了其晶体结构 ,研究了其电子吸收光谱 .1　实验部分1 …     

Colorimetric recognition and sensing of nitrite with unmodified gold nanoparticles based on a specific diazo reaction with phenylenediamine

A colorimetric sensor for nitrite ion with high selectivity and sensitivity by unmodified citrate-capped gold nanoparticles (Au NPs) is presented. Recognition of nitrite is developed on the basis of a highly specific diazo reaction between nitrite and phenylenediamine (PDA). PDA caused the Au NPs to aggregate owing to the strong covalent NH-Au bond, with a clear color change of solution from red to blue being visualized. In the presence of phosphoric acid and nitrite, the amines of PDA would readily be converted to diazo bonds, and a red solution was observed after the subsequent addition of Au suspension due to the much less strength of electrostatic interaction between the positive diazo groups and the negative citrate-capped Au NPs. With this colorimetric "light-up" method, <1 ppm of nitrite can be easily detected within 5 min at room temperature without instrumentation. Since the diazo reaction and the colorimetric response are separate, this approach features the use of pristine Au NPs in an assay where acidic environment is a necessity, making it a more convenient and cost-effective method for the sensing of nitrite when compared with those utilizing chemically modified Au NPs.     

Probing the electronic structure and chemical bonding of gold oxides and sulfides in AuOn(-) and AuSn(-) (n = 1, 2)

The Au-O and Au-S interactions are essential in nanogold catalysis and nanotechnology, for which monogold oxide and sulfide clusters serve as the simplest molecular models. We report a combined photoelectron spectroscopy and ab initio study on AuO (-) and AuO 2 (-) and their valent isoelectronic AuS (-) and AuS 2 (-) species to probe their electronic structure and to elucidate the Au-O and Au-S chemical bonding. Vibrationally resolved spectra were obtained at different photon energies, providing a wealth of electronic structure information for each species. Similar spectra were observed for AuO (-) and AuS (-) and for the linear OAuO (-) and SAuS (-) species. A bent isomer was also observed as Au(S 2) (-) in the AuS 2 (-) spectra, whereas a similar Au(O 2) (-) complex was not observed in the case of AuO 2 (-). High-level ab initio calculations were conducted to aid spectral assignments and provide insight into the chemical bonding in the AuX (-) and AuX 2 (-) molecules. Excellent agreement is achieved between the calculated electronic excitations and the observed spectra. Configuration interactions and spin-orbit couplings were shown to be important and were necessary to achieve good agreement between theory and experiment. Strong covalent bonding was found in both the AuX (-) and the XAuX (-) species with multiple bonding characters. While Au(S 2) (-) was found to be a low-lying isomer with a significant binding energy, Au(O 2) (-) was shown to be unbound consistent with the experimental observation. The latter is understood in the context of the size-dependent reactivity of Au n (-) clusters with O 2.     

Theoretical Studies on the Interactions of Cations with Diazine

1 INTRODUCTION Interaction between cations and π electron systems is a kind of common and important non-covalent inter- action[1～21]. It could be observed in many systems, such as gas ion-molecule complexes and biological macromolecular proteins. Especially, in biological macromolecular systems, this interaction is signi- ficant for revealing the structures and functions of proteins or disclosing the atomic essence of protein- ligand effect. Interaction between benzene and metal ions h…     

Geometric Effects on Conductance in Single Molecule Electron Transport Junctions

We studied electron transport properties of a dithiol‐benzene molecule covalently bonded between two gold electrodes by combining ab initio calculations for the central molecule and a green function method to calculate electron transport. Due to the large computational demand, this type of calculations usually involves certain ways of simplification. The simplification commonly used is to fix the contact surface of the electrodes by ignoring the disturbance of the Au contact surface by contacting with the central molecule, i.e. without scattering region relaxation. In this study, we intended to resolve the difference between models with and without the above simplification. The large conductance found in our models without scattering region relaxation is due to the highly symmetric arrangement of the Au contact surface and those layers near the contact. The disturbance of the Au contact surface by the contact of the central molecule is important since the increase of the Au‐S bond and the distortion of the Au atom on the FCC site can lower the transmission coefficient between the two electrodes. In order to obtain better results, the model should include scattering region relaxation. However, when such relaxation is not applicable or demands too much calculation resource, the center molecule of the electronic transport junction should be at least optimized by the calculation level including electronic correlation, i.e. post‐HF methods.     

Complexes of DNA bases and Watson-Crick base pairs with small neutral gold clusters

The nature of the DNA-gold interaction determines and differentiates the affinity of the nucleobases (adenine, thymine, guanine, and cytosine) to gold. Our preliminary computational study [Kryachko, E. S.; Remacle, F. Nano Lett. 2005, 5, 735] demonstrates that two major bonding factors govern this interaction: the anchoring, either of the Au-N or Au-O type, and the nonconventional N-H...Au hydrogen bonding. In this paper, we offer insight into the nature of nucleobase-gold interactions and provide a detailed characterization of their different facets, i.e., geometrical, energetic, and spectroscopic aspects; the gold cluster size and gold coordination effects; proton affinity; and deprotonation energy. We then investigate how the Watson-Crick DNA pairing patterns are modulated by the nucleobase-gold interaction. We do so in terms of the proton affinities and deprotonation energies of those proton acceptors and proton donors which are involved in the interbase hydrogen bondings. A variety of properties of the most stable Watson-Crick [A x T]-Au3 and [G x C]-Au3 hybridized complexes are described and compared with the isolated Watson-Crick A x T and G x C ones. It is shown that enlarging the gold cluster size to Au6 results in a rather short gold-gold bond in the Watson-Crick interbase region of the [G x C]-Au6 complex that bridges the G x C pair and thus leads to a significant strengthening of G x C pairing.     

Chemical bonding in group III nitrides

We analyze in this article the evolution of the chemical bonding in group III nitrides (MN, M = Al, Ga, In), from the N-N bond dominated small clusters to the M-N bond dominated crystals, with the aim of explaining how the strong multiple bond of N(2) is destabilized with the increase in coordination. The picture that emerges is that of a partially ionic bond in the solid state, which is also present in all the clusters. The covalent N-N bond, however, shows a gradual decrease of its strength due to the charge transfer from the metal atoms. Overall, Al clusters are more ionic than Ga and In clusters, and thus the N-N bond is weakest in them. The nitrogen atom charge is seen to be proportional to the metal coordination, being thus a bond-related property, and dependent on the M-N distance. This explains the behavior observed in previous investigations, and can be used as a guide in predicting the structures and defects on semiconductor quantum dot or thin film devices of these compounds.     

压缩变形对C20富勒烯分子电子传输特性的影响

The geometry,electronic structure and electronic transmission of Au electrode-compressed C20 fullerene Au electrode systems are investigated systemically,and some interesting results are obtained by use of molecular dynamics,Extend Hückel method of the first principle,and Green's function based method. The analytical results show that,due to intervention of Au electrodes,the electronic structure of compressed C20 fullerene is changed significantly,the coalescent between C20 fullerene and Au electrodes is intervenient of covalent bond and electrovalent bond,and the compressed C20 fullerenes are better conductors of electricity than those uncompressed or slightly compressed ones. The methods and the relative conclusions are beneficial to go further deep into electronic transmission of carbon fullerenes.     

Partial oxidation of propylene to propylene oxide over a neutral gold trimer in the gas phase: a density functional theory study

We report a B3LYP study of a novel mechanism for propylene epoxidation using H(2) and O(2) on a neutral Au(3) cluster, including full thermodynamics and pre-exponential factors. A side-on O(2) adsorption on Au(3) is followed by dissociative addition of H(2) across one of the Au-O bonds (DeltaE(act) = 2.2 kcal/mol), forming a hydroperoxy intermediate (OOH) and a lone H atom situated on the Au(3) cluster. The more electrophilic O atom (proximal to the Au) of the Au-OOH group attacks the C=C of an approaching propylene to form propylene oxide (PO) with an activation barrier of 19.6 kcal/mol. We predict the PO desorption energy from the Au(3) cluster with residual OH and H to be 11.5 kcal/mol. The catalytic cycle can be closed in two different ways. In the first subpathway, OH and H, hosted by the same terminal Au atom, combine to form water (DeltaE(act) = 26.5 kcal/mol). We attribute rather a high activation barrier of this step to the breaking of the partial bond between the H atom and the central Au atom in the transition state. Upon water desorption (DeltaE(des) = 9.9 kcal/mol), the Au(3) is regenerated (closure). In the second subpathway, H(2) is added across the Au-OH bond to form water and another Au-H bond (DeltaE(act) = 22.6 kcal/mol). Water spontaneously desorbs to form an obtuse angle Au(3) dihydride, with one H atom on the terminal Au atom and the other bridging the same terminal Au atom and the central Au atom. A slightly activated rearrangement to a symmetric triangular Au(3) intermediate with two equivalent Au-H bonds, addition of O(2) into the Au-H bond, and rotation reforms the hydroperoxy intermediate in the main cycle. On the basis of the DeltaG(act), which contains contribution from both pre-exponetial factor and activation energy, we identify the propylene epoxidation step as the actual rate-determining step (RDS) in both the pathways. The activation barrier of the RDS (epoxidation step: DeltaE(act) = 19.6 kcal/mol) is in the same range as that in the published computationally investigated olefin epoxidation mechanisms involving Ti sites (without Au involved) indicating that isolated Au clusters and possibly Au clusters on non-Ti supports can be active for gas-phase partial oxidation, even though cooperative mechanisms involving Au clusters/Ti-based-supports may be favored.     

Photoelectron imaging and theoretical studies of group 11 cyanides MCN (M = Cu, Ag, Au)

Photodetachment of group 11 cyanide anions MCN(-) (M = Cu, Ag, Au) has been investigated using photoelectron velocity-map imaging. The electron affinities (EAs) of CuCN (1.468(26)) and AgCN (1.602(22)) are larger, while that of AuCN (2.066(8)) is smaller than those of the free atoms. This intriguing observation was confirmed by theoretical studies and was assigned to the transition between ionic and covalent bond properties. The harmonic frequencies of the extended vibrational progressions in the M-C stretching mode are 460(50), 385(27), and 502(10) cm(-1), respectively, which suggests a stronger bond for Au-CN than for Ag-CN. Electronic structure analysis and model calculations suggest that all M-C bonds in group 11 cyanides are best described as single bonds. A model has been proposed to explain how the relativistic effects influence the Au-C bond strength in AuCN.     

Influence of the precipitation agent in the deposition-precipitation on the formation and properties of Au nanoparticles supported on Al2O3

Au nanoparticles supported on Al2O3 were prepared by deposition-precipitation of HAuCl4 with different precipitation agents NaOH and urea. The samples were investigated by means of different characterization techniques such as X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and transmission electron microscopy (TEM). The results show that depending on the precipitation agent, the Au particles have a different Au-Au coordination number and size after calcination at 523 K. Whereas the use of NaOH leads to the formation of Au nanoparticles with a Au-Au coordination number of 6.7 and a mean diameter below 2 nm, those prepared with urea have a mean size of 3.1 nm. The Au-Au coordination number could be determined as 8.6. At the smaller particles obtained with NaOH, hints for Au-O interactions were found. For these particles TEM results advise a rather flat lenticular morphology. Different deposition mechanisms depending on the precipitation agent are discussed as the reason for the formation of nanoparticles with different shapes, sizes, and valence states.