金团簇电催化二氧化碳还原反应的研究进展

二氧化碳电还原反应(CO₂RR)在改善能源利用方式、 实现可持续碳循环以及生产高附加值液体燃料和化学品等方面具有广阔的应用前景, 近年来受到广泛关注. 有机配体保护的金团簇具有确定的晶体结构, 其不同的尺寸、 配体及组成可以有效调控氧化还原电位, 作为一种独特的模型催化剂, 为探索原子水平的CO₂RR反应机理提供了新机遇. 本文综合评述了纯金团簇和异金属原子掺杂的金团簇催化CO₂RR的研究进展, 包括金团簇的电荷、 尺寸、 配体以及掺杂对CO₂RR性能的影响, 重点讨论了CO₂RR的反应机理, 总结了金团簇在CO₂RR中所面临的挑战, 并展望了金团簇在CO₂RR中未来的研究方向和发展前景.     

膦配体电子和空间效应对钯催化羰化酯化反应的影响

膦配体修饰的钯催化剂在不饱和化合物羰化酯化反应中使用广泛,其催化活性在很大程度上取决于金属周围的配体环境。膦配体电子和空间效应的调变,可以实现定向催化,甚至可以预测催化行为。新催化反应的开发和现有催化反应的优化都可以通过膦配体的合理设计来实现。配体已经是成为公认的最重要的需要详细研究的变量之一。本文综述了钯催化烯烃羰化酯化反应中,单齿膦配体、双齿膦配体、半稳定膦配体电子和空间效应对活性和选择性的调控作用,并对面临的问题和未来的发展方向进行了探讨,以期对未来设计高效高选择性羰化酯化反应催化体系提供指导。     

奎宁修饰的纳米铑簇合物催化丙酮酸乙酯对映选择性加氢反应研究

研究了奎宁作手性修饰剂修饰的负载型纳米铑簇合物催化剂 (Rh/ PVP-γ-Al2 O3)催化丙酮酸乙酯不对称氢化反应 ,在该反应中手性修饰剂奎宁不仅具有手性诱导作用 ,而且还有明显加速反应的作用 ;载体γ-Al2 O3在促进提高催化剂活性和对映选择性方面也有很重要的影响 .在优化的反应条件 [2 0℃ ,7.0 MPaH2 ,c(奎宁 ) =3 .86× 1 0 - 3mol/ L,四氢呋喃作溶剂 ]下 ,丙酮酸乙酯不对称加氢的转化频率 (TOF)为871 h- 1 ,对映选择性达到了 5 4.7% ;反应温度降低到 3℃时 ,对映选择性达到 5 9.2 % .     

双氰胺在金团簇上吸附的密度泛函理论和表面增强拉曼光谱研究

双氰胺是氰胺的二聚体,具有亚氨式和氨式两种互变异构体.将表面增强拉曼光谱(SERS)与密度泛函理论(DFT)结合,研究了互变异构的双氰胺分子在金表面的吸附行为.通过理论计算获得了亚氨式和氨式双氰胺分子的能量、分子轨道和光谱信息,以及双氰胺分子吸附在金簇表面的SERS响应.计算结果表明两种异构化的双氰胺分子都与Au₃簇形成较稳定的复合物,并且双氰胺分子中N₂原子优先吸附在金簇表面.拉曼实验结果与计算结果较为吻合,进一步说明具有互变异构的双氰胺分子在金基底中共存,并通过N₂原子垂直吸附到金表面,符合SERS电磁场增强机制.     

金团簇二十面体结构融合过程中其催化活性的演变

近年来,由有机配体保护的原子精确金属团簇在合成方面已取得了重要进展,其独特的原子结构对一些化学反应产生独特的催化效果.原子精确的团簇催化剂明显不同于纳米颗粒催化剂和单原子催化剂,是一种关联均相和多相的、原子数目确定、尺寸均一、结构精确的新型催化剂.从原子尺度上精确构筑团簇催化剂,探究亚纳米尺度的微观结构对催化性能的影响...     

无配体钯催化的烯丙基酯离去基团保留的高选择性芳基化反应

带有易离去基团的烯丙基酯类化合物的Heck反应由于竞争反应和选择性的难以控制，使得该反应一直属于比较挑战性的领域：（1）烯丙基酯类化合物很容易经过C-O键断裂和零价钯发生氧化加成（patha），与芳基卤化物对零价钯的氧化加成反应（pathb）形成竞争；（2）在钯物种对双键进行插入反应后，     

金纳米簇-多金属氧酸盐复合物的制备及催化选择性氧化环已烯性能研究

通过4-N,N二甲基胺基吡啶和多金属氧酸负离子形成的复合载体稳定金纳米颗粒,制得金纳米簇-多金属氧酸盐的复合物.复合物的组成以及金纳米颗粒的分布状态由XPS和TEM表征.利用多金属氧酸和金纳米颗粒的相互协助作用,使得这类复合物是一种优异的低温选择性氧化催化剂.     

金团簇的荧光性质及其生物应用

金纳米团簇作为一类新型纳米材料具有独特的光学特性。当金纳米团簇颗粒的尺寸小到与电子的费米波长（〈1nm）相当时,由于量子尺寸效应,金颗粒会受激发射出荧光。作为一种新型荧光材料,金纳米团簇具有发光颜色随团簇尺寸可调、荧光不易猝灭等许多优势。本文主要综述了金纳米团簇的荧光性质及其在生物标记、生物成像以及生物检测等方面的应用...     

碳水化合物含磷配体在不对称催化中的应用*

糖类化合物价廉易得,具有天然手性结构,糖环上的多个羟基经过修饰,可以连接多种官能团。近年来手性糖类化合物的合成与应用研究引起了人们的广泛关注,尤其是在不对称合成和催化中的应用研究已成为有机化学中非常活跃的领域。碳水化合物含磷手性配体在不对称催化反应中的应用研究进展十分迅速,本文综述了近年来碳水化合物含磷手性配体与金属形成络合物作为催化剂,在不对称催化氢化、不对称烯丙位取代和不对称氢甲酰化等反应中的研究进展。     

手性膦配体合成及其在不对称催化中的应用*

本文较为详细地综述了手性膦配体的合成进展, 并介绍了其在不对称氢化反应、不对称氢甲酰化反应及不对称氢酯基化反应中的应用。     

Tuning the Accessibility and Activity of Au25(SR)18 Nanocluster Catalysts through Ligand Engineering

In this work, the effects of thiolate ligands (‐SR, e.g., chain length and functional moiety) on the accessibility and catalytic activity of thiolate‐protected gold nanoclusters (e.g., Au₂₅(SR)₁₈) for 4‐nitrophenol hydrogenation is reported. The data suggest that Au₂₅(SR)₁₈ bearing a shorter alkyl chain shows a better accessibility to the substrates (shown by shorter induction time, t₀) and a higher catalytic activity (shown by higher apparent reaction rate constant, k_app). The functional moiety of the ligands is another determinant factor, which clearly suggests that ligand engineering of Au₂₅(SR)₁₈ would be an efficient platform for fine‐tuning its catalytic properties.     

中介尺度Au纳米团簇熔化的分子动力学模拟

采用分子动力学模拟技术，研究了原子个数为16～8628的 Au纳米团簇的熔化过程.采用 Johnson的EAM (embedded atom method) 模型,模拟结果表明，金属纳米团簇存在一中介尺度区域.对Au纳米团簇而言，当原子个数N >456时，团簇的热力学性质与团簇尺寸呈线性关系，熔化首先从表面开始，逐步向中心区域推进，且满足Tmb－Tmc(N)＝aN(－1/3)的关系.另外，计算了中介区域的团簇的尺寸、熔化温度、表面能、熵、焓等热力学量以及均方根位移（RMSD）等动力学量，为研究纳米团簇提供定量数据.     

Ligand Selectivity by Inserting GCGC-Tetrads into G-Quadruplex Structures

G-Quadruplexes (G4s) assembled from tandem G-rich repeat sequences exhibit significant biological functions and applications, which may well depend on their structural features, such as the planar arrangement of G-tetrads and flexibility of loop regions. It has been found that cytosine-intercalated G-repeat sequences also assemble to be quadruplex structures, involving the formation of nonplanar GCGC-tetrads. Herein, to investigate the effect of GCGC-tetrads on structural properties of G4s, some previously studied quadruplexes with or without GCGC-tetrads were selected, and were used to interact with various developed G4 ligands. Our data show that stacked G-tetrads in quadruplexes are important for the π–π stacking interactions, thus promoting the combination with end-stacking ligands, such as porphyrins or planar small molecules. This is confirmed by the observation that the quadruplex formed by d(GGGCT₄GGGC) with two internal G-tetrads and two external GCGC-tetrads can bind to planar ligands in the presence of specific G4-stabilizing cations, including K⁺ and Pb²⁺, and can realize the sensitive detection of Pb²⁺. However, the quadruplex composed of two external G-tetrads and two internal GCGC-tetrads formed by d(GCGGT₃GCGG) facilitates the binding of nonplanar ligands, such as triphenylmethane (TPM) dyes, owing to the structural flexibility induced by internal GCGC-tetrads. This work provides new insights into the interaction between DNA quadruplexes and specific ligands, which is beneficial to the development of quadruplex-based biosensors and the design of anticancer drugs.     

In Situ Assembly of Au Nanoclusters within Protein Hydrogel Networks

We report a new approach of in situ assembling gold nanoclusters (AuNCs) into hydrogel networks by exploiting the triple roles of protein as a gelator, a reducing agent as well as a template. The strategy simply involves the mixing of BSA and AuCl₄⁻ under alkaline condition. The obtained AuNCs‐protein nanocomposite hydrogels with injectable and moldable features can be made into semi‐transparent films or N‐doped C/Au composites. Our work demonstrates the feasibility of fabricating AuNCs in situ embedded in hybrid hydrogels, which can serve as multifunctional precursors for constructing diverse nanocomposite materials.     

The Structure–Property Correlations in the Isomerism of Au21(SR)15 Nanoclusters by Density Functional Theory Study

Isomerism of atomically precise noble metal nanoclusters provides an excellent platform to investigate the structure–property correlations of metal nanomaterials. In this study, we performed density functional theory (DFT) and time‐dependent (TD‐DFT) calculations on two Au₂₁(SR)₁₅ nanoclusters, one with a hexagonal closed packed core (denoted as Au₂₁ ^hcp ), and the other one with a face‐centered cubic core (denoted as Au₂₁ ^fcc ). The structural and electronic analysis on the typical Au–Au and Au–S bond distances, bond orders, composition of the frontier orbitals and the origin of optical absorptions shed light on the inherent correlations between these two clusters.     

Selectivity in the Ligand Functionalization of Photocatalytic Metal Oxide Nanoparticles for Phase Transfer and Self-Assembly Applications

The functionalization of photocatalytic metal oxide nanoparticles of TiO₂, ZnO, WO₃ and CuO with amine-terminated (oleylamine) and thiol-terminated (dodecane-1-thiol) alkyl-chain ligands was studied under ambient conditions. A high selectivity was observed in the binding specificity of a ligand towards nanoparticles of these different oxides. It was observed that oleylamine binds stably to only TiO₂ and WO₃, whereas dodecane-1-thiol binds stably only to ZnO and CuO. Similarly, polar-to-nonpolar solvent phase transfer of TiO₂ and WO₃ nanoparticles could be achieved by using oleylamine, but not dodecane-1-thiol, whereas the opposite holds for ZnO and CuO. The surface chemistry of ligand-functionalized nanoparticles was probed by attenuated total reflectance (ATR)-FTIR spectroscopy, which enabled the occupation of the ligands at the active sites to be elucidated. The photostability of the ligands on the nanoparticle surface was determined by the photocatalytic self-cleaning properties of the material. Although TiO₂ and WO₃ degrade the ligands within 24 h under both UV and visible light, ligands on ZnO and CuO remain unaffected. The gathered insights are also highly relevant from an application point of view. As an example, because the ligand-functionalized nanoparticles are hydrophobic in nature, they can be self-assembled at the air-water interface to give nanoparticle films with demonstrated photocatalytic as well as anti-fogging properties.     

金纳米团簇在盐酸和十二硫醇刻蚀作用下的原位生长动力学研究

了解金属纳米团簇的形成机制对于进一步发展其化学制备方法是必要的。我们利用盐酸(HCl)和十二硫醇(RSH)共同刻蚀L₃ (L₃: 1, 3-双二苯基膦丙烷)包覆的多分散性的Au_n (15 ≤ n ≤ 60)团簇成功制备出单分散性的Au₁₃(L₃)₂(SR)₄Cl₄纳米团簇,并结合原位同步辐射X射线吸收谱、原位真空紫外-可见吸收光谱和质谱技术,研究了Au₁₃(L₃)₂(SR)₄Cl₄纳米团簇的动力学形成过程。结果表明,Au团簇从多分散到单分散的转变经历了3个明显不同的动力学步骤。首先,尺寸较大的多分散金属团簇Au_n主要在HCl刻蚀作用下,形成尺寸较小的亚稳的中间产物Au₈–Au₁₁团簇。然后,这些中间产物与反应溶液中已有的Au(Ⅰ)-Cl物种反应,并与SR发生部分配体交换,逐渐长大为由SR和L₃保护的Au₁₃团簇。最后,形成的Au₁₃团簇经过一个较缓慢的结构重组过程,最终形成稳定的Au₁₃(L₃)₂(SR)₄Cl₄的纳米团簇。     

Au25纳米团簇合成与应用研究进展

综述了新型金属纳米材料Au25纳米团簇的合成机理和合成工艺改进,结合Au纳米团簇荧光作用机理说明其特有的荧光特性,利用Au纳米团簇荧光性质在离子检测、生物小分子检测、蛋白质检测和生物成像方面的应用,为Au纳米团簇的研究提供参考。