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71.
72.
CO oxidation over ceria-supported Au22 nanoclusters shows strong dependence on the support shape: the lattice oxygen in CeO2 rods is more reactive than in the cubes and thus make rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation. 相似文献
73.
The Origin of the Photoluminescence Enhancement of Gold‐Doped Silver Nanoclusters: The Importance of Relativistic Effects and Heteronuclear Gold–Silver Bonds 下载免费PDF全文
Dr. Xiao‐Ying Xie Dr. Pin Xiao Dr. Xiaoyan Cao Prof. Dr. Wei‐Hai Fang Prof. Dr. Ganglong Cui Prof. Dr. Michael Dolg 《Angewandte Chemie (International ed. in English)》2018,57(31):9965-9969
The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag29 nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag29 and gold‐doped Ag29?xAux (x=1–5) nanoclusters in the S0 and S1 states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag26Au3, Ag25Au4, and Ag24Au5, and that 2) heteronuclear Au?Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties. 相似文献
74.
Amrita Chakraborty Ann Candice Fernandez Dr. Anirban Som Biswajit Mondal Dr. Ganapati Natarajan Dr. Ganesan Paramasivam Dr. Tanja Lahtinen Prof. Hannu Häkkinen Dr. Nonappa Prof. Thalappil Pradeep 《Angewandte Chemie (International ed. in English)》2018,57(22):6522-6526
The self‐assembled structures of atomically precise, ligand‐protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding‐directed self‐assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p‐mercaptobenzoic acid (pMBA)‐protected atomically precise silver nanocluster, Na4[Ag44(pMBA)30], and pMBA‐functionalized GNRs were used. High‐resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H‐bonding, leading to octahedral symmetry. The use of water‐dispersible gold nanoclusters, Au≈250(pMBA)n and Au102(pMBA)44, also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities. 相似文献
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76.
Hanna Morales Hernández Qiwei Sun Matthew Rosati Prof. Rebecca L. M. Gieseking Prof. Christopher J. Johnson 《Angewandte Chemie (International ed. in English)》2023,62(35):e202307723
The role of hydrogen atoms as surface ligands on metal nanoclusters is of profound importance but remains difficult to directly study. While hydrogen atoms often appear to be incorporated formally as hydrides, evidence suggests that they donate electrons to the cluster's delocalized superatomic orbitals and may consequently behave as acidic protons that play key roles in synthetic or catalytic mechanisms. Here we directly test this assertion for the prototypical Au9(PPh3)8H2+ nanocluster, formed by addition of a hydride to the well-characterized Au9(PPh3)83+. Using gas-phase infrared spectroscopy, we were able to unambiguously isolate Au9(PPh3)8H2+ and Au9(PPh3)8D2+, revealing an Au−H stretching mode at 1528 cm−1 that shifts to 1038 cm−1 upon deuteration. This shift is greater than the maximum expected for a typical harmonic potential, suggesting a potential governing cluster-H bonding that has some square-well character consistent with the hydrogen nucleus behaving as a metal atom in the cluster core. Complexing this cluster with very weak bases reveals a redshift of 37 cm−1 in the Au−H vibration, consistent with those typically seen for moderately acidic groups in gas phase molecules and providing an estimate of the acidity of Au9(PPh3)8H2+, at least with regard to its surface reactivity. 相似文献
77.
Dr. Qiao-Qiao Yan Dr. XiaoYun Zhao Ting Zhang Prof. Dr. Si-Dian Li 《Chemphyschem》2023,24(9):e202200947
Planar, tubular, cage-like, and bilayer boron clusters Bn+/0/− (n=3∼48) have been observed in joint experimental and theoretical investigations in the past two decades. Based on extensive global searches augmented with first-principles theory calculations, we predict herein the smallest perfect core-shell octahedral borospherene Oh B@B38+ ( 1 ) and its endohedral metallo-borospherene analogs Oh Be@B38 ( 2 ), and Oh Zn@B38 ( 3 ) which, with an octa-coordinate B, Be or Zn atom located exactly at the center, turn out to be the well-defined global minima of the systems highly stable both thermodynamically and dynamically. B@B38+ ( 1 ) represents the first boron-containing molecule reported to date which contains an octa-coordinate B center covalently coordinated by eight face-capping boron atoms at the corners of a perfect cube in the first coordination sphere. Detailed natural bonding orbital (NBO) and adaptive natural density partitioning (AdNDP) bonding analyses indicate that these high-symmetry core-shell complexes X@B38+/0/− (X=B, Be, Zn) as super-noble gas atoms follow the octet rule in coordination bonding patterns (1S21P6), with one delocalized 9c-2e S-type coordination bond and three delocalized 39c-2e P-type coordination bonds formed between the octa-coordinate X center and its octahedral Oh B38 ligand to effectively stabilize the systems. Their IR, Raman, and UV-Vis spectra are computationally simulated to facilitate their spectroscopic characterizations. 相似文献
78.
Neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD) have no cure and pose a serious threat to human health. The accumulated amyloid has been the therapeutic target of various studies for over a decade, but there is a lack of effective treatments due to various limitations, such as the difficulty to cross the blood-brain barrier (BBB) and unfavorable bioaccumulation. To overcome these challenges, ultra-small metal nanoclusters (MNCs) (<2 nm) have emerged as promising new agents. Simple modifications of MNCs efficiently cross the BBB to reach the brain and dissociate amyloid fibrils into less toxic species. In addition, the enzymatic behavior of MNCs facilitates the scavenging of intracellular reactive oxygen species (ROS) and alleviates neuroinflammation. Herein, we summarize the reported anti-amyloid MNCs. Multiple promising functions of MNCs that may alleviate the harms of neurodegenerative diseases are exhibited. The physicochemical properties that influence the inhibition and degradation of common amyloid fibrils, including alpha-synuclein (α-syn) and amyloid beta-peptide (Aβ) are discussed. The prospect of optimizing MNCs to suppress more harm in the brain is presented to facilitate the development of practical therapies for neurodegenerative diseases. 相似文献
79.
采用沉淀法制备了具有p-n异质结结构的AgBr/CuO可见光催化剂,对其结构进行了表征,通过甲基橙溶液的降解率评价了AgBr/CuO的光催化活性,并通过活性物种测试及能带结构分析推测了其光催化机理,采用3%(质量分数)溴水对使用后的AgBr/CuO进行了再生处理.结果表明,在可见光照射下,0.1gAgBr/CuO光催化剂30 min对甲基橙溶液(初始浓度为15 mg/L)的降解率高达92%,远高于同等条件下的AgBr.AgBr/CuO光催化活性提高的原因是AgBr与CuO的复合一方面使催化剂的禁带宽度变宽,提高了光生电子与光生空穴的氧化还原能力;另一方面,在两者之间形成了p-n型异质结结构,有利于光生电子的转移及光生电子与空穴的分离.采用绿色环保的溴水再生法可显著恢复催化剂的光催化活性. 相似文献
80.
基于Hg~(2+)与DNA中胸腺嘧啶(T)结合的高度特异性和DNA铜纳米簇的荧光增强性质,构建了一种简便、灵敏检测汞离子的新方法.当Hg~(2+)存在时,聚T单链DNA(P1)通过T-Hg~(2+)-T特异性结合形成双链DNA,Cu~(2+)经抗坏血酸钠还原后生成的中间体Cu+与双链DNA螺旋结构间的氢键部分有强的结合力,促使Cu0附着聚集在双链DNA上形成铜纳米簇,导致体系荧光增强,从而实现对汞离子的高灵敏检测.体系荧光强度与Hg~(2+)浓度的对数值成正比,对Hg~(2+)检测的线性范围为1.0 nmol/L~10μmol/L,检出限达0.4 nmol/L,对湖水样品中Hg~(2+)检测的回收率达到97.2%~106.6%.与传统方法相比,该方法具有无需标记、检出限低及选择性好等优点,可用于环境水体中汞离子的测定. 相似文献