Ag2 and Ag3 Clusters: Synthesis,Characterization, and Interaction with DNA

Subnanometric samples, containing exclusively Ag₂ and Ag₃ clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag₃ clusters interact with DNA through intercalation, inducing significant structural distortion to the DNA. The lifetime of Ag₃ clusters in the intercalated position is two to three orders of magnitude longer than for classical organic intercalators, such as ethidium bromide or proflavine.     

Protection of Ag Clusters by Metal-Oxo Modules

Monodisperse and atomically precise Ag nanoclusters have attracted considerable recent research interest. A conventional silver cluster usually consists of a silver metallic kernel and an organic peripheral ligand shell. Nevertheless, the present inevitable problem is the unsatisfied stability of such nanoclusters. In this concept, we will give an introduction to Ag clusters protected by metal-oxo modules, which exhibit enhanced stability and unique properties. Accordingly, three different types of clusters are summarized: (1) Ag clusters protected by mononuclear oxometallates; (2) Ag clusters protected by block-like metal-oxo clusters; (3) Ag clusters protected by hollow-like metal-oxo clusters. The aim of this concept is to offer possible general guidance and insight into future rational design of more metal-oxo clusters protected silver clusters or even other coinage metal nanoclusters.     

An Ultrastable,Small {Ag7}5+ Nanocluster within a Triangular Hollow Polyoxometalate Framework

Small Ag_n nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face-centered-cubic-type small {Ag₇}⁵⁺ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si₃W₂₇O₉₆]¹⁸⁻. The cluster showed unique {Ag₇}⁵⁺-to-POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag₇}⁵⁺ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O₂, water, and solvents.     

An Ultrastable,Small {Ag7}5+ Nanocluster within a Triangular Hollow Polyoxometalate Framework

Small Ag_n nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face‐centered‐cubic‐type small {Ag₇}⁵⁺ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si₃W₂₇O₉₆]^18?. The cluster showed unique {Ag₇}⁵⁺‐to‐POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag₇}⁵⁺ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O₂, water, and solvents.     

两种钒配合物的合成、表征及与Ct-DNA作用研究

合成了两种钒-邻香草醛衍生物配合物[VO2(C10H11O3N)](HOCH2CH2NH3) (1)和VO(C8H8O3N)2 (2); 用FT-IR和X-ray单晶衍射对它们的晶体结构进行了表征; 用紫外吸收光谱法、荧光光谱法、循环伏安法、粘度法等分析了两种配合物与小牛胸腺DNA (Ct-DNA)的作用; 结果表明配合物1以非插入方式与Ct-DNA作用, 配合物2则以插入方式与Ct-DNA作用.     

Nestlike Silver(I) Thiolate Clusters with Tunable Emission Color Templated by Heteroanions

Four silver thiolate clusters, [H₃O][(Ag₃S₃)(BF₄)@Ag₂₇(tBuS)₁₈(hfac)₆H₂O] ⋅ H₂O ( 1 ; hfac = hexafluoroacetylacetone), [(Ag₃S₃)(CF₃CO₂)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ CF₃CO₂ ⋅ 4 CH₃CN ( 2 ), [(Ag₃S₃)(MoO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 2 CH₃CN ( 3 ), and [(Ag₃S₃)(CrO₄)@Ag₃₀(tBuS)₁₆(CF₃CO₂)₉(CH₃CN)₄] ⋅ 4 CH₃CN ( 4 ), were isolated. They have similar nestlike structures assembled by an [Ag₃S₃]³⁻ template together with one of the BF₄⁻, CF₃CO₂⁻, MoO₄²⁻, or CrO₄²⁻ anions. Interestingly, the solid-state emissions of 2 – 4 are dependent on the templating anions and are tunable from green to orange and then to red by changing the template from CF₃CO₂⁻ to MoO₄²⁻ and to CrO₄²⁻, and this may be correlated to the charge transfer between these templates to metal atoms. This work helps to understand the templating role of heteroanions and the relationship between structure and properties.     

金和银氮杂环卡宾原子簇化合物的合成结构与细胞毒性研究

由[Ag₃L₂(CH₃CN)₂](PF₆)₃(1,L=bis(N-pyridylimidazoliumyl)methane)通过金属转移反应合成了含有氮杂环卡宾配体的金银混合原子簇化合物,[Au₂AgL₂(CH₃CN)₂](PF₆)₃(2)和[Au₄AgL₄](PF₆)₅(3),用X-射线单晶衍射确定了2和3的晶体结构。化合物1和2结构相同,3个金属原子三角形排列。化合物3中5个金属原子呈链状排列,其中银原子居于中间。这些化合物在室温下分别在417,415和457 cm^-1处表现荧光。用MTT实验方法研究了对HuH7,C6和A375肿瘤细胞的毒性,其毒性顺序为1>2>3与这些化合物中银含量顺序相一致。     

A Simple Entropic-Driving Separation Procedure of Low-Size Silver Clusters,Through Interaction with DNA

Synthesis and purification of metal clusters without strong binding agents by wet chemical methods are very attractive for their potential applications in many research areas. However, especially challenging is the separation of uncharged clusters with only a few number of atoms, which renders the usual techniques very difficult to apply. Herein, we report the first efficient separation of Ag₂ and Ag₃ clusters using the different entropic driving forces when such clusters interact with DNA, into which Ag₃ selectively intercalates. After sequential dialysis of the samples and denaturalizing the DNA-Ag₃ complex, pure Ag₂ can be found in the dialysate after extensive dialysis. Free Ag₃ is recovered after DNA denaturation.     

Ag2S/Al2O3纳米复合物的水热合成及表征

采用水热技术结合煅烧的方法,成功制备了Ag2S/Al2O3纳米复合物。 通过SEM、EDX、XRD等测试技术对产品进行了表征,证明得到的产品是Ag2S/Al2O3纳米复合物;无孔Al2O3和多孔Al2O3作反应模板得到的复合物的形态和分布不同。     

A Facile Template Approach to High‐Nuclearity Silver(I) Alkynyl Clusters

Peanut clusters : Anion templates are used in a facile approach for the synthesis of high‐nuclearity silver clusters. The cluster nuclearity can be controlled by adjusting the size of the templating anions and by using different alkynyl ligands. The largest silver alkynyl cluster, which consists of 35 silver(I) centers in the shape of a peanut, has been prepared by using chromate anions as templates (see picture).

     

Heterometallic Clusters [CuSn3S9]5− and [Cu6Sn6S20]10−: Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f–3d thiostannates with general formula [Hen]₂[Ln(en)₄(CuSn₃S₉)] ? 0.5 en ( Ln1 ; Ln=La, 1 ; Ce, 2 ) and [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀] ? 3 en ( Ln2 ; Ln=Nd, 3 ; Gd, 4 ; Er, 5 ) were prepared by reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn₂S₆]^4? compounds and CuS powder. In 1 and 2 , three SnS₄ tetrahedra and one CuS₃ triangle are joined by sharing sulfur atoms to form a novel [CuSn₃S₉]^5? cluster that coordinates to the Ln³⁺ ion of [Ln(en)₄]³⁺ (Ln=La, Ce) as a monodentate ligand. The [CuSn₃S₉]^5? unit is the first thio‐based heterometallic adamantane‐like cluster coordinating to a lanthanide center. In 3 – 5 , six SnS₄ tetrahedra and six CuS₃ triangles are connected by sharing common sulfur atoms to form the ternary [Cu₆Sn₆S₂₀]^10? cluster, in which a Cu₆ core is enclosed by two Sn₃S₁₀ fragments. The topological structure of the novel Cu₆ core can be regarded as two Cu₄ tetrahedra joined by a common edge. The Ln³⁺ ions in Ln1 and Ln2 are in nine‐ and eightfold coordination, respectively, which leads to the formation of the [CuSn₃S₉]^5? and [Cu₆Sn₆S₂₀]^10? clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1 – 5 exhibit bandgaps in the range of 2.09–2.48 eV depending on the two different types of clusters in the compounds. Compounds 1 , 3 , and 4 lost their organic components in the temperature range of 110–350 °C by multistep processes.