系列Mo-Cu(Ag,Au)-Se簇合物的95Mo和31P NMR研究

报道了含硬币金属和四硒代钼酸盐的异金属硒簇合物的⁹⁵Mo NMR研究结果和含膦配体Mo(W)-Cu(Ag,Au)-Se配合物的³¹P NMR谱学性能。发现不同硬币金属对⁹⁵Mo核的化学屏蔽效应顺序为Au > Cu > Ag;对系列Mo-Cu-Se化合物的⁹⁵Mo NMR研究结果表明:⁹⁵Mo NMR的化学位移和线宽不仅与配位的Cu原子数目有关,而且对结构的变化特别敏感;[MoSe₄]^2-离子的相对四个方向被Cu⁺配位后,其Mo核的屏蔽基本饱和;外围配体对⁹⁵Mo NMR数据影响甚微。同时还用动态⁹⁵Mo NMR谱技术跟踪配体的取代反应和从MoCu₄到MoCu₁₀核的簇骼转变过程。此外,还讨论了这些化合物在不同构型之间,同一构型不同金属中心和不同配体基团的³¹P NMR化学位移的变化特征。     

Syntheses and structural characterization of two new nanostructured Bi(III) supramolecular polymers via sonochemical method

Two new bismuth(III) coordination supramolecular polymers, {[Bi₂(Hbpp)(bpp)(μ-I)₂I₆](Hbpp)·MeOH}_n (1) and [Bi(Hbpp)(Br₄)] (2), (bpp = 1,3-di(pyridin-4-yl)propane) were prepared and were structurally characterized by single crystal X-ray diffraction. Single crystalline one-dimensional materials were prepared using a heat gradient applied a solution of the reagents using the branched tube method. The structural determination by single crystal X-ray crystallography shows that compounds 1 and 2 form monoclinic polymers with symmetry space group P2₁ in the solid state. These new nanostructured Bi(III) supramolecular compounds, {[Bi₂(Hbpp)(bpp)(μ-I)₂I₆](Hbpp)·MeOH} (1) and [Bi(Hbpp)(Br₄)] (2), were also synthesized by sonochemical method. The nanostructures were characterized by Field Emission-scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD) and IR spectroscopy.     

Ultrasonic-assisted synthesis and structural characterization of two new nano-structured Hg(II) coordination polymers

Two new Hg(II) coordination polymers containing N,N′-Bis-pyridin-3-ylmethylene-naphtalene-1,5-diamine ligand were synthesized by conventional and sonochemical methods, characterized by spectroscopic techniques (FT-IR and elemental analysis), and their X-ray crystallographic structures were determined. The crystal packing and supramolecular features of these coordination polymers were studied using geometrical analysis and Hirshfeld surface analysis. The crystal structure analysis revealed that H⋯H contacts, C–H⋯π and C–H⋯X (X = Cl for 1 and X = Br for 2) hydrogen bonding interactions are strong enough to govern the supramolecular architecture. The BFDH analysis helps us to compare the predicted morphology to that obtained under ultrasonication. This study may provide further insight into discovering the role of weak intermolecular interactions in the context of nano-supramolecular assembly.     

Self-assembled structures of 4′-([2,2′:6′,2″-terpyridine]-4′-yl)-[1,1′-phenyl]-4-carboxylic acid molecules induced by metal atoms on ag(111) surface

The self-assembled supramolecular structures of 4′-([2,2′:6′,2″-terpyridine]-4′-yl)-[1,1′-phenyl]-4-carboxylic acid (Y) molecules on Ag(111) surface induced by metal elements have been studied by scanning tunneling microscopy. After annealing, the as-deposited monolayer of Y molecules shows four kinds of well-ordered structures due to the competition between dipole interaction, hydrogen bonding and Van der Waals interaction. Introduced Cu atoms drive ordered monolayer into a self-assembled supramolecular structure with bright spots. Deposited Ag atoms cause the monolayer change to a windmill shape self-assembled supramolecular structure. Though the Cu and Ag are in the same group of the periodic table, a Cu atom connects two COOH groups and an Ag atom trends to bind to three COOH groups during the formation of metal-organic bonding within both induced structures. Such result suggests that the self-assembled structures formed by metal-organic coordination bonding can be controlled by choosing the number of metal-organic coordination bonds, which can be helpful to design metal-organic molecular architectures comprising functional building blocks.     

Fresh perspectives for surface coordination chemistry

Surface coordination chemistry has been traditionally associated with analogies between metal–ligand bonding in coordination compounds and chemisorptive interactions, the anchoring of metal complexes or other units for interface functionalisation, or the chemistry of oxide surfaces. However, more recently it became clear that well-defined surfaces similarly represent versatile platforms to conduct metal–ligand reactions in two dimensions and engineer unique coordination compounds or layers by novel complexation or metal-directed assembly protocols. This approach presents a versatile strategy to realize coordinatively unsaturated species as well as metal–organic polymers and networks with distinct shape and functional properties.     

壳聚糖与Cd(Ⅱ),Pb(Ⅱ),Ce(Ⅲ),Zr(Ⅳ)配合物的制备及光谱分析

用壳聚糖(CTS)分别与硝酸亚铈,硝酸锆,硫酸镉和硝酸铅在酸性介质中反应,制备了壳聚糖-Ce(Ⅲ)、壳聚糖-Zr(Ⅳ)、壳聚糖-CA(Ⅱ)、壳聚糖-Pb(Ⅱ)四种壳聚糖-重金属离子配合物(用通式M-CTS表示).用红外光谱(IR)、X-ray衍射(XRD)和X射线光电子能谱(XPS)等光谱分析手段对M-CTS进行了结构表征.结果表明:在壳聚糖-Cd(Ⅱ)配合物中的配位原子是壳聚糖-NH2上的N原子,而在壳聚糖-Ce(Ⅲ)、壳聚糖-Zr(Ⅳ)、壳聚糖-Pb(Ⅱ)配合物中不仅壳聚糖-NH2上的N原子参与了配位,同时OH上的O原子也参与了配位.说明不同的重金属离子与壳聚糖之间形成配位键的配位原子是不完全相同的.     

Sonochemically synthesized mono and bimetallic Au–Ag reduced graphene oxide based nanocomposites with enhanced catalytic activity

Graphene oxide (GO) supported Ag and Au mono-metallic and Au–Ag bimetallic catalysts were synthesized using a sonochemical method. Bimetallic catalysts containing different weight ratios of Au and Ag were loaded onto GO utilizing a low frequency horn-type ultrasonicator. High frequency ultrasonication was used to efficiently reduce Ag(I) and Au(III) ions in the presence of polyethylene glycol and 2-propanol. Transmission electron microscopy (TEM–EDX) and X-ray photoelectron spectroscopy were used to analyze the morphology, size, shape and chemical oxidation states of the prepared metallic catalysts on GO. The catalytic efficiency of the prepared catalysts were compared using 4-nitrophenol (4-NP) reduction reaction and the subsequent formation of 4-aminophenol (4-AP) that was also monitored using UV–vis spectrophotometry. The results revealed that Au–Ag–GO bimetallic catalysts showed high activity for the conversion of 4-NP to 4-AP than their monometallic counterparts. Amongst different weight ratios (1:1, 1:2 and 2:1) between Au and Ag, the 1:2 (Au:Ag) catalyst exhibited very good catalytic performance for the conversion of 4-NP to 4-AP. A total reduction of 4-NP took place within a short period of time if Au–GO was reduced first followed by Ag reduction, whereas a lower reduction rate was observed if Ag–GO was reduced first. The same trend was observed for all the ratios of bimetallic catalysts prepared by this method. The initial unfavorable reduction potential of Ag(I) is likely to be responsible for the above order. It was found that applying dual frequency ultrasonication was a highly effective way of preparing bimetallic catalysts requiring relatively low levels of added chemicals and producing bimetallic catalysts with GO with improved catalytic efficiency.     

Comparison of SERS effectiveness of copper substrates prepared by different methods: what are the values of enhancement factors?

Surface‐enhanced Raman scattering (SERS) spectroscopy is an analytical method for the detection of low amounts of analytes adsorbed on an appropriate coinage metal (Au, Ag, Cu) surface. Generally, the values of the enhancement factor are the highest on silver, lower on gold and relatively very low on copper. In this study, we have focused on the estimation of the enhancement factors of copper surface/substrates formed by different preparation procedures. The SERS activity of large electrochemically prepared substrates and colloidal systems is compared. The surface morphology of the large substrates was studied using scanning electron microscopy and atomic force microscopy. The size distribution of colloidal nanoparticles was monitored by dynamic light scattering. The values of enhancement factor are in both cases more than 10⁵ for the FT‐SERS spectra, demonstrating the fundamental role of nanostructured copper as a substrate material at the excitation wavelength (1064 nm) used. Copyright © 2011 John Wiley & Sons, Ltd.     

双金属层状配位聚合物{[ML][FeⅡFeⅢ(ox)3]·1.5H2O}∞的合成和波谱表征

合成和表征了两种新的Schiff碱配合物[NiL(ClO4)*3H2O (1)和CuL(ClO4)*4H2O (2),其中L是由摩尔比为1∶1的水杨醛和二乙撑三胺缩合而成的Schiff碱.1(或2)、FeSO4*7H2O和K3[Fe(ox)3]*3H2O进一步反应,生成了双金属层状配位聚合物{[ML][FeⅡFeⅢ(ox)3] *1.5 H2O}∞,其中M2+ ＝ Ni2+ (3)或Cu2+ (4).红外光谱和Mssbauer谱测定结果表明,3和4具有二维层状结构,其阴离子层由[FeⅡFeⅢ(ox)3]-单元构成.     

<Emphasis Type="Italic">In situ</Emphasis> Oxidation of phenol and <Emphasis Type="Italic">o</Emphasis>-aminophenol in the channels of 3d-supramolecular coordination polymers

The host attractive properties of supramolecular coordination polymers of the type _￥³ _\infty^3 [(R₃Sn)₃FeIII(CN)₆], where R = methyl (I), n-butyl (II), and phenyl (III), afford the ability to be used as effective oxidizing reagents for phenol and o-aminophenol forming new host-guest supramolecular coordination polymers. Phenol was oxidized to 1,4-benzoquinone while o-aminophenol was oxidized to poly-o-aminophenol by the polymers I and II and to 2-aminophenoxazin-3-one by the polymer III. The oxidation products were investigated by methods of spectroscopy and high-performance liquid chromatography. The redox reactions were characterized by first-order kinetics. Moreover, mechanisms of the oxidation processes of phenol and o-aminophenol have been proposed.     

Ultrasonic assisted extraction of polyphenols from bayberry by deep eutectic supramolecular polymer and its application in bio-active film

Ultrasound and deep eutectic supramolecular polymers (DESP) is a novel combination of green extraction method for phytochemicals. In this study, a new type of green extractant was developed: DESP. It is a derivative of deep eutectic solvent (DES) and was prepared by supramolecular polymer unit β-cyclodextrin (β-CD) as hydrogen bond acceptor (HBA) and organic acid as hydrogen bond donor (HBD). The current work focuses on the use of ultrasonic-assisted (UAE) DESP extraction of polyphenolic compounds (PCs) from bayberry. The experimental results showed that DESP synthesized with β-CD and lactic acid (LA) in a ratio of 1:1 (w/w %) had the best extraction effect. And by using a three-level factor experiment and the response surface method, the predicted TPC content is very close to the actual content (28.85 ± 1.27 mg GAE/g). The DESP extract including PCs were further used as plasticizer for chitosan (CS) to prepare highly active green biofilms (DESP-CS). It is possible to reduce the tedious procedures for separating biologically active substances from DESP. The experiment proved that the prepared films have good mechanical properties, plastic deformation resistance, thermal stability and antioxidant activity.     

When adding an unreactive metal enhances catalytic activity: NOx decomposition over silver-rhodium bimetallic surfaces

Recent experiments indicate unexpectedly high catalytic activity for decomposition of NO_x species over Ag-Rh nanoparticles, but the crucial role played by the coinage metal remains unclear. We have therefore performed ab-initio density functional calculations aimed at elucidating key features of NO surface chemistry on Ag, Rh, and Rh-Ag alloy substrates. Through investigation of thermochemistry and reaction barriers, and analysis of the alloy density of states, we explain the paradox that addition of an unreactive coinage metal can radically enhance the activity of a transition metal catalyst.     

Synthesis and characterization of a new nano lead(II) 0-D coordination supramolecular compound: A precursor to produce pure phase nano-sized lead(II) oxide

Nano-structure of a new 0D Pb(II) coordination supramolecular compound, [Pb₄(8-Quin)₆](ClO₄)₂(1), L = 8-HQuin = 8-hydroxyquinolin ligand has been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and elemental analyses. The structure of compound 1 was determined by single-crystal X-ray diffraction. The single crystal X-ray data of compound 1 implies that the Pb⁺² ions are five coordinated. Each lead atom is coordinated to nitrogen and oxygen atoms of 8-hydroxyquinolin ligand. Topological analysis shows that the compound 1 is 1,2,3,4,4M12-1net. Nanoparticles of lead(II) oxide have been prepared by calcination of lead(II) coordination polymer at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD) and IR spectroscopy.     

Sonochemical syntheses of binuclear lead(II)-azido supramolecule with ligand 3,4,7,8-tetramethyl-1,10-phenanthroline as precursor for preparation of lead(II) oxide nanoparticles

The new neutral binuclear lead(II) azido coordination compound, [Pb₂(tmph)₂(μ-N₃)₂(CH₃COO)₂] (1) [tmph = 3,4,7,8-tetramethyl-1,10-phenanthroline], has been synthesized by a sonochemical method. Single crystal X-ray structure shows that the overall structure of 1 is binuclear unit. Complex 1 has a bridging azido pathway, end-to-end bridging azides between a pair of lead(II) centers. This is further extended into a one-dimensional (1D) and three-dimensional (3D) supramolecular structure by Pb⋯C and π–π weak directional intermolecular interactions. The coordination number of lead(II) ions is seven, PbN₄O₃, with two N-donor atoms from tmph ligands and three O-donors from acetate anions and two N-donors from two azide anions. It has a “stereo-chemically active” electron lone pair, and the coordination sphere is hemidirected. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO samples were further observed using scanning electron microscopy (SEM).     

Tetrahedral coordination for Zn in hexacyanometallates: Structures of Zn3A2[M(CN)6]2·xH2O with A=K, Rb, Cs and M=Ru, Os

Zinc hexacyanoruthenate (II) and hexacyanoosmate (II) were prepared and studied from X-ray diffraction (XRD), infrared (IR), and thermogravimetric (TG) data. These compounds were found to be isomorphous with the iron analogues, crystallizing with a rhombohedral unit cell (R−3c space group), where the zinc atom has tetrahedral coordination to N ends of CN groups. For Cs, compounds with formula unit ZnCs₂[M(CN)₆] and a cubic unit cell (Fm−3m) were also obtained. The crystal structures for the eight compositions were refined from the corresponding X-ray powder diffraction patterns using the Rietveld method. Related to the tetrahedral coordination for the Zn atom, the rhombohedral phase has a porous framework with ellipsoidal cavities of about 12.5×9×8 Å, communicated by elliptical windows of ∼5 Å. Within these cavities the exchangeable alkali metal ions are found. The filling of the cavity volume is completed with water molecules. IR spectrum senses certain charge delocalization from the inner metal, through the π-back donation mechanism. For Os compounds this effect is particularly pronounced, related to a more diffuse d orbitals for this metal.     

Ag-doped ZnO nanorods synthesized by two-step method

A two-step method is adopted to synthesize Ag-doped ZnO nanorods.A ZnO seed layer is first prepared on a glass substrate by thermal decomposition of zinc acetate.Ag-doped ZnO nanorods are then assembled on the ZnO seed layer using the hydrothermal method.The influences of the molar percentage of Ag ions to Zn ions(RAg/Zn) on the structural and optical properties of the ZnO nanorods obtained are carefully studied using X-ray diffractometry,scanning electron microscopy and spectrophotometry.Results indicate that Ag ions enter into the crystal lattice through the substitution of Zn ions.The<002>c-axis-preferred orientation of the ZnO nanorods decreases as RAg/Zn increases.At RAg/Zn >1.0%,ZnO nanorods lose their c-axis-preferred orientation and generate Ag precipitates from the ZnO crystal lattice.The average transmissivity in the visible region first increases and then decreases as R Ag/Zn increases.The absorption edge is first blue shifted and then red shifted.The influence of Ag doping on the average head face,and axial dimensions of the ZnO nanorods may be optimized to improve the average transmissivity at RAg/Zn <1.0%.     

重金属钋化物分子MPo(2∏),(M=Cu,Ag,Au)的结构和势能函数

利用相对论小核赝势研究了重金属钋化物分子MPo(X2∏),(M=Cu,Ag,Au).用群论方法结合原子分子反应静力学原理导出了分子的基电子状态和相应的离解极限,并在各种电子相关理论水平上计算了它们的平衡几何和振动频率.在此基础上用Murrell-Sorbie函数形式拟和势能曲线,得到了总的解析势能函数,并计算出了光谱数据和力常数.     

Ultrasound irradiation effect on morphological and adsorptive properties of a nanoscale 3D Zn-coordination polymer and derived oxide

In this work, Zn-based coordination polymer [Zn₂(1,3-bdc)bzim₂]_n was successfully synthesized by the sonochemical method using a 13 mm probe-type ultrasound operating at 20 kHz and amplitudes of 30, 40 and 50% corresponding to an acoustic power of 5.5, 8.6, and 10.3 W, respectively. Additionally, a sample was prepared by the slow-diffusion method for comparison. The samples were characterized by FTIR, PXRD, SEM, and BET techniques. The influence of the time and sonication amplitude on the yield of the reaction, crystallite size, and morphology were also studied. It was found that the sonochemical method provided the desired product in 83.9% within 20 min of sonication using the highest level of sonication amplitude. Moreover, this approach resulted in regular, controlled morphology, smaller particles, and higher surface area of the Zn-sample and derived oxide, than the slow diffusion method. The samples prepared by different methodologies were tested for the adsorption of BTEX (benzene, toluene, ethylbenzene, and xylenes) components in six different systems, and the uptakes were quantified by ¹³C NMR spectroscopy. Both samples showed excellent adsorption of benzene, 119.8 mmol/g, and 88.1 mmol/g, for the coordination polymers prepared via the sonochemical and slow-diffusion methods, respectively, corresponding to 63.9%, and 46.9%. These results are in agreement with the non-polar surface of these samples.     

Tb-Zn一维配位聚合物的合成及发光性质

采用流变相反应法合成了具有良好发光性能和可溶性的一维链结构配位聚合物Tb(Fur)₃(H₂O)₂.DMF和Tb₂Zn(Fur)₈(H₂O)₂及四核异金属配位聚合物Tb₂Zn₂(tpca)₁₀(phen)₂,用单晶和粉末X射线衍射法表征了晶体结构。在这些配合物中Tb³⁺分别是8配位、9配位和7配位,金属离子之间都是通过羧酸根-CO₂^-基团成桥连结。研究了配合物的紫外-可见吸收光谱、荧光激发和发射光谱,讨论了配位结构对荧光光谱性质的影响。     

Ag NPS/g-C3N4纳米复合材料制备及其SERS纳米传感器

通过化学氧化块状石墨型氮化碳(g-C3N4),获得在水中分散性好的片状g-C3N4.XRD,FTIR和XPS表明,所得片状g-C3N4含有氧官能团.这不仅可以作为锚定点负载纳米银粒子(Ag NPs),而且可以获得Ag NPs均匀分散的Ag NPS/g-C3N4纳米复合物.制备的复合材料中银纳米颗粒的重量百分比也会随着硝酸银与片状g-C3N4的质量变化而发生变化.基于g-C3N4对Co2+的明显的拉曼强度响应,Ag NPS/g-C3N4纳米复合物作为表面增强拉曼散射(SERS)传感器检测Co2+.通过拉曼强度的对照,发现随着Co2+浓度的增加,拉曼信号增加;而含有73％银纳米颗粒的Ag NPS/g-C3N4纳米复合物有高的灵敏性,检测极限浓度达到10-9 mol·L-1;复合材料同时显示出高的选择性,对其他如Cd2+,Cu2+和Zn2+的金属离子没有明显的拉曼增强信号.分析了复合材料对Co2+的增强机制.由于Co2+与g-C3N4中的=N-/-NH-基团的耦合,引发复合材料中Ag NPs聚集,从而产生局部电磁场,进而产生表面增强效应.可以预知,Ag NPS/g-C3N4纳米复合物将作为一种用于制造SERS传感器的新的理想材料.