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1.
Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au−C−M bonds (M=Au/Ag). Hexagold clusters [Au6L4](X)2 are obtained by reaction of (L−TMS)AuCl with AgX, whereas reaction with AgX and Ag2O leads to gold–silver clusters [Au4Ag2L4](X)2. Oxo-trigold(I) species [Au3O]+ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au5], [Au4Ag], and [Au12Ag4] clusters were also obtained. Clusters containing PAu−Au−AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions.  相似文献   

2.
Thin silver films (100–800 nm) were deposited by physical vapor deposition (PVD) on yttria-stabilized zirconia solid electrolyte. The electric percolation as a function of the film thickness was studied during deposition and annealing using a two-electrode in-situ resistance measurement technique. Electrical percolation was achieved in as-deposited films greater than 5.4?±?0.4 nm; however, thermal treatment (550 °C in air) resulted in film dewetting for Ag films as thick as 500 nm and formation of electronically isolated Ag nanoparticles, as was confirmed by SEM and XPS. In thermally treated samples, stable electronic conductivity associated with a continuous percolated network was only observed in samples greater than 600 nm in thickness. The effect of polarization on the electrochemical reactions at the three-phase (electrode-gas-electrolyte) and two-phase (electrode-electrolyte) boundaries of the electrode was investigated by solid electrolyte cyclic voltammetry (SECV) at 350 °C and P O2?=?6 kPa. With the application of positive potential, silver oxide (Ag2O) was found to form along the three-phase boundary and then extends within the bulk of the electrode with increasing anodic potentials. By changing the hold time at positive potential, passivating oxide layers are formed which results in a shift in favor of the oxygen evolution reaction at the working electrode. This oxide forms according to a logarithmic rate expression with thick oxides being associated with decrease in current efficiency for subsequent oxide formation.  相似文献   

3.
Hemoglobin (Hb) and silver–silver oxide (Ag–Ag2O) nanoparticles were co-immobilized on a bare silver electrode surface by cyclic voltammetry, and were characterized by UV–vis reflection spectroscopy, scanning electron microscopy, and electrochemical impedance spectroscopy. The immobilized Hb was shown to maintain its biological activity well. Direct electron transfer between Hb and the resulting electrode was achieved without the aid of any electron mediator. The reduction currents to hydrogen peroxide (H2O2) at co-immobilized electrodes showed a linear relationship with H2O2 concentration over a concentration range from 6.0?×?10?6 to 5.0?×?10?2 mol L?1, and a detection limit of 2.0?×?10?6 mol L?1 (S/N?=?3).  相似文献   

4.
A method of multicycle chronoamperometry at rotating ring-disc electrode is suggested for experimental separation of the disc polarization current into its components that correspond to the substrate metal ionization, an oxide formation, and the oxide chemical dissolution. The method was validated by the example of the Ag|Ag2O|OH?(H2O) system. At moderate anodic potentials of Ag-disc (0.48–0.51 V), silver active dissolution from open areas of its surface and through film’s pores dominates; the phase-forming current, hence, the current efficiency of this process drops down rapidly. At the potentials of the maximum at voltammograms (0.52–0.53 V), when the silver active dissolution current is suppressed, the phase-forming currents dominate; they exceed the oxide chemical dissolution rate significantly. The Ag2O film thickness increases rapidly, the current efficiency of the oxide formation process approaches 100% during the entire disc polarization period. The Ag(I)-oxide chemical dissolution rate constant practically does not depend on the anodic phase-formation potential; however, it somewhat varies depending on the oxide film thickness, thus reflecting changes in the film structure and, possibly, chemical composition (from AgOH to Ag2O).  相似文献   

5.
In the present work, the two‐dimensional (2D) polymer poly[[μ4‐2‐(4‐nitrobenzenesulfonamido)benzoato‐κ4O1:O1:O1′:N6]silver(I)] (AgL), [Ag(C13H9N2O6S)]n, was obtained from 2‐(4‐nitrobenzenesulfonamido)benzoic acid (HL), C13H10N2O6S. FT–IR, 1H and 13C{1H} NMR spectroscopic analyses were used to characterize both compounds. The crystal structures of HL and AgL were determined by single‐crystal X‐ray diffraction. In the structure of HL, O—H…O hydrogen bonds between neighbouring molecules result in the formation of dimers, while the silver(I) complex shows polymerization associated with the O atoms of three distinct deprotonated ligands (L?). Thus, the structure of the Ag complex can be considered as a coordination polymer consisting of a one‐dimensional linear chain, constructed by carboxylate bridging groups, running parallel to the b axis. Neighbouring polymeric chains are further bridged by Ag—C monohapto contacts, resulting in a 2D framework. Fingerprint analysis of the Hirshfeld surfaces show that O…H/H…O hydrogen bonds are responsible for the most significant contacts in the crystal packing of HL and AgL, followed by the H…H and O…C/C…O interactions. The Ag…Ag, Ag…O/O…Ag and Ag…C/C…Ag interactions in the Hirshfeld surface represent 12.1% of the total interactions in the crystal packing. Studies of the interactions of the compounds with human serum albumin (HSA) indicated that both HL and AgL interact with HSA.  相似文献   

6.
The coordination compound [Ag2L2(H2O)2] · 2H2O (I), L = C12H10NO2S has been synthesized by the reaction of AgNO3 with 4-methyl-2-quinolylthioacetic acid (HL) preliminarily neutralized with an equimolar amount of NBu4OH. Its crystal structure has been determined, and luminescence properties have been studied. Crystals of I are monoclinic, space group C2/c, a = 31.239(6) Å, b = 12.056(2) Å, c = 16.846(3) Å, β = 122.17(3)°, V = 5370.4(2) Å3, ρcalc = 1.861 g/cm3, Z = 16. The structure is formed by two crystallographically nonequivalent silver atoms Ag(1) and Ag(2) and two tridentate bridging ligands L coordinated through the S, N, and O atoms. These atoms, together with water molecules, form the coordination environments of the metal atoms with CN = 5 and 4, respectively. The Ag+ ions and the tridentate ligands form infinite [Ag4L4]n bands extended in the [001] direction. The presence of outer-sphere water molecules involved in O–H···O hydrogen bonding is responsible for the formation of a supramolecular framework structure. The photoluminescence spectrum of compound I shows two bands at ~450 and ~485 nm corresponding to the blue spectral range.  相似文献   

7.
The chemistry of binary and multinary silver oxides spans from subvalent species (with a mean oxidation number for Ag smaller than + 1) to compounds with Ag in high oxidation states as + 2 and + 3. We have investigated a range of silver oxides, including the binary compounds Ag2O, AgO, Ag3O4 and Ag2O3 as well as subvalent ternary oxides, by AgL3 and AgL1 XANES spectroscopy. The different valence states of silver are clearly reflected in AgL3 and AgL1 XANES spectra. The method thus allows the determination of average oxidation numbers. In addition, the degree of electronic interaction (localized or delocalized electronic states) in silver‐oxygen compounds can be estimated on the basis of AgL3 XANES spectra.  相似文献   

8.
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   

9.
Four Ag(I) complexes, [Ag(L1)2](NO3) (1), [Ag(L2)(NO3)] (2), [Ag(L3)3](NO3) (3), and [Ag(L4)2](NO3) (4), with ligands derived from halo-containing cyanoanilines (L1 = 4-amino-3fluorobenzonitrile, L2 = 4-amino-3-chlorobenzonitrile, L3 = 4-amino-3-bromobenzonitrile, L4 = 4-amino-2-bromobenzonitrile) were synthesized and characterized by C, H, and N elemental analysis, IR and 1H NMR spectroscopy and single crystal X-ray diffraction. Complexes 14 crystallized in the triclinic space group C2/c, P2(1)/n, P-1 and C2/c, respectively. In 1 and 4, Ag+ is four-coordinate with L1 or L4 to form 1-D {[Ag(L1/L4)2]+} polymeric cations. In 2, Ag+ is three-coordinate by two L2 ligands and one NO3? ligand to form a 1-D {[Ag(L2)(NO3)]} zigzag chain. In 3, Ag+ is four-coordinate by L3 to form a dinuclear [Ag(L3)3]+ cation. The NO3? is a 4-connector bridging group in 1 and 3 and a 5-connector bridging group in 2 and 4. The intermolecular hydrogen bonds and Ag?O weak interactions play important roles in forming 3-D networks of 14. The antibacterial activities for 14 were evaluated against Bacillus subtilis, Staphylococcus aureus and Escherichia coli with MTT method. The antibacterial results indicated that 2 showed the best inhibitory activity against the test bacterial strains, and was as potent as chloramphenicol.  相似文献   

10.
A new dual chemosensor (TTF-PBA) for Fe3+ and Cu2+ in different signal pathways was designed and synthesized. The absorption spectrum, fluorescence spectrum and cyclic voltammograms changed in the presence of Cu2+ and Fe3+. The optical color changed within 5 s from yellow to orange upon the addition of Cu2+, and it changed to dark yellow when Fe3+ existed. The cyclic voltammogram of Cu2+/TTF-PBA changed from Eox = 0.50 V, Ered = 0.32 V to Eox = 0.64 V, Ered = 0.80 V (vs Ag/AgCl) upon the addition of 2.0 equiv. Cu2+. As for Fe3+/TTF-PBA, its oxidation wave disappeared, and its reduction wave appeared at Ered = ?0.59 V (vs Ag/AgCl) upon the addition of 4.0 equv. Fe3+. The sensor displayed high selectivity for Cu2+ and Fe3+ over other ions including Pb2+, Zn2+, Ni2+, Ag+, Cr3+, Mn2+, Al3+, Co2+, Pd2+, Hg2+, Fe2+, Cd2+, Ce3+, Bi3+ and Au3+, the detection limits for Cu2+ and Fe3+ ion reached as low as 5.33 × 10?7 mol/L and 5.34 × 10?7 mol/L, respectively. Furthermore, when Fe3+ existed, Cu2+ can be detected sequentially by the sensor through the absorption spectrum and the color change observed by naked-eyes.  相似文献   

11.
In this review, oxygen activation and their aerobic oxidation over the Au nanoclusters are presented. The size-specificity, ligand engineering, and doping effects and the proposed reactions’ mechanism and the structure-activity relationships at the atomic level are also discussed.  相似文献   

12.
Water pollution due to industrial effluents from industries which utilize dyes in the manufacturing of their products has serious implications on aquatic lives and the general environment. Thus, there is need for the removal of dyes from wastewater before being discharged into the environment. In this study, a nanocomposite consisting of silver, silver oxide (Ag2O), zinc oxide (ZnO) and graphene oxide (GO) was synthesized, characterized and photocatalytically applied in the degradation (and possibly mineralization) of organic pollutants in water treatment process. The Ag–Ag2O–ZnO nanostructure was synthesized by a co-precipitation method and calcined at 400 °C. It was functionalized using 3-aminopropyl triethoxysilane and further anchored on carboxylated graphene oxide via the formation of an amide bond to give the Ag–Ag2O–ZnO/GO nanocomposite. The prepared nanocomposite was characterized by UV–Vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transformed infrared spectroscopy (FTIR), and Raman spectroscopy. The applicability of Ag–Ag2O–ZnO/GO nanocomposite as a photocatalyst was investigated in the photocatalytic degradation of acid blue 74 dye under visible light irradiation in synthetic wastewater containing the dye. The results indicated that Ag–Ag2O–ZnO/GO nanocomposite has a higher photocatalytic activity (90% removal) compared to Ag–Ag2O–ZnO (85% removal) and ZnO (75% removal) respectively and thus lends itself to application in water treatment, where the removal of organics is very important.  相似文献   

13.
Nanostructured Ag films composed of nanoparticles and nanorods can be formed by the ultrasonication of ethanol solutions containing Ag2O particles. The present work examined the formation process of these films from ethanol solutions by two different agitation methods, including ultrasonication and mechanical stirring. The mass-transfer process from Ag2O particles to ethanol solvent is accelerated by the mechanical effects of ultrasound. Ag+ ions and intermediately reduced Ag clusters were released into the ethanol. These Ag+ ions and Ag clusters provide absorption bands at 210, 275 and 300 nm in UV-vis spectra. These bands were assigned to the absorption of Ag+, Ag 4 2+ and Agn (n?≈?3). The Agn clusters that readily grow to become Ag nanoparticles were formed due to the surface reaction of Ag2O particles with ethanol under ultrasonication. The reactions of Ag+ ions in ethanol to form Ag nanomaterials (through the formation of Ag 4 2+ clusters) were also accelerated by ultrasonication.  相似文献   

14.
Two new inorganic-organic hybrid compounds based on α-Keggin clusters and Ag-(1H-Pyrazole) subunits, [AgL2]4[SiMo12O40] (1) and [AgL2]3[PMo12O40] (2) (L = pyrazole), have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction. In 1, there are two kinds of chains, the chains linked by two [AgL2]+ clusters and the other linked only by one [AgL2]+, which further connect by sharing [SiMo12O40]4? anions to construct a 2-D layer. In 2, four-supporting [PMo12O40]3? anions are fused by [Ag(1)L2]+ subunits to form a 1-D chain. Through weak interactions of Ag?O (3.091 Å) a 2-D supramolecular layer is constructed. Additionally, the electrochemical properties of title compounds and the photocatalytic properties of 2 have been studied.  相似文献   

15.
Two new Schiff base silver(I) complexes, {[Ag(L1)][H2O]} (1) and {[Ag(L2)][H2O]} (2), where L1 = 4-((2-diethylaminoethylimino)methyl)phenecarboxylate and L2 = 4-([3-(morpholin-4-yl)propyl]iminomethyl)phenecarboxylate, have been synthesized and characterized. X-ray crystallographic analysis reveals that silver ions in 1 are bridged by L1 to form a one-dimensional zigzag chain, while three silver ions in 2 are linked by L2 to produce a two-dimensional coordination polymer. Guest water molecules in 1 generate a one-dimensional hydrogen-bonded chain. Both 1 and 2 offer high antibacterial activity against Gram-positive bacteria Staphylococcus aureus with MIC values of 0.26 and 0.24 mM and to exhibit good inhibitory activity against urease with the respective IC50 values of 3.5 ± 0.1 and 3.8 ± 0.2 μM.  相似文献   

16.
The structures of small silver clusters (Ag2, Ag3, Ag13) and their interaction with ligands of the cholesterol series, namely, cholesterol (Ch) and thiocholesterol (TCh), are calculated by the density functional theory (DFT) methods and the second-order Møller–Plesset perturbation theory (MP2). Trends in the geometric structure and interaction energy of the silver–cholesterol ligand cluster are estimated depending on the size of the metal cluster and the replacement of cholesterol by the sulfur-containing analogue. For Ch–Ag13 and TCh–Ag13 systems, the geometric structure of the metallic subsystem is a slightly distorted icosahedron with the Ag–Ag bond length ranged 2.8–3.0 Å. Cholesterol is coordinated to the icosahedral facet so that the shortest Ag–O distances range from 2.3 to 2.4 Å. In the case of thiocholesterol, a configuration in which the ligand is coordinated by the edge of the icosahedron with two approximately equal distances of Ag–S (2.537 and 2.547 Å) is preferable.  相似文献   

17.
The three‐dimensional coordination polymer poly[[bis(μ3‐2‐aminoacetato)di‐μ‐aqua‐μ3‐(naphthalene‐1,5‐disulfonato)‐hexasilver(I)] dihydrate], {[Ag6(C10H6O6S2)(C2H4NO2)4(H2O)2]·2H2O}n, based on mixed naphthalene‐1,5‐disulfonate (L1) and 2‐aminoacetate (L2) ligands, contains two AgI centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five‐coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one AgI cation in a distorted trigonal–bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two AgI cations in a slightly octahedral coordination geometry. Ag3 is four‐coordinated by two O atoms from two L2 anions and two AgI cations in a slightly distorted square geometry, while Ag4 is also four‐coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one AgI cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one‐dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two‐dimensional layer, and the layers are further bridged by L1 anions to generate a novel three‐dimensional framework. Moreover, hydrogen‐bonding interactions consolidate the network.  相似文献   

18.
A new highly distorted hexacoordinated silver(I) complex [AgL2NO3] with 2-(bis(methylthio)methylene)-1-phenylbutane-1,3-dione (L) as ligand is synthesized and characterized using elemental analysis, FTIR, NMR, and X-ray single-crystal structure analysis. The ligand (L) and the nitrate group act as bidentate ligands. The geometry around the silver ion has an intermediate configuration between a trigonal prism (TP) and an octahedron (OCT). Continuous shape measure (CShM) analysis indicated a closer configuration to TP than OCT. Experimentally and theoretically, the Ag–S bonds are shorter than any of the Ag–O bonds, indicating a stronger interaction between Ag+ (soft metal) and S-atom as a softer site than oxygen. Natural bond orbital (NBO) analyses showed higher interaction energies between the S-atom lone pairs and the Ag–antibonding NBO (8.61–31.39 kcal/mol) than LP(O)→Ag (3.48–11.46 kcal/mol). The acceptor antibonding NBO of the Ag atom has mainly s-orbital character. The Ag atom has a natural charge of +0.7579 e at the experimental structure, suggesting that negative charge was transferred from the ligand (0.0666 e) and nitrate (0.1090 e) to the Ag ion. Using Hirshfeld surface analysis, the important intermolecular interactions between molecular units within the crystal lattice of the ligand and its Ag-complex were analyzed and compared.  相似文献   

19.
Calcium-activated chloride channels (CaCCs), for example TMEM16A, are widely expressed in a variety of tissues and are involved in many important physiological functions. We developed and validated an atomic absorption spectroscopy (AAS)-based detection system for high-throughput screening (HTS) of CaCC modulators. With this assay, Cl? flux from CHO cells stably transfected with TMEM16A is assayed indirectly, by measuring excess silver ions (Ag+) in the supernatant of AgCl precipitates. The screening process involved four steps: (1) TMEM16A CHO cells were incubated in high-K+ and high-Cl? buffer with test compounds, and with ionomycin as Ca2+ ionophore, for 12 min; (2) cells were washed with a low-K+, Cl?-free and Ca2+-free buffer; (3) CaCC/TMEM16A were activated in high-K+, Cl?-free buffer with ionomycin (10 μmol L?1) for 12 min; and (4) excess Ag+ concentration was measured using an ion channel reader (ICR, an AAS system). The assay can be used to screen CaCC activators and inhibitors at the same time. With this assay, positive control drugs, including NPPB, CaCCinh-A01, flufenamic acid (Flu) and Eact, all had good concentration-dependent effects on CaCC/TMEM16A. NPPB and CaCCinh-A01 inhibited the CaCC/TMEM16A currents completely at 300 μmol L?1, with IC50 values of 39.35?±?4.72 μmol L?1 and 6.35?±?0.27 μmol L?1, respectively; and Eact, activated CaCC/TMEM16A, with an EC50 value of 3.92?±?0.87 μmol L?1.  相似文献   

20.
Four new bridged silver(I) complexes, namely [Ag22‐teda)(μ2‐fbc)2] ( 1 ), [Ag22‐1,6‐dah)2](bpdc) · 4H2O ( 2 ), [Ag22‐2‐ap)(2‐ap)(bnb)] · 0.34H2O ( 3 ), [Ag22‐pyc)2(2‐apy)2] · 0.5H2O ( 4 ), have been synthesized and characterized by elemental analysis and crystallographic methods [fbc = 4‐fluorobenzoate, teda = triethylenediamine ( 1 ); bpdc = biphenyl‐4,4′‐dicarboxylate, 1,6‐dah = 1,6‐diaminohexane ( 2 ); bnb = 3,5‐binitrobenzoate, 2‐ap = 2‐aminopyrimidine ( 3 ); pyc = 3‐pyridinecarboxylate acid, 2‐apy = 2‐aminopyridine ( 4 )]. Complex 1 contains a 1D linear chain paralleling to the c‐axis, whereas in complex 2 silver(I) atoms were bridged by the 1,6‐dah ligand into a zigzag chain, further giving a 1D ribbon by weak Ag ··· Ag interactions. Complex 3 consists of a dinuclear silver(I) [Ag22‐2‐ap)(2‐ap)(bnb)] moiety and a lattice water molecule, forming a 3D network via a number of hydrogen‐bonding interactions such as N–H ··· O, N–H ··· N and C–H ··· O hydrogen bond and other weak interactions such Ag ··· Ag, Ag ··· N, N ··· O as well as O ··· O interaction. Similar to 3 , the asymmetric unit of 4 consists of one dinuclear silver(I) [Ag22‐pyc)2(2‐apy)2] moiety and half lattice water molecule, further generating a tetranuclear silver(I) {[Ag22‐pyc)2(2‐apy)2]2 · H2O} moiety. These moieties construct a 3D supramolecular network structure of 4 through N–H ··· O, O–H ··· O and C–H ··· O hydrogen bonds as well as other weak interactions such as Ag ··· O and N ··· O interactions.  相似文献   

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