Synthesis, Crystal Structure and Catalytic Behavior of 1-Ethyl-3-benyl-imidazolyl Tetranuclear N-Heterocyclic Carbene Silver Bromide

The title complex [Ag（carbene）2]2[Ag2Br4] has been synthesized by the reaction of Ag2O with 1-ethyl-3-benyl-imidazolium bromide in DMSO at room temperature, and characterized by elemental analysis, 1H NMR and single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P with a = 10.1597（10）, b =11.0646（11）, c = 13.0245（14） , α = 102.230（2）, β = 90.606, γ = 113.9250（10）o, V = 1300.3（2） 3, Mr = 748.06, Z = 2, Dc = 1.911 g/cm3, μ（MoKα） = 4.60 mm-1 and F（000） = 728. The structure was refined to R = 0.0316 and wR = 0.0835 for 3744 observed reflections with I 〉 2σ（I）. The title compound crystallizes as a centrosymmetric tetranuclear compound. One half of the molecule comprises the asymmetric unit of the structure. The Ag（1） atom is nearly linear or T-shaped when the Ag（1）-Ag（2） interaction is taken into consideration, which is bi-coordinated by two carbene carbon atoms. The Ag（2） atom adopts tetrahedral geometry. The catalytic behavior of the title complex has been investigated, and the results indicate it has a highly catalytic activation for L-lactide polymerization.

Synthesis, Crystal Structure and Photoluminescent Property of a Novel Silver(I) Compound {[Ag(bpp)]_2(Hphth)(NO_3)·(H_2O)_2}_n

Self-assembly of Ag（I） nitrate, 1,3-bis（4-pyridyl）propane （bpp） and phthalic acid monopotassium salt （KHphth） in CH3OH-H2O solution produced the title complex, {[Ag（bpp）]2（Hphth）（NO3）-（H2O）2}n, which was characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum, and photoluminescent spectrum. Single-crystal X-ray analysis revealed that the complex crystallizes in a monoclinic system, space group P2dc, with a = 15.4174（5）, b = 8.6398（2）, c = 25.2466（8）A, β = 91.072（1）^o, V = 3362.34（17）A3, Z = 4, C34H37N5O9Ag2, Mr = 875.43, De = 1.729 g/cm^3, u = 1.228 mm^-1, F（000） = 1768, the final R = 0.0749 and wR = 0.1580 for 5754 reflections with I 〉 2o（I）. The Ag atom is coordinated by two N atoms from two bpp molecules in an approximately linear geometry. The Ag（I） ions are linked by the bpp molecules to form one-dimensional zigzag chains propagating along the c axis. The Hphth- and nitrate counter-ions are bridged by solvent water molecules through hydrogen bonds to generate a one-dimensional chain extending along the b axis. Electrostatic interactions between cations and anions, extensive hydrogen bonds and re-re interactions are responsible for the three-dimensional supramolecular structure. In the solid state, the compound exhibits blue photoluminescence with the maximum at 436 nm upon excitation at 344 nm.

Fabrication of Large-area 3-D Ordered Silvercoated Colloidal Crystals and Macroporous Silver Films Using Polystyrene Templates

The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.

Syntheses and Crystal Structures of Silver(I) Complexes by Depolymerizing [Ag(C≡CPh)]_n with a NP_3 Ligand

Two silver(I) complexes were prepared by the reaction of [Ag(C≡CPh)]n with NP3 [NP3 = N(CH2CH2PPh2)3] or with NP3 and [Cu(CH3CN)4]ClO4. Complex 1 [(Ag2Cl(NP3)2)(Ag5- (C≡CPh)6)] contains both NP3 and PhC≡C- ligands. The complex cation is (Ag2Cl(NP3)2)+, in which two Ag(NP3)+ cations were bridged by a Cl- donor. The anion is (Ag5(C≡CPh)6)-, where five Ag+ ions are linked by six C≡CPh- to form a pentanuclear cluster. Complex 2 only contains NP3 ligand, where the silver center adopts a trigonal-bipyramidal geometry. Crystal data for 1: C133H116Ag7Cl3- N2P6, Mr = 2789.54, triclinic, space group P1, a = 13.0780(2), b = 15.3678(2), c = 31.2041(3) ?, α = 91.3928(7), β = 90.9328(8), γ = 96.0244(4)o, V = 6233.8(1) ?3, T = 293(2) K, Z = 2, Dc = 1.486 g/cm3, F(000) = 2796, μ = 1.266 mm-1, the final R = 0.0746 and wR = 0.1953 for 16475 observed reflections with I > 2σ(I). Crystal data for 2: C42H42AgClNO4P3, Mr = 861.00, trigonal, space group R3, a = 17.451(1), b = 17.451(1), c = 11.3985(7) ?, V = 3006.0(3) ?3, T = 293(2) K, Z = 3, Dc = 1.427 g/cm3, F(000) = 1326, μ = 0.731 mm-1, the final R = 0.0251 and wR = 0.0663 for 1499 observed reflections with I > 2σ(I).

FRACTAL STRUCTURE OF COLLOIDAL SILVER AND ITS EFFECTS ON SERS INTENSITIES OF CRYSTAL VIOLET

The surface-enhanced Raman spectra (SERS) of crystal violet on colloidal silver particles of different sizes and shapes were measured and the structural effect of the silver aggregates on the SEPS intensities was discussed in terms of fractal geometry. It is found that the SERS band intensities of crystal violet change significantly with the fractal dimension (D) of colloidal silver at 1.25<D<1.65, but remains nearly constant at D>1.8.

Crystal Structure of Di-μ-bromo-tris(triphenylphosphine) Di-silver(Ⅰ)

A binuclear silver complex,Ag2Br2(PPh3)3·CH2Cl2,Mr=1247.4,monoclinic P21/c,a=16.306(3).b=18.444(3),c=18.807(3),β=111.21(2)°,V=5274.1(4).,Z=4,Dc=1.575 g/cm3,λ(MoKα)=0.71073,μ(MoKα)=24.7cm(-1),F(000)=2480,final R=0.071,Rw=0.075 for 5007observed reflections.In the complex,Ag(1)and Ag(2)are bridged by two bromineatoms and coordinated in tetrahedral and trigonal geometries,respectively.

Synthesis and Crystal Structure of a Two-dimensional Silver Framework Constructed by H_2idc (H_2idc = Iminodiacetic Acid)

A new compound formulated [Ag2(idc)](NO3)?H2O (H2idc = iminodiacetic acid) was synthesized under mild conditions and characterized by IR spectrum and single-crystal X-ray diffraction. The crystal crystallizes in the monoclinic system, space group of P21/n with a = 5.5029(2), b = 11.1316(5), c = 15.5319 (1) ?, β = 96.038(3)o, V = 946.15(6) ?3, Z = 4, R = 0.0619 and wR = 0.1606. Its structure is a 2D polymer, whose repeat units consist of dinuclear silver cluster coordinated by two bridging iminodiacetic acids. In the complex, the Ag(I) ions adopt three coordinate fashions, and the Ag-Ag metal-metal contacts of 2.8418 ? are observed.

Synthesis and Crystal Structure of a Tetranuclear Silver Complex with Bis(diphenylphosphino) amine-dioxide as a Tridentate Ligand

The tetranuclear complex[Ag4（μ-Ph2PNHPPh2）2（μ-OPh2PNPPh2O）2] （PF6）2·CH3COCH3 containing bis（diphenylphosphino）amine （Ph2PNHPPh2） and deprotonated bis- （diphenylphosphino）amine-dioxide （OPh2PNPPh2O） was isolated and characterized by X-ray crystallography. The deprotonated OPh2PNPPh2O acts as a tridentate ligand in a chelating and bridging mode. Two of the four Ag atoms are in a trigonal planar environment composed of PO2 chromophore, whereas the other two are coordinated with PN donors in a distorted linear arrangement. The title complex （C51H47Ag2F6N2O3P5） crystallizes in triclinic, space group P1^- with a = 12.9552 （2）, b = 14.1691（3）, c = 15.8110（3）A°, α = 68.7500（10）, β= 86.8840（10）, γ = 75.6170（10）°, V= 2618.16 （8） A°^3, Mr= 1220.50, Z = 2, Dc= 1.548 g/cm^3, F（000） = 1228 and μ（MoKα） = 0.965 mm^-1. The final refinements converged at R = 0.0679 and wR = 0.1528 for 7001 observed reflections （I〉 2σ（I））.

Syntheses, Characterizations, and Crystal Structures of Two Binuclear Silver Complexes Based on O,O'-Dialkyldithiophosphate and 1,10-Phenanthroline

Two binuclear silver complexes, [Ag2{μ-S2P（OCH2Ph）2}2（phen）2] （1） and [Ag2{μ- SEP（OCH2CH2Ph）2}E（phen）2] （2）, were synthesized and characterized by elemental analysis, infrared spectrum, thermo-gravimetric analysis and X-ray single-crystal diffraction. Complex 1 crystallizes in the triclinic system, space group P1 with a = 9.7881（4）, b = 10.7726（4）, c = 13.1952（6） A, a = 103.686（4）, ,8= 99.477（3）, ）, = 107.494（4）°, F= 1246.88（9）A3, Dc = 1.591 g.m-3 and Z = 1; Complex 2 is of monoclinic system, space group P2jn with a = 10.6014（8）, b = 24.3969（15）, c = 11.5353（10）A,β= 14.125（10）°, F= 2722.9（4） A3, Dc = 1.526 g.m-3 and Z = 2. In the molecules of 1 and 2, O,O＇-dialkyldithiophosphate anions, （PhCHEO）PS2 and （PhCH2CHEO）PS2 act as bridging ligands and connect two Ag（I） centers into a binuclear unit with AgES4P2 eight-membered rings in ＂chair＂ conformations. In both crystal structures, face-to-face π-π stacking interactions between the adjacent paralleling aromatic rings of 1,10-phenanthroline play a prominent role in the crystal packing and result in a 1D chain. And such 1D chains are further linked into 3D networks by weak intermolecular C-H...π interactions for 1.

Syntheses and Crystal Structures of Two Silver(I) Complexes Isolated by the Reaction of [Ag(PPh_3)_2(MeCN)](SbF_6) with a N_6 Ligand

Two silver(I) complexes were obtained by the reaction of a N6 ligand with [Ag(PPh3)2(MeCN)](SbF6). In complex [AgL1(PPh3)](SbF6) 1, the silver center is bound to three N donors of the nitrogen ligand and P donor of one triphenylphosphine group, forming an irregular AgN3P tetrahedron. In complex [Ag(PPh3)4](SbF6) 2, the Ag+ ion is coordinated to four triphenyl- phosphine groups, affording a tetrahedral geometry. Crystal data for complex 1: C30H37AgF6N6PSb, Mr = 856.25, orthorhombic, space group Pbca, a = 19.0702(9), b = 15.9047(7), c = 21.498(1) ?, V = 6520.5(6) ?3, Z = 8, Dc= 1.744 g/cm3, F(000) = 3408, μ = 1.544 mm-1, the final R = 0.0367 and wR = 0.1077 for 5325 observed reflections with I > 2σ(I); and those for 2: C72H60AgF6P4Sb, Mr = 1392.70, trigonal, space group R3, a = 14.4577(6), b = 14.4577(6), c = 51.544(2) ?, V = 9330.5(7) ?3, Z = 6, Dc= 1.487 g/cm3, F(000) = 4224, μ = 0.913 mm-1, the final R = 0.0352 and wR = 0.1089 for 3498 observed reflections with I > 2σ(I).

Trace Level Gas Sensing Characteristics of Nano-Crystalline Silver Decamolybdate

A soft-chemical method has been developed for the synthesis of nano-crystalline powders of silver decamolybdate. Gas sensing characteristics of this composition both in porous pellet and thin film configurations were investigated. The compound Ag6Mo10O33 was found to sense selectively ammonia at 503 K. Above 503 K it has significant cross sensitivity to petroleum gas (PG). Spin coated thin films exhibited selective sensing towards PG.

Synthesis and Crystal Structure of a One-dimensional Silver(I) Coordination Polymer with 4,4'-Bipyridine

The title compound, { [Ag2（bipy）2（H2O）2]·pydc·2H2O}n （bipy = 4,4＇-bipyridine, pydc = pyridine-3,5-dicarboxylate）, has been synthesized by the reaction of Ag2O with pydc and bipy in CH3OH solution. It crystallizes in the monoclinic system, space group C2/c with a = 21.419（8）, b = 7.515（3）, c = 18.070（7） A,β = 108.273（6）°, Mr = 765.27, V = 2761.9（17） A^3, Z = 4, Dc = 1.840 g/cm^3, F（000） = 1528,μ = 1.478 mm^-1, the final R = 0.0307 and wR = 0.0681. The structure determined demonstrated that the Ag（I） is three-coordinated by two nitrogen atoms from bipy and one water molecule, forming a one-dimensional coordination polymer [Ag2（bipy）2（H2O）2]n^2n＋, which is further linked to generate a two-dimensional layer structure via Ag---Ag attractions.

Synthesis and Crystal Structure of Binuclear Silver(I) Complex with 2-nitro-(2-pyridylsulfanylmethyl)benzene

The reaction of 2-nitro-（2-pyridylsulfanylmethyl）benzene L with silver nitrate produces a centrosymmetric binuclear complex bis（2-nitro-（2-pyridylsulfanylmethyl）benzene-N,S）- bis（nitrato-O,O）-disilver（Ⅰ）, [AgLNO3]2 1. The crystal is of triclinic, space group PI, with a = 7.383 （3）, b = 8.340（3）, c = 12..003（4） A, a = 95.069（6）, β = 93.498（5）, γ = 102.734（6）°, C24H20Ag2N6- O10S2, Mr= 832.32, V = 715.6（4） ,A^3, Z = 1, Dc = 1.931 g/cm^3, F（000） = 412,μ = 1.581 mm^-1, R= 0.0351 and wR = 0.0749 Each silver atom is tetrahedrally coordinated by two O atoms from bidentate nitrate, one S atom from a ligand and one N atom from another ligand. Furthermore, Ag- Ag interactions have been observed in the complex.

Anionic Nanochanneled Silver-Deficient Oxalatochromate(III) Complex with Hydroxonium as Counter Ion: Synthesis, Characterization and Crystal Structure

Reaction of Ba0.50[Ag2Cr(C2O4)3]·5H2O with Ag2SO4 in an aqueous solution of sulfuric acid (pH ≈ 3) yielded the silver(I)/chromium(III) oxalate salt H0.50[Ag2.50Cr(C2O4)3]·5H2O (1). Compound 1 can be best described as an anionic silver-deficient oxalatochromate(III) complex [Ag2.50Cr(C2O4)3]0.5- with nanochannels containing hydrogen-bonded water molecules and protons. Thermal analyses show significant weight losses corresponding to the elimination of water molecules of crystallization followed by the decomposition of the network.

EFFECTS OF DIFFERENT FUNCTIONAL GROUP-CONTAINING ORGANICS ON MORPHOLOGY-CONTROLLED SYNTHESIS OF SILVER NANOPARTICLES AT ROOM TEMPERATURE

Silver nanoparticles with average particles sizes ranging from 2 to 131nm were manipulatively synthesized starting from silver nitrate using different functional group-containing organic modifiers at room temperature. The effects of the organic modifiers on the morphology of the resulting silver nanoparticles were strongly dependent on the intrinsic properties of the functional groups and the reducibility of the reductant. Numerous ether bonds （-0-）present in polyethylene glycol and Tween-80 were beneficial to the formation of silver nanoparticles with particle sizes of several nanometers in a narrow size distribution in both weak and strong reducing environments. Cetyltrimethylammonium bromide induced the formation of nanosized silver triangle plates in a weak reducing environment. The crystal growth of the silver nanoparticles with particle sizes of more than lOnm was postulated through an adhesion process of small-sized particles followed by a subsequent coalescence process under the present reaction conditions.

The ultratrace detection of crystal violet using surface enhanced Raman scattering on colloidal Ag nanoparticles prepared by electrolysis

Highly active, stable and affordable surface enhanced Raman scattering （SERS） substrates were obtained by electrolyzing a mixture of AgNO3 （4 × 10^-4 mol/L） and Na3C6H5OTH2O （6 × 10^-5 mol/L） for 1, 2, 3 and 4 h at 7 V. With crystal violet （CV） as a test molecule, a portable Raman spectrometer with 785 nm laser excitation was employed to carry out the SERS detection. Colloidal Ag nanoparticles prepared by electrolyzing for 3 h with the particle size of （65 ±17） nm is a perfect SERS substrate for the ultratrace detection of CV, which displayed an enhancement factor of ca. 1.3 × 10^8 and the detection limit of CV is down to ca. 10-15 mol/L （ca. 10^-4 ppb） with 10^-1 mol/L KBr as aggregating agent. Thus, this SERS substrate will provide a hopeful foreground in ultratrace detection. Meanwhile, it will provide a possibility to bring Raman analysis out of the laboratory to process in situ, real-time detection and identification.

Silver(Ⅰ)Complexes with Mixed Diphosphine Ligands:Syntheses,Characterization and Spectroscopic Properties

Two novel silver（I） complexes [Ag（DPEphos）（dppe）]Cl O4（1） and [Ag（DPEphos）-（dppe）]SCN（2）（DPEphos = bis[2-（diphenylphosphino）phenyl]ether, dppe = bis（diphenylphosphino）ethane） are synthesized and characterized by IR, 1H/31 P NMR spectroscopy and fluorescence spectra. Complex 1 crystallizes in monoclinic, space group P21/c with a = 14.8821（12）, b = 12.6620（11）, c = 36.025（3） ？, β = 112.633（2）°, V = 6265.7（9） ？3, C62H52 Cl O5P4Ag, Mr = 1144.24, Z = 4, Dc = 1.213 g/cm3, F（000） = 2352, μ = 0.510 mm-1, the final R = 0.0616 and w R = 0.1192 for 4003 observed reflections（I 〉 2σ（I））. Complex 2 crystallizes in monoclinic, space group P21/c with a = 14.9021（13）, b = 12.6100（11）, c = 35.920（3） A, β = 112.852（2）°, V = 6220.2（9） A3, C63H52NOP4 SAg, Mr = 1102.87, Z = 4, Dc = 1.178 g/cm3, F（000） = 2272, μ = 0.498 mm-1, the final R = 0.0912 and w R = 0.1706 for 3287 observed reflections（I 〉 2σ（I））. In mono-nuclear complexes 1 and 2, the Ag（I） atom is chelated by DPEphos and dppe ligand. In the 31 P NMR spectra, there are splitting signals（doublets or triplets） which can be attributed to the coupling of the 107,109Ag–31P（from DPEphos or dppe ligand）. All the emission peaks of these complexes are attributed to ligand-centered（π-π＊） transitions.

The Effect of Laser Irradiation on Surface Enhanced Raman Scattering for Silver Film

The laser irradiation effect on the SERS intensity for Ag film is discussed using crystal violet (CV) as a probe. The thickness of silver film,the etching time of the glass slide by gaseous hydrogen fluoride, and the laser irradiation time for different amounts of CV on silver films were investigated. The laser burn out model was proposed to explain the dependence of the SERS intensity of CV on the laser irradiation time.

Structure and Luminescent Property of a Tetrahedral Silver(Ⅰ) Cluster Complex Based on Phosphor and Sulphur Mixed-ligand System

A tetrahedral silver(I) cluster complex {Ag4[HC(PPh2)3](S2PPh2)3}ClO4(1,HC(PPh2)3 = 1,1,1-tris(triphenylphosphino)methane, S2PPh2 = diphenyldithiophosphinate) was synthesized by assembling silver ion with phosphor and sulphur mixed-ligand system. The complex was characterized by single-crystal X-ray crystallography, high-resolution mass spectroscopy and thermal analysis. In the crystal structure, an inverted tetrahedron was constructed from Ag4 metal skeleton. The Ag4 cage was stabilized by three diphenyldithiophosphinate ligands and one 1,1,1-tris(triphenylphosphino)methane ligand. 1 exhibits luminescent properties in solid state. A bright yellow-green emission centered at 533 nm has been observed in solid state. Large Stokes' shifts with long range of emissive lifetime indicate that the emission likely originates from a triplet state parentage.

A Silver Complex of 6,7-Dicyanodipyridoquinoxaline:π-Stacking Interactions and Luminescence

The reaction of 6,7-dicyanodipyridoquinoxaline （DICNQ） with AgNO3 in a 1：1 molar ratio by solution method gave a new complex [Ag（DICNQ）2]NO3 1. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the space group Ibca of orthorhombic system with eight formula units in a cell. Crystal data for 1： a = 15.7055（17）, b = 18.411（2）, c = 20.680（2）A, V = 5979.7（11）A3, Z = 8, C32Hl2AgN13O3, Mr = 734.42, Dc = 1.632 g/cm3, μ= 0.734 mm-1, F（000） = 2928, S = 1.023 and T= 293（2） K. The final R = 0.0659 and wR = 0.1927 for 2118 observed reflections with I 〉 2σ（I）, and R = 0.0801 and wR = 0.2196 for all data. The complex builds up a packing structure by π-π stacking interactions and shows a luminescent feature.