Construction of a three-dimensional network with open channels via Ag–Ag and π–π interactions between nanoscale sized molecular chains

The reaction of Ag₂O with pybz (pybz=4-(4-pyridyl)benzoate) gave the monomer compound [Ag(pycz)(H₂O)], 1. Using 4,4′-bipyridyl (bpy) as a spacer to increase the length of the monomer resulted in the nanosized molecular chain compound [Ag₂(pybz)₂(bpy)], 2. In 1, two monomers [Ag(pycz)(H₂O)] are combined together through Agπ, ππ and Ag(CC) interactions to form a dimer, with the distances of 3.34, 3.56 and 3.18 Å, respectively. In 2, the [Ag₂(pybz)₂(bpy)] units are held together via ππ (3.4–3.5 Å) interactions resulting in a 3D network with 1D open channels.     

Catalytic Preparation of Methyl Formate from Methanol over Silver

A catalytic reaction over a silver catalyst performed in an unregarded temperature region（473-873 K） with a long catalytic lifetime for the production of methyl formate from methanol was provided as a potential preparing route. The optimal yield of methyl formate（ca. 14. 8% ） with a selectivity 〉90% was obtained at about 573 K. Because α- oxygen species and bulk oxygen species coexist in the unregarded temperature region, a synergistic process concerning α-oxygen species and bulk oxygen species was proved over Oα -rich and Oγ-rich samples.     

An ab initio study of ionic liquid silver complexes as carriers in facilitated olefin transport membranes

Liquid phase isoprene/n-pentane mixtures can be separated through the use of facilitated transport membranes containing complexes of silver ions with an ionic liquid (IL). 1-Butyl-3-methyl imidazolium tetrafluoroborate and zwitterion-type imidazolium compounds containing covalently-bound sulfonate groups form complexes with AgX (X = BF₄, NO₃, and ClO₄). Facilitated isoprene transport has been observed with selectivities that depend on the counteranion of the silver salt. The facilitated transport phenomena of the olefin and IL/silver complexes were investigated theoretically by calculating their complexation energies (i.e., the energy of formation of the silver complexes with the olefin) with the density functional theory method. Among polymer/silver salt systems, the polymer/AgBF₄ system has been found to be generally more favorable for facilitated olefin transport than the polymer/AgNO₃ system because of the low lattice energy of AgBF₄. However, there is a different trend for IL/AgX systems. This difference may arise because the positively charged components of the IL can interact with the anions of the silver salt, which changes the olefin complexation activity. For IL/AgX systems, the selectivity varies inversely with the complexation energy, which implies that the diffusion of the carrier may be the significant factor affecting isoprene/n-pentane separation, once the appropriate complexation has occurred between olefin molecules and the ILsilver complexes.     

Silver(I) ion selective ionophores containing dithiocarbamoyl moieties on steroid backbone

Tweezer-type and non-tweezer-type ionophores containing dithiocarbamoyl groups on a 7-deoxycholic amide or cholane derivatives were designed and synthesized. Potentiometric evaluation of the poly(vinyl chloride) (PVC) membranes containing those deoxycholic amides/cholanes linked with tweezer-type dithiocarbamoyl moieties showed excellent affinity and selectivity to silver(I) ion over alkali, alkaline earth and other transition metal cations. On the other hand, deoxycholic amides/cholanes substituted with one dithiocarbamoyl group, i.e., non-tweezer-type ionophores, resulted in relatively poor potentiometric sensitivity and detection limits. The enhanced potentiometric properties of newly synthesized tweezer-type dithiocarbamoyl containing ionophores have been further improved by employing silver ion complexing reagent in the internal reference solution, which resulted in greatly reduced detection limit (∼100 ppt) for the electrodes based on them.     

Investigating direct routes to an advanced intermediate for the synthesis of C-20 diterpene alkaloids

Rapid access to the ABCE ring system of the C-20 diterpene alkaloids was achieved by silver (I) promoted intramolecular Friedel-Crafts arylation of a functional group specific 5-bromo-3-azabicyclo[3.3.1]nonane derivative.     

Structure and absolute configuration of an unsaturated anteiso fatty acid from Bacillus megaterium

Gas chromatography in combination with electron ionization mass spectrometry (GC/EI-MS) was used to determine the fatty acids of a membrane lipid from Bacillus megaterium. Special attention was put on the structure and absolute configuration of a monoenoic fatty acid previously described in this sample. GC/EI-MS operated in the selected ion monitoring mode was used to determine twelve fatty acids in the bacterium. Methyl esters were prepared to verify the presence of a 14-methylhexadecenoic acid (a17:1) isomer. The position of the double bond of the a17:1 isomer and four further monoenoic fatty acids was elucidated by means of their picolinyl esters produced by the transesterification of the phospholipid. For the a17:1 isomer, the double bond was located between C-5 and C-6. Silver ion liquid chromatography was used to verify that the double bond was in cis-configuration. The bacterial 14-methylhexadec-5-enoic acid (a17:1Δ5) is chiral due to the stereogenic C-14 carbon. Initial enantioselective measurements were carried out with isomers of a17:1Δ5 which were available in form of racemic and (S)-enantiopure cis- and trans-isomers of a17:1Δ12 previously synthesized. The cis-a17:1Δ12 enantiomers were partly resolved on a chiral stationary phase coated with 50% heptakis(6-O-tert.-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV-1701 (β-TBDM). However, resolution of the enantiomers of the trans-isomer of a17:1Δ12 failed. Only one peak was also observed for the a17:1Δ5 isomer from B. megaterium. Thus, it remained unclear whether the compound a17:1Δ5 was racemic or enantiopure in the sample. To clarify this point, we separated the cis-monoenoic fraction from the saturated fatty acids. Then, the monoenoic fraction was hydrogenated in order to transform a17:1Δ5 into 14-methylhexadecanoic acid (a17:0). This chiral fatty acid was known to be sufficiently enantioseparated on the β-TBDM column and was found to be (S)-enantiopure in the sample. Hence, these measurements verified that the B. megaterium sample contained enantiopure (S)-a17:1Δ5.     

Synthesis and characterization of organophosphine/phosphite stabilized silver(I) complexes bearing 2-acetyl-1,3-indandione ligand,crystal structure of [Ph3P·AgC11H7O3]

Six organophosphine/phosphite stabilized silver(I) complexes of 2-acetyl-1,3-indandione (2-AID) of type L_n·AgC₁₁H₇O₃ (L = PPh₃; n = 1, 2a; n = 2, 2b; L = P(OMe)₃; n = 1, 2c; n = 2, 2d; L = P(OEt)₃; n = 1, 2e; n = 2, 2f) have been prepared by reacting of [AgC₁₁H₇O₃], which could be obtained by reacting of 2-AID with AgNO₃, with triphenylphosphine, trimethylphosphite, or triethylphosphite in 1:1–2 M ratio. These complexes were obtained in high yields and characterized by elemental analysis, ¹H, ¹³C{H} NMR, IR spectroscopy, and thermal analysis (TG and DSC), respectively. The molecular structure of 2a has been determined by X-ray single crystal analysis in which the silver atom is in a distorted trigonal geometry.     

Heterometallic Cr2/Ag2 1D polymer: Synthesis,structure and properties

A 1D heterometallic Cr₂/Ag₂ polymer formulated as {[Ag(μ-H₂O)Ag(nta)Cr(μ-OH)(μ-AcO,O′)Cr(nta)]·H₂O}_n (1) (H₃nta = nitrilotriacetic acid) has been prepared and structurally characterized. {Cr(μ-OH)(μ-OAc)Cr} dimeric units containing two different bridging ligands, hydroxo and acetate groups are coordinated to six Ag atoms forming the 1D network. The temperature dependence of magnetic susceptibility for 1 which was fitted with an isotropic Hamiltonian including biquadratic exchange parameters, yielded antiferromagnetic interaction parameters (J = −8.5(1), j = −0.50(7) cm⁻¹ g = 2.0).     

Isothiouronium-modified gold nanoparticles capable of colorimetric sensing of oxoanions in aqueous MeOH solution

Isothiouronium-modified gold nanoparticles 1 with an average diameter of 5.8 nm were synthesized from bis(5-(N,N′-dimethyl-S-isothiouronio)pentyl) disulfide 2. The surface plasmon band at 524 nm in 10% (v/v) H₂O-MeOH showed a selective red shift upon adding anions, making this potentially useful as a new anion sensor material.     

纳米银/聚多巴胺修饰玻碳电极的制备及电化学行为

利用电聚合法和脉冲沉积技术制备了纳米银/聚多巴胺修饰的玻碳电极. 通过循环伏安法和示差脉冲伏安法研究了该修饰电极上对硝基苯酚的电化学行为; 讨论了扫描速度和支持电解质等条件对对硝基苯酚在修饰电极上催化还原的影响. 结果表明, 对硝基苯酚的示差脉冲峰电流在4×10^-5～3×10^-4 mol/L范围内呈良好的线性关系.