- Ethylene sensing by silver(I) salt-impregnated luminescent films
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Luminescent oligomers and polymers doped with silver(I) salts were used as optical sensors for ethylene and other gaseous small molecules. Films of poly(vinylphenylketone) (PVPK) or 1,4-bis(methylstyryl)benzene (BMSB) impregnated with AgBF4, AgSbF6, or AgB(C6F 5)4 respond to ethylene exposures with a reversible emission quenching that is proportional to the pressure of the gas. Experiments with various analytes revealed that only gases capable of forming coordinate bonds with Ag(I) ions (i.e., ethylene, propylene, and ammonia) produced a sensing response. Comparison of the effects of ethylene and tetradeuterioethylene revealed that the emission quenching was due to enhanced vibrational relaxation. The Ag(I) ions are essential to the observed optical response. The oligomer/polymer support enhances the response characteristics of the impregnated salt by promoting separation of Ag(I) from its anion, a separation that improves accessibility of the Ag(I) ion to the gaseous analytes. Salts with large lattice energies, where the anion is not dissociated from Ag(I) in the matrix, fail to sensitize film responses. Photoluminescence experiments with Ag(I)-impregnated BMSB films established that the Ag(I) ions serve to communicate the analyte-binding signal to the support by altering the support-based emission. These experiments demonstrate a sensing paradigm where simultaneous coordination of Ag(I) ions to the support matrix and to a gaseous analyte enables the optical response.
- Santiago Cintron, Michael,Green, Omar,Burstyn, Judith N.
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- Cyclopentadienyl thiocarbonyl complexes of iron: *Fe(CO)2CS>+, Cp*2Fe2(CO)2(CS)2, Cp2Fe2(CO)3(CS), and Cp2Fe2(CO)2(CS)2
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Nucleophiles generally react with the new iron thiocarbonyl complex *Fe(CO)2(CS)>+ (Cp* = η-C5Me5) by attacking at the carbon of the CS ligand.Thus, SMe- gives the dithioester, Cp*Fe(CO)2
- Choi, Moon-Gun,Daniels, Lee M.,Angelici, Robert J.
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- Formation of hierarchically-ordered nanoporous silver foam and its electrocatalytic properties in reductive dehalogenation of organic compounds
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Nanoporous silver foam on a glassy carbon electrode (AgNF/GC) was formed by cathodic deposition of silver from an acidic solution of AgBF4 at high current density. The material can be described (based on results of optical microscopy, SEM, TEM and XRD investigation) as hierarchically (micro/nano) porous matter with ca. 40 nm silver crystals assembled in irregular ca. 70-300 nm thick filaments arranged in a foam-like structure with ca. 20 μm cavities and ca. 7 μm walls. The AgNF surface area was estimated by pseudocapacitance measurement as ca. 12 times higher than the geometrical area. Reduction of bromobenzene and other aryl bromides containing redox-inactive (F-, CH3-, CH3O-) or redox-active (-NO2,-CN and CH3CO-) substituents, as well as alkyl bromides (CF3CHClBr, CF2Br2) on AgNF/GC was studied. The peak potentials of the processes assigned to debromination of the organic halides were less negative (up to +345 mV) than on smooth silver, indicating superior electrocatalytic properties of the nanoporous silver foam. Comparison of the CV peak currents of the processes on AgNF/GC and smooth silver, as well as their changes in cycling in different regimes allowed formation of a few kinds of electrocatalytically active sites on the AgNF surface to be suggested. Electrolysis of 1-bromo-4-fluorobenzene on the AgNF electrode led to fluorobenzene, and less than 1 mg of AgNF revealed performance comparable to 500 mg of smooth silver wire. The results can be utilized for creation of electrochemical sensors as well as for preparative detoxification of halogen-containing persistent organic pollutants.
- Mishura, Andrey M.,Lytvynenko, Anton S.,Gavrilenko, Konstantin S.,Baranchikov, Alexander E.,Grabovaya, Natalia V.,Kiskin, Mikhail A.,Kolotilov, Sergey V.
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- Carbon-ionic liquid double-layer capacitors
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A series of electrochemical capacitors, based on activated carbon powders (ACP, specific surface area 870 and 2600 m2/g) and ionic liquids as electrolytes, were prepared and tested. The ionic liquids consisted of 1-ethyl-3-methyl imidazolium (EMIm+), 1-butyl-3-methyl imidazolium (BMIm+) and 1-methyl-1-propyl pyrrolidinium (BMPy+) cations, as well as of tetrafluoroborate, hexafluorophosphate and bis((trifluoromethyl)sulfonyl) imide anions. A typical capacitor consisted of two electrodes each with a mass of ca. 15-30 mg, and showed a capacity of ca. 0.35-1.5F; this leads to a specific capacity of the carbon electrode material within the range of 45 (ACP 870 m2/g)-180 F/g (ACP 2600 m 2/g). The specific capacity expressed versus total surface of carbon material was within the range of 5.2-6.9 μF/cm2. The electrochemical stability window of ionic liquids determined at the glassy carbon electrode is within the range of ca. 3.0-4.2 V. The energy stored in a capacitor based on activated carbons and ionic liquids may be high, due to a broad practical electrochemical stability window of ca. 3 V. Ionic liquids are characterised by negligible vapour pressure; such a capacitor emits no volatile organic compounds and may be regarded as environmentally friendly.
- Lewandowski,Galiński
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- Capturing the missing [AgF2]- anion within an Ru2(iii/iii) dimeric dumbbell complex
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The complex {[Ru2(ap)4]2[AgF2]}[BF4]3 ({2}[BF4]3, ap = 2-anilinopyridine), containing the [AgF2]- anion ligated to two [Ru2]6+ cores, is prepared, characterized, and compared to dimeric dumbbell-type structures, monomeric Ru2 structures, as well as the known set of dihalo coinage-metalate anions. X-ray crystallography indicates that the Ru-Ru and Ru-F distances are rather short, 2.2835(3) ? and 2.054(1) ?, respectively, while the Ag-F distance of 2.274(1) ? is longer than that calculated for the free/un-ligated anion. Cyclic voltammetry in dichloromethane indicates that, while some of {2}3+ breaks apart into an [Ru2(ap)4F]+ ([3]+) monomer in solution, the remaining dimer has a single reversible two-electron redox feature for the Ru26/5+ couple that is at a lower potential than that of [3]+. This is one of the few examples of a ligated dihalo coinage-metalate, and it is the first example of a coinage metal difluoride anion, either free or ligated.
- Corcos, Amanda R.,Berry, John F.
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- Luminescent chains formed from neutral, triangular gold complexes sandwiching Tl(I) and Ag(I)
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It has been found that several trinuclear complexes of Au(I) interact with silver and thallium salts to intercalate Ag+ and Tl+ cations, thereby forming chains. The resulting sandwich clusters center the cations between the planar trinuclear moieties producing structures in which six Au(I) atoms interact with each cation in a distorted trigonal prismatic coordination. The resultant (B3AB3B3AB3)(∞) pattern of metal atoms also shows short (~3.0 A) aurophilic interactions between BAB molecular centers. These compounds display a strong visible luminescence, under UV excitation, which is sensitive to temperature and the metal ion interacting with the gold. X-ray crystal structures are reported for Ag([Au(μ-C2,N3-bzim)]3)2BF4·CH2Cl2 (P1, Z = 2, a = 14.4505(1)A; b = 15.098(2)A; c = 15.957(1)A; α = 106.189(3)°; β = 103.551(5)°; γ = 101.310(5)°); Tl([Au(μ-C2,N3-bzim)]3)2PF6·0.5C4H8O (P1, Z = 2, a = 15.2093(1)A; b =15.3931(4)A; c = 16.1599(4)A; α = 106.018(1)°; β = 101.585(2)°; γ=102.068(2)°); and Tl([Au(μ-C(OEt)=NC6H4CH3)]3)2PF6·C4H8O (P2(1)/n, Z = 4, a = 16.4136(3)A; b = 27.6277(4)A; c = 16.7182(1)A; β = 105.644(1)°). Each compound shows that the intercalated cation, Ag+ or Tl+, coordinates to a distorted trigonal prism of six Au(I) atoms. The counteranions reside well apart from the cations between the cluster chains.
- Burini, Alfredo,Bravi, Rita,Fackler Jr., John P.,Galassi, Rossana,Grant, Tiffany A.,Omary, Mohammad A.,Pietroni, Bianca R.,Staples, Richard J.
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- Coordination chemistry of silver(I) with the nitrogen-bridged ligands (C6H5)2PN(H)P(C6H5) 2 and (C6H5)2PN(CH3)P(C6H 5)2: The effect of alkylating the nitrogen bridge on ligand bridging versus chelating behavior
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The coordination chemistry of silver(I) with the nitrogen-bridged ligands (C6H5)2PN(R)P(C6H5) 2 [R = H (dppa); R = CH3 (dppma)] has been investigated by 31P NMR and electrospray mass spectrometry (ESMS). Species observed by 31P NMR include Ag2(μ-dppa)2+, Ag2(μ-dppa)22+, Ag2(μ-dppa)32+, Ag2(μ-dppma)2+, Ag2(μ-dppma)22+, and Ag(η2-dppma)2+. Species observed by ESMS at low cone voltages were Ag2(dppa)22+, Ag2(dppa)32+, Ag2(dppma)22+, and Ag(dppma)2+. (C6H5)2PN(CH3)P(C6H 5)2 showed a strong tendency to chelate, while (C6H5)2PN(H)P(C6H5) 2 preferred to bridge. Differences in the bridging versus chelating behavior of the ligands are assigned to the Thorpe - Ingold effect, where the methyl group on nitrogen sterically interacts with the phenyl groups on phosphorus. The crystal structure of the three-coordinate dinuclear silver(I) complex {Ag2[(C6H5)2PN(H)P(C 6H5)2]3}(BF4) 2 has been determined. Bond distances include Ag-Ag = 2.812(1) A, Ag(1)-P(av) = 2.492(3) A, and Ag(2)-P(av) = 2.509(3) A. The compound crystallizes in the monoclinic space group Cc at 294 K, with a = 18.102(4)°, Z = 4, V = 7261(3) A3, R = 0.0503, and Rw = 0.0670.
- Sekabunga,Smith, Michele L.,Webb,Hill
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- catena-poly[silver-μ-(di-2-pyridyl ketone)-N,O:N′,O] tetrafluoroborate
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The title complex, [Ag(C11H8N2O)]n+. n(BF4)-, contains polymeric [silver(di-2-pyridyl ketone)]n+ zigzag chains, counterbalanced by BF4-/sup
- Sommerer,Westcott,Jircitano,Abboud
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- Synthesis of new allyl palladium complexes bearing purine-based NHC ligands with antiproliferative and proapoptotic activities on human ovarian cancer cell lines
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A series of new palladium allyl complexes bearing purine-based carbenes derived from caffeine, theophylline and theobromine have been prepared and characterized by NMR spectroscopy, and elemental analysis and in two cases by single crystal X-ray diffraction. The cytotoxic and proapoptotic activities of compounds have been determined in vitro on human ovarian cancer A2780 and SKOV-3 cell lines. These experiments have shown that the palladium-allyl fragment induces a general cytotoxicity, but the choice of the supporting ligands is of paramount importance for achieving the best results. In particular complexes 4c, 4d and 5d exhibit a higher antiproliferative effect (IC50: 0.09, 0.81 and 0.85 μM respectively) than cisplatin (IC50: 1.5 μM) on A2780 cells, and 4d (IC50: 1.7 μM vs. 5.94 μM) on SKOV-3 cell line. Moreover in many cases it has been proved that the cytotoxicity of our complexes is associated with the induction of apoptosis.
- Scattolin, Thomas,Caligiuri, Isabella,Canovese, Luciano,Demitri, Nicola,Gambari, Roberto,Lampronti, Ilaria,Rizzolio, Flavio,Santo, Claudio,Visentin, Fabiano
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p. 13616 - 13630
(2018/10/15)
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- SYNTHESIS OF NUCLEOSIDES
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Processes for the synthesis of nucleoside analogues are provided.
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Page/Page column 28-30
(2009/06/27)
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- Facile oxidation-based synthesis of sterically encumbered four-coordinate bis(2,9-di-tert-butyl-1,10-phenanthroline)copper(I) and related three-coordinate copper(I) complexes
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A new oxidation-based synthetic route was developed for synthesis of Cu(I) complexes with weakly coordinating ligands, leading to the synthesis of the elusive [Cu(dtbp)2]+ (dtbp, 2,9-di-tert-butyl-1,10- phenanthroline) complex that may be useful as a sensor or as a dye for dye-sensitized solar cells. An acetone solution of either 1 or 2 equiv of dtbp was added to excess Cu(0) and 1 equiv of AgY (Y is O3SCF 3-, BF4-, SbFe6 -, or B(C6F5)4-) in a nitrogen-filled glove box. Following filtration and evaporation under vacuum, crystallization from CH2Cl2 and hexanes results in X-ray quality crystals of Cu(dtbp)(O3SCF3) (1), Cu(dtbp)(BF 4) (2), [Cu(dtbp)(acetone)][SbF6] (3), [Cu(dtbp) 2]-[B(C6F5)4]·CH 2Cl2 (4·CH2Cl2), [Cu(dtbp)2][BF4]·CH2Cl2 (5·CH2Cl2), and [Cu(dtbp)2][SbF 6]·CH2Cl2 (6·CH 2Cl2). Complexes 1-6 were characterized by X-ray crystallography and NMR. The Cu atom in complexes 1-3 exhibited distorted trigonal coordination geometries, reflecting the steric effect of the bulky tert-butyl substituents. The structures of the pseudotetrahedral complexes 4, 4·CH2Cl2, 5·CH2Cl2, and 6·CH2Cl2 revealed the longest average Cu-N distances (2.11 A, 2.11 A, 2.10 A, and 2.11 A, respectively) in this class of compounds-longer by more than three standard deviations from the average.
- Gandhi, Bhavesh A.,Green, Omar,Burstyn, Judith N.
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p. 3816 - 3825
(2008/10/09)
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- Silver(I) Undecafluorodiantimonate(V)
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The reaction between AgBF4 and excess of SbF5 in anhydrous hydrogen fluoride (aHF) yields the white solid AgSb2F 11 after the solvent and the excess of SbF5 have been pumped off. Reaction between equimolar amounts of AgSb2F 11 and AgBF4 yields AgSbF6. Meanwhile, oxidation of solvolyzed AgSb2F11 in aHF by elemental fluorine yields a clear blue solution of solvated Ag(II) cations and SbF 6- anions. AgSb2F11 is orthorhombic, at 250 K, Pbca, with a = 1091.80(7) pm, b = 1246.28(8) pm, c = 3880.2(3) pm, V = 5.2797(6) nm3, and Z = 24. The crystal structure of AgSb2F 11 is related to the already known crystal structure of H 3OSb2F11. Vibrational spectra of AgSb 2F11 entirely match the literature-reported vibrational spectra of β-Ag(SbF6)2, for which a formulation of a mixed-valence Ag(I)/Ag(III) compound was suggested (AgIAg III(SbF6)4). On the basis of obtained results it can be concluded that previously reported β-Ag(SbF6) 2 is in fact Ag(I) compound with composition AgSb2F 11.
- Mazej, Zoran,Benkic, Primoz
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p. 8337 - 8343
(2008/10/09)
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- Spontaneous oxidation of xenon to Xe(II) by cationic Ag(II) in anhydrous hydrogen fluoride solutions
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Blue solutions, prepared by dissolving AgF2 in anhydrous hydrogen fluoride (AHF) with BF3 or AsF5, oxidize Xe, at ～20 °C, to produce nearly colorless solids. Overall reactions (all in AHF) are as follows: 2AgF2
- ?emva, Boris,Hagiwara, Rika,Casteel Jr., William J.,Lutar, Karel,Jesih, Adolf,Bartlett, Neil
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p. 4846 - 4849
(2007/10/02)
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