Polymer Gold Research Articles

Scanning tunneling spectroscopy of single-wall carbon nanotubes on a polymerized gold substrate

The physics picture on scanning tunneling spectroscopy of single-wall carbon nanotubes (SWCNTs) was revisited recently [H. Lin et al., Nat. Mater. 9, 235 (2010)] with an image potential model under the framework of the many-body theory whose description is different from that of conventional one-particle tight-binding theory. The model is explored further in the present study of SWCNTs with an ultrahigh-vacuum scanning tunneling microscope. In the experiments, two types of samples were measured. In one sample, the nanotubes were in intimate contact with the gold surface and the observed tunneling gaps of semiconductor nanotubes fit the prediction of the one-particle model. In the other sample, the nanotubes were isolated by a thin polymer (4-vinylpyridine) layer from the gold surface. The semiconducting SWCNTs in the latter sample show tunneling gaps several hundreds of milli--electron volts larger than the prediction of the one-particle model. The results can, however, be interpreted by the modified image potential model, which takes into account the surface dielectric mechanism. The consistent picture of the tunneling gaps of the different samples provides insight into the scanning tunneling spectroscopy of SWCNTs from the standpoint of many-body theory.

Binding forms of gold(III) from solutions by cadmium diethyl dithiocarbamate: Thermal behavior and role of secondary interactions in the supramolecular self-assembly of polymeric complexes ([Au{S2CN(C2H5)2}2][AuCl4]) n and [Au{S2CN(C2H5)2}Cl2] n

The chemisorption interaction between the binuclear cadmium diethyl dithiocarbamate (EDtc), [Cd2{S2CN(C2H5)2}4], (chemisorbent I) and AuCl3 solutions in 2 M HCl results in the formation of polymeric gold(III) complexes: ([Au{S2CN(C2H5)2}2][AuCl4]) n (II) and [Au{S2CN(C2H5)2}Cl2] n (III) with the same Au : EDtc : Cl ratio (1 : 1 : 2). The alternating centrosymmetric cations and anions of complex II are structurally self-assembled to form linear polymeric chains: the gold atom in [Au{S2CN(C2H5)2}2]+ forms secondary Au(1)⋯Cl(1) bonds (3.7784 A) with two neighboring [AuCl4]− anions. This binding is additionally strengthened by secondary S(1)⋯Cl(1) interactions (3.4993 A). The mixed-ligand complex III comprises two structurally non-equivalent molecules [Au{S2CN(C2H5)2}Cl2]: A—Au(1) and B—Au(2), each being in contact with two nearest neighbors through pairs of unsymmetrical secondary bonds: Au(1)⋯S(1)a/b 3.4361/3.6329; and Au(2)⋯S(4)c/d 3.4340/3.6398 A. At the supramolecular level, this gives rise to independent zigzag-like polymeric chains, (⋯A⋯A⋯A⋯) n and (⋯B⋯B⋯B⋯) n along which antiparallel isomeric molecules of III alternate. The chemisorption capacity of cadmium diethyl dithiocarbamate calculated from the gold(III) binding reaction is 963.2 mg of gold per 1 g of the sorbent. The recovery conditions for the bound gold were elucidated by simultaneous thermal analysis of II and III. The DSC curves reflect different sets of heat effects, because thermolysis occurs for complex molecules (III) or for cations and anions (II). Nevertheless, the patterns of experimental TG curves are similar despite different structures of the complexes. The final product of thermal transformations is reduced gold.

Assembled Core-Shell Nanostructures of Gold Nanoparticles with Biocompatible Polymers Toward Biology

The present review focuses on core-shell nanostructures of spherical gold nanoparticles (Au NPs) and biocompatible polymers mainly from the view points of preparation approaches, nanocomposite properties and potential applications for biology. The preparation approaches are assorted into direct-reduction, covalent "graft-to", "graft-from" approach, surface bonding and physical adsorption. Various biocompatible polymers are involved such as the thermosensitive polymers, pH-responsive polymers, antibiofouling polymers, conductive polymers and several natural polymers. The encapsulating and loading properties, cellular uptake and drug release control, as well as biorecognition, targeting and sensing potential are discussed in connection with biological systems. These polymeric gold nanocomposites will have a great potential in biotechnology and life science but also face enormous challenge in future applications.

New Insight into Intermediate Precursors of Brust–Schiffrin Gold Nanoparticles Synthesis

There is an ongoing intensive debate on the mechanism of gold nanoparticles formation regarding the intermediate precursors prior to the addition of reducing agent. A new detailed view of the widely used Brust–Schiffrin two-phase method to prepare gold nanoparticles is presented here. Precursor species of these reactions have been identified and quantified by NMR, UV–visible, Fourier-transform Raman spectroscopy, etc. We demonstrate that tetraalkylammonium gold complexes ([TOA][AuX2]) and soluble gold thiolate ([TOA][AuSRX] and [TOA][Au(SR)2]) were detectable as the precursors by NMR spectroscopy. Their relative contents depend on the concentration of reactants. Higher concentration of the reactants is favorable for the formation of soluble thiolate. Polymeric gold thiolate [Au(I)SR]n could eventually precipitate from the solution under specific conditions. The clear mechanism presented here is of great significance to tailor the size and properties of the final products.

Synthesis and Evaluation of Polymeric Gold Glyco-Conjugates as Anti-Cancer Agents

The antitumor activity of organo-gold compounds is a focus of research from the past two decades. A variety of gold stabilizing ligands such as vitamins and xanthanes have been prepared and explored for their 'chelating effect' as well as for their antitumor activity. Dithiocarbamates (DTC) compounds and their metallic conjugates have been well explored for their antiproliferative activities. In this study, glycopolymer based DTC-conjugates are prepared by reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequently modified with gold(I) phosphine. These polymer-DTC derivatives and their gold compounds are tested for their in vitro toxicity in both normal and cancer cell lines. The Au(I) phosphine conjugated cationic glycopolymers of 10 kDa and 30 kDa are evaluated for their cytotoxicity profiles using MTT assay. Au(I) compounds are well-known for their mitochondrial toxicity, hence hypoxic cell lines bearing unusually enlarged mitochondria are subjected to these anticancer compounds. It is concluded that these polymeric DTC derivatives and their gold conjugates indeed show higher accumulation as well as cytotoxicity to cancer cells under hypoxic conditions in comparison to the normoxic ones. Hypoxic MCF-7 cells showed significant sensitivity toward the low molecular weight (10 kDa) glycopolymer-Au(I) complexes.

Binding of Au3+ from solutions by nickel(II) and cadmium diisopropyl dithiophosphates: MAS 31P NMR, structure and thermal behavior of the polynuclear complex [Au2{S2P(O-iso-C3H7)2}2] n

The paper deals with reactions of freshly precipitated diisopropyl dithiophosphate (Dtph) complexes of nickel(II), [Ni{S2P(O-iso-C3H7)2}2] and cadmium, [Cd2{S2P(O-iso-C3H7)2}4], with the [AuCl4]− in 2M HCl, resulting in gold transition from the solution to the precipitate as polymeric gold(I) diisopropyl dithiophosphate. The reduction of gold(III) to gold(I) noted in both cases is due to oxidation of the relevant part of the Dtph group to bis(O,O′-di-(iso)-propoxythiophosphoryl) disulfide, (iso-C3H7O)2P(S)S-S(S)P(O-iso-C3H7)2. The polynuclear gold(I) complex [Au2{S2P(O-iso-C3H7)2}2] n (I) was isolated on a preparative scale from the chemisorption system and studied by MAS 31P NMR and X-ray diffraction. The key structural unit of I is the non-centrosymmetric binuclear molecule [Au2{S2P(O-iso-C3H7)2}2] in which the gold atoms are connected by two bridging Dtph groups. The structure contains two types of non-equivalent binuclear molecules related as conformational isomers. Owing to the relatively weak Au-Au contacts, the neighboring binuclear [Au2{S2P(O-iso-C3H7)2}2] molecules are involved in an infinite polymeric chain with conformer alternation along the chain. To elucidate the conditions for the recovery of bound gold(I), the precipitates formed in the sorption systems were studied by simultaneous thermal analysis under argon. As the final product, thermolysis gives reduced metallic gold. The ability of dithiophosphate complexes to bind gold from a solution is much lower than that of dithiocarbamate complexes, which is due to oxidation of some Dtph groups to disulfide.

Conformation Changes and Luminescent Properties of Au-Ln (Ln = Nd, Eu, Er, Yb) Arrays with 5-Ethynyl-2,2′-Bipyridine

Reaction of polymeric gold(I) acetylide species (bpyC[triple bond]CAu)n (bpyC[triple bond]CH = 5-ethynyl-2,2'-bipyridine) with diphosphine ligands Ph2P(CH2)nPPh2 (n = 2-6) or 1,1'-bis(diphenylphosphino)-ferrocene (dppf) in dichloromethane induces isolation of binuclear gold(I) complexes (bpyC[triple bond]CAu)2{mu-Ph2P(CH2)nPPh2} or (bpyC[triple bond]CAu)2(mu-dppf). Complexation of Ln(hfac)3 (hfac = hexafluoroacetylacetonate, Ln = Nd, Eu, Er, Yb) subunits to the binuclear gold(I) complexes through 2,2'-bipyridyl chelation gives the corresponding Au4Ln4 or Au2Ln2 heteropolynuclear complexes. Noticeably, upon formation of the Au4Ln4 arrays by complexation of (bpyC[triple bond]CAu)2(mu-Ph2P(CH2)4PPh2) (3) with Ln(hfac)3 units, trans-conformation in 3 transforms dramatically to the cis-arranged form due to the strong driving force from ligand-unsupported Au-Au contacts between two Au2Ln2 subunits. In contrast, cis-conformation in (bpyC[triple bond]CAu)2(mu-dppf) (6) stabilized by Au-Au interactions is reversed to the trans-oriented form upon formation of Au2Ln2 arrays by introducing Ln(hfac)3 units through 2,2-bipyridyl chelation. The binuclear gold(I) complexes show bright blue luminescence featured by ligand-centered pi --> pi* (C[triple bond]Cbpy) states together with low-energy emission at 500-540 nm, associated with 3(pi-->pi*) excited states, mixed probably with some characteristic from (Au-Au) --> (C[triple bond]Cbpy) 3MMLCT transition. For Au4Ln4 or Au2Ln2 complexes, sensitized lanthanide luminescence is achieved by energy transfer from Au-acetylide chromophores with lifetimes in the sub-millisecond range for EuIII complexes, whereas in the microsecond range for near-infrared emitting NdIII, ErIII, and YbIII species.

New Gold-Doped Foams by Copolymerization of Organogold(I) Monomers for Inertial Confinement Fusion (ICF) Targets

The incorporation of metallic elements, such as gold, into porous polymeric foams is an important focus for inertial confinement fusion (ICF) experiments. Incorporation was attempted from copolymerization of new organogold(I) monomers and various co-monomers by three development methods. This report describes the preparation of new polymeric gold foams, polymerizable high internal phase emulsion (polyHIPE) foams, divinylbenzene (DVB) foams and acrylate foams (TMPTA foams). The resulting gold-doped foams are characterized by elemental analysis, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). A very homogeneous distribution of gold into the polymeric structure is obtained.

Gold Nanoparticles Linked by Pyrrole- and Thiophene-Based Thiols. Electrochemical, Optical, and Conductive Properties

A series of new alkyl-substituted pyrrole, bithiophene, and terthiophene thiols, terthiophene and sexithiophene dithiols, and polythiophene polythiol have been synthesized. The compounds form self-assembled monolayers on gold with high surface coverages generally in the range (2–4) × 10−10 mol cm−2 as indicated by cyclic voltammetry and UV–vis spectroscopy. The thiols were reacted with 5 nm gold nanoparticles in toluene to form monodisperse, stable, and soluble thiol-capped gold clusters with the same gold core diameter, which were oxidatively coupled electrochemically (in solution or as films) and chemically (with iodine) to polymeric gold clusters. The dithiols (including ethanedithiol) and the polythiol formed analogous polymeric structures via layer-by-layer alternation with gold nanoparticles on gold-modified ITO and glass surfaces. The new materials were investigated by cyclic voltammetry, UV–vis and FTIR spectroscopy, and conductivity. The capped gold clusters display conductivities in the range 10−7–10−2 S cm−1 and give solvoconductive responses fast and stable, which parallel the degree of swelling measured by QCM. The conductivities of the polymeric clusters are in the range 2 × 10−2−10−1 S cm−1. Comparison with the literature indicates 10−1 S cm−1 as a practical limit to the conductivity in such systems.

Characterization of polymeric Gold(I)-captopril complex using viscosity and various spectroscopic techniques

The characterization of polymeric gold(I)-captopril (Aucap) n is carried out using viscosity, electronic, mass, and 13C, 15N NMR spectroscopy. From viscosity measurements, it is observed that the degree of association in (Aucap) n is much higher than in (Autm) n. The (Aucap) n was further polymerized in the presence of SCN − and SeCN − ions; however, the CN − ion caused the breakdown of the polymer. After a few hours of the addition of SeCN − to (Aucap) n solution, SeCN − underwent decomposition to produce CN − and “Se” metal which caused dissociation of the polymer. The mass spectroscopic results showed two characteristic routes of fragmentation for (Aucap) n. Electronic spectroscopy indicated the generation of [Au(CN) 2] − at a CN −:(Aucap) n ratio ≥ 1, whereas 13C, 15N NMR spectroscopic studies have indicated the detection of [Au(CN) 2] − even at a 1:12 ratio of CN −:(Aucap) n. The 13C NMR is found to be sensitive to the configuration of the penultimate captopril moiety.

Monomeric to polymeric gold(I) complexes from bifunctional ligands R 2PCCH

Oligomeric and polymeric gold(I) complexes in which gold(I) complexes in which gold(I) centers are bridged by R 2PCC − ligands are reported. The new ligand iPr 2PCCH was prepared by reaction of iPr 2PCl with HCCMgBr. Displacement of SMe 2 from [AuCl(SMe 2)] by R 2POCH gave [AuCl(R 2PCCH)], R = Ph or iPr, which were characterized spectroscopically and, for R = iPr, by single crystal X-ray diffraction analysis [triclinic, space group P 1 , Z = 2, a = 9.229(2), b = 9.345(1), c = 7.654(1) Å, α = 112.79(1), β = 105.49(1), γ = 99.33(1)°, V = 559.7(2) Å 3]. Treatment of [AuCl(R 2PCCH)] with NaOMe gave elimination of HCl with formation of [{Au(R 2PCCH)} x ]. When R  Ph, the product is insoluble in all common organic solvents and is presumed to be polymeric but, when R  iPr, the product is partially soluble in chlorinated organic solvents and is suggested to exist as a mixture of cyclic oligomers and linear polymer.

ChemInform Abstract: Syntheses and Reactivity of Acetylide‐Containing Clusters of Group 1B Metals. Part 8. Preparation, Characterization and Possible Structure of a Novel Pentanuclear Trimetallic Cluster (Au3AgCu(C2Ph)6)‐. Reactions of Pentanuclear and Trinuclear Acetylide Complexes.

AbstractDuring the studies on the possible formation of high polynuclearity clusters when starting with the pentanuclear Au3Cu2 phenylacetylide complex, its reaction with a mixture of polymeric gold and silver acetylide affords the trimetallic title cluster in 56% yield, whose possible structure is discussed.

ChemInform Abstract: BINUCLEAR AND POLYMERIC GOLD(I) COMPLEXES

Chemischer InformationsdienstVolume 16, Issue 30 Physical Organic Chemistry ChemInform Abstract: BINUCLEAR AND POLYMERIC GOLD(I) COMPLEXES Y. JIANG, Y. JIANGSearch for more papers by this authorS. ALVAREZ, S. ALVAREZSearch for more papers by this authorR. HOFFMANN, R. HOFFMANNSearch for more papers by this author Y. JIANG, Y. JIANGSearch for more papers by this authorS. ALVAREZ, S. ALVAREZSearch for more papers by this authorR. HOFFMANN, R. HOFFMANNSearch for more papers by this author First published: July 30, 1985 https://doi.org/10.1002/chin.198530062AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue30July 30, 1985 RelatedInformation

Binuclear and polymeric gold(I) complexes

Calculs par la methode de Huckel generalisee sur [Au 2 (S 2 PH 2 ) 2 ] 2 et [Au 2 (S 2 PH 2 ) 2 ] n : structure electronique, conformation

The effect of cyanide on the uptake of gold by red blood cells

Cyanide markedly increased the rate of uptake of gold by red blood cells when incubated with sodium aurothiomalate, a polymeric gold complex. Thiocyanate had no significant effect on gold uptake. The effect of cyanide was demonstrated to be due to the conversion of aurothiomalate to the complex ion, aurocyanide, which is rapidly taken up by red blood cells. At a low ratio (1:20) of cyanide to aurothiomalate, cyanide appeared to act as a shuttle to carry gold into red blood cells. Tobacco smoking is known to increase the concentrations of gold in red blood cells in patients treated with aurothiomalate. The present data indicate that this effect of smoking is most likely due to cyanide inhaled in tobacco smoke and not to thiocyanate, a circulating metabolite of cyanide. An effect of cyanide on the uptake of polymeric gold complexes to target cells such as polymorphonuclear leukocytes and monocytes is suggested.

Differences between the structure of the anti-arthritic gold drug “myocrisin” in the solid state and in solution: a kinetic study of dissolution

Detailed analyses of changes in the ultraviolet-visible absorption spectra of the anti-aithritic gold drug disodium gold(I) thiomalate·0 3 glycerol·2H 2O with time, suggest that the solid may contain about 23% of a species with λ max of 337 and 370 nm. This disappears in a two-step process soon after dissolution in water. The reaction was monitored at a variety of temperatures (20–47°C), pH's (6–11), and ionic strengths (0.05–0.61 M). The first step is complete in ca. 3 min. The second step is independent of Au(tm) concentration with k o' = 8.5 × 10 −2min −1 and activation parameters of Δ H ± = 82.1 ≠ 4.1 kJmol −1 and Δ S ≠ = 13.65 KJ −1 mol −1. The logarithm of the rate of this step increases linearly with the square root of the ionic strength. The reaction is readily reversed at high ionic strengths and is interpreted as a cooperative structural transition of polymeric gold( I) thiomalate, possibly involving Au(I)-Au(I) bonding. The relationship of these observations to reactions of other 1:1 Au(I) thiolate complexes and their method of preparation is discussed.

Cyclopentyl-und Cyclohexyl-dimethyl-methylen-phosphoran aus w-Haloalkyl-trimethylphosphonium-salzen. Goldkomplexe mono-und difunktioneller Ylide / Cyclopentyl-and Cyclohexyl-dimethyl-methylene-phosphoranes from w-Haloalkyl-trimethylphosphonium Salts. Gold Complexes of Mono-and Difunctional Ylides

(CH3)3 Pconvertsa,a,w-dibromopentaneand-hexane into w-bromoalkyltrimethylphos-phonium bromides,which undergo a cyclizationon treatment with NaNH2 in tetrahydro-furane to form the cyclopentyl-and cyclohexyl-dimethyl-methylenephosphoranes 4 and 5. From the bis-phosphonium salt(CH3)3P(CH2)6P(CH3)3 2⊕ 2Br⊖ the difunctional bis-ylide CH2=(CH3)2P(CH2)6P(CH3)2=CH2(7)is obtained. The ylide 4 was characterized by the crystalline metallocyclic Au(I)derivative 8.7 forms a polymeric gold complex.