Polymeric Silver Research Articles

A Mild Synthetic Route to Zinc, Cadmium, and Silver Polymers with (2‐Pyridyl)phosphonic Acid: Synthesis and Analysis

AbstractFive new metal pyridylphosphonate polymers have been prepared, fully characterized, and their room‐temperature luminescence probed. The reaction of (2‐pyridyl)phosphonic acid (2pypo) with ZnX2 (X = Br, Cl) afforded two‐dimensional polymers [Zn(X)(2pypo)]n {X = Cl = (1), X = Br = (2)}, which feature cyclic 12‐membered Zn–O–P cores that are interlinked by bridged oxygen atoms from the phosphonate moiety. From the room–temperature, aqueous reactions of 2pypo and the corresponding metal salts, the one‐dimensional polymers [Cd(μ‐Cl)2(2pypo)]n (3) and [Hg(2pypo)]n (4) were isolated in moderate yield. The one‐dimensional structure of 3 is supported through bridging chlorides and two η2‐phosphonate oxygen atoms, while 4 is a highly symmetrical polymer that exhibits pyridyl nitrogen coordination to the mercury center and uses two μ2‐oxygen atoms to polymerize. Reaction of silver triflate (CF3SO3Ag) with 2pypo afforded a crystalline silver polymer that displays a zig‐zag arrangement of silver atoms with argentophilic interactions and that is stablized through bridged triflate and phosphonate moieties. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Mononuclear, dinuclear, hexanuclear, and one-dimensional polymeric silver complexes having ligand-supported and unsupported argentophilic interactions stabilized by pincer-like 2,6-bis(5-pyrazolyl)pyridine ligands

The mononuclear complexes [Ag(H2L1)(Py)2](NO3) x H2O (1, H2L1 = 2,6-bis(5-methyl-1H-pyrazol-3-yl)pyridine) and [Ag(NO3)(L()] (2, L2 = 2,6-bis(5-methyl-1-isopropyl-1H-pyrazol-3-yl)pyridine), dinuclear complex [Ag2(H2L3)2(HL4)2] (3, H2L3 = 2,6-bis(5-phenyl-1H-pyrazol-3-yl)pyridine, HL4 = 6-(5-phenyl-1H-pyrazolyl-3-yl)picolinate), one-dimensional polymer {[Ag2(H2L1)2](NO3)2 x H2O}(n) (4), and hexanuclear clusters [Ag6(HL1)4](X)2 (X = NO3-, 5 ; BF4-, 6 ; ClO4-, 7) stabilized by pincer-like bispyrazolyl ligands have been prepared and characterized using (1)H NMR spectroscopy, elemental analysis, IR spectroscopy, luminescence spectroscopy and X-ray diffraction. In complex , there is a ligand unsupported Ag-Ag bond between the two silver atoms. Complex displays a one-dimensional polymer consisting of an infinite Ag-Ag chain and every two adjacent silver ions are bridged by an H2L1 ligand. Complexes and have the same Ag6 cores in which six silver atoms are held together by four HL1 and five Ag-Ag bonds, while complex was held together by six Ag-Ag bonds. The silver-silver distances in these complexes are found in the range of 2.874(1)-3.333(2) A for ligand supported, and 3.040(1) A for ligand unsupported Ag-Ag bonds, respectively. Complexes 3-7 are strongly luminescent due to either intraligand or metal-ligand charge transfer processes.

Synthesis of Ag-PVA and Ag-PVA/PET-s20 composites by supercritical CO2 method and study of silver nanoparticle growth

Supercritical CO2 has been used to prepare silver polymer composites, silver/poly(vinyl alcohol) and silver/poly(vinyl alcohol)/sulfonated poly(ethylene terephthalate) through impregnation of a silver precursor in solid-state polymeric matrices followed by thermal reduction of the silver precursor. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, thermogravimetric analysis and UV/vis spectroscopy indicate that synthesis conditions and polymeric matrix composition affect silver particle size, shape and distribution in polymeric matrices. Silver particles are smaller, have a more uniform shape and present narrower size distribution in PVA-rich than in PETs-rich composites.

Plasmonic properties of silver in polymer

In the present research silver nanoparticles were produced by e-beam evaporation of metal on polymer-modified silica substrate at room temperature (20 °C) and elevated temperature (80 °C). Modification of the silica substrate was done by different weight concentration polymer (PMMA/PS) blends formed from the polymer solutions by spin coating. The silver layer thickness varied from 1 nm to 10 nm. Silver nanoparticles in polymer matrix were characterized by XRD, AFM and UV–vis spectrometry. The crystalline silver nanoparticles showed surface plasmon resonance (SPR) with absorption maximum at 420–550 nm that was dependent on the silver layer thickness, PMMA and PS weight concentration in polymer blends and substrate temperature during vacuum deposition. The silver nanoparticles in polymer with selective light properties resulting from the controlled SPR shifting to the UV–vis wavelength region were produced.

Ligand and Counterion Control of Ag(I) Architectures: Assembly of a {Ag8} Ring Cluster Mediated by Hydrophobic and Ag···Ag Interactions

A strategy combining ligand design and counterion variation has been used to investigate the assembly of silver(I) complexes. As a result, dinuclear, octanuclear, and polymeric silver(I) species have been synthesized by complexation of the rigid aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and cis-3,5-diamino-trans-tert-butyldimethylsilylanyloxycyclohexane (DATC) with silver(I) triflate, nitrate, and perchlorate. The compositions of these aggregates, established by X-ray crystallography and elemental analysis, are [{Ag(DAHC)}2](CF3SO3)2 (1), [{Ag(DAMC)}2](CF3SO3)2 (2), [{Ag(DAMC)}2](NO3)2 (3), [{Ag(DATC)}6{Ag(DAHC)}2](NO3)8 (4), and [{Ag(DATC}n](NO3)n (5), where the DAHC present in 4 is formed by in situ hydrolysis of the acid labile silyl ether group. The type of aggregate formed depends both upon the noncoordinating O-substituent of the ligand and the (also noncoordinating) counterion, with the normal preference of the ligand topology for forming Ag2L2 structures being broken by introduction of the bulky, lipophilic O-tert-butyldimethylsilyl (TBDMS) group. Of particular note is the octanuclear silver ring structure 4, which is isolated only when both the O-TBDMS group and the nitrate counteranion are present and is formed from four Ag2L2 dimers connected by Ag...Ag and hydrogen-bonding interactions. Diffusion rate measurement of this {Ag8} complex by 1H NMR (DOSY) indicates dissociation in CD3OD and CD3CN, showing that this supramolecular ring structure is formed upon crystallization, and establishing a qualitative limit to the strength of Ag...Ag interactions in solution. When solutions of the {Ag8} cluster in methanol are kept for several days though, a new UV-vis absorption is observed at around 430 nm, consistent with the formation of silver nanoparticles.

Propylene sorption and coordinative interactions for poly(N‐vinyl pyrrolidone‐co‐vinyl acetate)/silver salt complex membranes

AbstractWhen poly(N‐vinyl pyrrolidone‐co‐vinyl acetate) (PVP‐co‐PVAc) containing amide and ester groups were complexed with silver salts to form silver polymer electrolyte membranes, their separation performance of propylene/propane mixtures showed the high selectivity of propylene over propane of 55 and the high mixed gas permeance of 12 GPU (1 GPU = 1.0 × 10−6 cm3(STP) cm−2 s−1 cmHg−1). The separation performance strongly depends on the composition of the copolymer: the higher concentration of PVP in the copolymer, the better separation performance was achieved. These results suggest that the amide group is more effective in facilitated propylene transport than the ester group, primarily due to the stronger interaction of the silver ions with the amide than the ester oxygens, as demonstrated by FT‐IR and FT‐Raman spectroscopies. In‐situ FT‐IR spectra upon propylene sorption also demonstrate that the interaction strength of the silver ions with the ligands is arranged: amide > CC > ester. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2263–2269, 2007

Synthesis, crystal structures and in vitro anti-fungal activities of two silver(I) coordination polymers with fluconazole

Two new polymeric silver(I)-fluconazole complexes: [Ag(HFlu)(NO 3)] n ( 1) and {[Ag(HFlu) 2](ClO 4)} n ( 2), have been synthesized and structurally characterized. The crystal structure of 1 consists of infinite 1D single strand helical coordination arrays with alternative …PMPM… arrangements, which are interlinked through hydrogen bonding interactions to generate a 3D network. The shortest intrachain Ag⋯Ag distance bridged by HFlu ligand is 8.287(1) Å. In 2, each Ag(I) ion is coordinated by four triazole N atoms from four HFlu ligands to form a 2D coordination layer, which has a helical arrangement along the [1 0 0] direction. The results of anti-fungal studies demonstrate that both silver(I) complexes are more active in comparison to the fluconazole drug.

Silver(i) ions bridged by pyridazine: doubling the ligand functionality for the design of unusual 3D coordination frameworks

Nitrogen donor tetradentate ligands 4,4'-bipyridazine (bpdz) and pyridazino[4,5-d]pyridazine (pp) were prepared by inverse electron demand Diels-Alder cycloaddition reactions of 1,2,4,5-tetrazine. Examination of their behaviour towards silver(I) ions revealed a special potential of the ligands for the design of 3D coordination frameworks involving characteristic polynuclear and polymeric silver(I)-pyridazine motifs and multiple coordination of the ligands. Ag4(pp)5(ClO4)4 and Ag4(pp)5(SiF6)(BF4)(2).4H2O adopt a unique 3D trinodal 4,4,5-connected topology based upon five-fold coordination of the metal ions and tetradentate bridging function of the organic modules. Complexes Ag3(L)3(SO3CF3)3.nH2O and Ag4(L)3(X)4.nH2O (L = bpdz, pp; X = BF4-, 0.5SiF(6)(2-)) illustrate formation of highly-connected frameworks incorporating trinuclear clusters as an origin of the net connectivity. In the carboxylate complexes Ag2(L)(R(F)COO)2 (R(F) = CF3, C2F5, C3F7) the pyridazine and acido ligands act as complementary linkers for generation of 3D frameworks involving helicate motifs. Fused bicyclic pyridazine pp is a unique system combining very efficient sigmaN-donor ability and pronounced pi-acidity. The coordination frameworks commonly exhibit strong anion-pi interactions, including unprecedented examples of double anion-pi,pi binding that occur between pyridazino[4,5-d]pyridazine as a double pi,pi-receptor for geometry complementary SiF(6)(2-) anions.

Analysis of Silver Ink Bow-Tie RFID Tag Antennas Printed on Paper Substrates

In this study, polymeric silver inks, paper substrates, and screen printing were used to produce prototype Bow-Tie tags. Because of increasing interest in applying passive UHF-RFID systems in paper industry, the Bow-Tie antenna used in this study was designed to work through paper. The maximum reliable read ranges of the tags were measured thorough stacked paper and also in air. The analysis and functioning of the antenna design are also discussed. All inks and paper substrates were suitable as antenna material and the prototype tag antennas had good reading performance. The maximum reliable read ranges were quite the same as for copper and aluminum tags studied elsewhere. This means that printed UHF tags are competitive solutions for the identification of simple mass products.

Syntheses and Characterizations of Two Novel Silver Polymers from Assembly 5-Bromosalicylic Acid and 2-Aminobenzoic Acid, with High Inhibitory Activities againstJack Bean Urease

Two novel two-dimensional silver(I) polymers, [Ag(5-bsa)]n (1) and [Ag(2-aba)]n (2) (5-bsaH = 5-bromosalicylic acid and 2-abaH = 2-aminobenzoic acid), have been synthesized from the reaction of Ag2O and carboxylate ligands in ammonia solution and structurally determined by single-crystal X-ray diffraction analyses. 1 crystallizes in the monoclinic space group P21/c with a = 7.316(2), b = 8.171(2), c = 13.051(3) A, U = 777.0(3) A3, β = 95.14(3) and Z = 4. 2 crystallizes in the orthorhombic space group Pna21 with a = 5.9486(8), b = 24.227(3), c = 4.9042(6) A, U = 706.8(2) A3, and Z = 4. In 1, 5-bsa serves as tridentate ligands coordinating to three Ag+ ions through its hydroxyl and bridging ligand carboxyl groups, with the Ag-Ag bonding and two carboxylate ions defined in a slight distorted plane and further extending into a two-dimension layer through the hydroxyl and the overlapping and off-set stacking interactions. In 2, adjacent Ag+ ions via Ag-Ag bonding interactions generate a one-dimension silver chain and adjacent silver chains are further linked by μ2-N, O atoms of 2-aba to result in a two-dimensional configuration, with the inter-chain hydrogen bonding interaction forming a three-dimension supramolecular structure. Both the two silver(I) complexes have strong inhibitory activities against Jack Bean urease with the IC50 values of 21.98 μM for 1 and 25.34 μM for 2, but neglectable inhibition activity on Xanthine Oxidase.

Preparation of micron size flake silver powders for conductive thick films

The preparation of micron size flake silver powders with chemical-mechanic method was investigated. Reaction of silver nitrate with ascorbic acid gives fine spherical silver powders. The spherical silver powders were processed by globe mill to make micron size flake silver powders having excellent dispersability and uniform shape. The XRD and thermal analyzer were employed to analyze as—prepared flake silver powders. The flake silver powders were employed to make polymer silver thick film and fire-type thick film. The application of small molecule surfactant in the stage of synthesizing precursor and large specific area of flake particles give a low resistivity of polymer thick film. The fire-type silver thick film was studied by SEM and EDX. SEM photograph shows that the grain boundaries of silver are prominently visible, and the densification of the fired thick film is high. The fire-type thick film has a low bulk resistivity and high adhesion strength.

Rhombic Dodecahedral Ag8M6 (M = Cu, Ag, Au) Cluster Complexes of Ferrocenylethynyl Prepared by Reaction of (AgC⋮CFc)n with [M2(Ph2PNHPh2)2(MeCN)2]2+ (M = Cu, Ag, Au)

Reaction of the polymeric silver ferrocenylacetylide (AgC⋮CFc)n with [M2(Ph2PNHPPh2)2(MeCN)2]2+ (M = Cu, Ag, Au) gave rise to the isolation of rhombic dodecahedral AgI8MI6 cage complexes together with the unusual 1,2,5-azadiphospholium product [FcCCH(Ph2PNPPh2)](BF4) by the cyclic addition of FcC⋮C to Ph2PNHPPh2. Distinct redox wave splitting occurs in the AgI8CuI6 cage complex with ΔE1/2 = 0.15 V due to successive oxidation of the Fc groups, induced probably by electronic interactions between iron centers in the ferrocenylacetylides.

Cover Picture: Fabrication and Characterization of Three-Dimensional Silver-Coated Polymeric Microstructures (Adv. Funct. Mater. 13/2006)

Kuebler and co-workers report on p. 1739 a method for preparing conductive and optically reflective silver-coated polymeric microstructures having virtually any 3D form. Shown are reflection images of a silvered five-layer simple-cubic lattice having a period of 2.4 μm (background) and a macroscopic silvered polymer film (inset). To prepare metallopolymeric microstructures, 3D polymeric scaffolds are first created by multiphoton direct laser writing, then functionalized with gold particles, and metallized using nucleated electroless silver deposition. A method is reported for fabricating complex 3D silver-coated polymeric microstructures. The approach is based on the creation of a crosslinked polymeric microscaffold via patterned multiphoton-initiated polymerization followed by surface-nucleated electroless deposition of silver. The conductivity and reflectivity of the resulting silver–polymer composites and the nanoscale morphology of the deposited silver are characterized. Sub-micrometer thick layers of silver can be controllably deposited onto surfaces, including those of 3D microporous forms without occluding the interior of the structure. The approach is general for silver coating crosslinked polymeric structures based on acrylate, methacrylate, and epoxide resins and provides a new path to complex 3D micrometer-scale devices with electronic, photonic, and electromechanical function.

Nanocomposite silver polymer electrolytes as facilitated olefin transport membranes

Solid-state silver polymer electrolyte membranes containing AgNO 3 dissolved in poly(2-ethyl-2-oxazoline) (POZ) as an olefin carrier are not efficient for the separation of olefin/paraffin mixtures (selectivity ∼1). The addition of fumed silica nanoparticles into the POZ/AgNO 3 complex membranes, however, resulted in a surprisingly significant enhancement of the permeance and selectivity (higher than 80) for propylene/propane mixtures. These enhancements are explained in terms of the silver ion activity in olefin coordination. FT-IR, X-ray photoelectron spectroscopy (XPS) and FT-Raman demonstrate that the silver ion activity continuously increases by Lewis acid–base interactions upon incorporation of the silica nanoparticles up to 0.1 mole ratio of silica, above which it abruptly decreases. Furthermore, the structural change of polymer electrolyte membranes took place by the presence of nanoparticles, supported by the T g measurement.

Hollow polycarbonate fiber for Er:YAG laser light delivery

We developed hollow fibers with polycarbonate (PC) capillaries for use as a supporting tube. The PC capillaries were prepared by using a glass-drawing technique. Hollow PC fibers are safer and more flexible than hollow glass fibers because no fragments are released when the fibers are broken in various applications. Inner coating layers of silver and cyclic olefin polymer (COP) enhanced the reflection rate at the Er:YAG laser light wavelength. Using these fibers, we attained low loss for Er:YAG laser light transmission. By adjusting the drawing temperature in the fabrication of the PC capillaries, we created a smooth inner surface and uniform PC capillaries. We also demonstrated low-loss properties for visible pilot beams.

Control of Ionic Interactions in Silver Salt−Polymer Complexes with Ionic Liquids: Implications for Facilitated Olefin Transport

The ionic liquids 1-butyl-3-methyl imidazolium BMIM+NO3- and BMIM+BF4- have been successfully utilized to increase the activity in reversible π-complexation with olefins of silver cations in silver polymer electrolytes consisting of AgNO3 dissolved in poly(2-ethyl-2-oxazoline) (POZ). In the absence of the ionic liquids, AgNO3 is not readily dissolved in POZ and is instead because of its high lattice energy present mostly as chemically less active ion pairs or higher order aggregates. The activation of Ag+ in silver polymer electrolytes in the presence of these ionic liquids is principally due to the reduction of the interactions between Ag+ and NO3- produced by the interaction between BMIM+ and NO3-, and this effect does not occur in the presence of common salts such as NaNO3. We investigated these systems with FT-IR, FT-Raman, and XPS and calculated the theoretical electronic structures of the relevant species. The increased activity in these membranes of Ag+ in reversible π-complexation with olefins was further confirmed by evaluating the sorption and desorption behavior of propylene and the performances of the membranes in the separation of olefin/paraffin mixtures.

Effect of the polymer matrix on the formation of silver nanoparticles in polymer–silver salt complex membranes

AbstractWhen polymer–silver salt complex membranes were exposed to UV irradiation, the separation performances of both the permeance and selectivity for propylene–propane decreased, which was primarily attributed to the reduction of the silver ions in the membranes to silver nanoparticles. Here, the effect of the polymer matrix on the formation of silver nanoparticles in the polymer–silver salt complex membranes was investigated. This effect was assessed for the complexes of two kinds of silver salts (AgBF4 and AgCF3SO3) with several polymeric ligands containing three different carbonyl groups, including poly(vinyl pyrrolidone) (PVP) with an amide group, poly(vinyl methyl ketone) (PVMK) with a ketone group, and poly(methyl methacrylate) (PMMA) with an ester group. UV–vis spectra and transmission electron microscopy (TEM) images clearly indicated that the reduction rate of the silver ions has the following order in the various polymer matrices: PVP > PVMK > PMMA, whereas the size and the distribution of the nanoparticles exhibited the reverse order. The tendency to form silver nanoparticles was explained in terms of the differences between the comparative strengths of the interactions of the silver ions with the different carbonyl oxygens in the matrices, as well as that of the silver ions with counteranions, which was characterized by X‐ray photoelectron spectroscopy (XPS) and FT‐Raman spectroscopy. It was concluded that when the concentration of free silver ions was low due to weak polymer–silver ion and strong silver ion–anion interactions, as found with PMMA, the reduction rate of silver ions to silver nanoparticles was slow. Therefore, the PMMA–silver complex membranes were less sensitive to decreases in separation performance upon UV irradiation than compared to the PVP membranes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1168–1178, 2006

Improved omnidirectional reflectors in chalcogenide glass and polymer by using the silver doping technique

We describe the fabrication and characterization of omnidirectional reflectors based on silver-doped chalcogenide glass and polymer. We deposited periodically alternating layers of thermally evaporated Ge33As12Se55 chalcogenide glass, sputtered silver, and spun-cast polyamide-imide polymer. The silver was subsequently dissolved into each adjacent chalcogenide glass layer, either by exposing the multilayer to visible light (photodoping) or by heating the sample. The resultant silver concentration within the chalcogenide glass layers is estimated to be ~20 at. %. Silver doping red-shifts the band edge of the glass, and produces an increase of ~0.3-0.4 in the refractive index. The glass retains good transparency in the near infrared after doping, and the technique enables the omnidirectional bandwidth to be increased from ~100 nm to ~200 nm in the 1550 nm wavelength region.

Adjusting the frameworks of polymeric silver(i) complexes with 2-aminopyrimidyl ligands by changing the counterions

The complexes [Ag2(L)2(SO4)]∞, (L = 2-aminopyrimidine) 1, [Ag(L)1.5(ClO4)]∞, 2, and [Ag(L)(OAc)·2H2O]∞, 3, were prepared by layering the aqueous solution of the corresponding Ag(I) salt with L in ethanol, while [Ag(L′)(NO3)]∞, 4, and [Ag(L′)(ClO4)·H2O]∞, 5, were prepared by refluxing AgNO3 and AgClO4, respectively, with 2-amino-4,6-dimethylpyrimidine (L′) in H2O. Reaction of Ag2SO4 with L′ in methanol afforded the complex [Ag4(L′)2(SO4)2(H2O)4]∞, 6. In complex 1, the L ligands are coordinated to the Ag(I) metal centers in new tridentate fashions, forming 2-D pleated molecular sheets which are interlinked by the SO42− anions to form a 3-D layer structure. Complex 2 forms a pleated molecular sheet consisting of twenty four-membered metallocycles, involving six Ag ions which are bridged by six L ligands through the pyrimidyl nitrogen atoms. Complex 3 forms linear chains with sinusoidal geometry, which are interlinked through extensive Ag⋯Ag interactions (Ag⋯Ag = 3.102 A) to form 2-D wavy rectangular grids. Complex 4 forms single-strained helical coordination polymers, which are interlinked through a series of Ag⋯O interactions (2.667 and 2.699 A) to form 2-D chair like grids. The silver atoms of 5 are bound to the nitrogen atoms of two symmetry-related L′ ligands in a distinctly non-linear geometry, forming zigzag chains. The structure of 6 consists of clusters of the formula [Ag8(L′)4(SO4)4(H2O)8], which are interlinked through L′ ligands to form 2-D sheets. The μ1-O, μ2-O′- bonding mode of the SO42− anion in complex 6 is unique for Ag(I) complexes. Their thermal properties have been investigated by using differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA)

Preparation of highly reflective and conductive metallized polyimide films through surface modification: processing, morphology and properties

Silvered polyimide films have been prepared by potassium hydroxide hydroxylation of polyimide film surfaces and incorporation of silver ions through subsequent ion exchange. Thermal curing not only recycloimidized the poly(amic acid) into polyimide, but also reduced silver ions into silver atoms and near-atomic silver clusters, which diffused and aggregated to give reflective and conductive surfaces without need of the addition of reducing agents. Films were characterized by X-ray photoelectron spectrometer, transmission electron microscopy, scanning electron microscopy and tapping mode atomic force microscopy. The thickness of the silvered layers and the reflectivity and conductivity of the silvered films can be controlled. By this method, the double-sided silvered polyimide films with excellent reflective (reflectivity > 97%) and conductive surfaces (surface resistivity = 0.02 Ω cm−2) could be easily fabricated. Their essential mechanical properties could be maintained, and the silver–polymer adhesion was outstanding.