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A new type of Ag/AgCl electrodes based on a hydrophobic ionic liquid has been proposed. The electrode consists of a Ag/AgCl electrode immersed in or coated with a AgCl-saturated ionic liquid, 1-methy-3-octylimidazolium bis(trifluoromethylsulfonyl)imide ([[C.sub.8][mim.sup.+]]-[[C.sub.1][C.sub.1][N.sup.-]]), instead of the internal aqueous solution. The [[C.sub.8][mim.sup.+]]-[[C.sub.1][C.sub.1][N.sup.-] phase plays dual roles, that is, as a medium dissolving AgCl and an ionic-liquid-type salt bridge upon contact with an aqueous solution. The gelation of the [[C.sub.8][mim.sup.+]]-[[C.sub.1][C.sub.1][N.sup.-]] phase allows us to prepare coatedwire-type solid-state reference electrodes with a well-defined thermodynamic basis for the electrode potential. Both gelled and nongelled types show stable electrode potentials against the change in the concentration of KCl between 0.05 mmol [dm.sup.-3] and 2 mol [dm.sup.-3]. This new class of reference electrodes opens the way for a variety of miniaturized and solid-state reference electrodes.

Several analyses are conducted to compare the structural and electrical characteristics to point out the influence of defects on the electrical characteristics of mercury-drop junctions in the self-assembled monolayers (SAMs) of n-alkanethiolates formed on rough, as well as smooth silver substrates. The analysis shows that the defects occurring in such SAMs highly lead to the failure of the junctions and the high degree and sources of uncertainty in the current density of the substrates.

A dual microelectrode electrochemical time-of-flight technique in which diffusion flux of [Ag.sup.+], [Cl.sup.-], or [H.sup.+] ions electrochemically produced at a generator electrode is measured by recording potential--time transients with Ag, Ag/AgCl, or iridium oxide potentiometric microsensors, respectively, is developed. The generator and microsensor electrodes are typically spaced by 50-100 [micro]m and are incorporated in the lithographically fabricated thin-layer-type devices. Under conditions of moderate rates of the ion electrogeneration, the potential--time (E--t) transients recorded with the three microsensors show excellent agreement with theory involving linear diffusion equations and the experimentally determined Nernstian slopes of the microsensors. However, when the generator current, or the initial concentration of the primary ion of interest is low, appreciable delays in the recorded E--t transients are observed due to the finite capacitance of the micro-potentiometric sensors. The recorded delay in the E--t transients can be quantitatively accounted for by including the sensor capacitance (C) in the theoretical description of the transients. Direct comparison between the theoretical and the experimental E--t transients yields the sensor's capacitance. This capability of our new technique is unique in that it allows determination of the capacitance of a potentiometric sensor at open circuit. In the cases of silver electrodes, this method results in C = 31 [+ or -] 2 [micro]F/ [cm.sup.2], a value that is in agreement with those obtained by other methods. The results for silver chloride sensors yield a C in the range of 100-140 [+ or -] 10 [micro]F/[cm.sup.2]. The specific values depend on sensor preparation and the resulting roughness of the Ag/AgCl interface. Iridium oxide sensors show a capacitance that linearly depends on the thickness of the film. Specific capacitance of these microporous films was determined to be 59 [+ or -] 6 F/[cm.sup.3].

The manner of harnessing the polymorphism of individual molecular components for the fabrication of binary supramoloecular structures is described. The manner in which the properties of different single-component phases select pathways to binary supramolecular arrangements is demonstrated.

A facile in situ replacement route reaction is successfully introduced for synthesizing Ag nanoshells with outer diameters of 40-50 nm and inner diameters of 20-30 nm using Co nanoparticles as sacrificial templates, and also, the products are characterized and the formation mechanism is discussed. The UV-vis spectrum of this nanostructure exhibits a distinct difference from that of solid nanoparticles, making it suitable for application in photothermal materials.

This study features the fabrication of a planar-form, solid electrolyte modified, (PSEM) Ag/AgC1 reference electrode using a screen-printing method. The PSEM Aft/AgCl reference electrode uses agar gel as the inner electrolyte and chloroprene rubber for the liquid junction and insulator. These common low-cost materials and the simple fabrication processes involved render the proposed reference electrode an ideal candidate for cost-efficient mass production. It is shown that the developed reference electrode is insensitive to most of the physiologically important ionic species, including [Na.sup.+], [K.sup.+], [Li.sup.+], [Ca.sup.2+], N[H.sup.+.sub.4], and [Cl.sup.-], under continuous measurement conditions. Moreover, as with conventional commercial reference electrodes, the proposed reference electrode exhibits a reversible response, which is maintained until the agar gel dries out. The PSEM Ag/AgCl reference electrode is integrated with an iridium oxide modified Pt-based pH indicator electrode to form a chip-type pH biosensor. The performance of this biosensor is consistent with that obtained from a pH meter based on a macroscopic commercial Ag/AgCl reference electrode. The experimental results confirm that the proposed biosensor is capable of providing precise pH measurements of various real samples. Accordingly, the PSEM Ag/AgCl reference electrode presented in this study provides a viable alternative to the macroscopic Ag/AgCl reference electrode used in many conventional chip-based pH sensors.

A novel complex-assisted hydrothermal route is presented to fabricate ultralong Ag/C nanocables with length ranging from 100 to 180 mum on a large scale, based on the reaction of sulfamic acid silver and salicyclic acid. By chemical etching of these Ag/C nanocables, high-quality carbonaceous nanotubes could be obtained at room temperature.

A facile, controllable synthesis of semiconductor (Ag.sub.2)S nanorods are reported in the Bovine Serum Albumin aqueous solution at room temperature. The exploitation of a common protein to prepare the protein-conjugated nanorods provides a novel pathway for biomodified nanomaterials.

Three novel silver complexes with a 1-D to 3-D architecture constructed through ligand-unsupported argentophilic interactions are solvothermally synthesized. These three complexes are revealed to be potential luminescent materials.

A new experimental method for depositing and voltammetric study of Ag nanoparticles at the water-nitrobenzene (W-NB) interface is recommended by means of thin-film electrodes. Ag-particles deposited at the W-NB interface affect the ion transfer across the interface, which provides the basis for voltammetric inspection of the metal deposit at the liquid-liquid interface with thin-film electrodes.

Au-Ag nanoalloys were prepared through three different procedures by using laser induced heating and it was found that the procedure, which uses 532nm laser irradiation, was advantageous for the production of spherical alloy nanoparticles. As the total concentration of Ag and Au in the mixture increased, large scale interlinked networks were observed revealing that this selective heating strategy can be extended to prepare other bi- or multi-metallic nanoalloys.

N-(2-Mercaptopropionyl)gycine (tiopronin)-coated silver nanoparticles (average diameter of metal core=5 nm) were prepared by a modified Brust method. It is found that increasing the particular layer contributes to florescence enhancement.

The first quantitative structural data for the Ag(III) (square root of 7 x square root of 7)- R 19 degrees -CH3S surface phase is presented by using the NIXSW method to show that a simple over layer on an unreconstruated Ag(III) surface. The results allow one to provide one structural model that can be used to satisfactorily reconcile the experimental NIXSW data.

The self-assembly of racemic and enantiopure binaphthylbis(amidopyridyl) ligands with silver(I) salts to form extended metal-containing arrays is described. Results reveal that the self assembly with racemic ligands could lead to homochiral or heterochiral polymers, through self-recognition or self-discrimination of the ligand units.

The nanosized Ag-Mo multilayered samples are designed and prepared for the equilibrium immiscible Ag-Mo system characterized by a large positive heat of formation to include sufficient interfacial free energy to elevate their initial energetic states to be higher than that of either the amorphous phase or solid solution. Results show that a uniform amorphous alloy can be obtained within a composition range at least from 25 to 88 atom % of Mo.

The difference in mean particle sizes (MPS), particle size distribution and dispersion for four fresh Ag/Al2O3 catalysts with different metal loadings were determined by means of HRTEM, high angle annular dark field (HAADF), O2-chemisorption and X-ray energy dispersive spectroscopy (EDXS). The MPS values determined by HRTEM resulted in increasing MPS value with increasing metal loading as expected.

The scattering spectra of a single gold, silver, and bimetallic gold-silver particles (both core-shell and alloyed) was examined using dark-field microscopy. The results show that the plasmon resonances for the bimetallic particles are broader than those of the pure silver or pure gold particles.

The embedded cluster method combined with multireference configuration interaction (MRD-CI) procedure is employed for the study of photoinduced dissociation of a formaldehyde molecule adsorbed on the Ag(111) cluster that leads to the surface polymerization of H(sub 2)CO. It is demonstrated that the lowest state of the O + CH(sub 2) fragments on the Ag(111) surface is a closed-shell singlet.

Study is conducted to show that ZnCdSe nanowires can be grown by metalorganic chemical vapor deposition (MOCVD) using Au as a catalyst. The presence of an Au-Cd-Zn alloy particle at the tip of the nanowires support vapor-liquid-solid as the growth mechanism while the appearance of constrictions in some of nanowires is found to be linked to the existence of structural defects, possibly stacking faults, during growth.

The preparations and structural characterization of the Au(super III)-M(super I) (M = Cu, Ag, Au) heterovalent or heteronuclear complexes, together with luminescent properties of the mixed-valence Au(super III)Au(sub 4)(super I) compound are described. The structural characterization reveals that the dithiolate tdt (toluene-3-4-dithiolate) can afford versatile coordination modes and bonding orientations to give rich structural topology of the Au(super III)-M(super I) cluster complexes.

Ensembles of silver nanowires (AgNEs) with diameters ranging from 200 nm to 1.0 [micro]m have been prepared by electrochemical step edge decoration. These AgNEs showed a rapid ( |-50%|) irreversible decrease in resistance was seen upon exposures to acids including HCl, HN[O.sub.3], and [H.sub.2]S[O.sub.4]. Based on these and other data, we propose a model in which oxidized constrictions in silver nanowires limit the conductivity of the wire and provide a means for 'gating' conduction based on the protonation state of the oxide surface.

The structural and thermodynamic studies of a partially substituted derivative, 5,11,17,23,tetra-tert-butyl[25,27-bis(hydroxy)-26,28-bis(ethylthioethoxy)]-calix(4)arene, and its neutral (1H NMR) and cation complexes in various media are reported. The thermodynamics of cation complexation involving analogous calix(4)arene derivatives in acetonitrile is used to build up a model in which the additive contribution of pendant arms is demonstrated.

Low-temperature hydrothermal techniques are used to investigate single crystals of Ag(sub 4)V(sub 2)O(sub 6)F(sub 2). The crystal structure determination reveals a compound with sheets of vanadium oxide fluoride chains separated by silver cations.

The analysis of the electronic structure of the isolated silver copper oxide Ag2Cu2O4 is presented along with its precursor Ag2Cu2O4 and similar binary oxides, Ag2O, AgO, CuO, and NaCuO2. The results for AgCu2O4 reveal an electronic distribution in which silver and copper share a delocalized valence scheme with both metals in formal oxidation states larger than the usual Ag(super I) and Cu(super II).

The metal-binding specificity and affinity of N-terminal domain in ZntA is investigated. It is found that N1-ZntA could bind both divalent metal ions such as Cd(II), Pb(II) and Zn(II) and monovalent metal ions such as Ag(I), with a stoichiometry of 1 while N2-ZntA can bind Zn(II) and Cd(II) with a stoichiometry of 1 but not Pb(II).

Ag nanosphere and nanorod particles are attached to indium tin oxide (ITO) surfaces by applying a seed-mediated growth method. The results reveal that the formed nanostructures were very sensitive to the amount of ascorbic acid in the growth solution.

The formation of Ag nanoparticles by electrochemical techniques is investigated through a time-resolved UV-vis spectroscopy study. The formation of Ag(super 2+)(sub 4) clusters is suggested as the main precursors to the particle formation.

The absorption spectra and the Hyper-Rayleigh scattering (HRS) signals of a highly monodisperse 10.5-nm diameter silver colloids are measured with the addition of KNO(sub 3) and pyridine. Strongly enhanced HRS signals are observed by 15x and 6x respectively.

The reactions and ligand exchange of hydrated silver cations Ag(super +)(H2O)(sub n) with NH3 as well as the complementary process, the reaction of large ammoniated silver cations Ag(super +)(NH3)(sub n) with H2O are examined in order to gain insight into the coordination chemistry of silver cations in mixed solvent systems. The experiments show that in mixed clusters the first and second ammonia ligand, however, are much more strongly bound than water because they cannot be exchanged.

N-Heterocyclic carbene (NHC) complexes with silver were investigated as sources of unsaturated NHC carbene catalysts via thermal decomposition. A study was conducted to demonstrate that silver carbene complexes are competent catalysts for the ring-opening polymerization of lactide, as well as the transesterification of methyl benzoates.

Heterometallic metal-organic frameworks (MOFs) are built by the application of a new procedure of employing tris(dipyrrinato) coordination complexes as construction blocks. The amalgamation and characterization of Co/Ag and Fe/Ag heterometallic network solids are also accomplished.

The chemical reduction method is used for obtaining Ag-Rh alloys and XRD and STEM-EDX has shown that the alloys are mixed at the atomic level. The measurements of hydrogen pressure-composition isotherms and solid-state [super 2]H NMR have shown that Ag-Rh solid-solution alloys have absorbed hydrogen and the total amount of hydrogen absorbed has reached a maximum at the ratio of Ag:Rh = 50:50, where the electronic structure is similar to that of Pd.

A study is conducted to identify and quantify precursor species of Brust-Schiffrin metal nanoparticle syntheses for Au, Ag, and Cu systems. The study result outlined a new scheme for the two-phase synthesis and could have significant implications for the M(I) thiolate formation and modifications in nanoparticle synthesis.

A facile colloidal method for synthesizing Janus bimetallic nanoparticles is demonstrated. The eccentric polymer shells in the nanoparticles could be exploited to fabricate eccentric bimetallic cores.

An in situ electrochemical surface-enhanced Raman spectroscopic study was carried out to characterize various surface species in different electrode potential regions and gain better insight into the electrocatalytic mechanism of silver on reduction of benzyl chloride. The benzyl radical and its anionic derivate as the key intermediates bonded on a silver electrode implied that the pathway could drastically differ from the outer sphere concerted electron reduction at inert electrodes.

A new type of sensing platform that is based on electrodissolution of a metallic bipolar electrode (BPE) is reported. The decrease observed in the length of the BPE could be directly correlated to the number of electrons passing through the BPE and hence to the sensing reaction at the cathode.

A room-temperature composition study of the [Ag.sub.2]O/[V.sub.2][O.sub.5]/[HF.sub.(aq)] ternary system that leads to the precipitation of either various silver vanadates having Ag/V ratios from 1/2 to 3/1 or the new silver vanadium oxyfluoride and nanocrystalline silver compounds are reported. The reversible and simultaneous combination of two active redox processes (silver and vanadium) could be applied to significantly optimize the cathode gravimetric capacity.

The diffusion of Au in [Ag.sub.2]S from the inner core to the surface of [Ag.sub.2]S is described and a new nanocomposite of core-shell and Au nanoparticles is derived by the diffusion phenomenon. Ostwald ripening is observed and this has elucidated the mechanism of formation of semiconductor-metal heterostructures as a consequence of Au diffusion in [Ag.sub.2]S nanocrystals.

Spontaneous elongation from nanorod to nanowire in the presence of an amine is described for nanocrystals of cadmium sulfide and silver sulfide. A mechanism of oriented attachment is seen by the doubling in length of asymmetrically gold tipped CdS nanorods with the corresponding absence of elongation in symmetrically tipped nanorods.

The three-component coupling reaction between phenylacetylene, carbon dioxide, and 3-bromo-1-phenyl-1-propyne was explored to develop a simple synthesis method for arylnaphthalene lignan lactones as valuable natural products. The level of regioselectivity for obtained products with promising anticancer and antiviral properties were enhanced by tuning the electronic properties.

The density functional theory-based first principle method was used to perform molecular dynamics simulations for an Ag complex-based ionic liquid, Ag[([C.sub.2][H.sub.4]).sub.2.sup.+][B[F.sub.4.sup.-]. The studies identified a mechanism of ethylene transfer similar to the Grotthus type of proton transfer in water which might contribute to fast transport of olefins through ionic liquid membranes based on silver complexes for olefin/paraffin separation.

Aromatic molecules have a strong affinity for silver(I) and are dissolved to a limited extent in [Ag.sub.0.51][K.sub.0.42][Na.sub.0.07]N[O.sub.3], which is a low-melting eutectic mixture of silver, potassium and sodium nitrates. Aromatic nitration in this inorganic ionic liquid has led to products arising from nonelectrophilic substitution pathways.

Protein-conjugated [Ag.sub.2]S nanorods are prepared in aqueous solution and high-resolution transmission electron microscopy (HRTEM) is used for tracking the whole process of the nanorod growth. The results have shown that the final products are formed via two-step oriented attachment, particle-particle and rod-rod oriented.

The preparations of seven new isostructural uranium chalcogenides AMU[Q.sub.3] compounds (where A = alkali metal, M = Cu or Ag, Q = S or Se) via solid-state reactions are reported. The compounds are found to be semiconductors with optical band gaps smaller than 0.73 eV and density-of-state analysis revealed the M-Q orbital to overlap in the valence band and U-Q orbital to overlap in the conduction band.

Density function theory is employed to study the electronic structure of [[M(tpm)].sup.+] molecular ion conformers and the energetics of their interconversion, where M = Cu, Ag and tmp = tris(pyrazol-1-yl)methane. M-ligand interaction is found to be independent of the coordinative mode and is dominated by the ligand -> M(I) [sigma] donation with negligible contribution from back-donation.

The metal-centered and macrocycle-centered electron-transfer oxidations and reductions of silver(II) porphyrins are characterized in nonaqueous media by electrochemistry and density functional theory calculations. The introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle has provided a unique androgynous character to Ag(II) quinoxalinoporphyrins that has enabled them to act as both electron donors and good electron acceptors.

Several theoretical electronic structure calculations are conducted to study the photoinduced dissociation of water adsorbed on silver clusters. The energy barrier for the transfer of hydrogen between the clusters is shown to be very high in the ground states.