Crystal Structure Of Ag Research Articles

Ternary Nanocomposite of Activated Charcoal/Reduced Graphene Oxide-Silver Nanoparticles [ACH/Ag@rGO] as a Novel Platform for the First Sensitive Prucalopride Drug Detection in Generic and Innovator Tablets and Human Plasma

Ag@rGO nanocomposite was prepared using an in situ reduction approach of silver ions and the as-synthesized graphite oxide (GO). TEM analysis reveals the crumpled and folded layered structure of rGO with homogeneous dispersed spherical Ag NPs on these rGO nanosheets. The intensity ratio of the D to G bands (ID/IG) in Raman spectra for Ag@rGO indicates a large defect due to Ag NPs intercalation and deposition on rGO surface. XRD pattern indicates the face centered cubic crystal structure of Ag with average crystalline size of 19.63 nm. An electrochemical sensor based on Ag@rGO is first designed for Prucalopride drug oxidation and characterized applying EIS and cyclic voltammetry. Its electrocatalytic effect was enhanced upon utilizing a characterized activated charcoal (ACH) as an electro-modified carbon nanomaterial for CPE. The ternary nanocomposite [ACH/Ag@rGO] as a platform of CPE supposed three times higher response to Prucalopride compared to CPE. Prucalopride was quantified over wide linear ranges of (5.0 × 10−9– 1 × 10−6 M) and (2.0 × 10−8– 1.4 × 10−6 M), with LOD values of 7.95 × 10−10 M and 8.51 × 10−9 M in bulk form and spiked human plasma, respectively. This sensor can thus be adopted easily for the quality control analysis of Prucalopride in formulation and human plasma and for pharmacokinetic study.

Crystal Growth and Crystal Structures of Gold(V) Compounds: Cu(AuF6)2, Ag(AuF6)2, and O2(CuF)3(AuF6)4 ⋅ HF

AbstractCrystal growth from anhydrous hydrogen fluoride solutions of M2+(M=Cu, Ag) and [AuF6]−gave M(AuF6)2salts (M=Cu, Ag). Similar attempts to prepare single crystals of the corresponding nickel, zinc and magnesium salts failed. The crystal structure of Cu(AuF6)2consists of layers of Cu2+cations connected by [AuF6]−anions, thus forming slabs. Only van der Waals interactions exist between adjacent slabs. The crystal structure of Ag(AuF6)2consists of a three‐dimensional framework in which Ag+cations are linked by [AuF6]−anions. Both structures are members of the MII(XVF6)2family, in which seven different structure types have been observed to date. In the crystal structure of O2(CuF)3(AuF6)4 ⋅ HF, the bridging AuF6units connect [−Cu−F−Cu−F−]∞chains to form stacks between which O2+cations and HF molecules are located.

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Imines are fundamental organic compounds used as synthetic intermediates and as ligands in coordination chemistry. They are also found to be important pharmacophores in various bioactive compounds. In this report, two Schiff bases were prepared using the traditional condensation of 4-pyridinecarboxaldehyde with 2-thiophenemethylamine and 2-quinolinecarboxaldehyde with furfurylamine to form (E)-1-(pyridin-4-yl)-N-(thiophen-2-ylmethyl)methanimine (L1) and (E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine (L2) respectively. L1 and L2 were complexed with silver perchlorate in 2:1 [M:L] stoichiometry to obtain complexes 1 and 2, respectively. The crystal structures of 1 and 2 were unequivocally determined by single-crystal X-ray diffraction analysis. The resulting structures revealed 2 to be a four-coordinate as expected. In contrast, an unexpected chemoselective hydrolytic cleavage of one mole of the (CH=N) imine ligands occurred in complex 2 and, further, the amines (thiophenemethylamine) homo-coupled to form a new imine ligand derivative in situ (L1a) before coordinating to the Ag(I) center along with L1. This observation described an alternative synthetic route to be explored to synthesize a diverse range of imine derivatives, which involves the Ag(I)-promoted homo-coupling of amines. Herein, the crystal structures of Ag(I) complexes of pyridinyl [Ag(L1)(L1a)]ClO4 (1) and quinolinyl [Ag(L2)2]ClO4 (2) Schiff bases are presented.

Effect of silver coating on the optical, morphological, PL and crystal structure of Ag– TiO2 thin films

Abstract In this research work, Ag– TiO2 thin films were deposited on microscope glass slides by spray pyrolysis and thermal vacuum evaporation combination techniques. The effect of substrate temperature and silver doping on crystal structure, surface morphology, hydrophilicity, hydrophobicity, and optical properties of the prepared thin layers were investigated by various techniques such as XRD, AFM, SEM, optical and photoluminescence spectroscopy. The results show the root mean square roughness deviation of pure TiO2 films decreased and the water contact angle increased with increasing of substrate temperature as well as silver thickness in the visible range. On the other hand, hydrophilicity nature of Ag–TiO2 layers raised with increase in the time of UV radiation. The optical absorption increased with silver doping due to collective oscillation of free electrons of small noble nanoparticles. The attained results indicate that the optical absorption increases with silver doping, because the radiated photon was trapped by silver nanoparticles in the TiO2 layers and so increases optical absorption. Anatase phase was dominant crystalline phase in all the prepared samples which is the best phase in photo catalyst and self-cleaning applications.

Synthesis and crystal structure of Ag(I) p-toluenesulphonate complex with 5-methyl-3-allyl-2-thiohydantoin

Synthesis and crystal structure of Ag(I) p-toluenesulphonate complex with 5-methyl-3-allyl-2-thiohydantoin

Crystal structures of AgI and TlI cyanoximates: guide for search for light-insensitive compounds, and valuable tool for characterization of new ligands

Crystal structures of Ag^I and Tl^I cyanoximates: guide for search for light-insensitive compounds, and valuable tool for characterization of new ligands

Canted Antiferromagnetism in Two-Dimensional Silver(II) Bis[pentafluoridooxidotungstate(VI)

By slow reaction between colorless AgIW2O2F9 and elemental F2 in liquid anhydrous HF, violet platelike single crystals of Ag(WOF5)2 were grown. The crystal structure of Ag(WOF5)2 consists of layers built from Ag2+ cations bridged by [WOF5]- anions and not, as previously assumed, from infinite [AgII-F]+∞ chains and [W2O2F9]- anions. A majority (97%) of the disordered AgII cations are found with square-planar coordination of F/O ligands within the same layer, and they form additional long contacts with O/F atoms originating from the neighboring layers. The remaining 3% the of Ag(II) ions are coordinated only by F atoms in a square-planar fashion. The magnetic moments of Ag2+ from the same layer are almost perfectly antiferromagnetically aligned. Weak ferromagnetic interlayer interactions cause a small tilt (∼1.5°) of the magnetic moments, resulting in canted antiferromagnetism. Because of the lowering of the symmetry of [WOF5]- in the solid state, the vibrational spectra show more bands than expected for regular C4v symmetry. The electronic spectrum of Ag(WOF5)2 is reported and analyzed.

Crystal chemistry of cation-exchanged forms of epistolite-group minerals, Part I. Ag- and Cu-exchanged lomonosovite and Ag-exchanged murmanite

The paper presents the first data on the crystal chemistry of the cation-exchanged forms of layered titanosilicates belonging to the epistolite group. It was found that these heterophyllosilicates have high exchange capacity and selectivity for cations of chalcophile elements (Ag, Cu and Zn) and could be considered as potentially novel raw materials or, more likely, as possible prototypes of cation-selective synthetic microporous materials. The crystal structures of Ag- and Cu-exchanged forms of lomonosovite and Ag-exchanged form of murmanite were studied by single-crystal X-ray diffraction. The topology of the main structural unit, the HOH block, remains unchanged in cation-exchanged forms as compared to the initial lomonosovite Na 4 Ti 4 (Si2O 7 ) 2 O 4 • 2Na 3 PO 4 ( P -1) and murmanite Na 4 Ti 4 (Si 2 O 7 ) 2 O 4 • 4H 2 O ( P -1). In Ag-exchanged murmanite, Ag cations occupy two crystallographically non-equivalent positions: one in the heteropolyhedral ( H ) sheet and another one in the octahedral ( O ) sheet corresponding to the positions of Na in initial murmanite. The crystal structure of the Ag-exchanged form of lomonosovite is characterized by an increased unit-cell parameter c and doubled parameter b as compared to initial lomonosovite. Ten large-cation sites statistically occupied by Ag and Na correspond to the Na sites in the initial lomonosovite: six in the interlayer space, two in the H sheet and two in the O sheet. Silver significantly replaces Na in sites in the interlayer space and in the O sheet, whereas sites in the H sheet are less affected by the ion exchange. Unit-cell parameter c of the Cu-exchanged form of lomonosovite decreases by 3.58% as compared to the initial lomonosovite whereas a and b remain almost the same. The Cu cations occupy two crystallographically independent positions. The Cu(1) site, corresponding to the Na(3) site in the initial lomonosovite, is located in the interlayer space. The low-occupancy Cu(2) site is located on the inversion centre in the O sheet; this site is vacant in the initial lomonosovite. The Cu(2) site is surrounded by six O atoms forming an octahedron distorted due to the Jahn-Teller effect.

Microwave-Assisted Synthesis of a Series of Ag/ZnO Nanocomposites and Evaluation of Their Photocatalytic Activities under Multi-Mode Photodegradation

A series of Ag/ZnO nanocomposites were prepared under microwave irradiation of different powers (100, 200, and 300 W). The crystal structure, morphology, and surface physicochemical properties of the as-synthesized samples were characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, scanning electron microscopy, and nitrogen adsorption–desorption analyses. Compared with the Ag/ZnO prepared by conventional sedimentation process, the crystal structures of Ag and ZnO did not exhibit any transformation after microwave irradiation; however, slight increases or decreases were observed in their absorption spectra and the specific surface areas. Moreover, the morphologies of all Ag/ZnO samples were changed dramatically by microwave irradiation, showing morphologies such as octagonal nano-pyramidal and multi-angled nano-pyramidal. The multi-mode photocatalytic degradation studies showed that the photocatalytic activities of the Ag/ZnO nanocomposites prepared under microwave irradiation of different powers were enhanced to different extents and were much higher than that of P25, ZnO, and Ag/ZnO prepared in the absence of microwave irradiation.

A Novel Precursor for Preparation of Silver Nanoparticles: Synthesis, Characterization and Crystal Structure of Ag(PPh3)2(2-pyCOO)

A novel silver complex, Ag(PPh3)2(2-pyCOO)·0.5H2O·0.5C2H6O, was prepared from Ag(CH3COO)(PPh3)2 and 2-pyridinecarboxylic acid and after characterization by elemental analysis, infrared, 1H and 31P NMR spectroscopes, and X-ray crystallography, was used as a precursor for the preparation of silver nanoparticles. The silver nanoparticles were obtained by thermolysis of the silver complex at 350 °C in the presence of oleic acid as a surfactant. Resulting silver nanoparticles were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The formation of silver nanoparticles with an average size of 60 nm and spherical morphology was confirmed by SEM. Bulk silver particles were obtained instead of silver nanoparticles when thermolysis of the silver complex was carried out in the absence of oleic acid.

ChemInform Abstract: Mixed Valence Tungsten (IV,V) Compounds with Layered Structures. Part 3. Synthesis and Crystal Structure of Ag1‐x[W2O2Cl6] and Investigations on the Ag+ Ion Mobility.

AbstractTitle compounds with x = 0, 0.38, and 0.82 are synthesized either by reaction of WOCl3 with AgCl in the presence of a small amount of WCl6 (510→700 K, 40 d), or by reaction of WOCl4 with metallic Ag (690 K, 7 d).

Mixed Valence Tungsten (IV,V) Compounds with Layered Structures (Part III) [2]: Synthesis and Crystal Structure of Ag1–x[W2O2Cl6] and Investigations on the Ag+ Ion Mobility

AbstractThe reaction of metallic silver with tungsten tetrachlorideoxide WOCl4 or the reaction of AgCl with WOCl3, both at 690 K, lead to Ag1–x[W2O2Cl6] as black lustrous crystal needles. The compound shows a substantial phase field width in the silver content depending on reaction temperature and reaction time and crystals with x = 0, 0.38 and 0.82 were isolated. The crystal structure determinations (monoclinic, C2/m) show the structure to be isotypic to those of Tl[W2O2Cl6] and K0.84[W2O2Cl6] with the presence of 1D polymeric [W2O2Cl6]n strands and Ag+ ions with a variety in the occupation of the respective crystallographic site. Ag1–x[W2O2Cl6] represents a mixed valence compound with a variable ratio of W(IV) and W(V) in the W2 dumbbells with a short W–W separation of 2.85 Å. In Fourier maps the electron density of the Ag ion appears smeared over a large area. By structure determinations of stoichiometric Ag1.0[W2O2Cl6] at temperatures of 123, 193, and 293 K a double minimum potential was found with the silver ion dynamically disordered over two flat basins with a thermal activation barrier of 13 meV. No long range ion mobility is present since the Ag+ ions are trapped within a coordinating cage consisting of ten chlorine atoms of the surrounding [W2O2Cl6] strands forming a distorted bicapped cube. By MAS‐NMR spectroscopic measurements on the 109Ag nuclei at different temperatures, the spin lattice relaxation times were determined giving a thermally activated barrier of 15 meV. The electronic conductivity of pressed powder samples of Ag[W2O2Cl6] by a four‐probe measurement applying direct current is 1 Ω–1·cm–1 at room temperature and 10–3 Ω–1·cm–1 at 25 K. For the conduction mechanism at low temperatures a variable range hopping mechanism is suggested, whereas at higher temperatures a standard semi‐conductivity with a bandgap of 60 meV is present.

2-Cyano-2-isonitrosoacetamide and its Ag(i) complexes. Silver(i) cyanoximate as a non-electric gas sensor

The 2-cyano-2-isonitrosoacetamide, NC-C(N=OH)-C(O)NH(2) (1), its Na(+), Cs(+) salts and four silver(I) complexes with N-donor ligands were synthesized and characterized using a variety of techniques including IR, UV-vis spectroscopy, solid state photoluminescence, X-ray analysis, and solution electrical conductivity. All four reported here Ag(I) complexes were crystallographically characterized and revealed completely different structures. Thus, the combination of chelate and bridging function of the cyanoxime anion in Ag{NC-C(N=O)-C(O)NH(2)} (complex 6) leads to a unique layered 2D coordination polymer of silver(i) with pronounced argentophilic interactions at 3.194 A. The structure of Ag{NC-C(N=O)-C(O)NH(2)} x 2Pic (Pic = 2-methylpyridine; complex 7) represents the monomeric complex containing bidentate chelate anion 1(-). The crystal structure of monomeric Ag{NC-C(N=O)-C(O)NH(2)} x 2NH(3) (complex 8) reveals the formation of a linear Ag(NH(3))(2)(+) cation non bonded to the metal cyanoxime anion 1(-). This is the first structure of a silver(i) diammine cation with an oxime-based anion. Similarly to 8, the crystal structure of Ag(14ane[N(4)]){NC-C(N=O)-C(O)NH(2)} x CH(3)CN with tetraaza-meso(macrocyclic) ligand (complex 9) contains a metal center not bound to the cyanoxime ligand as well. Instead, the agostic interaction at 2.591 A between the methylene group of the macrocyclic ligand and silver(I) center was found in 9. This is the shortest CH(2)-Ag distance between an aliphatic group and metal observed so far in non-organometallic silver complexes with neutral ligands. We also documented a remarkable visible-light insensitivity of complex 6. Room temperature solid state photoluminescence of this compound was examined in details, including studies of its emission in the presence of several gases of industrial importance: H(2), CO, NO, NH(3), SO(2), acetylene C(2)H(2) and ethylene C(2)H(4). A significant sensitization of to visible light after the exposure was observed, which is a useful property that may be utilized in development of battery-less colorimetric sensors for these gases.

ChemInform Abstract: The Reactions of Silver, Zirconium, and Hafnium Fluorides with Liquid Ammonia: Syntheses and Crystal Structures of Ag(NH3)2F·2NH3, [M(NH3)4F4]·NH3 (M: Zr, Hf), and (N2H7)F.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The Reactions of Silver, Zirconium, and Hafnium Fluorides with Liquid Ammonia: Syntheses and Crystal Structures of Ag(NH3)2F·2NH3, [M(NH3)4F4]·NH3 (M = Zr, Hf), and (N2H7)F

AbstractBy reaction of the tetrafluorides MF4 or the ternary silver fluorides Ag3M2F14 (M = Zr, Hf) with dry liquid ammonia at –40 °C, the pentaammoniates [M(NH3)4F4]·NH3 (1, M = Zr; 2, M = Hf) were obtained, and these compounds represent hitherto unknown molecular inorganic Zr and Hf compounds that simultaneously bear nitrogen and fluorine ligands. The compounds crystallize isotypically in the shape of colorless needles in the tetragonal space group P4/ncc. As a further product [NH4(NH3)]F (3) was isolated in the form of colorless cubes in the orthorhombic space group Pca21. It is the first ammoniate of ammonium fluoride. Ag(NH3)2F·2NH3 (4) can be synthesized either from AgF or AgF2 in liquid ammonia. The compound crystallizes merohedrally twinned in the orthorhombic space group Pnna and represents the first crystallographically characterized diamine silver(I) halide complex. In the latter two structures, free fluoride anions are encountered. The ammoniates are highly temperature‐sensitive and decompose at temperatures above –30 °C due to their ammonia pressure.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Crystal Structures of Ag2ZrF6·8NH3 and Ag2HfF6·8NH3 and Their Synthesis by the “Reactive Fluoride Route” in Liquid Ammonia

AbstractStarting from the ternary transition‐metal fluorides Ag3M2F14 (M = Zr, Hf) and dry liquid ammonia, [Ag(NH3)4(μ‐NH3)Ag(NH3)3]ZrF6 (1) and [Ag(NH3)4(μ‐NH3)Ag(NH3)3]HfF6 (2) have been prepared as colorless single crystals crystallizing isotypically in the space group Pnma‐D2h16 (No. 62). The compounds feature weak Ag···Ag interactions known as argentophilicity, which is yet unknown in fluorides. It is also shown that ionic silver(II) fluorides are suitable starting materials for fluorine chemistry in liquid ammonia and are easily reduced to AgI by oxidizing ammonia. This driving force bypasses the generally high lattice energy of ionic fluorides, so that they can be dissolved easily. We would like to introduce the term “reactive fluoride route” for this method of dissolving reactive ionic fluorides in liquid ammonia. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Radical‐Enhanced Atomic Layer Deposition of Silver Thin Films Using Phosphine‐Adducted Silver Carboxylates

AbstractMetallic silver films are deposited by radical‐enhanced atomic layer deposition (REALD) using (2,2‐dimethylpropionato)silver(I)triethylphosphine and hydrogen radicals. The silver precursor used is synthesized in‐house, and characterized using CHN elemental analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR), mass spectrometry (MS), and thermogravimetric analysis/single differential thermal analysis (TGA/SDTA). The crystal structure of Ag(O2CtBu)(PEt3) is also solved. Trimeric units are revealed as the building blocks. The hydrogen radicals are produced by dissociating molecular hydrogen with a microwave plasma discharge. The evaporation temperature of the silver precursor is 125 °C, and the film deposition temperature is 140 °C. The deposition is successful on glass and silicon, and the films are conformal. The saturated growth rate is 0.12 nm per cycle, with a 3 s silver precursor pulse and 5 s hydrogen radical pulse time. The overall cycle time is 14 s. The films are polycrystalline and are visually mirror‐like. The films contain 10 at.‐% oxygen, 4.0 at.‐% phosphorous, 1.0 at.‐% carbon, and 5.0 at.‐% hydrogen as impurities. Nevertheless, the films exhibit low resistivity, only 6 μΩ cm for a 40 nm thick film.

Silver(I) N-Heterocyclic Carbenes with Long N-Alkyl Chains

Silver(I) N-heterocyclic carbene complexes (Ag(I)−NHCs) with long N-alkyl side chains formulated as (a) ion pairs, (b) halide-bridged neutral complexes, and (c) disilver tetrahalide anion bridged tetranuclear complexes were obtained by the reaction of benzimidazolium and imidazolium halide salts with Ag2O. Interestingly, when excess Ag2O was used, Ag nanoparticles were formed along with Ag(I)−NHCs. Crystal structures of Ag(I)−NHC complexes including both long and short N-alkyl chains were determined. The diversity of the solid-state structures depended on the halide ions, chain length, carbene cores, and crystallization conditions. The Ag(I)−NHCs of long alkyl chains did not show liquid crystal properties but did so when mixed with their corresponding imidazolium salts. These organic−inorganic hybrids were good single-source precursors for silver nanomaterials.

The Quasi‐Ternary System Ag2S—CdS—GeS2 and the Crystal Structure of Ag2CdGeS4.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and Crystal Structure of Hg2+Complex with an S2O2Donor Dipodal Ligand. A Search for New Voltammetric Sensor for Hg2+

Heavy metal complexations with host molecules have been received much attention, not only because of prime environmental concern, but also the heavy metal binding is one of fundamental problems of molecular recognition. Based on the optimal requirement of cooperative effect of the mixed coordinating sites via thiaoxa donor set for heavy metals, we have reported the solvent extraction, membrane transport and crystal structures of Ag and Pd complexes with the new system of the cyclic and acyclic ionophores incorporating a potential thiaoxa donor system. Particularly, the acyclic thiaoxa ionophores can be obtained simply and cheaply because there is no need for expensive and timeconsuming steps, such as high dilution or template methods, which is usually required in preparations of cyclic analogues. In the continuing work on the metal complexation, we were recently able to prepare the new Hg complex of the S2O2 dipodal ligand L and have determined its X-ray crystal structure. Although the stability constant for the Hg complex with L is not yet available, this result is enough to motivate the works on the stripping voltammetry by using the modified carbon paste electrode (CPE) as a more sophisticated detection procedure for Hg. Herein, we describe the preparation of the Hg complex of L together with its crystal structure. In addition, the characteristics of the L-modified CPEs are presented in terms of the Hg detection.