"One-step" alkynylation of adamantyl iodide with silver(I) acetylides

[reaction: see text] Silver(I) acetylides allow one-step alkynylation of adamantyl iodide in yields ranging from 25 to 68%.     

Structural studies of silver(I) coordination polymers with aryl iodide derived ligands

This paper reports novel silver polymers, built with iodine--silver interactions, with interesting structural motifs. Four silver(I) coordination polymers of the aryl iodide derived ligands, triiodobenzoic acid (HL1), tris(4-iodophenyl)amine (L2), and 5,7-diiodo-8-hydroxyquinoline (HL3), have been synthesized and characterized by X-ray crystallography. Treatment of Ag(CH3COO) with HL1 yielded [Ag(L1)] (1), whose structural analysis revealed 2D layers of ladders connected through weak Ag...I interaction. Reactions of AgClO4 and L2 in benzene and nitrobenzene afforded, respectively, two different products, [Ag(L2)(H2O)]ClO4.C6H6(2) and [Ag(L2)(ClO4)](3). While the structure of 2 could be described as a 2D layer of square and octagons perpendicular to [100], complex 3 is formed by 2D layers of the same topology of 2 (8(2).4), alternating as ABAB. In contrast, complex 4, [Ag2(H2L3)(CF3SO3)3], obtained by reaction of Ag(CF3SO3) and HL3, was found to consist of a 2D layer based on columnar arrays AgH2L3-Ag(triflate). The solid-state FT-IR and 109Ag NMR spectra of theses complexes are discussed on the basis of their crystal structures.     

Microdetermination of dissolved oxygen in water by a rapid spectrophotometric method

A spectrophotometric method utilizing the dye indigo carmine has been applied to the analysis of dissolved oxygen in water samples. Oxygen concentration has been determined by the decrease in absorbance at 410 mμ of reduced indigo carmine solutions oxidized by dissolved oxygen. A simple modification of the sample compartment of a Bausch and Lomb Spectronic 20 or 340 spectrophotometer allows rapid and accurate measurements to be made within 3 min. Dissolved oxygen in the ranges of 0 to 10% and 0 to 100% saturation can be analyzed without many of the interferences inherent in the standard Winkler method.     

Microdetermination of heavy metal ions: A potentiometric method using thioacetamide and iodine

Summary A new potentiometric method for the determination of mg range of silver, cadmium and copper ions is described. The heavy metal ions are first precipitated from an ammoniacal solution by an excess of thioacetamide. The precipitate is then separated by filtration. The unused thioacetamide is adjusted to the proper p_H and temperature, and then titrated with a standard solution of iodine potentiometrically. It is assumed that other metal ions, which form ammine complexes, can also be analyzed by this new method.

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Zusammenfassung Ein neues potentiometrisches Verfahren zur Bestimmung von Milligramm Ag, Cd und Cu wurde beschrieben. Die Schwermetallionen werden zunächst aus ammoniakalischer Lösung mit überschüssigem Thioacetamid gefällt. Der Niederschlag wird abfiltriert. Der überschuß an Thioacetamid wird nach Einstellung des p_H und der Temperatur mit einer Jodstandardlösung potentiometrisch zurücktitriert. Es ist anzunehmen, daß auch andere Metallionen, die Amminkomplexe bilden, so bestimmt werden können.

     

New spot-test for silver(I) based on double iodide formation with bismuth(III)

The formation of an intense brownish-maroon or maroon-red product by the interaction of silver(I) and bismuth(III) solution in the presence of iodide forms the basis of a new and specific spot-test procedure for silver. The test is conducted on a spot plate with 2 or 3 drops of 2% potassium iodide solution, 1 drop of 1% bismuth(III) nitrate solution, and 1 drop of test solution. Limit of detection is 0.01 mug; limit of dilution is 1:5 x 10(6). Most cations and anions do not interfere. Only Tl(I), Cs, S(2)O(2-)(3), EDTA, pyridine, excess of thiourea, oxidizing ions (NO(-)(2), IO(-)(3), IO(-)(4), MnO(-)(4), BrO(-)(3), and S(2)O(2-)(8)) and ions such as Cl(-), Br(-), I(-), SCN(-), and N(-)(3) which cause precipitation of silver, interfere. The product formed is most probably Ag(2)BiI(5).     

Ion-selective carbon-paste electrodes for halides and silver(I) ions

The behaviour of a simple type of ion-selective electrode for halogens and silver has been studied. The electrode consists of a plastic body filled with carbon paste, the surface of which can be easily renewed. The paste composition is based on carbon-nujol (5:1, w/v) or carbon-paraffin wax (3:1,w/w) containing a prepared mixture of silver halide-silver sulphide (1–30%). The electrodes have low ohmic resistance and show a rapid Nernstian response (within 2–5 mV) for halide and silver ions down to 5·10^-5M chloride, 1·10^-5M bromide and 5·10^-7M iodide with the respective electrodes. Ions forming very stable complexes with halide or silver and those having strong oxidizing or reducing action interfere.     

Pyrimidine-pyrimidine base pairs stabilized by silver(I) ions

In the presence of Ag(I) ions, the C-T and m(5)iC (5-methylisocytosine)-T base pairs showed comparable stability to the C-Ag(I)-C base pair, and the m(5)iC-C base pair was highly stabilized by the synergetic effect of Ag(I) coordination and possible hydrogen bonding.     

Stripping voltammetry of bromide and iodide ions at a renewal silver electrode

The behavior of bromide and iodide ions at a silver electrode renewed by cutting off a thin 0.5-μm surface layer was studied. The advantage of this method of electrode renewal over some variants of mechanical renewal was demonstrated. It was shown that bromide and iodide ions can be determined in concentration ranges from 10^-6 to 10^-3 M and from 10^-7 to 10^-3 M, respectively. Deceased.     

Low-temperature phases of rubidium silver iodide: crystal structures and dynamics of the mobile silver ions

Recently, broad-band conductivity spectra have been taken in the low-temperature gamma-phase of the archetypal fast ion conductor RbAg4I5. Attempts to reproduce the experimental data in a simple model calculation have led to the conclusion that strictly localized displacive movements of interacting ionic charge carriers should play an important role in the low-temperature phase. However, with no detailed structural study of gamma-RbAg4I5 available, the relevant processes could not be identified within the crystal structure. This state of affairs has triggered the present investigation of the structures of all three phases of rubidium silver iodide. Powder diffraction data of RbAg4I5 have been collected at the high-resolution powder diffractometer at ID31 at the European Synchrotron Radiation Facility (ESRF). The structure of the gamma-phase has been solved by successive Rietveld refinements in combination with difference Fourier analyses. The same structural principle is found to prevail in all three phases, interconnected distorted RbI6 octahedra forming a three-dimensional framework, which undergoes only displacive structural changes during the alpha-beta and beta-gamma phase transitions. With decreasing temperature, the disorder in the silver sublattice is found to decrease, and a clustering of the disordered silver ions is found to develop. In the gamma-phase, "pockets" containing partially occupied silver sites have been identified, and it is suggested that the localized displacive motion detected by conductivity spectroscopy is performed by the silver ions located within these pockets.     

Triangular and tetrahedral array of silver(I) ions by a novel disk-shaped tridentate ligand: dynamic control of coordination equilibrium of the silver(I) complexes

A disk-shaped tridentate ligand 1 arranges silver(I) ions in a two-dimensional triangular and a three-dimensional tetrahedral fashion in the metal-ligand ratios, 3:2 and 1:1, respectively. The resulting sandwich-type (Ag312) and tetrahedral (Ag414) architectures are in a dynamic equilibrium in solution.     

Potentiometric determination of tetraphenylborate ions with silver nitrate. Determination of silver, potassium and thallium(I)

Summary The potentiometric determination of tetraphenylborate with silver nitrate solution was investigated a) at i=0 in the presence of calomel reference electrode and silver resp. silicone rubber based halide-selective indicator electrodes and b) at i0 in the presence of silver (cathode)-calomel, silver-silver, silver-platinum, platinum-silver and graphite-silver electrode couples. An indirect method is described for the determination of potassium ions with potentiometric end-point indication. Experiments were also carried out in order to develop methods for the titration of silver, potassium and thallium(I) ions with sodium tetraphenylborate solution in the presence of anodic polarized graphite and calomel reference electrodes. The relative standard deviations were 0.38–0.49% for tetraphenylborate, 1.96% for potassium and 1.07% for thallium(I).

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Potentiometrische Bestimmung von Tetraphenylborationen mit Silbernitrat. Bestimmung von Silber, Kalium und Thallium(I)

Zusammenfassung Die Möglichkeit der potentiometrischen Bestimmung von Tetraphenylborat mit Silbernitrat wurde untersucht a) in Anwesenheit von Kalomel-Bezugselektrode und Silber- bzw. haloidselektiven Silicongummi-Indicatorelektroden bei i=0 und b) in Anwesenheit von Silber (Kathode)-Kalomel-, Silber-Silber, Silber-Platin-, Platin-Silber- und Graphit-Silber-Elektrodenpaaren bei i0. Eine Methode zur indirekten potentiometrischen Bestimmung von Kalium sowie Verfahren zur Bestimmung von Silber-, Kalium- und Thallium(I)-ionen mit Natriumtetraphenylboratlösung in Anwesenheit einer anodisch polarisierten Graphitelektrode und einer Kalomel-Referenzelektrode wurden ausgearbeitet. Die relativen Standardabweichungen betragen für Tetraphenylborat 0,38–0,49%, für Kalium und Thallium 1,96 bzw. 1,07%.

     

Reactions of pentaamminechloroplatinum(IV) with iodide and sulfite ions

The reactions of pentaamminechloroplatinum(IV) with potassium iodide and sodium sulfite are studied. In the presence of an equimolar amount of the iodide, the chloride ions are completely substituted without subsequent displacement of the ammonia molecules that are in the trans position to the entering iodide ions. The reaction with sodium sulfite is accompanied by the reduction of Pt(IV) to Pt(II). The reaction kinetics of pentaamminechloroplatinum(IV) with potassium iodide at 22, 40, and 50°C are studied. The rate constants and activation energy of this reaction are calculated.     

Remarks on the reactions of a tetracarboxylic porphyrin with gold and silver ions: A spectrophotometric,TEM and SEM study

The coproporphyrin-I (CPI) behaves as a reducing agent for silver and gold metal ions and as stabilizing agent for the formed colloidal metallic nanoparticles. The peculiarity of silver and gold nanoparticles obtained in the reactions of monomeric form of CPI with their metal ions has been studied. The optical properties of the colloidal forms of these metals have been investigated by UV–Vis spectrophotometry, and their morphology by TEM and SEM measurements. The structures and the size distributions of Ag and Au particles have been characterized and determined by computerized TEM images.     

A highly selective photometric method for uranium(VI) using a pyrimidyl azo dye in the presence of EDTA

The sodium salt of 2,4,6-tris(1-hydroxy-4-sulphonaphthyl-2-azo)pyrimidine gives a 1:1 violet coloured complex with uranyl(II) at pH 5.5–6.5 in the presence of EDTA absorbing maximum at 560 nm, where no other metal, including lanthanides, forms a complex. The Sandell's sensitivity of colour reaction is 6.14 ngU(VI)/cm². The developed method has been applied to the determination of uranium(VI) in synthetic samples corresponding to mineral monazite and some uranium alloys.     

Sulfoethylated polyaminostyrene: Synthesis in a gel and selectivity of sorption of silver(I) and copper(II) ions

A procedure was developed for preparing a new chelating ampholytic polymer, poly[N-(2-sulfoethyl) aminostyrene], by synthesis in a gel via treatment of polyaminostyrene with sodium 2-bromoethanesulfonate. The procedure allows preparation of the polymer with the degree of substitution of up to 0.7. Sulfoethylated polyaminostyrene with the degree of modification of 0.5 selectively takes up silver(I) and copper(II) ions from multicomponent solutions.     

The extraction of thallium(I) and silver(I) ions with 1,3-alternate calix[4]arene derivatives

Tetraallyloxy and tetrabenzyloxy derivatives of calix[4]arenes in cone and 1,3-alternate conformations were synthesised and their capacity to extract thallium(I) and silver(I) ions was investigated. ??Low??-temperature single crystal X-ray structure determinations were recorded for two derivatives in which the calixarene conformation was that of an alternating cone, the aromatic rings lying closely quasi-parallel to the $ \overline{4} $ -axis of the cone. The structure of a tetraallyloxy derivative in the cone conformation was also determined in which a molecule of acetonitrile was included within the calixarene cavity.     

Ternary complexes in the spectrophotometric determination of trace amounts of silver(I) and cadmium(II)

The reaction of silver(I) and cadmium(II) with 1,10-phenanthroline (PHEN) and Eosin (2,4,5,7-tetrabromofluorescein) gives coloured association complexes. The solution spectra of the mixed-ligand complexes are characterised by high intensity (∈ ≈ 10⁴) metal-to-ligand charge-transfer bands at 540–555nm. The optimum conditions for the spectrophotometric determination of Ag(I) or Cd(II) have been established. A simple, sensitive and selective method was proposed for the determination of traces of the metal ions either in aqueous or organic media. In the presence of EDTA only aluminium and cyanide interfere.     

Fluorescent detection of silver(I) and cysteine using SYBR Green I and a silver(I)-specific oligonucleotide

We report on a novel method for the determination of silver ion (Ag⁺) and cysteine (Cys) by using the probe SYBR Green I (SGI) and an Ag+-specific cytosine-rich oligonucleotide (C-DNA). The fluorescence of SGI is very weak in the absence or presence of randomly coiled C-DNA. If, however, C-DNA interacts with Ag⁺ through the formation of cytosine-Ag⁺-cytosine (C-Ag⁺-C) base pairs, the randomly coiled C-DNA undergoes a structural changes to form a hairpin-like structure, thereby increasing the fluorescence of SGI. This fluorescence turn-on process allows the detection of Ag⁺ in the 10–600?nM concentration range, with a detection limit of 4.3?nM. Upon the reaction of Ag⁺ with Cys, Cys specifically removes Ag⁺ from the C-Ag⁺-C base pairs and destroys the hairpin-like structure. This, in turn, results in a decrease in fluorescence intensity. This fluorescence turn-off process enables the determination of Cys in the 8–550?nM concentration range, with a detection limit of 4.5?nM. The method reported here for the determination of either Ag⁺ or Cys is simple, sensitive, and affordable, and may be applied to other detection systems if appropriately selected DNA sequences are available.