Bismuth Iodide Complex Research Articles

Memristive properties and synaptic plasticity in substituted pyridinium iodobismuthates.

This study explores the impact of organic cations in bismuth iodide complexes on their memristive behavior in metal-insulator-metal (MIM) type thin-layer devices. The presence of electron-donating and electron withdrawing functional groups (-CN, -CH3, -NH2, and -N(CH3)2) on pyridinium cations induces morphological alterations in crystals, thus influencing the electronic or ionic conductivity of devices comprising sandwiched thin layers (thickness = 200 nm ± 50) between glass/ITO as bottom electrode (∼110 nm) and copper (∼80 nm) as the top electrode. It was found that the current-voltage (I-V) scans of the devices reveal characteristic pinched hysteresis loops, a distinct signature of memristors. The working voltage windows are significantly influenced by both the types of cation and the dimensionality of ionic fragments (0D or 1D) in the solid-state form. Additionally, the temperature alters the surface area of the I-V loops by affecting resistive switching mechanisms, corresponding log-log plots at three temperatures (-30 °C, room temperature and 150 °C) are fully studied. Given that a memristor can operate as a single synapse without the need for programming, aligning with the requirements of neuromorphic computing, the study investigates long-term depression, potentiation, and spike-time-dependent plasticity-a specific form of the Hebbian learning rule-to mimic biologically synaptic plasticity. Different polar pulses, such as triangle, sawtooth, and square waveforms were employed to generate Hebbian learning rules. The research demonstrates how the shape of the applied pulse series, achieved by overlapping pre- and post-pulses at different time scales, in association with the composition and dimensionality of ionic fragments, lead to changes in the synaptic weight percentages of the devices.

Influence of crystal structure and composition on optical and electronic properties of pyridinium-based bismuth iodide complexes.

This study investigates the impacts of structure and composition on the optical and electronic properties of a series of pyridinium-based bismuth iodide complexes. Organic substrates with various functional groups, such as 4-aminopyridine (4-Ampy), 4-methylpyridine (4-Mepy), 4-dimethylaminopyridine (4-Dmapy), and 4-pyridinecarbonitrile (4-CNpy) with different electron-donating and electron-withdrawing groups at the para position of the pyridine ring were employed. Crystallographic analysis reveals various bismuth iodide structures, including 1D chains and discrete 0D motifs. The optical band gap of these materials, identified via diffuse reflectance spectroscopy (DRS) and verified with density functional theory (DFT) calculations, is influenced by the crystal packing and stabilising interactions. Through a comprehensive analysis, including Hirshfeld surface (HS) and void assessment, the study underscores the influence of noncovalent intermolecular interactions on crystal packing. Spectroscopic evaluations provide insights into electronic interactions, elucidating the role of electron donor and acceptor substituents within the lattice. Thermogravimetric differential thermal analysis (TG-DTA) indicates structural stability up to 250 °C. Linear sweep voltammetry (LSV) reveals significant conductivity in the range of 10-20 mS per pixel at 298.15 K. X-ray absorption spectroscopy (XAS) at the Bi L3 edge indicates a similar oxidation state and electronic environment across all samples, underscoring the role of bismuth centres surrounded by iodides.

Light Excitation of a Bismuth Iodide Complex Initiates I-I Bond Formation Reactions of Relevance to Solar Energy Conversion.

The titration of iodide into acetonitrile solutions of BiI3 resulted in the formation of [BiI6]3-. Ligand-to-metal charge transfer (LMCT) excitation of [BiI6]3- yielded a transient species assigned as the diiodide anion I2•- directly ligated to Bi, [Bi(I2•-)Ix]n. With 20 ns time resolution, transient absorption measurements revealed the appearance of two species assigned on the analysis of the iodine molecular orbitals as an η2 ligated I2•-, [(η2-I2)BiI4]3- (λmax = 640 nm), and an η1 species [(η1-I2)BiI4]3- (λmax = 750 nm). The rapid appearance of this intermediate was attributed to intramolecular I-I bond formation. The [(η2-I2)BiI4]3- subsequently reacted with 1 equiv of iodide to yield [(η1-I2)BiI5]4-. Interestingly, [(η1-I2)BiI5]4- decayed to ground state products with a first-order rate constant of k = 2 × 103 s-1. Under the same experimental conditions, I2•- in CH3CN rapidly disproportionates with a tremendous loss of free energy, ΔGo = -2.6 eV. The finding that metal ligation inhibits this energy wasting reaction is of direct relevance to solar energy conversion. The photochemistry itself provides a rare example of one electron oxidized halide species coordinated to a metal ion of possible relevance to reductive elimination/oxidation addition reaction chemistry of transition metal catalysts.

TOXICITY AND TISSUE DISTRIBUTION STUDIES ON THE HYDROCHLORIDE, BISMUTH IODIDE COMPLEX AND A RESINATE OF EMETINE.

Abstract The hydrochloride, the bismuth iodide complex and a resinate of emetine have been compared on mice, cats and dogs for toxicity, on cats for emetic activity and on rats for distribution of emetine in the tissues. Emetine hydrochloride, injected sub-cutaneously, was as toxic as emetine hydrochloride or emetine bismuth iodide administered orally, but only one-sixth as emetic. Given orally emetine resinate was considerably less toxic and emetic than the other preparations. The patterns of emetine distribution in the tissues of rats were similar for all the preparations, but the tissue concentrations were much lower with emetine resinate. In infected rats the resinate was as amoebicidal as the hydrochloride or the bismuth iodide complex. It is suggested that emetine resinate might be better than emetine bismuth iodide for the treatment of intestinal amoebiasis.

Spectophotofluorometric determination of emetine in animal tissues.

Abstract A simple rapid spectrophotofluorometric method for assaying emetine in animal tissues is described. Tissue emetine concentrations have been determined in rats at intervals up to 14 days after single doses of emetine hydrochloride or emetine bismuth iodide: the hydrochloride was administered orally or subcutaneously and the bismuth iodide complex orally. Subcutaneously administered emetine hydrochloride produced the highest concentrations. Given orally, emetine hydrochloride produced higher tissue levels than did emetine bismuth iodide.

Determination of Traces Of Bismuth in Water with Polyurethane Foak Thin-Layer Spectrophotometry

Abstract A method for the spectrophotometric determination of bismuth is described. The method is based on using polyether polyurethane foam sorbent as a favourable matrix. Sorption of the bismuth iodide complex into the foam thin layer contributed into substantial improvement of the measured absorbance value of the coloured species. In this way quite satisfactory results were achieved, the average recovery amounts to 105.25%.

Determination of lead-210 in standard samples of soil, ores, and mill tailings

Up to 5-G samples were dissolved in hyrofluoric acid and pyrosulfate fusion in the presence of bismuth tracer. The cake was dissolved in hydrochloric acid and bismuth-210 was extracted into diethyldithiocarbamate, separating it from most interferences including its lead-210 parent. Bismuth was then coprecipitated with barium sulfate and counted in a low-background ..beta.. counter through a 6 mg/cm/sup 2/ aluminum absorber to remove ..cap alpha.. particles from polonium-210. After the sample was counted, the barium sulfate was dissolved in alkaline ehtylenediaminetetraacetic acid, excess potassium iodide was added, and the solution was acidified. The yellow bismuth-iodide complex was measured in a spectrophotometer and the absorbance was compared with that from an identical aliquot of the bismuth solution to determine the chemical yield. Some results obtained in the analysis of soil, uranium ores, and mill tailings that were prepared for use as standards are given. When sufficient activity was present, the relative experimental standard deviations of 10 individual measurements about their own mean was less than 2%. On standards, the results obtained were within 3% of the known values at the 95% confidence level. Chemical yields were generally higher than 98% overall and were determined to better than 0.5%. Detection limits aremore » about 0.1 pCi/g for 5-g samples and 6-h counts.« less

Heat capacity and internal motion of molten Bi+BiI3mixtures

Measurements of the heat capacities, Cp, of molten Bi+BiI3 mixtures at compositions up to around 50 mol.% Bi were made with an adiabatic calorimeter. The deviation Delta Cp,a from the Dulong-Petit law of the atomic heat capacities was calculated over the whole concentration range, including proviously published data for Cp above 50 mol.% Bi. A drastic increase of Delta Cp,a for the ionic liquid-semiconductor regime between around 20 and 50 mol.% Bi (i.e. it has a maximum value of around 2.7R at 50 mol.% Bi) is satisfactorily explained in terms of the internal motions (i.e. the vibrational and rotational modes) of the bismuth homopolyatomic ions, in addition to a contribution from the bismuth iodide complex ions. Between the onset ( approximately 50 mol.% Bi) and the end ( approximately 90 mol.% Bi) of the miscibility gap, Delta Cp,a decreases to less than half of its maximum value. This is because the metallic micro-regions, which are made up of the aggregation of a few of the polybismuth ions or more with the increase of the Bi content, no longer show any internal motion and do not give rise to the large value of Delta Cp,a. Since the molten mixtures between approximately 50 and approximately 90 mol.% Bi are microscopically inhomogeneous solutions consisting of the ionic liquid-semiconducting and metallic micro-regions, the so-called inhomogeneous cluster model is applied to the Delta Cp,a of these mixtures.

Ion-exchanger colorimetry—IV microdetermination of bismuth in water

Ion-exchanger colorimetry for the microdetermination of bismuth(III) in water samples is described. The yellow bismuth—iodide complexes are specifically sorbed and concentrated on an anion-exchange resin in the sulphate form. The resin-phase absorbances at 492 and 700 nm are measured directly. Bismuth in the ppb—ppm range can be determined without interference, except in presence of a large amount of copper(II), silver(I) and lead(II). The detection limit is 6.4 × 10 −9 M, i.e., 1.3 ppb. The distribution ratio is larger than 10 7. It is, therefore, possible to enhance the sensitivity by increasing the sample volume. The method is useful for the determination of bismuth in natural waters and industrial effluents.

Determination of traces of bismuth by isotopic exchange reaction in the organic phase

A new radioanalytical method has been developed based on homogeneous isotopic exchange in the organic phase. The theory of the method is presented and discussed. This method has been applied for the simple, selective and rapid determination of bismuth based on the isotopic exchange between bismuth diethyldithiocarbamate and bismuth iodide complex labelled with210Bi. As little as 0.01 μg of the metal can be determined.

Raman spectra and structure of bismuth iodide complexes

The complex ions formed between bismuth triiodide and iodide ions in acetone solution have been studied by Raman Spectroscopy. The (BiI 4) − ion appears to have C 2v symmetry, suggesting a trigonal bipyramidal structure with one equatorial position occupied by a lone pair. The (BiI 6) 3− ion appears to be octahedral in solution and in the crystalline state. No evidence was found for the formation of complex ions other than these two species.

Bismuth iodide complexes in aqueous solution of high iodide concentration

Bismuth iodide complexes in aqueous solution of high iodide concentration

On the use of cation exchangers for the study of complex systems—II: The systems bismuth (III)-bromide, iodide and fluoride

Distribution measurements of bismuth-210, between 1·890 M perchloric acid solution and the cation exchangers Dowex 50W-X8 and X16, were explored as functions of the added HF-, Br −-, and I −-concentrations. For the F- and Br-systems stability constants and distribution coefficients for a number of the complexes could be calculated by a method previously described. (1) For the Br-system we found: β 1 = (2·30 ± 0·05) × 10 2, β 2 = (2·6 ± 0·2) × 10 4, β 3 = (1·8 ± 0·3) × 10 6, β 4 = (5 ± 2) × 10 7, and for the F-system: β 2H = 27 ± 1 and β 2H = 58 ± 4 from which the approximate values β 1 ≈ 5 × 10 4 and β 2 ≈ 2 × 10 8 are calculated. The distribution curves for the Bi 3+I − system, in contrast with the other systems, showed points of inflection. It is suggested that this is caused by absorption of, for example, a negatively charged bismuth-iodide complex. From measurements on the highest cross-linked resin a value of β 1 = 800 ± 200 could be determined for the complex BiI 2+.

A spectrophotometric investigation of bismuth iodide complexes

A spectrophotometric investigation of bismuth iodide complexes

Determination of caesium-137/potassium ratios in diet and in the human body by urine analysis.

A RADIOCHEMICAL method1 has been developed for the determination of cæsium-137 in urine. Acidified urine containing cæsium carrier is passed through a column of ammonium phosphomolybdate mixed with an equal weight of asbestos to give adequate porosity. The ammonium phosphomolybdate acts as a highly selective cation-exchanger and retains the cæsium quantitatively, even at comparatively high flow-rates. Other cations, including sodium, potassium and the alkaline earths, are not retained to any significant extent. After all the sample has passed through the column, the ammonium phosphomolybdate is dissolved in sodium hydroxide solution and the cæsium precipitated as the cobaltinitrite. The removal of final traces of potassium and rubidium from the cæsium is ensured by its subsequent precipitation as the bismuth iodide complex and finally as the chloroplatinate, which is filtered, dried and beta-rays counted. The recovery of carrier normally exceeds 80 per cent. The sensitivity of this method makes it particularly useful for the determination of fall-out cæsium-137 in urine, as current concentrations are low and are likely to decline still further.

Extraction of bismuth iodide complexes as a spot test for bismuth

The extraction of bismuth iodide in the presence of excess iodide ions by methyl isobutyl ketone has been studied as a spot test for bismuth. Interferences have been prevented through the use of hypophosphorous acid and oxalic acid, or by preliminary treatments. The test, as performed in the extraction pipet, is sensitive to 1 γ of bismuth, with platinum and palladium constituting the only interferences.