Influence of different copper(II) salts on the oxidation and doping reactions of emeraldine base polyaniline

A spectroscopic investigation of the products formed in the reaction of emeraldine base (EB-PANI) with copper(II) ions in dimethylacetamide (DMA) is presented. It is well known that metal cations can dope emeraldine base polyaniline (EB-PANI) through a pseudo-protonation reaction. Resonance Raman, UV–vis-NIR, and EPR data, obtained for Cu²⁺/EB-PANI solutions prepared using CuCl₂·2 H₂O, Cu(NO₃)₂· 3 H₂O or Cu(CH₃COO)₂·H₂O as Cu²⁺ sources, showed that the species formed in reactions of EB-PANI and Cu²⁺ ions are dependent on the anions of the copper salt employed. EPR spectra pointed out that the environments of Cu²⁺ ions with acetate, chloride or nitrate as anions in DMA solution are distinct. Resonance Raman and UV–vis-NIR data demonstrated that the main reactions are the oxidation of EB-PANI to pernigraniline base (PB-PANI) and doping of EB-PANI to ES-PANI (emeraldine salt) when a direct coordination of Cu²⁺ ions to PANI exists. With nitrate as very weak coordinating anion, ES-PANI is formed preferentially. When copper chloride is used, both oxidation and doping of EB-PANI are verified. Conversely with acetate, the dimeric cage structure of this copper salt is preserved in solution, and oxidation of EB-PANI to PB-PANI is the only observed reaction. These results demonstrate the possibility of modulating the products of reaction between Cu²⁺ ions and EB-PANI in DMA solution by changing the counter ion of the Cu²⁺ source.     

Miniature Ion-selective Electrodes with Mesoporous Carbon Black as Solid Contact

Herein, we demonstrated miniature solid-contact ion-selective electrodes (ISEs) using a commercial mesoporous carbon black (MCB) as ion-to-electron transducer. MCB is attractive in its high surface area, good conductivity, relative low cost and availability. ISEs for potassium (K⁺) and nitrate (NO₃⁻) ions were prepared by subsequently coating the sealed glass capillaries (1.5 mm) with MCB and ion-selective membranes. Addition of MCB substantially stabilized electrode response by providing adequate double-layer capacitance and lowering resistance by more than 100× compared to the coated-wire electrodes. The electrodes exhibited near-Nernstian slopes of 59.6 (K⁺ ionophore), 57.8 (K⁺ ion-exchanger) and −54.8 (NO₃⁻ ion-exchanger) with standard solutions in the range of 10⁻⁵ to 10⁻¹ M. Fast response (∼10 s) and reproducible sensitivities were also obtained in a mixed electrolyte containing interfering ions, although with a baseline drift of 2–10 mV/day in the long term. Importantly, the electrodes can be simply stored in air between measurements and used directly without conditioning in solutions. With simple fabrication and free maintenance, these sensors offer a low cost and convenient alternative to bulk ISEs, especially when sample volumes or space are limited.     

Binuclear copper complexes with non-steroidal anti-inflammatory drugs as studied by electrospray ionization mass spectrometry

The solutions containing one of the copper salts (CuCl₂, Cu(ClO₄)₂, Cu(NO₃)₂, and CuSO₄) and one of the non-steroidal anti-inflammatory drugs (NSAIDs, ibuprofen, ketoprofen or naproxen) were analyzed by electrospray ionization mass spectrometry. Three of the salts, namely CuCl₂, Cu(ClO₄)₂ and Cu(NO₃)₂, yielded binuclear complexes of drug:metal stoichiometry 1:2. Existence of the complexes of such stoichiometry has not been earlier observed. For copper(II) chloride the complexes (ions of the type [M-HCOOH+Cu₂Cl]⁺ and [M+Cu₂Cl]⁺, M stands for the drug molecule) were formed in the gas phase. When copper(II) perchlorate or copper(II) nitrate was used, the observed binuclear copper complexes (ions of the type [M-H+Cu₂(ClO₄)₂+CH₃OH]⁺, [M-H+Cu₂(ClO₄)₂]⁺ and [M-H+Cu₂(NO₃)₂+CH₃OH]⁺, [M-H+Cu₂(NO₃)₂]⁺) were observed at low cone voltage, thus these complexes must have already existed in the solution analysed. Therefore, such complexes may also exist under physiological conditions.      

Determination of nitrate based on the increase of electrical conductivity of polyacetylene film in acidified nitrate solutions

The electrical conductivity of polyacetylene, prepared as a free-standing film, changes drastically when treated with aqueous solutions of nitrate in the presence of sulphuric acid (5.7 M). Linear calibration plots are obtained for 2–40 × 10^?3 M nitrate. Common non-oxidating ions do not interfere.     

Lanthanide-nitrate interaction in anhydrous acetonitrile and coordination numbers of the lanthanide ions: FT‒IR study

The interaction between lanthanide ions Ln^III (Ln = La, Nd, Sm–Dy, Er, Yb) and nitrate ions is investigated by FT-IR spectroscopy in dilute anhydrous MeCN solution. The work is performed for ratios R = [NO]_t/[Ln^III]_t ranging from 0 to 8 and for solutions generally 0.05M in Ln^III, prepared from anhydrous lanthanide perchlorates Ln(ClO₄)₃. When nitrate is progressively added to the Ln(ClO₄)₃ solutions, the formation of [Ln(NO₃)_n]^(3?n)+ species is clearly evidenced by the FT-IR spectra. All the NO₃^? ions are coordinated and bidentate. A quantitative study was performed using the v₁ and v₆ vibrational modes for coordinated NO ions. The average coordination numbers estimated for Nd, Eu, Tb, and Er in solutions of trinitrates are 9.0, 9.1, 8.3 and 8.2, respectively (±0.3 unit). In presence of an excess NO, these numbers become 9.8, 10.2, 10.0, 9.8, 9.9, and 9.9 (±0.3 unit) for La, Nd, Eu, Tb, Er, and Yb, respectively. No hexanitrato species forms under the experimental conditions used (R up to 8). The structural aspect of the various nitrato species is also investigated. In the pentanitrato species, all the ligands appear to be equivalent, while large inequivalences are observed for Ln(NO₃)₃ solutions. Since for the latter most of the absorption bands assigned to nitrate vibrations contain several components, a curve-fitting procedure has been used for decomposing the v₂, v₄ and v₆ vibrations. There is a considerable difference between Ln^III ions, the nitrate inequivalences being larger in the middle of the series.     

CuAg nanoparticles formed in situ on electrochemically pre‐anodized screen‐printed carbon electrodes for the detection of nitrate and nitrite anions

CuAg nanoparticles (CuAgNPs) were electrochemically formed in situ on pre‐anodized, screen‐printed carbon electrodes (SPCEs) that possessed many oxygen‐containing functional groups capable of adsorbing metal ions, namely Cu²⁺ and Ag⁺. Pre‐anodization was achieved using continuous cyclic voltammetry in the range of potential 0.3–2.0 V under a scan rate of 50 mV/s. Cu²⁺ and Ag⁺ ions were adsorbed on the pre‐anodized SPCE by immersing the electrode in solutions containing both metal ions, and then CuAgNPs were formed in situ via electrochemical reduction in a deaerated, neat NaClO₄ solution after the electrode was ultrasonicated to remove physically adsorbed metal ions. Although CuNPs showed higher activity than AgNPs toward both nitrate (NO₃⁻) and nitrite (NO₂⁻) ions, the instability of CuNPs hindered the application, so CuAgNPs were employed to achieve a compromise between sensitivity and stability. The SPCE/anodized/CuAgNP electrodes showed activity toward the electrochemical reduction of NO₃⁻ and NO₂⁻, respectively, with the limit of detection (LOD) of 15.6 μM (0.97 ppm) and 11.1 μM (0.51 ppm), which is sufficient to fit the allowed values (50 and 3 ppm, respectively) in drinking water as suggested by the World Health Organization (WHO).     

Hydrogen-bonded Networks in Crown Ether Complexes of Hydrated Metal Ions

Abstract

The hydrated metal nitrates (M(NO₃)₃.6H₂O, M[dbnd]Co, Ni, Cu, Zn and Cd) have been crystallised from water in the presence of 18-crown-6 and their structures determined by X-ray crystallography. In the case of copper, a pseudo four-coordinate square planar complex resides in an extended six-coordinate octahedral array which is further bound in a single-stranded one-dimensional hydrogen bonded polymeric mode. For M[dbnd]Co,Ni,Zn and Cd isomorphous complexes are isolated where the octahedral [M(H₂O)₅(NO₃)⁺ cation resides in a two-dimensional polymeric network through hydrogen bonds between the water ligands and either the crown ether oxygens or unbound nitrate ions or water molecules.     

Extraction from mixed HCl−H2C2O4 solutions purification of some actinides

Carrier-free⁹⁰Y isotope was used to study the distribution between the aqueous solution of nitric acid and sodium nitrate and HDOP in cyclohexane. The distribution coefficients (D) were measured as a function of the acidity and the nitrate concentration (M_{NO 3}) in the aqueous phase. The acid dependence was studied in a HNO₃ concentration range of 1–14M. The curve IgD vs. lgM_{HNO 3} in the range of 1–4 gives a slope of 3. The anion effect of nitrate ions shows a complexing influence on the yttrium ions changing its distribution between the two phases. The results can be useful in hydrometallurgical processes in which the solutions are highly acidic and contain a large amount of the dissolved materials as nitrate salts.     

Electron impact,chemical ionization and negative chemical ionization mass spectra,and mass-analysed ion kinetic energy spectrometry–collision-induced dissociation fragmentation pathways of some deuterated 2,4,6-trinitrotoluene (TNT) derivatives

Mass-analysed ion kinetic energy spectrometry (MIKES) with collision-induced dissociation (CID) has been used to study the fragmentation processes of a series of deuterated 2,4,6-trinitrotoluene (TNT) and deuterated 2,4,6-trinitrobenzylchloride (TNTCI) derivatives. Typical fragment ions observed in both groups were due to loss of OR′ (R′ = H or D) and NO. In TNT, additional fragment ibns are due to the loss of R₂′O and 3NO₂, whilst in TNTCI fragment ions are formed by the loss of OCI and R₂′OCI. The TNTCI derivatives did not produce molecular ions. In chemical ionization (Cl) of both groups. MH⁺ ions were observed, with [M – OR′]⁺ fragments in TNT and [M – OCI]⁺ fragments in TNTCI. In negative chemical ionization (NCI) TNT derivatives produced M^?′, [M–R′]^?, [M–OR′]^? and [M–NO]^? ions, while TNTCI derivatives produced [M–R]^?, [M–Cl]^? and [M – NO₂]^? fragment ions without a molecular ion.     

Synthesis and Structure of Copper(II) Nitrate Complexes with 2, 6‐Bis(pyrazolyl)pyridine

Three mononuclear copper(II) complexes of copper nitrate with 2, 6‐bis(pyrazol‐1‐yl)pyridine ( bPzPy ) and 2, 6‐bis(3′,5′‐dimethylpyrazol‐1‐yl)pyridine ( bdmPzPy ), [Cu(bPzPy)(NO₃)₂] ( 1 ), [Cu(bPzPy)(H₂O)(NO₃)₂] ( 2 ) and [Cu(bdmPzPy)(NO₃)₂] ( 3 ) were synthesized by the reaction of copper nitrate with the ligand in ethanol solution. The complexes have been characterized through analytical, spectroscopic and EPR measurements. Single crystal X‐ray structure analysis of complexes 1 and 2 revealed a five‐coordinate copper atom in 1 , whereas 2 contains a six‐coordinate (4+2) Cu^II ion with molecular units acting as supramolecular nodes. These neutral nodes are connected through O–H ··· O(nitrate) hydrogen bonds to give couples of parallel linear strips assembled in 1D‐chains in a zipper‐like motif.     

Morphological studies of the mechanism of pit growth of pure aluminum in sulfate ion- or nitrate ion-containing 0.1 M NaCl solutions

The mechanism of pit growth of pure aluminum (Al) in sulfate ion (SO₄ ^2–)- or nitrate ion (NO₃ ^–)-containing 0.1 M sodium chloride solutions has been studied in terms of the morphological changes of artificial pits using potentiodynamic polarization experiment, potentiostatic current transient technique and optical microscopy. The increase in SO₄ ^2– and NO₃ ^– ion concentrations in NaCl solution raised the pitting potential E _pit of pure Al, which is ascribed to the impediment to pit initiation on pure Al by the addition of SO₄ ^2– or NO₃ ^– ions. From the potentiostatic current transients of artificial pits in aqueous 0.1 M NaCl solution, the average value of the pit current was observed to increase with increasing SO₄ ^2– ion concentration, whereas that value of the pit current in the presence of NO₃ ^– ions increased up to ca. 0.4 M NO₃ ^– ion concentration and then decreased abruptly with increasing NO₃ ^– ion concentration. From observations of the morphologies of the pits, it appears that the pit grows preferentially in the lateral direction or in the downward direction by adding SO₄ ^2– or NO₃ ^– ions to aqueous 0.1 M NaCl solution, respectively. Based upon the experimental results, two different pit growth mechanisms by anion additives can be proposed: (1) pit growth by the preferential attack of both SO₄ ^2– and Cl^– to the pit wall in SO₄ ^2–-containing solutions; (2) pit growth by the creation of an aggressive environment at the pit bottom up to 0.4 M NO₃ ^– ion concentration due to the lower mobility of NO₃ ^– than Cl^– in NO₃ ^–-containing solutions. Electronic Publication     

Thermal properties of 1,2,4-triazole-3-one and copper nitrate mixtures

1,2,4-Triazole-3-one (TO) is anticipated to have applications as a high performance alternative gas generating agent, while basic copper nitrate (BCN) is typically used as the oxidizing agent in air bag systems. In order to obtain a better understanding of the thermal properties of TO/BCN mixtures, thermal behavior was investigated using the differential scanning calorimetry. Mixtures of TO with copper, copper oxide, and trihydrated copper nitrate (Cu(NO₃)₂·3H₂O) were also examined for comparison purposes. Samples were prepared at TO/BCN ratios (on a per mass basis) of 10/0, 7/3, 5/5, 3/7, 2/8, 1.6/8.4, 1/9, and 0/10. The endothermic onset temperatures for TO/BCN mixtures were lower than those for either pure TO or pure BCN. TO/BCN mixtures exhibited an initial exothermic peak immediately after an endothermic peak, in the range of 219–234 °C. TO/BCN mixtures with ratios of 3/7, 2/8, 1.6/8.4, and 1/9 displayed a second series of exothermic peaks in the range of 260–300 °C, which appear to result from the oxidation–reduction reaction of previously formed intermediate species with NO₂ and NO generated by unreacted BCN. The TO/CuO mixtures are believed to undergo reaction between molten TO and CuO at approximately 230 °C. In general, the presence of copper was shown to be effective at promoting the decomposition of TO. The reaction between TO and Cu(NO₃)₂·3H₂O seems to be initiated by the melting of Cu(NO₃)₂·3H₂O, following which TO reacts with nitric acid resulting from the dissociation of Cu(NO₃)₂·3H₂O. Overall, the triggering event for the reaction between TO and each of the copper nitrate species is a phase change of one of the two mixture components.     

Ternäre Lithium-Selten-Erd-Nitrate mit einsamen Nitrationen: Li3[M(NO3)5](NO3) (M = Gd?Lu,Y). Die Kristallstruktur von Li3Er(NO3)6

Ternary Lithium Rare Earth Nitrates with Lonesome Nitrate Ions: Li₃[M(NO₃)₅](NO₃) (M = Gd? Lu, Y). The Crystal Structure of Li₃Er(NO₃)₆ Single crystals of the ternary nitrate Li₃Er(NO₃)₆ are obtained from a solution of “Er(NO₃)₃” in the melt of LiNO₃. In Li₃Er(NO₃)₆ (monoclinic, P2₁/n, Z = 4; a = 776.0(1); b = 748.86(8); c = 2 396(1) pm; β = 90.76(3)°; R1 = 0.0490; wR2 = 0.0792), Er³⁺ is surrounded by five bidentate nitrate ligands yielding the anionic units [Er(NO₃)₅]^2?. These are arranged in the direction of the 2₁ screw axis. Two lonesome NO₃^? ions are in the middle of such a “helix” and are connected by Li⁺ with the anions [Er(NO₃)₅]^2?. The helices are moved against each other by about half of the lattice constant a and are connected by further Li⁺ ions.     

Collision-Induced Dissociation Analysis of Negative Atmospheric Ion Adducts in Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry

Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R]^– formed between various types of organic compounds M and atmospheric negative ions R^- [such as O₂ ^–, HCO₃ ^–, COO^–(COOH), NO₂ ^–, NO₃ ^–, and NO₃ ^–(HNO₃)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R]^– adducts were fragmented to form deprotonated analytes [M – H]^– and/or atmospheric ions R^–, whose intensities in the CID spectra were dependent on the proton affinities of the [M – H]^– and R^– fragments. Precursor ions [M + R]^– for which R^- have higher proton affinities than [M – H]^– formed [M – H]^– as the dominant product. Furthermore, the CID of the adducts with HCO₃ ^– and NO₃ ^-(HNO₃) led to other product ions such as [M + HO]^– and NO₃ ^–, respectively. The fragmentation behavior of [M + R]^– for each R^– observed was independent of analyte type (e.g., whether the analyte was aliphatic or aromatic, or possessed certain functional groups).      

Synthese und Struktur der ersten Wasserfreien ternären Lithiumnitrate der Lanthanide,Li2[M(NO3)5] (M = La,Pr?Eu)

Synthesis and Structure of the First Anhydrous Ternary Lithium Nitrates of the Lanthanides, Li₂[M(NO₃)₅] (M = La, Pr? Eu). Single crystals of the ternary lithium nitrates of the lanthanides, Li₂[M(NO₃)₅] (M = La, Pr? Eu), are obtained by dissolving the respective anhydrous nitrate, previously obtained by dehydration of M(NO₃)₃ · 6 H₂O at 180°C under vacuum, in a melt of LiNO₃. In the crystal structure of Li₂[Pr(NO₃)₅] (orthorhombic, Pnnm, Z = 4, a = 899.6(2), b = 1 052.7(2), c = 1 178.6(2)pm; R = 0.072, R_w = 0.034) there are two crystallographically different Pr³⁺ ions, each surrounded by six bidentate nitrate ligands. One nitrate group is bridging between Pr1 and Pr2 resulting in a winded chain, [(O_2/2NO_2/1)Pr1(NO₃)₄(O_2/2NO_2/1)Pr2(O_2/2NO_2/1)(NO₃)₄]^5?, running along [010]. The chains are packed hexagonally and held together by lithium ions. The coordination polyhydron of Li⁺ may be described as a bicapped trigonal prism.     

Equilibrium and kinetics studies on adsorption of Cu(II) from aqueous solutions onto a graft copolymer of cross-linked starch/acrylonitrile (CLSAGCP)

A synthetic graft copolymer of cross-linked starch/acrylonitrile was used as an adsorbent for the removal of Cu(II) ions from an aqueous solution of copper nitrate hexahydrate Cu(NO₃)₂ · 6H₂O at different temperatures and fixed pH. The amount adsorbed increased with increasing concentration of Cu(II) ions and decreasing temperature. The length of time taken to reach equilibrium of the adsorption of Cu(II) ions was the same at all temperatures tested. Kinetics studies showed that the adsorption process obeyed first-order reversible kinetics and the adsorption isotherms followed the Freundlich model. Furthermore, the thermodynamic parameters, i.e. standard free energy (ΔG^∘), standard enthalpy (ΔH^∘), and standard entropy (ΔS^∘), of the adsorption process were calculated and the results are discussed in detail.     

Mutual separation of210Po,210Bi,and210Pb with solvent extraction using copper dithizonate −CCl4 and dithizone −CCl4 solutions

Displacement-extraction of tracer concentrations of²¹⁰Po in 1.0M (H, Na)NO₃ solutions has been studied by using copper dithizonate–CCl₄ solutions. Furthermore, based on the results of the displacement-extraction of polonium, a mixture of²¹⁰Po,²¹⁰Bi, and²¹⁰Pb of tracer concentrations in 1.0M (H, Na)NO₃ solutions could be satisfactorily separated with successive extractions by copper dithizonate–CCl₄ and dithizone–CCl₄ solutions in acidic conditions.     

New structures in the bi­pyridine–copper(II) nitrate–methanol system: [(bpy)2Cu(NO3)]NO3·CH3OH and [(bpy)2Cu(NO3)]NO3

Reaction of 2,2′‐bi­pyridine (bpy) and copper(II) nitrate in methanol results in two complexes, namely light‐blue bis(2,2′‐bi­pyridine)­nitrato­copper(II) nitrate methanol solvate, [Cu(NO₃)(C₁₀H₈N₂)₂]NO₃·CH₃OH, (I), which is unstable in air, and the product of its decomposition, catena‐poly­[[[bis(2,2′‐bi­pyridine)copper(II)]‐μ‐nitrato‐O:O′] nitrate], {[Cu(NO₃)(C₁₀H₈N₂)₂]NO₃}_n, (II). The crystal structures of both compounds were determined from one crystal at room temperature. Later, the structure of (I) was redetermined at low temperature. In (I) and (II), the Cu atom is coordinated by two bpy and one or two nitrate ions, respectively. The second nitrate ion in (I), along with the methanol solvent mol­ecule, is found in the outer coordination sphere, not bonded to Cu. The nitrate in (I) is chelating, while in (II), it bridges (bpy)₂Cu complexes, forming a one‐dimensional chain structure. The Cu cation in (II) lies on a twofold axis and the uncoordinated NO₃^? ion is located close to a twofold axis and is therefore disordered. Compound (I) converts into (II) upon loss of solvent.     

Conductivity monitoring of inorganic anions with a Cu(II)-containing poly(3-methylthiophene) electrode in single-column ion chromatography

An amperometric detector unit equipped with a Cu(II)-containing poly(3-methylthiophene) working electrode is described for the single-column ion chromatographic detection of electroinactive inorganic anions, such as F^?, Cl^?, Br^?, NO₂^? and NO₃^?. Chromatograms obtained with this unit and with a commercial conductivity detector are almost identical with regard to peak height. Thus, an amperometric unit employing this modified electrode can be used as a conductance monitor in ion chromatographic analysis. Although the responses of this electrode seem to be conductivity related, the detection principle is probably based on a dual mechanism involving equilibria between copper ions and various anions of the system in addition to simple conductivity changes associated with the passage of analyte plugs. This explains the difference in responses observed with platinum and stainless-steel electrodes used in the same cell configuration. The detector displays a linear range of at least two orders of magnitude on a logarithmic scale.     

Sequential Spectrophotometric Determination of Microgram Amounts of Nitrate and Nitrite in Mixtures

This paper describes three new methods: the first may be used for the determination of nitrite; the second is applicable to determination of nitrate; and the third permits sequential determination of both nitrite and nitrate in mixtures with no prior separation. For the determination of nitrite and nitrate in synthetic mixtures containing 1:5 to 5:1 ratios of the ions, in tap water, and in river water, mean recoveries (for 3 to 22 μg of added NO⁻₃and NO⁻₂) are 96.1 and 98.1% (n= 15) and coefficients of variation are 2.2 and 2.5% for NO⁻₃and NO⁻₂(n= 5), respectively.