<Superscript>13</Superscript>C-labeled bilirubin: synthesis of 3<Superscript>1</Superscript>(3<Superscript>2</Superscript>),17<Superscript>1</Superscript>(17<Superscript>2</Superscript>)-di-[<Superscript>13</Superscript>C]-mesobilirubin-XIIIα

Abstract  The title compound, labeled with ¹³C in the ethyl groups was synthesized from K¹³CN and low-molecular-weight components. The synthetic relay compound was 3¹(3²)[¹³C]-xanthobilirubinic acid methyl ester in a synthetic route that leads to a label in the ethyl β-substituent of a dipyrrinone model for bilirubin. This labeled dipyrrinone was oxidatively coupled to the dimethyl ester of mesobiliverdin-XIIIα, thereby providing a route to a ¹³C-labeled mesobiliverdin and mesobilirubin, with one carbon of each ethyl being 98% ¹³C-enriched. Graphical Abstract        

Interactions between AuCl<Subscript>4</Subscript><Superscript>−</Superscript> and CTA<Superscript>+</Superscript> ions in water

The solubility of hexadecyltrimethylammonium tetrachloroaurate (CTA·AuCl₄) in water was measured at different temperatures of 288.2, 293.2, 298.2, 303.2, and 308.2 K. The enthalpy change associated with the formation of the CTA·AuCl₄ precipitate was estimated on the basis of the van’t Hoff equation and was found to be −42.5 ± 2.8 kJ mol⁻¹ at 298.2 K. The calorimetric enthalpy change for the CTA·AuCl₄ precipitate formation was directly determined by isothermal titration calorimetry performed at 298.2 K and was found to agree well with that estimated from the van’t Hoff equation.     

Identification of Anionic Supramolecular Complexes of Sulfonamide Receptors with Cl<Superscript>−</Superscript>, NO<Stack><Subscript>3</Subscript><Superscript>−</Superscript></Stack>, Br<Superscript>−</Superscript>, and I<Superscript>−</Superscript> by APCI-MS

As part of a mass spectrometric investigation of the binding properties of sulfonamide anion receptors, an atmospheric pressure chemical ionization mass spectrometric (APCI-MS) method involving direct infusion followed by thermal desorption was employed for identification of anionic supramolecular complexes in dichloromethane (CH₂Cl₂). Specifically, the dansylamide derivative of tris(2-aminoethyl)amine (tren) (1), the chiral 1,3-benzenesulfonamide derivatives of (1R,2S)-(+)-cis-1-amino-2-indanol (2), and (R)-(+)-bornylamine, (3), were shown to bind halide and nitrate ions in the presence of (n−Bu)₄N⁺X⁻ (X⁻ = Cl⁻, NO₃⁻, Br⁻, I⁻). Solutions of receptors and anions in CH₂Cl₂ were combined to form the anionic supramolecular complexes, which were subsequently introduced into the mass spectrometer via direct infusion followed by thermal desorption. The anionic supramolecular complexes [M+X]⁻, (M=1–3, X⁻=Cl⁻, NO₃⁻, Br⁻, I⁻) were observed in negative mode APCI-MS along with the deprotonated receptors [M−H]⁻. Full ionization energy of the APCI corona pin (4.5 kV) was necessary for obtaining mass spectra with the best signal-to-noise ratios.     

Interaction of [В<Subscript>10</Subscript>H<Subscript>10</Subscript>]<Superscript>2–</Superscript> and [В<Subscript>12</Subscript>H<Subscript>12</Subscript>]<Superscript>2–</Superscript> with nitro compounds

The interaction of the [B₁₀H₁₀]^2– and [B₁₂H₁₂]^2– anions with aliphatic and aromatic nitro compounds (RNO₂, where R = Et, n-Pr, i-Pr, tert-Bu, Ph) has been studied under irradiation with visible and UV light. It has been shown that, depending on the reaction conditions, both mono- and disubstituted nitro-closo-decaborates can be selectively obtained in yields up to 50%.     

Validation of <Superscript>239,240</Superscript>Pu, <Superscript>238</Superscript>Pu separation method using molecular recognition product AnaLig<Superscript>®</Superscript> Pu02 gel and extraction chromatography TRU<Superscript>®</Superscript> resin

Two separation techniques for plutonium determination using AnaLig^® Pu02 molecular recognition technology product (MRT) and extraction chromatography TRU^® resin were tested. The methods performance was investigated by analysis of National Physical Laboratory (NPL-Alpha-Beta High, ABH 2003, 2005) intercomparison test samples. The results obtained for both procedures were compared in terms of activities and recoveries. Data analysis showed good agreement with the reference values. The AnaLig^® Pu02 separation method for ^239,240Pu, ²³⁸Pu determination was successfully validated with the same performance as the TRU^® resin method.     

Relativistic coupled cluster calculations of the electronic structure of KrH<Superscript>+</Superscript>, XeH<Superscript>+</Superscript> and RnH<Superscript>+</Superscript>

Potential energy curves of NgH⁺ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei, and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH⁺ and XeH⁺ are in good agreement with available experimental data, while those for RnH⁺ have been determined for the first time at this level of theory.     

Photochemical arene exchange in the naphthalene complex [CpRu(η<Superscript>6</Superscript>-C <Subscript>10</Subscript>H<Subscript>8</Subscript>)]<Superscript>+</Superscript>

The cation [CpRu(η⁶-C₁₀H₈)]⁺ was shown to exchange naphthalene for other arenes under visible-light irradiation to form the complexes [CpRu (η⁶-arene)]⁺ (arene = C₆H₆, 1,4-C₆H₄Me₂, 1,3,5-C₆H₃Me₃, or 1,2,4,5-C ₆H₂Me₄) in 70–95% yields. The reaction rate of exchange decreases in the series arene = 1,4-C₆H₄Me₂ > C₆H₆ > 1,3,5-C₆H₃Me₃ > 1,2,4,5-C ₆H₂Me₄ >> C₆Me₆ and increases with the coordinating ability of the solvent in the order CH₂Cl₂ < THF—CH₂Cl₂ mixture (1: 1) < acetone.     

A simple and quick method for the preparation of radionuclide <Superscript>87</Superscript>Y/<Superscript>87m</Superscript>Sr generator using the <Superscript>nat</Superscript>Rb(α,xn)<Superscript>87</Superscript>Y reaction

A rapid method for the preparation of ⁸⁷Y/^87mSr radionuclide generator from a rubidium chloride target irradiated with 35 MeV α-particles is described. A simple two-step procedure is used to obtain a carrier-free ^87mSr isotope with a high enough radiochemical yield and high purity in the final aqueous fraction.     

The effect of NO<Stack><Subscript>3</Subscript><Superscript>−</Superscript></Stack> and OH<Superscript>−</Superscript> ions on the laser ablation of Cs<Superscript>+</Superscript> ion on Type 304 stainless steel

Type 304 stainless steel specimens artificially contaminated with CsCl solution were treated with KOH solution and KNO₃ solution, respectively. Cs⁺ ion removal tests by a Q-switched Nd:YAG laser at 1064 nm at a given fluence of 57.3 J/cm² were performed. The surface morphology and the relative atomic mole ratio of the specimen surface were investigated by SEM and EPMA. The order of Cs⁺ ion removal efficiency of laser was no-treatment < KOH < KNO₃ during the 42 shots. From the investigation of XPS peaks around 532.7 and 292.9 eV, KNO₃ on a surface of specimen was found to be fully decomposed during the laser irradiation. It was suggested that Cs₂O particulates formed by the reaction between the reactive oxygen generated from the nitrate ion and Cs⁺ ion on the metal surface could be easily suspended. For the KOH system, FeOOH was formed during the laser irradiation and it changed into Fe₂O₃. It was also suggested that Cs₂O particulates were formed by the reaction between the reactive oxygen generated from the decomposition of K₂O and Cs⁺ ion on the metal surface..     

Primary photophysical and photochemical processes upon UV excitation of PtBr<Subscript>6</Subscript><Superscript>2–</Superscript> and PtCl<Subscript>6</Subscript><Superscript>2–</Superscript> complexes in water and methanol

Primary photophysical and photochemical processes were studied for Pt^IVBr₆ ^2– and Pt^IVCl₆ ^2– complexes in water and methanol by ultrafast kinetic spectroscopy upon excitation in the band region of charge transfer from the ligand-centered group π-orbitals to the e_g*-orbital of Pt^IV complex anion (LMCT bands). The data obtained earlier upon excitation in the region of d—d bands were compared. Irrespective of the excitation wavelength, the photochemical properties of complexes are caused by the reactions of intermediates proceeding in the picosecond time range. These intermediates were identified as Pt^IVBr₅ ^– upon photolysis of Pt^IVBr₆ ^2– and, presumably, the Adamson radical pair [Pt^IIICl₅ ^2–(C _4v )...Cl?] upon photolysis of Pt^IVCl₆ ^2–. The difference in the exciting light wavelengths has an impact only on the first step of these processes, i.e., transition from the Franck—Condon excited state to intermediates.     

Short-lived <Superscript>224</Superscript>Ra and <Superscript>223</Superscript>Ra isotopes in the Anadyr River–Bering Sea system

The first results of activity measurement of short-lived radium isotopes dissolved in water in the Anadyr River–Bering Sea transit system are presented. The trends of the radionuclide behavior after passage through high-gradient river–coastal sea water mixing zone were identified and the exchange rate of the horizontal mixing was determined. The ²²⁴Ra/²²³Ra activity ratio was used to construct the “radium age” model, which served for estimating the residence time of brackish water in the Anadyr River estuary. The factors affecting this value were elucidated.     

A study of the hydrolysis of ZrF<Stack><Subscript>6</Subscript><Superscript>2−</Superscript></Stack> and the structure of intermediate hydrolysis products by <Superscript>19</Superscript>F and <Superscript>91</Superscript>Zr NMR in the 9.4 T field

The high-field ¹⁹F and ⁹¹Zr NMR method is used to study the hydrolysis and polycondensation of hexafluorozirconate ZrF₆²⁻ in aqueous and water-peroxide solutions. During hydrolysis in aqueous solutions only ZrF₆²⁻ and F⁻ ions were observed by NMR, however, in the water-peroxide medium, an intermediate product of hydrolysis ([F₅Zr-OO-ZrF₅]⁴⁻ dimer) was detected. The dimer structure is confirmed by ¹⁹F and ⁹¹Zr NMR. In high fields (¹⁹F NMR frequency > 200 MHz), the fluorine exchange between ZrF₆²⁻ and F⁻ is slow in the ¹⁹F NMR scale and has a multisite character.     

Comparative study of Cl<Superscript>−</Superscript>, Br<Superscript>−</Superscript>, and I<Superscript>−</Superscript> ions adsorption from dimethyl formamide at Hg- and Ga-electrodes

The adsorption of Cl⁻, Br⁻, and I⁻ ions from their 0.1 M solutions in dimethyl formamide at renewable liquid Hg- and Ga-electrodes was studied under similar experimental conditions by the differential-capacitance and jet-electrode methods. The data obtained points out to a strong effect of the metal nature on adsorption parameters and the halogenide-ion surface activity series. The halogenide-ion surface activity at the Hg-electrode increased in the following sequence: Cl⁻ < Br⁻ < I⁻; at the Ga-electrode, in the reverse sequence: I⁻ < Br⁻ < Cl⁻. The results are explained qualitatively in terms of the Andersen-Bockris model. It follows from the obtained data that (1) the free energy of the metal-halogenide-ion interaction increases in the following sequence: I⁻ < Br⁻ < Cl⁻; (2) the free energy of the Ga-halogenide-ion interaction exceeds that of the Hg⁻halogenide-ion interaction; and (3) the difference of the Cl⁻, Br⁻, and I⁻ ions interaction with the metals increased significantly when passing from Hg⁻ to Ga-electrode.     

Electrical conductivity of potassium titanyl phosphate KTiOPO<Subscript>4</Subscript> pure crystals and those doped with Na<Superscript>+</Superscript>, Rb<Superscript>+</Superscript>, and F<Superscript>–</Superscript> ions

KTiOPO₄ crystals, both pure and doped with rubidium Rb⁺ and fluorine F^– ions, were grown in temperature range from 1060 to 846°С from salt solvent containing potassium metaphosphate КРО₃ and potassium orthophosphate К3РО₄ by using a Czochralski modified method. Potassium–sodium titanyl phosphate crystals were obtained from KTiOPO₄ crystals by the potassium isomorphic replacement with sodium; to this purpose, sodium chemical diffusion from NaNO₃ melt was used. Their ionic conductivity was studied by the electrochemical impedance spectroscopy method. The KTiOPO₄ crystal doping with rubidium and sodium ions was shown to lower the conductivity, whereas the doping with fluorine ions results in increased conductivity.     

Isothermal solubility diagram of the 2Na<Superscript>+</Superscript>,Mg<Superscript>2+</Superscript>‖2Cl<Superscript>−</Superscript>, 2ClO<Stack><Subscript>3</Subscript><Superscript>‒</Superscript></Stack>-H<Subscript>2</Subscript>O quaternary system at 20 and 100°C

The solubility in the 2Na⁺,Mg²⁺‖2Cl⁻, 2ClO₃⁻-H₂O system was studied at 20 and 100°C and the solubility diagrams were plotted. New compounds were not found to form in the title quaternary reciprocal system. The sodium chloride field was observed to expand with rising temperature.     

Extractive separation of Cu<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> and Ni<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> mixtures using <Emphasis Type="Italic">N</Emphasis>-salicylideneaniline

A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures.     

High performance liquid chromatographic separation of <Superscript>228,229</Superscript>Th and <Superscript>232,233</Superscript>U and their estimation by α- and γ-ray spectrometry

The activities of ^228,229Th and ^232,233U from an irradiated ThO₂ sample were radiochemicaly separated by using high performance liquid chromatography. Plancheted sources of the separated samples were made and the amount of ^232,233U and ^228,229Th were estimated by using alpha and gamma-ray spectrometric techniques. These estimations are important for the Th–U fuel reprocessing cycle of advanced heavy water reactor and accelerator driven sub-critical system.     

Quantum Chemical Study of Niobium and Tantalum M<Subscript>4</Subscript>O<Subscript>10</Subscript> Oxide Clusters and M<Subscript>4</Subscript>O<Stack><Subscript>10</Subscript><Superscript>–</Superscript></Stack> Anions

Structural parameters and vibrational frequencies of the clusters (T_d)–Nb₄O₁₀, (C_3v)-TaNb₃O₁₀, (D_2d)-Nb₄O ₁₀ ^– , and (C_s)-TaNb₃O ₁₀ ^– were calculated. According to the (U)DFT/SDD calculations with BLYP, B3LYP, and PBE0 functionals magnetization of the anion (D_2d)-Nb₄O ₁₀ ^– is distributed equally among four niobium atoms. In the anion (C_s)-TaNb₃O ₁₀ ^– unpaired electron presumably occupies niobium atoms. The distinction in contributions from Nb atoms in the magnetization of the tantalum-containing cluster grows with the exchange component of the DFT functional in the series of functionals BLYP < B3LYP < PBE0 < UHF.     

Measuring <Superscript>226</Superscript>Ra and <Superscript>232</Superscript>Th activity in soil and vegetation samples using a method of double γ-coincidences

A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement with ones obtained by the HPGe spectrometer.