<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        

Cyclotron production of <Superscript>211</Superscript>At/<Superscript>211g</Superscript>Po by <Superscript>209</Superscript>Bi(α,2n) reaction

Astatine-211 (T _1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g (T _1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm⁻¹) and a half-life suitable for metabolic radiotherapy; the overall α branching of the ²¹¹At/^211gPo system is 100%. The direct production of ²⁰⁹Bi(α,2n)²¹¹At/^211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using α-energy higher than 28.61 MeV in order to produce, via ²⁰⁹Bi(α,3n) reaction, small amounts of the γ-emitter ²¹⁰At (used as internal spike).     

Production possibility of <Superscript>186</Superscript>Re via the <Superscript>192</Superscript>Os(p,α3n)<Superscript>186</Superscript>Re nuclear reaction

Experimentally measured cross-sections are presented for the first time for the ¹⁹²Os(p,α3n)¹⁸⁶Re nuclear reaction up to 67 MeV. Highly enriched thin ¹⁹²Os targets (15 pcs), prepared by electro-deposition onto Cu backings, were irradiated with an external proton beam delivered by the SSC cyclotron of iThemba LABS. The excitation function curve of the ¹⁹²Os(p,α3n)¹⁸⁶Re reaction shows a maximum cross-section of ~82 mb at about 24 MeV. According to the yield calculations based on the present results, the available cumulative no-carrier-added ¹⁸⁶Re yield is 7.76 MBq/μAh (0.21 mCi/μAh) over the energy region 13.4 → 27.3 MeV.     

CN (<Emphasis Type="Italic">B</Emphasis><Superscript>2</Superscript>Σ<Superscript>+</Superscript> → <Emphasis Type="Italic">X</Emphasis><Superscript>2</Superscript>Σ<Superscript>+</Superscript>) Violet System in a Cold Atmospheric-Pressure Argon Plasma Jet

\( {\text{CN}} (B^{2}\Sigma ^{ + } \to X^{2}\Sigma ^{ + } ) \) violet system was investigated using optical emission spectroscopy in a non-equilibrium microwave atmospheric-pressure plasma jet in argon expanding in air. From the analysis of the emission spectra of the discharge in the range of 380 and 400 nm, the violet system of CN was found to be overlapped with the \( {\text{N}}_{2}^{ + } \left( {B^{2}\Sigma _{u}^{ + } , v = 1 \to X^{2}\Sigma _{g}^{ + } , v = 1} \right) \) and \( {\text{N}}_{2} \left( {C^{3}\Pi _{u} \to B^{3}\Pi _{g} } \right) \) bands, sequence \( \Delta \upsilon = - \;3 \). A numerical disentangle technique, developed in this work, permitted to obtain a well resolved violet system from the different systems observed, namely the nitrogen First Negative and the Second Positive systems. The \( {\text{CN}} (B^{2}\Sigma ^{ + } \to X^{2}\Sigma ^{ + } ) \) band head intensity was determined and analysed as function of discharge powers between 30 and 150 W and fluxes between 2.5 and 10.0 slm. With aid of this numerical approach it was also possible to obtain the rotational temperature, from (1600 ± 100) to (2300 ± 100) K and vibrational temperature between (9000 ± 800) and (14,000 ± 800) K along the plasma jet. The kinetics of \( {\text{CN}} (B^{2}\Sigma ^{ + } ) \) state was analysed as well.     

Isomeric yield ratio of <Superscript>152m1</Superscript>Eu(8<Superscript>−</Superscript>)–<Superscript>152m2</Superscript>Eu(0<Superscript>−</Superscript>) produced in (γ, n) photonuclear reaction in the giant dipole resonance region

In this work, the isomeric ratio of ^152m1Eu(8^?)–^152m2Eu(0^?) produced from the ¹⁵³Eu(γ, n)¹⁵²Eu reaction have been measured in the whole giant dipole resonance region by the activation method. In order to improve the accuracy of the experimental results, the necessary corrections were made in the gamma activity measurements and data analysis. The results were discussed and compared with the similar data from literature to examine the excitation energy, the spin difference and the nuclear reaction channel effects and can be used for the interpretation on the structure of the nucleus and the mechanisms of nuclear reactions. The data for bremsstrahlung end-point energies of 19–23 MeV are first-time measurements.     

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.     

Synthesis and crystal structure of a cyanide-bridged one-dimensional nickel(II) complex with alternating [Ni(En)<Superscript>2</Superscript>]<Superscript>2+</Superscript> and [Ni(CN)<Subscript>4</Subscript>]<Superscript>2−</Superscript> ions

The complex [Ni(En)₂][Ni(CN)₄] · 3.5H₂O (I) (En = ethylenediamine) was synthesized by the reaction of [Ni(En)₂](ClO₄)₂ and K₂[Ni(CN)₄] in an H-shaped tube. The crystal structure of I has been determined by single-crystal X-ray analysis. The crystal of complex I is orthorhombic, space group Pnna with a = 28.151(3), b = 8.3946(8), c = 14.5441(13)Å, M =404.76, Z = 8, V = 3437.0(5)ų. The structure of complex I reveals infinite zigzag chains shaped structure are formed by cis-Ni(En)₂-μ-(NC)₂, cis-μ-(NC)₂Ni(CN)₂, and trans-μ-(CN)₂Ni(En)₂.     

Gas-phase electronic absorption spectroscopy of substituted bis(η<Superscript>6</Superscript>-benzene)chromium derivatives: Rydberg transitions in bis(η<Superscript>6</Superscript>-anisole)chromium and bis(η<Superscript>6</Superscript>-2,6-dimethylpyridine)chromium

Gas-phase electronic absorption spectra of chromium bisarene complexes with oxygen- and nitrogen-containing ligands, (⁶-PhOMe)₂Cr (1) and (⁶-2,6-Me₂C₅H₃N)₂Cr (2), were first measured. Rydberg bands disappearing on going to the condensed-phase spectra were revealed. The first ionization potentials of complexes 1 and 2 (5.30 and 5.40 eV, respectively) were determined from the Rydberg frequencies. The Rydberg transitions were assigned and the corresponding Rydberg term values and quantum defects were determined. The effect of heteroatoms on the Rydberg structure parameters was revealed by comparing the spectra of complexes 1 and 2 with those of unsubstituted analogs. The appearance, in the ligand side chain, of an oxygen atom capable of being involved in conjugation with the -electron system of the aromatic ring results in substantial broadening of the observed Rydberg bands. This can be associated with an increased ligand contribution to the HOMO of the sandwich compound. The influence of the oxygen atom on the ionization energy of the molecule is insignificant. In contrast to this, introduction of a nitrogen atom into the carbocycle leads to a noticeable increase in the ionization potential of the molecule, while the ligand contribution to the HOMO of the complex remains practically unchanged.Based on materials of a lecture presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (Moscow, May 30–June 4, 2004).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1854–1859, September, 2004.     

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.     

Structure and stability of endohedral complexes <Superscript>4/2</Superscript>X@(HAlNH)<Subscript>2</Subscript> (X = N,P, As,C<Superscript>−</Superscript>, Si<Superscript>−</Superscript>)

The structures of a closo-hedral cluster (HAlNH)₁₂ and endohedral complexes ^4/2X@(HAlNH)₁₂ (X = N, P, As, C⁻, Si⁻) are studied by density functional theory (DFT) at the B3LYP/6-31G(d) level. The geometries, natural bond orbital (NBO), vibrational frequency (ν₁), energetic parameters, magnetic shielding constants (σ), and nucleus independent chemical shifts (NICSs) are discussed. It is found that all guest species are minima at the cage center. Inclusion energies (ΔE _inc) of all species are negative except those of ⁴N and ^4/2P. In all species, the endohedral quartet states (⁴X) are energetically less favorable than their doublet states (²X). The calculations predict that caged X states only donate <0.50 e to the cage and preserve their unencapsulated ground states.     

Chemical Bonding in the Complexes XeF<Stack><Subscript>5</Subscript><Superscript>+</Superscript></Stack>XF<Stack><Subscript>6</Subscript><Superscript>−</Superscript></Stack> (X = P,As, Sb,and Bi)

Ab initio quantum-chemical calculations of the complexes XeF ₅ ⁺ XF ₆ ^? (X = P, As, Sb, and Bi) were performed with the use of relativistic pseudopotentials for heavy atoms and full-electron basis sets. The chemical bonds were characterized by the parameters of critical points (electron density, its Laplacian, total electron energy, and its kinetic and potential components). It was demonstrated that the interaction between the XeF ₅ ⁺ cation and the XF ₆ ^? anion in XeF ₅ ⁺ XF ₆ ^? follows a key-lock scheme involving directed interactions of bridging fluorine atoms F_b → Xe and that the structuring function of the lone electron pair of the Xe atom is to compensate the destabilizing electrostatic interaction between the Xe and X atoms bearing excess positive charges.     

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.     

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.     

Study on the thermal behavior of the complexes of the type [PdX<Subscript>2</Subscript>(tdmPz)] (X = Cl<Superscript>−</Superscript>, Br<Superscript>−</Superscript>, I<Superscript>−</Superscript>, SCN<Superscript>−</Superscript>)

Four new mononuclear Pd(II) complexes of the type [PdX₂(tdmPz)] {X = Cl⁻ (1); Br⁻ (2); I⁻ (3); SCN⁻ (4); tdmPz = 1-thiocarbamoyl-3,5-dimethylpyrazole} have been synthesized and characterized by elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H}-NMR experiments. The thermal behavior of the complexes 1–4 has been investigated by means of thermogravimetry (TG) and differential thermal analysis (DTA). From the initial decomposition temperatures, the thermal stability of the complexes can be ordered in the sequence: 3 < 4 ≡ 2 < 1. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.     

Nature of interaction energy anisotropy in the Li(<Superscript>2</Superscript>S)–HF (˜X<Superscript>1</Superscript>Σ<Superscript>+</Superscript>) van der Waals complex. A theoretical study

The potential-energy surface for the Li(²S)–HF (? X¹Σ⁺ interaction, where HF is kept rigid, is calculated using the supermolecular unrestricted fourth-order Møller–Plesset perturbation theory. The basis set superposition error corrected potential indicates two minima. The global minimum occurs for the bent Li...FH structure at R=1.95 Å and θ=70° with a relatively deep well of D_e=1,706 cm^?1 and the secondary minimum is found for the linear Li...HF configuration at R=4.11 Å with a well depth ofD_e=288 cm^?1. A barrier of 177 cm^?1 (with respect to the secondary linear minimum) separates these two minima. In this study 27 bound states of the bent Li...FH minimum and eight bound states of the linear Li...HF minimum up to the Li+HF dissociation threshold are calculated. The energy partitioning using the intermolecular perturbation theory scheme shows that the origins of the stability of the structures studied are entirely different. The global minimum is stabilised using the attractive Coulombic interaction and unrestricted Hartree–Fock deformation energy. The latter term originates from the mutual electric polarisation effects. The secondary linear minimum is mostly determined by the anisotropy of the repulsive Heitler–London exchange-penetration and attractive dispersion energies.     

Preparation of <Superscript>235m</Superscript>U targets for <Superscript>235</Superscript>U(n,n′)<Superscript>235m</Superscript>U cross section measurements

This paper describes the preparation of samples for an experiment to measure the cross-section for ²³⁵U(n,n′)^235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of ^235mU have been prepared for the calibration of the internal conversion electron detector that is used for the ^235mU measurement. Two methods are described for the preparation of ^235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha recoil collection method. Thin, uniform samples of ^235mU+²³⁵U were prepared for the experiment using electrodeposition.     

Synthesis,structural and multinuclear natural abundance (<Superscript>13</Superscript>C, <Superscript>31</Superscript>P, <Superscript>195</Superscript>Pt) CP/MAS NMR studies of crystalline O,O′-dialkyldithiophosphate platinum(II) complexes

Platinum(II) O,O′-dicyclohexyl dithiophosphate [Pt{S₂P(O-cyclo-C₆H₁₁)₂}₂] (I) and platinum(II) O,O′-diisopropyl dithiophosphate [Pt{S₂P(O-iso-C₃H₇)₂}₂] (II) complexes were obtained and studied by solidstate ¹³C, ³¹P, and ¹⁹⁵Pt CP/MAS NMR spectroscopy. The dithiophosphate (Dtph) ligands in molecular structure I were found to be coordinated by platinum in S,S′-bidentate fashion to form the planar chromophore [PtS₄] (single-crystal X-ray diffraction data). For complex II, a new α-form (α-II) was obtained and identified by ³¹P MAS NMR spectroscopy. The ³¹P chemical shift anisotropy δ_aniso and the asymmetry parameter η of the ³¹P chemical shift tensor were calculated from the whole MAS spectra.     

Stabilization of [Sc(NCS)<Subscript>6</Subscript>]<Superscript>3−</Superscript> anion by [M(18C6)]<Superscript>+</Superscript> complexes in solvation systems

The [M(18C6)]₄[Sc(NCS)₆]Cl · nH₂O complexes were established to form in the solutions ScCl _x -Solv-MNCS-18C6, where Solv is ethanol, THF, acetonitrile, or isopropyl alcohol; M = Na, K; 18C6 is 1,4,7,10,13,16-hexaoxocyclooctadecane. X-ray diffraction analysis of [K(18K6)]₄[Sc(NCS)₆]Cl · 3.33H₂O showed that the thiocyanate ion was coordinated by Sc through the N atom. The structure consists of octahedral Sc(NCS) ₆ ^3? that are united via nonvalent K-S interaction with macrocyclic dimers [M(18C6)]₂ into chains. Each 18C6 molecule coordinates one K atom.