Theoretical evaluation of the radiative lifetimes of LiCs and NaCs in the A<Superscript>1</Superscript>Σ<Superscript>+</Superscript> state

Calculations of the adiabatic potential energy curves and the transition dipole moments between the ground (A¹Σ⁺) and the first excited (A¹Σ⁺) states have been determined for the LiCs and NaCs molecules. The calculations are performed using an ab initio approach based on non-empirical pseudopotentials for Cs⁺, Li⁺ and Na⁺ cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The potential energy curves and the transition dipole moment are used to estimate the radiative lifetimes of the vibrational levels of the A⁺Σ⁺ state using the Franck–Condon (FC) approximation and the approximate sum rule method. The radiative lifetimes associated with the A⁺Σ⁺ state are presented here for the first time. These data can help experimentalists to optimize photoassociative formation of ultracold molecules and their longevity in a trap or in an optical lattice.     

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.     

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.     

<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        

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.     

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.     

Pulse radiolysis study of the oxidation of the I<Superscript>−</Superscript> ions with the radical anions Br<Subscript>2</Subscript><Superscript>·−</Superscript> in an aqueous solution: formation and properties of the radical anion BrI<Superscript>·−</Superscript>

The radiation chemical redox transformations in solutions of bromides in the presence of minor additives of iodides were studied by pulse radiolysis. The change in the concentrations of the Br⁻ and I⁻ ions changes the ratio of the formed short-lived radical anions Br₂ ^·−, BrI^·−, and I₂ ^·−. The spectrum of the mixed radical anion BrI^·− contains a broad optical band at 370 nm with ɛ₃₇₀ = 9650 L mol⁻¹ cm⁻¹. The reduction potential of the BrI^·−/Br⁻, I⁻ pair is 1.25 V. The rate constants for the forward and backward reactions Br₂ ^·− + I⁻ ⇌ BrI^·− + Br⁻ are k _f = 4.3·10⁹ and k _r = 1.0·10⁵ L mol⁻¹ s⁻¹, respectively; for the reactions BrI^·− ⇌ Br⁻ + I^·, k _f = 5.7·10⁸ s⁻¹ and k _r = 1.0·10¹⁰ L mol⁻¹ s⁻¹. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1787–1792, September, 2008.     

Quantum-chemical simulation of the elementary step of the oxidation reactions of styrene and its derivatives involving <Superscript>1</Superscript>О<Subscript>2</Subscript> (<Superscript>1</Superscript>Δg)

The results of simulation of the oxidation reaction of styrene and its methyl (two isomers) and phenyl derivatives with molecular oxygen in the excited singlet state (¹Δg) have enabled the conclusion that the reaction can proceed through several mechanisms. For styrene and its phenyl derivative, three reaction channels are possible, and for the methyl derivative, there are four possible channels. For the first two substrates, the major channel is 1,2-addition to form dioxetane; for the methyl derivatives, an extra channel to give a hydroperoxide species is possible in addition to the above channel. The multichannel reaction character revealed by calculations makes it possible to qualitatively understand the reason behind the moderate selectivity (no more than 70%) of such reactions in the case of styrene and its derivatives.     

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.     

Experimental Determination of the Isotherm at 15°C of the System Mg<Superscript>2+</Superscript>/Cl<Superscript>−</Superscript>, SO<Subscript>4</Subscript><Superscript>2</Superscript>–H<Subscript>2</Subscript>O

Summary.  The diagram of the ternary system Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO₄·6H₂O, MgSO₄·7H₂O, and MgCl₂·6H₂O. The solubility field of MgSO₄·7H₂O is important whereas those of MgSO₄·6H₂O and MgCl₂·6H₂O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO₄:MgCl₂=2.73:33.80 and MgSO₄: MgCl₂=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.  Corresponding author. E-mail: ariguib@planet.tn Received October 16, 2002; accepted (revised) December 3, 2002 Published online April 24, 2003 RID="a" ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70^th birthday     

Synthesis of the [<Superscript>2</Superscript>H,<Superscript>15</Superscript>N]-labeled antiviral drug “triazavirine”

Selective methods for the incorporation of stable isotopes ¹⁵N and ²H into the structure of antiviral medicine “triazavirine” 1 were developed. The synthesized isotopically modified “triazavirine” 1– ² H ₃ , ¹⁵ N ₃ contained the labeled atoms in both the azole and the azine rings. ¹³C and ¹⁵N NMR spectra of the isotope-containing sample 1– ² H ₃ , ¹⁵ N ₃ were thoroughly analyzed.     

Crystallinity of Dynasan<Superscript>®</Superscript>114 and Dynasan<Superscript>®</Superscript>118 matrices for the production of stable Miglyol<Superscript>®</Superscript>-loaded nanoparticles

This study focuses on the physicochemical characterization of lipid materials useful for the production of the so-called solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). The chosen lipids were Dynasan^®114 (glyceril trimyristate) and Dynasan^®118 (glyceril tristearate) as solid lipids (SL), melting temperature above 80 °C, and Miglyol^®812 (caprylic/capric triglyceride) and Miglyol^®840 (propylene glycol dicaprylate/dicaprate) as liquid lipids (LL), crystallizing below ?15 °C. Raw lipids (pure or SL:LL mixtures) were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and Polarized Light Microscopy (PLM), before and after tempering at 80 °C for 1 h. The selected SL:LL combination was 70% (Dynasan^®114 and 118) and 30% (Miglyol^®812 and 840) for the production of SLN and NLC by high-pressure homogenization (HPH), respectively. Particles with a mean size of 200 nm (polydispersity index <0.329) and zeta potential of ?15 mV were obtained, and their long-term stability was confirmed for 3 months of storage at 7 °C.     

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..     

Triboluminescence of zirconium η<Superscript>5</Superscript>-complexes

This work describes a comparative study of tribo- and photoluminescence of metallocenes (Cp₂HfCl₂, Cp₂TiCl₂, Cp₂ZrCl₂, (CpMe)₂ZrCl₂, rac-Me₂C(3-Bu^t-Cp)₂ZrCl₂, Ind*₂ZrCl₂). Occurring under mechanodestruction of polycrystals, triboluminescence of zirconium bis-cyclopentadienyl complexes, Cp₂ZrCl₂, (CpMe)₂ZrCl₂, and rac-Me₂C(3-Bu^t-Cp)₂ZrCl₂ has been revealed for the first time. The triboluminescence spectrum in air is similar to the photoluminescence spectrum of zirconocene polycrystals. The triboluminescence spectrum does not show *N₂ luminescence. Ne and Ar lines are observed in the triboluminescence spectrum in the atmosphere of these gases. An increase in the number of substituents in zirconocene ligands leads to a bathochromic shift of the emission band maximum in triboluminescence spectra of the complexes. Possible mechanisms of zirconocene triboluminescence excitation are discussed.     

Stereo-dynamics study of O + HCl → OH + Cl reaction on the <Superscript>3</Superscript>A″, <Superscript>3</Superscript>A′, and <Superscript>1</Superscript>A′ states

Using three accurate potential energy surfaces of the ³A″, ³A′, and ¹A′ states constructed recently, we present a quasi-classical trajectory (QCT) calculation for O + HCl (v = 0, j = 0) → OH + Cl reaction at the collision energies (E _col) of 14.0–20.0 kcal/mol. The three angular distribution functions—P(q_r ) P(\theta_{r} ) , P(j_r ) P(\varphi_{r} ) , and P(q_r ,j_r ) P(\theta_{r} ,\varphi_{r} ) , together with the four commonly used polarization-dependent differential cross-sections, \frac2ps \fracds₀₀ dw_t , \frac2ps \fracds₂₀ dw_t , \frac2ps \fracds_{22 +} dw_t , \textand \frac2ps \fracds_{21 -} dw_t {\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{00} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{20} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{22 + } }}{{d\omega_{t} }}},\,{\text{and}}\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{21 - } }}{{d\omega_{t} }}} are exhibited to get an insight into the alignment and the orientation of the product OH radical. There is a similar behavior of the tendency scattering direction for the two triplet electronic states (³A″ and ³A′)—backward scattering dominates, however, forward scattering prevails for the case of ¹A′ state. Also, obvious differences have been found in the stereo-dynamical information, which reveals the influences of the potential energy surface and the collision energy. The degrees of polarization and the influence of the collision energy on the stereo-dynamics characters of the title reaction are both demonstrated in the order of ³A′ > ³A″ > ¹A′.     

Photochemistry of the IrCl<Subscript>6</Subscript><Superscript>2−</Superscript> complex in aqueous solutions in the presence of the bromide anions

Laser flash photolysis (308 nm) was applied to study photochemistry of the IrCl₆ ²⁻ complex in aqueous solutions in the presence of the Br⁻ anions. The formation of the Br₂ ^·− radical anions in the reaction between the Br⁻ ion and secondary radical pair formed after the photon absorption by the initial complex was observed. The Br₂ ^·− radical anions decay both in recombination and in the reaction with the initial IrCl₆ ²⁻ complex.     

Counterion effects on the isotopic properties of the Cl<Superscript>−</Superscript> and Li<Superscript>+</Superscript> ions in aqueous solutions

The reduced partition function ratios between isotopic forms (β-factors) were calculated by the ab initio RHF/6-311++G**(3df, 3p) and MP2/6-311++G**(3df, 3p) quantum-chemical methods for hydrated chloride ion and ion pair hydrates NaCl·nH₂O and LiOH · nH₂O. The influence of the Na⁺ cation on the β-factor value and the chlorine isotope separation factor in the precipitation of NaCl from concentrated aqueous solutions was found to be substantial. At the same time, the presence of OH^? counterions had no noticeable effect on the β-factor of the hydrated Li⁺ cation.     

Influence of ion size on the stability of chloroplumbates containing PbCl<Stack><Subscript>5</Subscript><Superscript>−</Superscript></Stack> or PbCl<Stack><Subscript>6</Subscript><Superscript>2−</Superscript></Stack>

The enthalpies of formation of PbCl₄, PbCl₅⁻ and PbCl₆²⁻, originating from quantum mechanics, have enabled the thermodynamic behaviour of these ions with respect to Cl-detachment to be assessed. The stability of salts containing PbCl₅⁻ and PbCl₆²⁻ as a function of the dimensions of these anions and complementary cations was studied using an approach combining the Kapustinskii-Yatsimirskii equation with basic thermochemical relationships. It was found that hexachloroplumbates of monovalent metal cations will not dissociate into metal chlorides and PbCl₄, provided the complementary cations are suitably large in size. Hexachloroplumbates of divalent metal cations have not yet been synthesised since no known metal cations attain the requisite large size. Such salts will not dissociate if the divalent metal cations are able to complex suitably large electron-donating ligands. The pentachloroplumbates of both monovalent and divalent metal cations are unstable, since no known metal cations have appropriately large ionic radii. The approach adopted appears to be useful for the examination of the thermal behaviour, stability and reactivity of chloroplumbates.     

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.     

Separation of phosphorous by liquid–liquid extraction for the measurement of <Superscript>32</Superscript>P

Phosphorous containing radioisotope waste was separated and determined by liquid–liquid extraction method through liquid scintillation counter (LSC). In this process, ammonium phosphate was converted to phosphomolybdate (PMo) by the reaction of ammonium molybdate (Mo) in HCl solution (0.02 M) and maximum UV/VIS absorbance (λ_max) 218 nm was observed. The PMo solution was extracted with TOA (Tri-n-Octylamine)/xylene mixture and λ_max 290 nm was found for this organic layer. Absorbance of aqueous and organic layer was linear through concentration. The impurities such as Co, Cr, Gd, etc. remain in aqueous layer by treating with Mo which was determined by ICP-AES and AAS. The quenching correction curve for ³²P was calculated using LSC results. No counting change was observed as the volume of quenchers increased. The recovery was 98% and 81% for the extraction and separation process from the test using H₃³²PO₄ as standard tracer.