ZrO<Subscript>2</Subscript>–Carbon nanotubes composite sorbent for treatment of aqueous solutions to remove boron

A composite adsorbent based on zirconium dioxide hydrosol and functionalized carbon nanotubes for removing soluble boron compounds from aqueous solutions was synthesized by the sol–gel method. Measurements of the borate adsorption on the synthesized adsorbent samples showed that introduction of carbon nanotubes into ZrO₂ sols used for preparing the adsorbents enhanced the adsorption ability of the adsorbents.     

The remarkable chemistry of trannulenes: green fluorinated fullerenes with unconventional aromaticity

We report the first reaction of trannulenes involving their thermal isomerization to a new class of compounds termed "triumphenes". The thermodynamically controlled conversion of trannulenes into triumphenes is accompanied by an unprecedented migration of three organic addends from one hemisphere of the fullerene cage to another. The reaction products, bearing aliphatic substituents, might find applications in materials science as strong electron acceptors due to the presence of fifteen electron-withdrawing fluorine atoms in their molecular framework. It was revealed that the isomerization of trannulenes can be affected by the presence of unsaturated compounds in the reaction mixture. Heating of trannulenes C(60)F(15)R(3) with C(60), C(70), anthracene, or pentacene at reflux in 1,2-dichlorobenzene yields fluorinated derivatives C(60)F(14)R(2)A, which possess a fused cyclic addend A. The products of this reaction have "triumphene-type" addition patterns and seem to be formed through an unprecedented sequence of elimination, addition, and isomerization steps. The molecular structure of a representative triumphene was proven unambiguously by X-ray single-crystal diffraction analysis and by NMR spectroscopy. The reactions revealed here open up numerous opportunities for chemical derivatization of fluorinated fullerenes. This method promises to provide a new path towards valuable photoactive materials and a new generation of fullerene-based compounds that are suitable for biomedical applications.     

Mechanism of Spectrum Excitation in a Solid Aerosol-Laden Plasma Jet of a Two-Jet Argon Arc Plasmatron

A possible reason for the high intensity of the ion emission in the spectrum excitation in a plasma jet generated by a two-jet argon arc plasmatron was considered. The injection of a test substance as an air–solid suspension between the plasma jets (i.e., mixing of a hot plasma with a cold directional carrier-gas flow) created a radial temperature gradient and induced an intense argon influx from the dense plasma jets to the cold axial plasma zone used for analytical purposes. Favorable conditions were thus created for the analyte Penning impact ionization with argon ions. This was confirmed by the existence of a correlation between an increase in the intensity of ion lines with the carrier-gas flow rate (cooling rate) and the total energy of ionization and excitation of an element. It was shown that charge transfer from the argon ion to the analyte occurred only in the case when the total energy of the element was lower than 16 eV, i.e., lower than the ionization energy of argon plus its kinetic energy.     

Crystal structure of cobalt(III) compound with ethylenediamine-N,N′-Di-3-propionic acid, [Co(H2 Eddp)(HEddp)]Br2 ⋅ 4H2O

The crystal structure of [Co(H₂ Eddp)(HEddp)]Br₂ ? 4H₂O is determined [R1 = 0.0551 and wR2 = 0.1298 for 2580 reflections with I > 2σ(I)]. The structure consists of the [Co(H₂ Eddp)(tHEddp)]²⁺ cationic complexes, Br^? anions, and molecules of crystallization water. Two tridentate ligands, which differ in the degree of protonation, coordinate the Co atom by two N atoms and one O atom, each forming a meridional isomer. In the complex, the configurations of the N(2) and N(4) atoms, which are included in two chelate rings each, differ from those of the N(1) and N(3) atoms, which are included only in the five-membered rings and bear uncoordinated propionate groups. The Co-N(1) and Co-N(3) bonds are longer than the Co-N(2) and Co-N(4) bonds (mean 1.987 and 1.957 Å, respectively). The Co-O(5) bond with the neutral ligand is longer than the Co-O(1) bond with the negatively charged carboxyl group (1.927 and 1.901 Å, respectively). The C(13)-O(5) carbonyl bond in the coordinated COOH group is elongated to 1.266 Å. The system of hydrogen bonds interlinks the cationic complexes, Br^? anions, and water molecules into a three-dimensional framework.     

Complexes in the Ni2+-imidazole-RN(CH2COO−)2 systems. The crystal structures of tris(imidazole)iminodiacetatonickel(II) monohydrate, hexa(imidazole)nickel(II) bis(N-methyliminodiacetato)nickelate(II) hexahydrate, and tetra(aqua)bis(imidazole)nickel(II) bis(N-benzyliminodiacetato)nickelate(II)

Crystals of different compositions, namely, [Ni(Ida)(Im)₃] ? H₂O (I), [Ni(Im)₆][Ni(Mida)₂] ? 6H₂O (II), and [Ni(Im)₂(H₂O)₄][Ni(Bida)₂] (III), have been precipitated from aqueous solutions of the Ni²⁺-Lig ^2?-Im systems, where Lig ^2? is Ida, Mida, and Bida, respectively. The crystal structures of I–III are determined by X-ray diffraction analysis (R = 0.0307, 0.0348, and 0.0302 for 3061, 4706, and 2882 reflections, respectively). Crystals I are built of monomeric mixed-ligand complexes and molecules of crystallization water, which are interlinked by hydrogen bonds into a three-dimensional framework. In II and III, the ligands Lig ^2? and Im form charged complexes separately. In II, the cationic and anionic layers of the complexes alternate along the c-axis. Numerous hydrogen bonds involving molecules of crystallization water link the layers into a three-dimensional framework. In III, the cationic and anionic complexes, which serve as proton donors and acceptors, respectively, are bound into layers parallel to the xy plane.     

Crystal structures of strontium and barium ethylenediaminetetraacetato cobaltates(III), Sr[CoEdta]2·9H2O and Ba[CoEdta]2·8H2O: Comparison of the structures of complexes in the series M’[CoEdta]2·nH2O (M’ = Mg, Ca, Sr, Ba; n = 7–10)

Cobalt(III) complexes, namely, Sr[CoEdta]₂·9H₂O (I) and Ba[CoEdta]₂·8H₂O (II) (where Edta ^4- is the ethylenediaminetetraacetate ion), are synthesized. The crystal structures of these compounds are determined using X-ray diffraction. Crystals of compound I are triclinic, a = 6.514(1) Å, b = 11.410(2) Å, c = 12.317(2) Å, α = 67.87(1)°, β = 88.73(2)°, γ = 84.22(2)°, V = 843.63(3) ų, Z = 1, space group P1, and R = 0.0295 for 4130 reflections with I > 2σ(I). Crystals of compound II are monoclinic, a = 6.543(2) Å, b = 12.895(3) Å, c = 19.489(4) Å, β = 95.24(3)°, V = 1637.5(5) ų, Z = 2, space group P2₁, and R = 0.050 for 3016 reflections with |F| > 3σ(|F|). The structures of compounds I and II are compared with those of the previously studied complexes Mg[CoEdta]₂·10H₂O (III) and Ca[CoEdta]₂·7H₂O (IV). The crystal structure of the cobalt(III) complex with the strontium cation (I) is topologically similar to the crystal structure of cobalt(III) complex with the calcium cation (IV). The former structure is built up of the two symmetrically independent homochiral anionic complexes [CoEdta]^? (A _I and B _I), the aqua cations [Sr(H₂O)₈]²⁺, and the molecules of crystalization water w _cr. The structure of compound II involves two independent anions [CoEdta]^? (A _II and B _II) with different chiralities (i.e., they are kryptoracemates). The A _II anions are linked via the barium cations into {Ba(H₂O)₇[CoEdta]} _1∞ ⁺ chain agglomerates due to the incorporation of two terminal oxygen atoms O_u of the anions neighboring in the chain into the coordination sphere of the barium atom. All four structures (I–IV) contain stacks composed of the [CoEdta]^? homochiral anions forming layers aligned parallel to the (001) plane. The aqua cations [Sr(H₂O)₈]²⁺, [Mg(H₂O)₆]²⁺, and [Ca(H₂O)₇]²⁺ or the partially hydrated barium cations [Ba(H₂O)₇(O_u)₂]²⁺ (in structure II), as well as water molecules w _cr, are located between the anion layers. The octahedral environment of the cobalt(III) atoms consists of donor atoms (2N and 4O) of the Edta ^4? ligand. The Co-N bonds in the A _I, B _I, A _II, and B _II anions [the mean bond lengths are 1.927(4), 1.921(4), 1.910(6), and 1.921(6) Å, respectively] are considerably longer than the Co-O bonds [the mean bond lengths are 1.908(5), 1.902(5), 1.904(6), and 1.908(6) Å, respectively]. The mean distances Sr-O_w and Ba-O_w in the strontium and barium polyhedra are 2.609(4) and 2.834(8) Å, respectively. The mean distance Ba-O_u is 2.814(7) Å.     

Transient reaction of a three-layer plate to a live load

Zaporozh'e Industrial Institute. Translated from Prikladnaya Mekhanika, Vol. 27, No. 9, pp. 71–77, September, 1991.     

Crystal and molecular structure of the monohydrate of the internal salt of 7-[2-(fluorosulfonyl)-4-sulfophenyl]-4,10-dimethyl-1,2,3,4,10,11,12,13-octahydropyrano [2,3-F∶6,5-F′]diquinolinium hydroxide

All-Union Chemical Reagents and High-Purity Chemicals Research Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 3, pp. 97–102, May–June, 1990.     

Synthesis and ESR study of Co and Ni hydrazides and hydroxamates containing 2,6-di-tert-butylphenol moiety in the ligands

A series of Co and Ni hydrazides and hydroxamates containing the 2,6-di-tert-butylphenol moiety as a potential free radical precursor in the ligand environment of the complexes were synthesized. ESR spectroscopy was used to study the dependence of the stability of metal complexes incorporating a paramagnetic center in the ligand on the type of the coordination environment of the metal and the nature of the ligand. The complexes, in which a saturated aliphatic bridging group separates the 2,6-di-tert-butylphenol moiety and the coordination environment of the metal, can undergo oxidation to produce stable paramagnetic species with an unpaired electron in the ligand environment. The interaction of the free radical center in the ligand with the coordination environment of the metal is practically absent (excepting the weak spin-spin interaction). Metal complexes incorporating a hydrazine moiety conjugated with the 2,6-di-tert-butylphenol substituent do not produce detectable stable paramagnetic forms with a free radical in the ligand.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1794–1797, September, 1995.