Solvent extraction of Au(III) using 2-mercaptobenzimidazole into n-butanol

A method has been developed for the extraction of Au(III) with 2-mercaptobenzimidazole into n-butanol.¹⁹⁹Au has been used as a tracer for establishing the ideal extraction parameters such as effect of pH, time of equilibration, solvents and anions. Separation factor and decontamination factor have also been evaluated to determine the selectivity of the method with respect to various elements. The interfering elements were suppressed by the use of suitable masking agents which increased the selectivity. The stoichiometry of metal to reagent was determined by the method of substoichiometric extraction and slope ratio method.     

X-ray crystal structures of alpha-KrF(2),[KrF][MF(6)](M=As,Sb,Bi),[Kr(2)F(3)][SbF(6).KrF(2), [Ke(2)F(3)2[SbF(6)]2.KrF(2), and [Kr(2)F(3)][AsF(6)].[KrF][AsF(6)]; synthesis and characterization of [Kr(2)F(3)][PF(6).nKrF(2); and theoretical studies of KrF(2), KrF+, Kr(2)F(3)+, and the [KrF][MF(6)](M=P,As,Sb,Bi) ion pairs

The crystal structures of alpha-KrF(2) and salts containing the KrF(+) and Kr(2)F(3)(+) cations have been investigated for the first time using low-temperature single-crystal X-ray diffraction. The low-temperature alpha-phase of KrF(2) crystallizes in the tetragonal space group I4/mmm with a = 4.1790(6) A, c = 6.489(1) A, Z = 2, V = 113.32(3) A(3), R(1) = 0.0231, and wR(2) = 0.0534 at -125 degrees C. The [KrF][MF(6)] (M = As, Sb, Bi) salts are isomorphous and isostructural and crystallize in the monoclinic space group P2(1)/c with Z = 4. The unit cell parameters are as follows: beta-[KrF][AsF(6)], a = 5.1753(2) A, b = 10.2019(7) A, c = 10.5763(8) A, beta = 95.298(2) degrees, V = 556.02(6) A(3), R(1) = 0.0265, and wR(2) = 0.0652 at -120 degrees C; [KrF][SbF(6)], a = 5.2922(6) A, b = 10.444(1) A, c = 10.796(1) A, beta = 94.693(4) degrees, V = 594.73(1) A(3), R(1) = 0.0266, wR(2) = 0.0526 at -113 degrees C; [KrF][BiF(6)], a = 5.336(1) A, b = 10.513(2) A, c = 11.046(2) A, beta = 94.79(3) degrees, V = 617.6(2) A(3), R(1) = 0.0344, and wR(2) = 0.0912 at -130 degrees C. The Kr(2)F(3)(+) cation was investigated in [Kr(2)F(3)][SbF(6)].KrF(2), [Kr(2)F(3)](2)[SbF(6)](2).KrF(2), and [Kr(2)F(3)][AsF(6)].[KrF][AsF(6)]. [Kr(2)F(3)](2)[SbF(6)](2).KrF(2) crystallizes in the monoclinic P2(1)/c space group with Z = 4 and a = 8.042(2) A, b = 30.815(6) A, c = 8.137(2) A, beta = 111.945(2) degrees, V = 1870.1(7) A(3), R(1) = 0.0376, and wR(2) = 0.0742 at -125 degrees C. [Kr(2)F(3)][SbF(6)].KrF(2) crystallizes in the triclinic P1 space group with Z = 2 and a = 8.032(3) A, b = 8.559(4) A, c = 8.948(4) A, alpha = 69.659(9) degrees, beta = 63.75(1) degrees, gamma = 82.60(1) degrees, V = 517.1(4) A(3), R(1) = 0.0402, and wR(2) = 0.1039 at -113 degrees C. [Kr(2)F(3)][AsF(6)].[KrF][AsF(6)] crystallizes in the monoclinic space group P2(1)/c with Z = 4 and a = 6.247(1) A, b = 24.705(4) A, c = 8.8616(6) A, beta = 90.304(6) degrees, V = 1367.6(3) A(3), R(1) = 0.0471 and wR(2) = 0.0958 at -120 degrees C. The terminal Kr-F bond lengths of KrF(+) and Kr(2)F(3)(+) are very similar, exhibiting no crystallographically significant variation in the structures investigated (range, 1.765(3)-1.774(6) A and 1.780(7)-1.805(5) A, respectively). The Kr-F bridge bond lengths are significantly longer, with values ranging from 2.089(6) to 2.140(3) A in the KrF(+) salts and from 2.027(5) to 2.065(4) A in the Kr(2)F(3)(+) salts. The Kr-F bond lengths of KrF(2) in [Kr(2)F(3)][SbF(6)].KrF(2) and [Kr(2)F(3)](2)[SbF(6)](2).KrF(2) range from 1.868(4) to 1.888(4) A and are similar to those observed in alpha-KrF(2) (1.894(5) A). The synthesis and Raman spectrum of the new salt, [Kr(2)F(3)][PF(6)].nKrF(2), are also reported. Electron structure calculations at the Hartree-Fock and local density-functional theory levels were used to calculate the gas-phase geometries, charges, Mayer bond orders, and Mayer valencies of KrF(+), KrF(2), Kr(2)F(3)(+), and the ion pairs, [KrF][MF(6)] (M = P, As, Sb, Bi), and to assign their experimental vibrational frequencies.     

Diffusion mechanism of CO2 in 13X zeolite beads

A systematic study of the diffusion mechanism of CO₂ in commercial 13X zeolite beads is presented. In order to gain a complete understanding of the diffusion process of CO₂, kinetic measurements with a zero length column (ZLC) system and a volumetric apparatus have been carried out. The ZLC experiments were carried out on a single bead of zeolite 13X at 38 °C at a partial pressure of CO₂ of 0.1 bar, conditions representative of post-combustion capture. Experiments with different carrier gases clearly show that the diffusion process is controlled by the transport inside the macropores. Volumetric measurements using a Quantachrome Autosorb system were carried out at different concentrations. These experiments are without a carrier gas and the low pressure measurements show clearly Knudsen diffusion control in both the uptake cell and the bead macropores. At increasing CO₂ concentrations the transport mechanism shifts from Knudsen diffusion in the macropores to a completely heat limited process. Both sets of experiments are consistent with independent measurements of bead void fraction and tortuosity and confirm that under the range of conditions that are typical of a carbon capture process the system is controlled by macropore diffusion mechanisms.     

Entrapment of ionic tris(2,2'-bipyridyl) ruthenium(II) in hydrophobic siliceous zeolite: O2 sensing in biological environments

Synthesis of the ionic dye, tris(2,2'-bipyridyl) ruthenium(II) chloride (Ru(bpy) 3 2+.2Cl (-)) within the supercages of a highly hydrophobic zeolite Y is reported. Use of the neutral precursor Ru(bpy)Cl 2(CO) 2 allowed for high loading levels of Ru(bpy) 3 2+ (1 per 7 and 25 supercages). The emission quenching of the Ru(bpy) 3 2+-zeolite crystals dispersed in polydimethoxysiloxane (PDMS) films by dissolved oxygen in water was examined. The quenching data as a function of oxygen concentration was fit to a linear Stern-Volmer plot ( R2 = 0.98). Using the Stern-Volmer plot as calibration, changes in concentration of dissolved oxygen due to reaction with glucose in the presence of glucose oxidase was monitored. Human monocyte-derived macrophages internalized the submicron-sized Ru(bpy) 3 2+-zeolite crystals, and intracellular oxygen concentrations initiated by zymosan-mediated oxidative burst could be monitored by measuring the emission from Ru(bpy) 3 2+ by confocal fluorescence microscopy.     

Gadolinium-based mixed-metal nitride clusterfullerenes Gd(x)Sc(3-x)N@C80 (x=1, 2).

The first gadolinium-based mixed-metal nitride clusterfullerenes Gd(x)Sc(3-x)N@C(80) (I) (1, x=2; 2, x=1) have been successfully synthesized by the reactive gas atmosphere method and isolated facilely by recycling high-performance liquid chromatography (HPLC). The sum yield of 1 and 2 is 30-40 times higher than that of Gd(3)N@C(80) (I). Moreover, an enhanced relative yield of 2 over the Sc(3)N@C(80) (I) is achieved under the optimized synthesis conditions. According to the UV/Vis/NIR spectroscopic characterization, 1 and 2 are both stable fullerenes with large optical band-gaps while 1 has higher similarity to Gd(3)N@C(80) (I) and 2 resembles Sc(3)N@C(80) (I). The vibrational structures of 1 and 2 are studied by Fourier-transform infrared (FTIR) spectroscopy as well as density functional theory (DFT) computations. In particular, the structures of the encaged Gd(x)Sc(3-x)N clusters within 1 and 2 are analyzed.     

Phasenumwandlungen im system Cu x II Mn 1−x II Fe 2 III (OH)8

Zusammenfassung Die gemeinsam gefällten, ursprünglich amorphen Cu(II)Mn(II)Fe(III) Hydroxide gehen im Verlauf der Alterung durch Kochen in kristalline Phasen über, von denen wenigstens eine den Alterungsprodukten ferromagnetische Eigenschaften verleiht. Da es nicht möglich ist direkt zu entscheiden ob-Fe₂O₃ oder entsprechende Ferrite diese Eigenschaft hervorrufen, ist es notwendig, sich für die Identifizierung der Alterungsprodukte die thermische Instabilität von-Fe₂O₃ nutzbar zu machen. Die an Mn(II) sehr reichen Präparate zeigen einen Temperaturinvervall, in welchem sie überhaupt keine ferromagnetischen Eigenschaften aufweisen. Es ist dies ein Beweis dafür, daß der primär während des Kochens erworbene Ferromagnetismus ausschließlich von-Fe₂O₃ herrührt. Der bei hohen Temperaturen erneut auftretende Ferromagnetismus ist eine Eigenschaft der infolge thermischer Bearbeitung entstehenden Ferrite.

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After being boiled in water, the originally amorphous mixture of coprecipitated Cu(II), Mn(II) and Fe(III) hydroxides is transformed into crystalline phases, at least one of them being ferromagnetic. Since it can not be ascertained directly whether this property is due to the presence of-Fe₂O₃ or/and a corresponding ferrite, the identification must be based on the thermally metastable nature of-Fe₂O₃.The species with high Mn(II) contents exhibit temperature ranges in which the ferromagnetic properties disappear completely. This is the proof that the primarily acquired ferromagnetism stems exclusively from a ferromagnetic modification of iron oxide, namely-Fe₂O₃.As a result of thermal treatment at higher temperatures, the ferromagnetism reappears, this time due to the formation of ferrites.

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Résumé Les mélanges initialement amorphes des hydroxydes coprécipités de Cu(II), Mn(II) et Fe(III), se transforment, après chauffage dans de l'eau bouillante, en phase cristallines, dont l'une au moins est ferromagnétique. Comme il n'est pas possible de s'assurer directement que cette propriété est conditionnée par la présence de-Fe₂O₃ et/ou du ferrite respectif, l'identification doit reposer sur la nature thermiquement métastable de-Fe₂O₃.Dans le cas des préparations à teneur élevée en manganèse il existe un intervalle de températures où les propriétés ferromagnétiques disparaissent complêtement. C'est la preuve de ce que le ferromagnétisme acquis primitivement provient exclusivement d'une modification ferromagnétique ou d'un oxyde, notamment-Fe₂O₃.Le traitement thermique à des températures plus élevées a pour résultat la réapparition du ferromagnétisme, cette fois dû à la formation de ferrites.

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Cu(II), Mn(II) Fe(III) , , , . , —Fe₂O₃ , , —Fe₂O₃. Mn(II) , . , , —Fe₂O₃. , , .

     

A rigid cavity containing tetra-cobalt(III) [2 x 2] grid complex

The synthesis and structure of a rigid, cavity containing tetra-cobalt(III) [2 x 2] grid complex using an unusual bis(bipyridine)dimethoxynaphthyridine ligand is described.     

Isolation of hemoglobin from human blood using solid phase extraction with lanthanum(III) modified zeolite

Microchimica Acta - A direct solid-phase extraction procedure for the selective isolation of hemoglobin from complex matrices using lanthanum(III) modified zeolite (clinoptilolite) as sorbent was...     

Electronic spectroscopy of I(2)-Xe complexes in solid Krypton

In the present work, we have studied ion-pair states of matrix-isolated I(2) with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I(2)-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I(2) with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm(-1) from the X → D transition of I(2). Observed redshift can be explained by symmetry breaking of ion-pair states within the I(2)-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I(2) ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I(2) dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.     

Chemiluminescence detection of five-membered heteroaromatic compounds using electrogenerated tris(2,2'-bipyridine)-ruthenium(III).

Heteroaromatic compounds, such as 2,5-dimethylthiophene, 2,5-dimethylpyrrole, and 2,5-dimethylfuran, were found to act as reducing agents for the tris(2,2'-bipyridine)ruthenium(III), Ru(bpy)3(3+), chemiluminescent reaction. In order to characterize the chemiluminescent reaction of Ru(bpy)3(3+) with heteroaromatic compounds, we have investigated various mono-, di-, and tri-heteroaromatic compounds. The pi-electron density and stability of aromatic rings influence the chemiluminescent efficiency of the reaction. Above all, 2,5-dimethylthiophene produced strong chemiluminescence under acidic conditions. In addition, we confirmed that the rate of the chemiluminescent reaction of Ru(bpy)3(3+) with 2,5-dimethylthiophene is very fast.     

Linking iron(III) carboxylates into high-nuclearity complexes by using Bis-tris

We describe the synthesis, structure and magnetic properties of two decanuclear Fe(III) complexes with novel core topologies, assembled using the tetra-deprotonated form of Bis-tris {2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol, H5L}.     

High temperature metalation of functionalized aromatics and heteroaromatics using (tmp)2Zn x 2 MgCl2 x 2 LiCl and microwave irradiation

A wide range of polyfunctional aryl and heteroaryl zinc reagents were efficiently prepared in THF via direct zincation using (tmp)2Zn x 2 MgCl2 x 2 LiCl and microwave irradiation. Ester and cyano functions as well as ketones are compatible with the high temperatures of the zincation. The resulting bis-organo zinc species undergo a number of subsequent reactions leading to highly functionalized aromatics and heteroaromatics in good to excellent yields.     

ChemInform Abstract: Phosphoryl Nitride Isomeric Dimers,Trimers, and Tetramers: (NPO)x (x = 2-4).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

4-Substituted-3,4-dihydro-3-methyl-2H-1,3-benzoxazin-2-ones. III (2,3). Solvolytic-reductive transformation of 4-(2-keto)-benzoxazin-2-ones into oxazin-2-ones

A series of 4-(2-keto-substituted)-3,4-dihydro-3-methyl-2H-1,3-benzoxazin-2-ones 1 (Table I) was synthesized by condensation of 3-alkyl-3,4-dihydro-4-hydroxy-2H-1,3-benzoxazin-2-ones 4 with ketones 5 having active alpha hydrogens. In the presence of alcoholic potassium borohydride, compounds 1 underwent reductive transacylation to give 1,3-oxazin-2-one derivatives 3 (Table III, a,b,c). When the other side of the ketone possessed substituents other than hydrogen, there were always also normal reduction products, i.e., secondary alcohols 2 (Table II) in addition to 3.     

Intrinsic adsorption properties of CO2 on 5A and 13X zeolite

Data for the adsorption of CO₂ on 5A (CaA) and 13X (NaX) zeolite are critically evaluated. In addition, fresh data for the adsorption of CO₂ on 13X zeolite is reported. Three intrinsic properties are examined: q _max , the saturation loading, K _H , the Henry constant, and (?ΔH) _q , the isosteric heat of sorption. Below a reduced temperature T _r , of 0.9, the q _max values for both 5A and 13X zeolites are similar to theoretical values that may be derived using zeolitic crystallographic properties and the sorbate density calculated using the Rackett equation. For the region 0.9 ≤ Tr ≤ 1.0, the calculated q _max values exceed the theoretical values similarly calculated, indicating that the molecules have a smaller molar volume than in a similar liquid phase. This is a similar result to that observed in ionic liquids. Linear regressed equations are derived for q _max for the region 0.9 ≤ Tr ≤ 1.25. The Henry constant values for 5A are remarkably consistent for the five studies examined, with a correlation coefficient, R, of 0.999 for the van’t Hoff equation, but for the seven studies examined in 13X the data is more disperse as indicated by a correlation coefficient R of 0.899 for the van’t Hoff equation. The values of (?ΔH) _q , the isosteric heat of sorption are in agreement with the literature. An explanation is advanced for the discrepancy between the higher heats of sorption values obtained calorimetrically from those obtained from isosteric adsorption studies. Finally, the fresh data is observed to fit the Toth model with regression coefficients of 0.999. However, the parameters obtained for the Toth equation by regression are significantly different from the intrinsic properties derived earlier, indicating the difficulty of deriving intrinsic parameters from isotherm fits.     

Very large breathing effect in the first nanoporous chromium(III)-based solids: MIL-53 or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)] x [HO(2)C-C(6)H(4)-CO(2)H](x) x H(2)O(y)

The first three-dimensional chromium(III) dicarboxylate, MIL-53as or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)].[HO(2)C-C(6)H(4)-CO(2)H](0.75), has been obtained under hydrothermal conditions (as: as-synthesized). The free acid can be removed by calcination giving the resulting solid, MIL-53ht or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)]. At room temperature, MIL-53ht adsorbs atmospheric water immediately to give Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)] x H(2)O or MIL-53lt (lt: low-temperature form, ht: high-temperature form). Both structures, which have been determined by using X-ray powder diffraction data, are built up from chains of chromium(III) octahedra linked through terephthalate dianions. This creates a three-dimensional structure with an array of one-dimensional large pore channels filled with free disordered terephthalic molecules (MIL-53as) or water molecules (MIL-53lt); when the free molecules are removed, this leads to a nanoporous solid (MIL-53ht) with a Langmuir surface area over 1500 m(2)/g. The transition between the hydrated form (MIL-53lt) and the anhydrous solid (MIL-53ht) is fully reversible and followed by a very high breathing effect (more than 5 A), the pores being clipped in the presence of water molecules (MIL-53lt) and reopened when the channels are empty (MIL-53ht). The thermal behavior of the two solids has been investigated using TGA and X-ray thermodiffractometry. The sorption properties of MIL-53lt have also been studied using several organic solvents. Finally, magnetism measurements performed on MIL-53as and MIL-53lt revealed that these two phases are antiferromagnetic with Néel temperatures T(N) of 65 and 55 K, respectively. Crystal data for MIL-53as is as follows: orthorhombic space group Pnam with a = 17.340(1) A, b = 12.178(1) A, c = 6.822(1) A, and Z = 4. Crystal data for MIL-53ht is as follows: orthorhombic space group Imcm with a = 16.733(1) A, b = 13.038(1) A, c = 6.812(1) A, and Z = 4. Crystal data for MIL-53lt is as follows: monoclinic space group C2/c with a = 19.685(4) A, b = 7.849(1) A, c = 6.782(1) A, beta = 104.90(1) degrees, and Z = 4.