CO(2) capture by a task-specific ionic liquid

Reaction of 1-butyl imidazole with 3-bromopropylamine hydrobromide, followed by workup and anion exchange, yields a new room temperature ionic liquid incorporating a cation with an appended amine group. The new ionic liquid reacts reversibly with CO2, reversibly sequestering the gas as a carbamate salt. The new ionic liquid, which can be repeatedly recycled in this role, is comparable in efficiency for CO2 capture to commercial amine sequestering reagents, and yet is nonvolatile and does not require water to function.     

Formation of higher chloride complexes of Np(IV) and Pu(IV) in water-stable room-temperature ionic liquid [BuMeIm][Tf2N

A UV/vis/near-IR spectroscopic study shows that in [BuMeIm][(CF3SO2)2N] hydrophobic room-temperature ionic liquid solutions, [BuMeIm]2[AnCl6] complexes, where BuMeIm+ is 1-n-butyl-3-methylimidazolium and An(IV) is Np(IV) or Pu(IV), have an octahedral An(IV) environment similar to that observed in solid complexes. Water has no influence on the absorption spectra of AnCl6(2-) complexes, indicating their stability to hydrolysis in ionic liquid. Adding [BuMeIm]Cl modifies the UV/vis/near-IR absorption spectra of An(IV) in the ionic liquid and causes solids to precipitate. The solid-state reflectance spectra of the precipitates reveal considerable differences from the corresponding An(IV) hexachloro complexes. A voltammetric study indicates that AnCl6(2-) complexes are electrochemically inert in [BuMeIm][(CF3SO2)2N] at the glassy carbon working electrode. By contrast, quasi-reversible electrochemical reduction An(IV)/An(III) and An(IV) oxidation are observed in ionic liquids in the presence of [BuMeIm]Cl. The oxidation wave of noncoordinated chloride ions interferes with the An(IV) oxidation waves. The spectroscopic and voltammetric data clearly indicate the formation of nonoctahedral actinide(IV) chloride complexes with a Cl-/An(IV) ratio exceeding 6/1 in [BuMeIm][(CF3SO2)2N] in excess chloride ions.     

First principles molecular dynamics simulation of a task-specific ionic liquid based on silver-olefin complex: atomistic insights into a separation process

First principles molecular dynamics based on density functional theory is applied to a hypothetical ionic liquid whose cations and anions are silver-ethylene complex [Ag(C2H4)2+] and tetrafluoroborate [BF4-], respectively. This ionic liquid represents a group of task-specific silver complex-based ionic liquids synthesized recently. Molecular dynamics simulations at two temperatures are performed for five picoseconds. Events of association, dissociation, exchange, and recombination of ethylene with silver cation are found. A mechanism of ethylene transfer similar to the Grotthus type of proton transfer in water is identified, where a silver cation accepts one ethylene molecule and donates another to a neighboring silver cation. This mechanism may contribute to fast transport of olefins through ionic liquid membranes based on silver complexes for olefin/paraffin separation.     

Complexation between uranyl(VI) and CMPO in a hydroxyl-functionalized ionic liquid: An extraction,spectrophotography, and calorimetry study

The extraction complexes of uranyl(VI) in HNO₃ to a hydroxyl-functionalized ionic liquid (IL) phase, HOEtmimNTf₂ bearing CMPO, were investigated. Three possibly successive extraction complexes, UO₂L²⁺ (L = CMPO), UO₂L₂²⁺ and UO₂L₃²⁺, were detected based on variable U/L ratios. Uranyl(VI) prefers to be extracted as complex UO₂L₃²⁺, combining with the ions from HOEtmimNTf₂ to construct a solid material through self-assembly. The thermodynamics of complexes, UO₂L_j²⁺ (j = 1-3), were studied by spectrophotometry and microcalorimetry. All the formation reactions are principally driven by entropy, although a small part of the driving force of complexes UO₂L₂²⁺ and UO₂L₃²⁺ comes from enthalpy. Based on the thermodynamic properties for complex UO₂L₃²⁺, we provide a possible coordination mode in HOEtmimNTf₂: the first CMPO molecule coordinates with UO₂²⁺ in a bidentate fashion while the others do in a monodentate fashion. The results offer a thermodynamic insight into the formation behaviors of the uranyl(VI)/CMPO complexes involving the special IL HOEtmimNTf₂, which is of significance to advance the novel IL extraction strategy.     

Organotin(IV) azepane dithiocarbamates: Synthesis and characterization of the first organotin(IV) complexes with seven-membered cyclic dithiocarbamates

Abstract

We report the synthesis and spectroscopic characterization of the first organotin(IV) complexes with cyclic seven-membered dithiocarbamate ligands: the azepane-1-carbodithioate and the homopiperazine-1,4-bis-carbodithioate with two different organotin entities, di-n-butyltin and tri-cyclohexyltin: [(C₄H₉)₂Sn{S₂CN(CH₂)₆}₂] (3), [(C₆H₁₁)₃Sn{S₂CN(CH₂)₆}] (4), and [(C₆H₁₁)₃Sn}₂ (μ-S₂CN(C₅H₁₀)NCS₂)] (5). Compounds (3–5) are air-stable both in solid-state and in solution, and were characterized by elemental analyses, IR, FAB⁺–MS, and multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy. Their molecular structures were unambiguously established by single-crystal X-ray diffraction studies. The geometrical arrangement around the tin atom can be described as distorted octahedral for (3) and distorted trigonal bipyramid for (4) and (5). The coordination mode for both ligands is considered as asymmetric bidentate, as happens in other organotin(IV) dithiocarbamates. Furthermore, (4) and (5) do not exhibit intermolecular secondary interactions, while (3) presents intermolecular interactions between the tin and a sulfur atom with the reciprocally neighboring molecule, giving rise to a zig-zag polymeric structure.     

Solvent extraction of Np(IV) and Pu(IV) with mixtures of TOPO and HTTA

Solutions of HTTA are known to extract tetravalent actinides as M(TTA)₄ species. When TOPO is added to HTTA solutions, the extracting of Np(IV) and Pu(IV) from aqueous perchloric acid was enhanced enormously. The species responsible for the enhanced extraction were identified from the extraction data by the slope ratio method and JOB's method. It was found that the predominant species responsible for enhancement in the extraction, when [HTTA]≫[TOPO], was M(TTA)₄. TOPO for both Np(IV) and Pu(IV). Furthermore, it was established that depending on the relative concentrations of HTTA and TOPO, a number of species with the composition M(TTA)_a(ClO₄)_4-a·b TOPO, with a ranging from 1 to 4 and b having values of 1 or 2, are involved in the extraction. Several equilibrium constant values are given. Fuel Reprocessing Division.     

Convolution-deconvolution cyclic voltammetric equilibria study on cadmium(II)-L-histidinate in aqueous solutions

POLAG computer programme was employed for processing convoluted-deconvoluted cyclic voltammetric data to study cadmium(II)-L-histidinate system. This was performed in 0.1 mol/dm(3) NAClO(4) aqueous solution at different pH's at 298K. The results show that the reduction of cadmium(II) and its complexes proceeds via a reversible and diffusion-controlled wave of two electrons at the entire range of pH. The system was studied at two ranges of pH (6.73-7.44 and 8.53-8.92). It was evident that the system at the first range of pH is well described by the presence of a mixture of binary complexes, [Cd(HisO.H)], [Cd(HisO.H(2))(2)] and a ternary one [Cd(HisO.H)(HisO.H(2))]. For the second pH range, it was revealed that the most likely model corresponds to the presence of a mixture of [Cd(HisO)(2)] and [Cd(OH)] species. The overall stability constants were computed. The structure of the detected complexes was discussed on the basis of ligating sites of histidine.     

Nonenzymatic glucose voltammetric sensor based on gold nanoparticles/carbon nanotubes/ionic liquid nanocomposite

In this paper, a novel nonenzymatic glucose voltammetric sensor based on a kind of nanocomposite of gold nanoparticles (GNPs) embedded in multi-walled carbon nanotubes (MWCNTs)/ionic liquid (IL) gel was reported. The surface morphology of this nanocomposite was characterized using X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. It can be found that most of GNPs lie close to the ektexine of MWCNTs and the others have obviously inserted the inner of MWCNTs through the defects or ends of MWCNTs, due to the attraction between GNPs and MWCNTs as well as the repulsion between GNPs and IL. Voltammetry was used to evaluate the electrocatalytic activities of the nanocomposite biosensor toward nonenzymatic glucose oxidation in alkaline media. The GNPs embedded in MWCNTs/IL gel have strong and sensitive voltammetric responses to glucose, owing to a possible synergistic effect among GNPs, MWCNTs and IL. Under the optimal condition, the linear range for the detection of the glucose is 5.0-120 μM with the correlation coefficient of 0.998, based on the oxidation peak observed during cathodic direction of the potential sweep. The kinetics and mechanism of glucose electro-oxidation were intensively investigated in this system. This kind of nanocomposite biosensor is also highly resistant toward poisoning by chloride ions and capable of sensing glucose oxidation in the presence of 20 μM uric acid and 70 μM ascorbic acid. This work provides a simple and easy approach to the detection of glucose in body fluid with high sensitivity and excellent selectivity.     

A cyclic voltammetric study of iron(II)/ruthenium(II) complexes with bis(tertiary phosphines)

Summary Nine complexes of Fe^IIRu^II with bis(tertiary phosphines), namely, 1,2-bis(diphenylphosphino)ethane (dppe), 1,2-bis (diphenylphosphino)ethylene (dppen) and o-phenylenebis (diphenylphosphine) (o-diphos) were studied using cyclic voltammetry. The half-wave potentials for the complexes studied are: (1) [FeCl₂(dppe)], 0.050V; (2) [Fe(NCS)₂(dppe)₂], 0.265V; (3) [RuCl₂(dppe)₂], 0.548V; (4) [FeCl₂(dppen)₂], 0.225V; (5) [Fe(NCS)₂-(dppen)₂], 0.290V; (6) [RuCl₂(dppen)₂], 0.690V; (7) [FeCl₂(o-diphos)₂] 0.160V; (8) [Fe(NCS)₂(o-diphos)₂] 0.582V; and (9) [RuCl₂(o-diphos)₂], 0.265V. The redox potentials are related to the nature of the ligand, the nature of the metal, the stereochemistry of the complex and the ligand field strength.     

The first lanthanide(III) monoporphyrin complex liquid crystal

Hydroxy [5,10,15,20-tetra[P-decyloxy- ^m -methyloxy)phenyl]porphyrin Yb(III) exhibits a discotic hexagonal columnar phase, it is the first example of a monoporphyrin rare earth complex liquid crystal.     

The first lanthanide(III) monoporphyrin complex liquid crystal

Hydroxy [5,10,15,20-tetra[ p -decyloxy- m -methyloxy)phenyl]porphyrin Yb(III) exhibits a discotic hexagonal columnar phase, it is the first example of a monoporphyrin rare earth complex liquid crystal.     

Potentiometric studies on aqueous fluoride complexes of actinides: Stability constants of Th(IV)-, U(IV)-, Np(IV)- and Pu(IV)-fluorides

The extraction behaviour of Th(IV) and U(VI) in extraction chromatography has been investigated on the basis of partition and infrared studies. The stationary phase was purified undiluted TBP supported on Amberlite XAD-4 and the mobile phase was nitric acid. The results have shown that the equilibria for the extraction of Th(IV) and U(VI) by the TBP/XAD-4 resin agreed very closely with those in solvent extraction.     

Thermodynamics of extraction of U(VI), Np(IV) and Pu(IV) with some long chain aliphatic sulphoxides

Distribution data for U(VI), Np(IV) and Pu(IV) from 2 M nitric acid medium with 0,2 M di-n-hexyl sulphoxide (DHSO) and di-n-octyl sulphoxide (DOSO) in Solvesso-100 have been obtained in the temperature range 20–50°C. From these data, the enthalpy, entropy and free energy changes associated with their extraction were evaluated. Extraction of Np(IV) and Pu(IV) with both sulphoxides is favoured by negative enthalpy and positive entropy changes whereas the extraction of U(VI) is favoured only by high negative enthalpy change. This behaviour has been explained as arising due to the higher hydration of Np⁴⁺ and Pu⁴⁺ ions as compared to the UO₂²⁺ ion.     

Interaction of Aluminium (III) with the f-Family Ions Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) in the Course of Simultaneous Hydrolysis

The interaction of Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) with Al(III) in solutions at pH 0–4 was studied by the spectrophotometric method. It was shown that, in the range of pH 3–4, the hydrolyzed forms of neptunyl and plutonyl react with the hydrolyzed forms of aluminium. In the case of Pu(VI), the mixed hydroxoaqua complexes (H₂O)₃PuO₂(-OH)₂Al(OH)(H₂O)₃ ²⁺ or (H₂O)₄PuO₂OAl(OH)(H₂O)₄ ²⁺ are formed at the first stage of hydrolysis. Np(VI) also forms similar hydroxoaqua complexes with Al(III). The formation of the mixed hydroxoaqua complexes was also observed when Np(IV) or Pu(IV) was simultaneously hydrolyzed with Al(III) at pH 1.5–2.5. The Np(IV) complex with Al(III) has, most likely, the formula (H₂O) _n (OH)Np(-OH)₂Al(OH)(H₂O)₃ ³⁺. At pH from 2 to 4.1 (when aluminium hydroxide precipitates), the Np(V) or Nd(III) ions exist in solutions with or without Al(III) in similar forms. When pH is increased to 5–5.5, these ions are almost not captured by the aluminium hydroxide precipitate.     

Anion-selective electrodes based on ionic liquid membranes: effect of ionic liquid anion on observed response

A systematic study of the behavior of ion-exchanger anion-selective electrodes prepared from seven different trihexyltetradecylphosphonium ionic liquids (ILs) was performed. The effective ion-exchange capacity of prepared ion-selective electrodes (ISEs) increased with decreasing IL anion lipophilicity, and analyte anion response slopes became more Nernstian concomitantly. With ILs having the most lipophilic constituent anions, incorporation of tridodecylmethylammonium chloride into membranes significantly enhanced responses toward all ions. However, ILs based on bis(trifluoromethylsulfonyl)imide and dodecylsulfate maintained sub-Nernstian responses upon such addition apparently due to their ability to coordinate cations. Electrodes prepared with high IL content displayed regions of super-Nernstian response, which could be eliminated by reducing percent of IL in the membrane; percentages at which optimal linear range was achieved also followed a trend with decreasing constituent IL anion lipophilicity. While selectivities of all electrodes followed the Hofmeister pattern, selectivity coefficient ranges generally were narrower than observed with traditionally plasticized ISEs, and selectivities for more hydrophilic analytes were improved slightly in ILs containing the most hydrophilic constituent anions.     

Isolation of the first ferromagnetically coupled Mn(III/IV) complex

Binuclear manganese complexes Mn2(III/IV)(dtsalpn)2DCBI, 1, Mn2(III/III)(dtsalpn)2HDCBI, 2, containing the ligand dicarboxyimidazole (DCBI) have been prepared in order to address the issue of imidazole bridged and ferromagnetically coupled Mn sites in high oxidation states of the OEC in Photosystem II (PS II). Temperature dependent magnetic susceptibility studies of 1 indicates that the interaction between the two Mn(III)/Mn(IV) ions is ferromagnetic (J = +1.4 cm(-1)). Variable temperature EPR spectra of 1 shows that a g = 2 multiline is as an excited state signal corresponding to S = 1/2.     

Ab initio X-ray absorption spectroscopy study of the solvation structure of Th(IV), U(IV), and Np(IV) in aqueous solution

The coordination structures of U(IV), Np(IV), and Th(IV) in aqueous solution have been determined by studying the X-ray absorption near edge structure (XANES) of the actinide (An) L(3)-edge absorption spectra. The high sensitivity of XANES to the bonding geometry provides an unambiguous determination of the coordination polyhedron. On the basis of the comparison of ab initio computations with the experimental data we conclude that the hydration sphere of the three An(IV) aqua-ions studied is best modeled by 9 water molecules forming a tricapped trigonal prism.     

Imidazolium‐based poly(ionic liquid)s with poly(ethylene oxide) main chains: Effects of spacer and tail structures on ionic conductivity

Ten types of cationic glycidyl triazole polymers (GTPs) are prepared from combinations of five alkyl‐imidazolium units (methyl‐, ethyl‐, n‐propyl‐, iso‐propyl‐, and n‐butyl‐imidazoliums) and two spacers [di‐ and tri(ethylene glycol)s]. Since these poly(ionic liquid)s are prepared from the same sample of glycidyl azide polymer by postfunctionalization method, they have the same degree of polymerization. Therefore, the structure–property relationship can be discussed without influence of molecular weight difference. The samples are characterized by NMR, differential scanning calorimetry, and thermogravimetric analysis. The ionic conductivity data are obtained by impedance measurements. The GTPs with the tri(ethylene glycol) spacer and ethyl‐ and n‐butyl‐imidazolium units afford the highest anhydrous conductivity of 1.5 × 10^?5 S cm^?1 at 30 °C. Based on electrode polarization (EP) analysis, we calculate the conducting ion (carrier) concentration and mobility. We discuss the effect of the spacer and N‐alkyl tail structures on the ionic conductivity using the data obtained by EP analysis and X‐ray diffraction. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2896–2906