Online NMR spectroscopic study of species distribution in MEA–H2O–CO2 and DEA–H2O–CO2

Quantitative online NMR spectroscopy was used for studying the species distribution in solutions of carbon dioxide in aqueous monoethanolamine (MEA) and diethanolamine (DEA). The mass fraction of the amine in the unloaded solution was 0.2 and 0.3 g/g, respectively, the carbon dioxide loading was up to 1.1 ??molCO₂/molamine$1.1\text{\hspace{0.17em}??}\text{mo}{\text{l}}_{\text{C}{\text{O}}_2}/\text{mo}{\text{l}}_{\text{amine}}$, temperatures were between 293 and 353 K. A special apparatus was designed that allows preparing the mixtures gravimetrically and applying pressures up to 25 bar to keep the carbon dioxide in solution. It was coupled to a 400 MHz NMR spectrometer by heated capillaries. By using both ¹H and ¹³C NMR spectroscopy quantitative information on the concentrations of the following species were obtained: amine, carbamate, bicarbonate, and carbon dioxide. Due to the fast proton transfer between molecular and protonated amine, only the sum of their concentrations can be determined. Furthermore, a byproduct, 2-oxazolidone, was observed and quantified. The experimental data were used for developing a thermodynamic model of the studied electrolyte solutions based on the extended Pitzer G^E-model. In the model development, also vapor–liquid equilibrium data from the literature were included. The model gives reliable results both for the species distribution and the vapor–liquid equilibrium of the studied mixtures.     

Visible-light deposition of CrOx cocatalyst on TiO2:Cr valence regulation for superior photocatalytic CO2reduction to CH4

Photodeposition is widely adopted for implanting metal/metal oxide cocatalysts on semiconductors.However,it is prerequisite that the photon energy should be sufficient to excite the host semiconductor.Here,we report a lower-energy irradiation powered deposition strategy for implanting CrO_x cocatalyst on TiO₂.Excitingly,CrO_x-400 implanted under visible-light irradiation significantly promotes the CH4 evolution rate on TiO₂to 8.4μmolg·^-1h^-1 with selectivity of98%from photocatalytic CO₂reduction,which is 15 times of that on CrO_x-200 implanted under UV-visible-light irradiation.Moreover,CrO_x-400 is identified to be composed of higher valence Cr species compared to CrO_x-200.This valence states regulation of Cr species is indicated to provide more active sites for CO₂ adsorption/activation and to modulate the reaction mechanism from single Cr site to Cr-Cr dual sites,thus endowing the superior CH₄production.This work demonstrates an alternative strategy for constructing efficient metal oxides cocatalysts on wide bandgap semiconductor.     

Vapor phase methylation of pyridine with CO?H2 and CO2?H2 over a Ni catalyst

Pyridine was methylated selectively to 2-picoline with CO−H₂ and with CO₂−H₂ over a Ni catalyst. 2,6-lutidine was producedvia the methylation of 2-picoline.     

Ambient temperature sol–gel synthesis of CeO2–SiO2 and TiO2–CeO2–SiO2 films with high efficiency of UV absorption and without destructive oxidation on heat sensitive organic substrate

Highly efficient UV absorption films of CeO₂–SiO₂ and TiO₂–CeO₂–SiO₂ were synthesized through an epoxide assisted sol–gel strategy. As proven by their UV–vis transmittance spectra, the obtained films show very strong absorption in the UV region, at the same time, keeping the high transparency in the visible range. Due to the unique chemistry of this route and the delicate selection of Ce precursor salts, the ceria in the film can be crystallized at ambient temperature, resulting in the effective UV absorption and oxidation minimization of the films. These advantages guarantee their application in the protection of heat-sensitive organic materials.     

Molecular structures and electronic properties of helical thiophene carbon–sulfur oligomers, H2(C2S)nC2H2 (n?=?1–20)

Structure optimizations of the thiophene carbon–sulfur H₂(C₂S) _n C₂H₂ (n = 1–20) were carried out using density functional theory calculations at the B3LYP/6-31G(d) level. The B3LYP/6-31G(d) geometrical data for heptamer H₂(C₂S)₇C₂H₂ and undecamer H₂(C₂S)₁₁C₂H₂ are in good agreement with the X-ray crystallographic data for the helical (C₂S)_n β-heptathiophene and β-undecathiophene, respectively. Structural and electronic properties of helical oligothiophenes obtained at the B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level are reported. The strain energy formula of n oligothiophenes as a linear function of their molecular length was obtained.     

Electrocatalytic construction of the C–N bond from the derivates of CO2 and N2

Electrochemical synthesis of C-N bond-containing compounds(e.g.,urea,amino acid,amide,amine,and their derivates)from CO₂/N₂and their derivates is emerging as a promising sustainable strategy[1-7].CO₂and its derived products,CO,HCOOH,(COOH)₂,etc.,could serve as carbon sources(Figure 1)[8].N₂,making up 80%of air,is an appealing nitrogen source.However,the low solubility of N2 and the high dissociation energy for the N≡N bond limit its application.     

Syngas production from methane reforming with O2 and CO2 over Ni–La2O3/SiO2 catalysts using EDTA salt precursors

Ni–La₂O₃/SiO₂ catalysts (NLS) were prepared by the incipient-wetness impregnation method using EDTA salt precursors. XRD measurements revealed that the promoter of La₂O₃ is highly dispersed on the NLS. The TPR profiles indicated a strong interaction between NiO and La₂O₃ to form a La–Ni complex oxide like species over the NLS, which may be the origin of its high catalytic performance.     

Synthesis of (C8H11N)2·Zn(OAc)2, (C8H11N)2·Cu(OAc)2, and (C8H11N)2·CuCl2 complexes and application to the Henry reaction

(C₈H₁₁N)₂·Zn(OAc)₂ (1a), (C₈H₁₁N)₂·Cu(OAc)₂ (1b), and (C₈H₁₁N)₂·CuCl₂ complexes are synthesized by a simple one-pot method. The crystal structures of 1a, 1b, and 1c are determined by X-ray crystallography. The complexes are also characterized by NMR, IR, MS, and elemental analysis and used as the catalysts applied to the Henry reaction; moderate to high yields are obtained at room temperature.     

Fe(CO)5 promoted C-S bond activation and formation of an unusual C2S3 ligand in [{Fe2(CO)6}2(μ-C2S3)]

Photolysis of a hexane solution containing Fe(CO)₅ and CS₂ leads to desulfurization and formation of a novel cluster [{Fe₂(CO)₆}₂(μ-C₂S₃)] (1). Its molecular structure was determined by single crystal X-ray diffraction methods and shown to consist of two distinct Fe₂(CO)₆ units linked by an unusual C₂S₃ unit.     

Oxidative addition of the Mo-Cl bond to the Pt0 complex. Synthesis and structure of Cp′Mo(μ-CO)2(C2Ph2)Pt2(PPh3)2(CO)Cl

A reaction of Cp′Mo(CO)₃Cl(Cp′ = MeC₅H₄) with (PPh₃)₂Pt(C₂Ph₂) gave the heterometallic cluster Cp′Mo(μ-CO)₂(C₂Ph₂)Pt₂(PPh₃)₂(CO)Cl (I) as the sole product. According to X-ray diffraction data, complex I contains single Pt-Mo bonds (2.7962(5) and 2.7699(5) ?) but no Pt-Pt bond (Pt…Pt 2.9746(3) ?). The coordinated diphenylacetylene molecule forms two Pt-C σ-bonds (2.054(6) and 2.083(5) ?) and a π-bond to the Mo atom (Mo-C 2.265(6) and 2.272(5) ?; C≡C 1.387(8) ?). Original Russian Text ? A.A. Pasynskii, I.V. Skabitskii, Yu.V. Torubaev, S.S. Shapovalo, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 410–413.     

A simple route to obtain TiO2 nanowires by the sol–gel method

In this work, titanium dioxide (TiO₂) nanowires were synthesized by the sol–gel method, without using any kind of templates, instead of that acetic acid was used as morphological modifier. In order to control crystalline phases and crystal size, TiO₂ was calcinated at 400, 500 and 600 °C during 1 h. The resulting morphology was nanowires, which diameter was maintained constant after calcination at different temperature (about 76 nm). Moreover, crystalline phases in order of predominance were anatase, anatase–rutile and rutile–anatase at 400, 500 and 600 °C, respectively. Additionally, the crystallite size increases with respect to temperature from 13 to 75 nm.     

A Robust Heterometallic Cd（Ⅱ）/Ba（Ⅱ）-Organic Framework with Exposed Amino Group and Active Sites Exhibiting Excellent CO2/CH4 and C2H2/CH4 Separation

A microporous and robust bimetal-organic framework [Cd₂Ba（NH₂-BTB）₂]·2（DMA）·2（H₂O）(1) was constructed by mixing the heterometallic nodes and an tridentate carboxyl ligand with amino group, benefiting from the synergistic effect of active sites, exposed amino groups and ultramicroporous structure. This compound displays an extraordinary selectivity of CO₂/CH₄ and C₂H₂/CH₄（16.7 and 146.3） at 298 K an...     

Synthesis, crystal structure, and biological activity of the binuclear complex [Pr2(C10H9N2O4)2(C7H5O3)4(H2O)2] · 2H2O

A novel binuclear praseodymium(III) complex with N-(2-propionyl)salicyloylhydrazone (C₁₀H₁₀N₂O₄, H₃L) and p-hydroxybenzoic acid (C₇H₆O₃, Phba) was prepared in a H₂O-C₂H₅OH mixed solution, and the crystal structure of [Pr₂(H₂L)₂(Phba)₄(H₂O)₂] · 2H₂O (I) was determined by X-ray single crystal diffractometry. Complex I crystallizes in the monoclinic system, space group P2₁/c, a = 1.1050(4), b = 1.9534(7), c = 1.2376(4) ?, β = 94.955(7)°, and Z = 4. In the structure each Pr³⁺ ion lies in a single capped square antiprism geometry coordinated by carboxyl O and acyl O atoms and azomethine N atom of one ligand (H₂L⁻ form), which coordinates via the keto form, four carboxyl O atoms from two Phba, and O atoms of two water molecules. In each molecule, two tridentate ligands were coordinated by the H₂L⁻ form, and each Pr³⁺ ion was chelated by the carboxyl group from Phba. The carboxyl groups of H₂L⁻ and other two Phba were coordinated via μ₂-bridging form and bidentate bridging form, respectively. Complex I and ligands Phba and H₃L were also searched for biological activity against Valsa mali by the growth rate method. The result showed that the inhibitory rate of ligands Phba and H₃L is better than complex I, especially Phba.     

Reactions of linked tetrahedron clusters [Co2(CO)6(μ-HC2CH2O)-]2R with Rh2(CO)4Cl2 to give mixed-metal linked alkyne-bridged butterfly clusters containing C2Co2Rh2 unit

The reactions of compound Rh₂(CO)₄Cl₂, 1 with [Co₂(CO)₆(μ-HC₂CH₂O)-]₂R (R = C₆H₄, 2; (COCH₂)₂, 3; C₆H₄-1,4-(CO)₂, 4; (COCH)₂, 5; (CO)₂, 6) in benzene at 60 °C produce five new mixed-metal linked clusters Rh₂Co₂(CO)₁₀(μ₄,η²-HC₂CH₂O-R-OCH₂C₂H-μ)Co₂(CO)₆ (R = C₆H₄, 7a; (COCH₂)₂, 7b; C₆H₄-1,4-(CO)₂, 7c; (COCH)₂, 7d; (CO)₂, 7e) and five known linked octahedral clusters [Rh₂Co₂(CO)₁₀(μ₄,η²-HC₂CH₂O-)]₂R (R = C₆H₄, 8a; (COCH₂)₂, 8b; C₆H₄-1,4-(CO)₂, 8c; (COCH)₂, 8d; (CO)₂, 8e), respectively. Treatment of clusters 7a-8e in benzene at room temperature under air for 24 h with stirring afford the precursor clusters 2-6, respectively. The structure of cluster 7a has been determined by single-crystal X-ray diffraction. The linked cluster 7apossesses two isomers A and B in its structures, the Rh₂(CO)₄ unit inserts into one of two Co-Co bonds and coordinates to the Co₂C₂ core forming one distorted closo-Rh₂Co₂C₂ octahedron framework which is connected to the Co₂C₂ tetrahedron unit via C₆H₄(OCH₂)₂-1,4 as a bridging ligand. All clusters were characterized by C, H elemental analysis, IR and ¹H NMR spectroscopy.     

An efficient and stable Mn–K/CeO2–Al2O3 catalyst for hydrogenation of benzoic acid to benzaldehyde

A Mn–K/CeO₂–Al₂O₃ catalyst for the hydrogenation of benzoic acid (BAC) to benzaldehyde (BAD) has been developed. The catalyst exhibits efficient activity in the reaction and is still stable after 102 h of testing.     

Isolation and structural characterization of 1,5-benzodiazepinium cation in an inorganic–organic hybrid compound [C12H17N2]3[Bi2Cl9]·2EtOH

The compound [C₁₂H₁₇N₂]₃[Bi₂Cl₉]·2EtOH (1) has been synthesized from bismuth trichloride and o-phenylenediamine (opda) in ethanol at an aerial ambient condition. This preparation includes the conversion of opda to 2,3-dihydro-1H-1,5-benzodiazepinium cation through its reaction with acetone that is formed in situ from aerial ethanol oxidation. Compound 1 crystallizes in triclinic system (space group P−1). In the crystal structure of 1, the supramolecular hydrogen bonding interactions between [Bi₂C₉]³⁻ and [C₁₂H₁₇N₂]⁺ play an important role in the stabilization of cationic form of 2,3-dihydro-1H-1,5-benzodiazepine and in obtaining emission signals of the organic moiety, which is otherwise not emissive. Compound [C₁₂H₁₇N₂]₃[Bi₂Cl₉]·2(2-PrOH) (2), that has been isolated from 2-propanol (instead of ethanol), is isostructural with compound 1.     

Synthesis of Mo(CO)2(η-PPh2(o-C6H4)C(O)H)2 and its reaction with C60

Reaction of Mo(CO)₃(NCMe)₃ and PPh₂(o-C₆H₄)C(O)H (abbreviated as PCHO) at room temperature affords Mo(CO)₂(η³-PCHO)₂ (1), while compound 1 and the phosphine-imine complex Mo(CO)₄(η²-PPh₂(o-C₆H₄)CHNMe) (2) are obtained by using Mo(CO)₃(η³-(MeNCH₂)₃) as the reactant. Thermal reaction of 1 with C₆₀ products Mo(CO)₂(η⁴-(PPh₂(o-C₆H₄)CH)₂)(η²-C₆₀) (3) in low yield, apparently through coupling of the formyl moieties. The structures of 1 and 3 have been determined by an X-ray diffraction study. The two aldehyde groups of 1 and C₆₀ ligand of 3 are coordinated to the molybdenum atom in a π-fashion.     

Molecular Packing in the Crystal Structures of Mixed-Ligand Complexes [ZnPhen{(i-C4H9)2PS2}2] and [Zn(2,2′-Bipy){(i-C4H9)2PS2}2]

Volatile mixed-ligand complexes of Zn(i-Bu₂PS₂)₂ with Phen and 2,2-Bipy have been synthesized. The crystal structures of the complexes ZnPhen{(i-C₄H₉)₂PS₂}₂ and Zn(2,2-Bipy){(i-C₄H₉)₂PS₂}₂ were determined by single crystal X-ray diffractometry (CAD-4 diffractometer, MoK radiation, 2100 F_hkl, R = 0.0423 for the first complex and 2003 F_hkl, R = 0.0486 for the second). The crystals are monoclinic with cell dimensions a = 17.580(4), b = 9.969(2), c = 19.175(4) , = 90.33(3)°, V = 3360(1) ³, Z = 4, d _calc = 1.313 g/cm³, space group P2/n (for the Phen complex); a = 24.219(5), b = 11.386(2), c = 24.916(5) , = 97.70(3)°, V = 6809(2) ³, Z = 8, d _calc = 1.249 g/cm³, space group C2/c (for the 2,2-Bipy complex). The complexes are constructed from discrete monomer molecules. The coordination polyhedra of the Zn atoms are distorted tetrahedra formed by two S atoms of the two monodentate i-Bu₂PS ₂ ^- ligands and two N atoms of the cyclic bidentate Phen or 2,2-Bipy molecules. Intermolecular interactions and packings in the structures are analyzed.