Liquid NH3 Research Articles

Preparation via the polymer route and photoluminescence properties of CeSi3N5

CeSi3N5 has been prepared via the polymer route, a one-pot and liquid-phase synthesis, based on a reaction between SiCl4 and liquid NH3 in which Ce[N(Si(CH3)3)2]3 was suspended. The sample was characterized by powder X-ray diffraction analysis, diffuse reflection and photoluminescence spectroscopies. CeSi3N5 exhibits a strong absorption peaking at 365 nm. Furthermore, it has a broad emission band at 468 nm due to 4f05d1 → 4f1 transition of Ce3+. Obviously, CeSi3N5 appears to be a good candidate for use as a blue phosphor, which can be pumped by near-UV-LEDs.

ChemInform Abstract: Synthesis and Crystal Structure of Triammine Pentafluorido Tantalum(V) [TaF5(NH3)3

AbstractTaF5(NH3)3 is prepared by reaction of Sr(HF)3(TaF6)2 with liquid NH3 (‐40 °C, several months of crystal growth).

ChemInform Abstract: A Novel Production Method for Nitridosilicate‐Type Phosphors.

AbstractM2‐xEuxSi5N8 (M: Ca, Sr, Eu) orange‐to‐red phosphors for white‐LED applications are prepared by reacting SiCl4 with liquid NH3 in which Ca, Sr, or Eu metals are dissolved, or Eu[N(SiMe3)2]3 is suspended.

ChemInform Abstract: Polytellurides of Mn, Fe, and Zn from Mild Solvothermal Reactions in Liquid Ammonia.

Abstract[Mn(NH3)6]Te4 (I), [Fe(NH3)6]Te4·NH3 (II), and [Zn(NH3)4]2Te15 (III) are obtained by solvothermal reaction of elemental Mn, Fe, and Zn with Te in liquid NH3 at 50 °C (≤50% yield for (II), 100% yield for (I) and (III)).

ChemInform Abstract: First Incorporation of the Tetrahedral [Sn4]4‐ Cluster into a Discrete Solvate Na4[Sn4]·(NH3)13 from Solutions of Na4Sn4 in Liquid Ammonia.

AbstractNa4[Sn4]·13NH3 is obtained from deep red suspensions of Na4Sn4, Cu‐Mst, and 18‐crown‐6 in liquid NH3 (‐70 °C, 19 weeks, 25% yield).

A Novel Production Method for Nitridosilicate‐type Phosphors

AbstractM2–xEuxSi5N8 (M = Ca, Sr, and Eu), well performing orange‐to‐red phosphors for white‐LED applications, were prepared with a novel production route based on employing molecular and polymeric precursors. The procedure presented allows a one‐pot, solution‐based synthesis of the desired phosphors by reacting SiCl4 with liquid NH3, in which Ca, Sr, and Eu metals are dissolved, or Eu[N(Si(CH3)3)2]3 is suspended. The significant advantages of this new approach over the conventional solid state syntheses are easily achievable high purities of the starting compounds, and thus of the final phosphors, as well as processing at mild conditions, avoiding laborious handling and complex equipments.

Formation of diamond powders from melamine under high pressure and high temperature

High pressure pyrolysis of melamine has been attracting great interest recently, due to it being considered as a suitable precursor to realize the g-C3N4 and even superhard C3N4. In this work, we studied the detailed pyrolysis behavior of melamine at 22 GPa. Melamine was stable at 800 °C, and decomposed to diamond in the form of powder at 1500–2000 °C under this pressure condition. At 2000 °C, the pure cubic diamond powders with 0.1–0.5 μm grain size were obtained. The diamond particles exhibited euhedral forms and dispersed to each other, we proposed that these novel features were caused by the presence of liquid N2 and NH3 during diamond formation. The high pressure pyrolysis of melamine may provide a new means of producing micrometer-sized diamond powders.

ChemInform Abstract: 1D Coordination Polymers with Polychalcogenides as Linkers Between Metal Atoms.

AbstractCompounds (III), (IV), (VI), and (IX) are solvothermally synthesized in liquid NH3 or MeNH2 and characterized by single crystal XRD, Raman, and diffuse reflectance spectroscopy.

Sol–gel synthesis of tetragonal ZrO2 nanoparticles stabilized by crystallite size and oxygen vacancies

In this letter, we present a facile route to produce metastable tetragonal zirconia (ZrO2) nanoparticles via pH-controlled precipitation of dilute zirconyl nitrate dihydrate [ZrO(NO3)2·2H2O] solution in liquid NH3 under ambient conditions and calcination at 500 °C for 2 h. The phase pure tetragonal ZrO2 nanoparticles are obtained at pH 9. The effect of pH on metastable phase stabilization in precipitated ZrO2 nanoparticles is demonstrated with the help of XRD, SEM/EDX, and X-ray photoelectron spectroscopy techniques. The stability of tetragonal ZrO2 phase is attributed to the smaller crystallite size and greater oxygen deficiency in phase-pure tetragonal ZrO2.

Searching for Magnetism in Hydrogenated Graphene: Using Highly Hydrogenated Graphene Prepared via Birch Reduction of Graphite Oxides

Fully hydrogenated graphene (graphane) and partially hydrogenated graphene materials are expected to possess various fundamentally different properties from graphene. We have prepared highly hydrogenated graphene containing 5% wt of hydrogen via Birch reduction of graphite oxide using elemental sodium in liquid NH3 as electron donor and methanol as proton donor in the reduction. We also investigate the influence of preparation method of graphite oxide, such as the Staudenmaier, Hofmann or Hummers methods on the hydrogenation rate. A control experiment involving NaNH2 instead of elemental Na was also performed. The materials were characterized in detail by electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy both at room and low temperatures, X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, combustible elemental analysis and electrical resistivity measurements. Magnetic measurements are provided of bulk quantities of highly hydrogenated graphene. In the whole temperature range up to room temperature, the hydrogenated graphene exhibits a weak ferromagnetism in addition to a contribution proportional to field that is caused not only by diamagnetism but also likely by an antiferromagnetic influence. The origin of the magnetism is also determined to arise from the hydrogenated graphene itself, and not as a result of any metallic impurities.

ChemInform Abstract: Superconducting Phases in Potassium‐Intercalated Iron Selenides.

AbstractFrom a series of KxFe2Se2(NH3)y (x = 0.1—1.0) samples prepared by intercalation of K into β‐FeSe in liquid NH3, K0.3Fe2Se2(NH3)0.47 and K0.6Fe2Se2(NH3)0.37 are obtained as pure phases of the 44 K and 30 K superconducting systems, respectively.

Effects of O2 and H2O2 on TiO2 Photocatalytic Efficiency Quantified by Formaldehyde Formation from Tris(hydroxymethyl)aminomethane

AbstractThe impact of O

ChemInform Abstract: Copper(I)‐Catalyzed Amination of Aryl Halides in Liquid Ammonia.

AbstractCuI in combination with ascorbic acid promotes the coupling of aromatic iodides and bromides with liquid NH3 and allows selective formation of a number of primary amines in good to high yields.

Vibrational energy relaxation of the ND-stretching vibration of NH2D in liquid NH3

The vibrational energy relaxation from the first excited ND-stretching mode of NH(2)D dissolved in liquid NH(3) is studied using molecular dynamics simulations. The rate constants for inter- and intramolecular energy transfer are calculated in the framework of the quantum-classical Landau-Teller theory. At 273 K and an ammonia density of 0.642 g cm(-3) the calculated ND-stretch lifetime of τ = 9.1 ps is in good agreement with the experimental value of 8.6 ps. The main relaxation channel accounting for 52% of the energy transfer involves an intramolecular transition to the first excited state of the umbrella mode. The energy difference between both states is taken up by the near-resonant bending vibrations of the solvent. Less important for the ND-stretch lifetime are both the direct transition to the ground state and intramolecular relaxation via the NH(2)D bending modes contributing 23% each. Our calculations imply that the experimentally observed weak density dependence of τ is caused by detuning the resonance between the ND-stretch-umbrella energy gap and the solvent accepting modes which counteracts the expected linear increase of the relaxation rate with density.

ChemInform Abstract: μ‐Oxido‐bis(pentammine Iron(III))‐chloride‐ammonia(1/8), [Fe2(μ—O)(NH3)10] Cl4·8NH3.

AbstractThe title compound is synthesized by reaction of FeCl3·6H2O with liquid NH3 and characterized by single crystal XRD.

ChemInform Abstract: mer‐Triammine Trifluorido Iron(III), mer‐[FeF3(NH3)3

AbstractThe title compound is synthesized in quantitative yield by reaction of FeF3 with liquid NH3 at ‐40 °C.

ChemInform Abstract: The Complex Amide K2[Zr(NH2)6

AbstractThe title compound is synthesized by reaction of ZrF4 with elemental potassium dissolved in liquid NH3 (‐78 → ‐40 °C, 4 weeks).

ChemInform Abstract: Regeneration of Ammonia Borane Spent Fuel by Direct Reaction with Hydrazine and Liquid Ammonia.

AbstractPolyborazylene which is formed by removal of more than two equivalents of H2 per molecule from NH3·BH3 is converted back to ammonia borane nearly quantitatively by a 24‐hour treatment with N2H4 in liquid NH3 at 40 °C (sealed pressure vessel).

Compressed hydrogen production via reaction between liquid ammonia and alkali metal hydride

Ammonia NH 3 is recognized as one of the attractive hydrogen H 2 carriers because it has a high hydrogen content of 18 mass% and it is easily liquefied under about 1 MPa of pressure at a room temperature. NH 3 can react with alkali metal hydrides and generate H 2 even at room temperature, resulting that metal amides are formed as reaction products. The H 2 generation is exothermic reaction, and it is not effectively prevented by H 2 partial pressure in a closed system as thermodynamic properties. In this work, we demonstrated the production of compressed H 2 by the reaction between liquid NH 3 and lithium hydride LiH in a closed pressure vessel, where liquid NH 3 would realize better kinetic properties for the reaction with metal hydride than gaseous NH 3. Actually, more than 12 MPa H 2 was obtained within several hours.

Facile Synthesis of trans-S-1-Propenyl-L-Cysteine Sulfoxide (Isoalliin) in Onions (Allium cepa)

Scheme 1 Allium species such as onions (Allium cepa) and garlic (Allium sativum) contain a variety of sulfur compounds which exhibit significant biological activities including anticarcinogenic, antitumorigenic, antimutagenic, antimicrobial, immunomodulatory, cardiovascular-protective, and antioxidant effects. Several S-alk(en)yl-L-cystein sulfoxides have been reported to be present in genus Allium in the form of nonprotein sulfur amino acids. Trans-S-1-propenyl-L-cystein sulfoxide (isoalliin, 1) has been isolated from onions, 8 and it has been shown to be the precursor of the lachrymatory properties of Allium cepa by the action of the enzyme alliinase on the conversion of odorless trans-S-1-propenyl-L-cystein sulfoxide into the corresponding volatile thiosulfinate. Quantification of S-alk(en)yl-L-cystein sulfoxides is an important issue in Allium research. The unusual amino acid transS-1-propenyl-L-cystein sulfoxide (1) is in demand in the field of Allium chemistry including metabolism and biological studies, and serves as a standard for determination of S-alk(en)yl-Lcystein sulfoxides. Herein, we describe the facile synthesis of trans-S-1-propenyl-L-cystein sulfoxide in three steps. The synthesis of trans-S-1-propenyl-L-cystein sulfoxide (1) was reported by three research groups. Nishimura and co-workers performed the isomerization of a terminal triple bond (ethyl prop-2-ynyl sulfide) to ethyl prop-1-ynyl sulfide and the subsequent reductive coupling with alkyl chloride as key reaction steps. Parry and Sood reported the synthesis of compound 1 in five steps without presenting a detail experimental description. They also used the isomerization of a terminal triple bond (benzyl prop-2-ynyl sulfide) to benzyl prop-1-ynyl sulfide in the scheme of synthesis of 1. Namyslo and Stanitzek utilized palladium-catalyzed coupling of a thiol with alkenyl bromide and completed the synthesis of compound 1 in five steps. Our synthesis started with the formation of vinylsulfide 3 from the commercially available (E)-1-bromo-1-propene (2), which by treatment with t-BuLi and the successive addition of dibenzyl disulfide afforded (E)-1-(benzylthio)-1-propen (3) (Scheme 1). The isomerically pure trans-(1-propen) compound 3 was obtained providing the characteristic large NMR coupling of the trans-olefinic protons (J = 15.0 Hz). Reductive cleavage of a C-S bond in compound 3 by Na in liquid NH3 followed by addition of 3-chloro-L-alanine hydrochloride gave trans-S-1-propenyl-L-cystein (4). Finally, the oxidation of sulfide 4 by aqueous hydrogen peroxide provided sulfoxide 1 in a quantitative yield. Compound 1 was obtained as a mixture of two diastereomers with a new formed sulfur chiral center. The structure of 1 was confirmed by a comparision with those in the literature. In summary, a natural amino acid, trans-S-1-propenyl-Lcystein sulfoxide (1) was synthesized from (E)-1-bromo-1-propene in a concise way, via the sequential (i) the formation of vinylsulfide from lithiated propene and disulfide, (ii) reductive cleavage/alkylation of vinylsulfide, (iii) sulfide oxidation to sulfoxide. This compound is widely used as a reference for studies on Allium chemistry including biosynthesis of S-alkenylL-cystein sulfoxides, metabolism studies and biological investigations.