High-molecular-weight Polyethylene Prepared with Early Transition Metal Catalysts

Early transition metal catalysts [N,N]MCln, in which [N,N] is N-（2,6-diisopropylphenyl） pyridine-2-carboxaldimine （C18H22N2, NN-1）, N-（2,6-diisopropylphenyl）-6-methylpyridine-2- carboxaldimine （C19H24N2, NN-2）, N-（2,4,6-trimethylphenyl）pyridine-2-carboxaldimine （CIsH16N2, NN-3）, M is Ti, Zr and V, and n is 3 or 4, e.g. [NN-1]TiCh 1a, [NN-1]ZrCh 1b, [NN-1]VC13 1c, [NN-2]TiCh 2a, [NN-2]ZrCh 2b, [NN-2]VC13 2e, [NN-3]TiCh 3a have been investigated to catalyze ethylene polymerization in the presence of methylaluminoxane （MAO）. It was noteworthy that polyethylene characteristic of high molecular weight and wide or bimodal molecular weight distribution was formed with moderate to high activities.     

Oxidative Methylation of Toluene with Methane over Basic Zeolite Catalysts Promoted with Alkali Metal Bromides and Alkali Metal Oxides

IntroductionStyrene is one of the most important industrial monomers. At present, styrene is mainlyproduced by alkylation of benzene with ethylene followed by oxidative dehydrogenationof the resulting ethylbenzene. However, this process is very expensive and complex. Anew method of synthesizing ethylbenzene and styrene directly from toluene and methanewas discovered by Khcheyan el al. ', and Yakovich and Bakareva2. The process wouldpotentially reduce the cost because of the production of sty…     

Gas-Chromatographic Study of Hydrazine Reaction with Metal β-Diketonates

When treated with hydrazine, metal -diketonates undergo decomposition to form the corresponding pyrazoles, irrespective of the kinetic stability of the chelates. With substituted metal chelates, the main reaction products are pyrazoles bearing in position 4 the -substituent of the compex. Other products are formed when the substituent has centers sensitive to nucleophilic substitution and/or elimination. The reaction can be used for structural assessment of the starting -diketonate.     

Rhenium Compounds with Metal–Metal Multiple Bonds: X-Ray Spectral Study of the Electronic Structure

The electronic structures of the binuclear complexes [(NH₄)₂Re₂Cl₈)] · 2H₂O and Re₂(CH₃COO)₄Br₂ were studied using ReL₅ X-ray emission spectra. The distribution of the Re 5d AOs and Cl 3p AOs in the MOs of these complexes was analyzed. The ReL₅ spectra of the complexes exhibit components corresponding to the metal–metal -bond. The contribution of the rhenium 5d AOs to the bond in [(NH₄)₂Re₂Cl₈)] · 2H₂O is almost twice as low as in Re₂(CH₃COO)₄Br₂.     

Synthesis of Metal Porphyrins Tailed with Salicylic Acid and their Interaction with Bovine Serum Albumin

A synthetic method of porphyrins tailed with salicylic substituents is described.Reaction of bromoalkoxyphenyl porphyrin 1 with salicylic acid gave porphyrins 2-5. These new compounds were confirmed by ^1H NMR, IR, UV-vis, MS and elemental analysis, and observed their interaction with bovine serum albumin (BSA) in fluorescence spectrum.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

Enthalpic Interaction for α-Amino Acid with Alkali Metal Halides in Water

The studies of the enthalpic interaction parameters, hxy, hxyy and hxxy, of alkali metal halides with glycine, α-alanine and α-aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the α-amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt‘s effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxyWith the radius of cations is not evident. The value of hxyywill increase with the increase of the radii of the ions. As the increase of the number of carbon atoms of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α-alanine for the ions which have small size. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.     

Transitional Metal Complexes with 1,2,4-Triazole Ligand： Syntheses and Crystal Structures

Four novel transitional metal complexes with 3-（4-pyridly）-4-phenyl-5-sulfhydryl- 1,2,4- triazole （HL1） and 3-（3-pyridly）-4-phenyl-5-sulfhydryl-l,2,4-triazole （HLz） were synthesized and characterized by elemental analysis, IR and X-ray diffraction. Complexes 1, 3 and 4 have two-dimensional （2-D） neutral rhombohedral grid with a （4, 4） topology. In 1, 3 and 4, all the metal ions are six-coordinated to four nitrogen atoms of four distinct ligands and two O atoms from water molecules. Complex 2 has tetranuclear CuaCI4 units which are interconnected by four desulfuri- zation ligands （L1-S） via Cu-N bonds to form a 2-D layer with （4,4） topology.     

Synchronous Dual Electrolyte Additive Sustains Zn Metal Anode with 5600 h Lifespan

Despite conspicuous merits of Zn metal anodes, the commercialization is still handicapped by rampant dendrite formation and notorious side reaction. Manipulating the nucleation mode and deposition orientation of Zn is a key to rendering stabilized Zn anodes. Here, a dual electrolyte additive strategy is put forward via the direct cooperation of xylitol (XY) and graphene oxide (GO) species into typical zinc sulfate electrolyte. As verified by molecular dynamics simulations, the incorporated XY molecules could regulate the solvation structure of Zn²⁺, thus inhibiting hydrogen evolution and side reactions. The self-assembled GO layer is in favor of facilitating the desolvation process to accelerate reaction kinetics. Progressive nucleation and orientational deposition can be realized under the synergistic modulation, enabling a dense and uniform Zn deposition. Consequently, symmetric cell based on dual additives harvests a highly reversible cycling of 5600 h at 1.0 mA cm⁻²/1.0 mAh cm⁻².     

Complexes of Some Metal Nitrates with 4′-Nitrobenzo-15-Crown-5

Complexes of Ag, Cu, Ca, Nd, and Er nitrates with 4-nitrobenzo-15-crown-5 (NB15C5) were synthesized and their IR absorption spectra were studied. Macrocyclic conformation in the complexes was determined. The structures of the complexes were proposed with account of the data of IR absorption spectra and of the previous X-ray diffraction study. In the Ag, Cu, and Ca complexes, NB15C5 was found in the inner sphere, while in the Nd and Er complexes, it was found to be the outer-sphere ligand.     

Syngas Production by Methane Reforming with Carbon Dioxide on Noble Metal Catalysts

A series of noble metal catalysts (Ru, Rh, Ir, Pt, and Pd) supported on alumina-stabilized magnesia (Spinel) were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were characterized using BET, TPR, TPO, TPH, and H2S chemisorption techniques. The activity results showed high activity and stability for the Ru and Rh catalysts. The TPO and TPH analyses indicated that the main reason for lower activity and stability of the Pd catalyst was the formation of the less reactive deposited carbon and sintering of the catalyst.     

Metal Ions Extraction with Glucose Derivatives as Chelating Reagents in Supercritical Carbon Dioxide

A series of glucose derivatives have been used as chelating reagents to extract metal ions in supercritical carbon dioxide. With perfluoro-1-octanesulfonic acid tetraethylammonium salt as additive, glucose derivatives were selective for Sr2 and Pb2 extraction in supercritical carbon dioxide.     

Catalytic Hydrogenation of Diacetyl Monoxime to Tetramethylpyrazine with the Soluble Transition Metal Catalysts

Tetramethylpyrazine(TMP)isausefulcompoundinfoodindustry'.InrecentyearsithasbeenfoundasanactiveingredientinChuanxi0ng(ligusticumwallichiifranch),whichisatraditionalChineseherb.NowTMPhasbeenwidelyusedinthetreatmentofpatientswithcerebralischemicdiseasesinChina2.OneoftheimportantmethodsforthepreParationoftetramethylpNazineistheselfcondensati0noftwomoleculesof2-aminobutanoneto2,5-dihydrotetramethlipyrazineandsubsequentoxidati0ntoTMP3.2-Aminobutanoneispreparedusuallyinsituviathereductionofthec…     

Metal–Organic Gels from Silver Nanoclusters with Aggregation-Induced Emission and Fluorescence-to-Phosphorescence Switching

Luminescent metal nanoclusters (NCs) are emerging as a new class of functional materials that have rich physicochemical properties and wide potential applications. In recent years, it has been found that some metal NCs undergo aggregation-induced emission (AIE) and an interesting fluorescence-to-phosphorescence (F-P) switching in solutions. However, insights of both the AIE and the F-P switching remain largely unknown. Now, gelation of water soluble, atomically precise Ag₉ NCs is achieved by the addition of antisolvent. Self-assembly of Ag₉ NCs into entangled fibers was confirmed, during which AIE was observed together with an F-P switching occurring within a narrow time scale. Structural evaluation indicates the fibers are highly ordered. The self-assembly of Ag₉ NCs and their photoluminescent property are thermally reversible, making the metal–organic gels good candidates for luminescent ratiometric thermometers.     

Metal catalysed reactions of β,β′-tricarbonyl derivatives with isocyanates

The reactions of β,β′-tricarbonyl derivatives with isocyanates are catalysed by 2 mol % transition metal acetylacetonates (e.g., [Co(acac)₂] and [Zn(acac)₂]) at room temperature. 3-Oxo-1,5-pentanedioic acid dimethylester (1) reacts with RNCO (R=Et, CH₂CHCH₂, CH₂Ph, Ph, 4-Cl-Ph) to give 1:1 adducts involving the formation of a new C-C bond between the intercarbonylic methylene and the isocyanato group. Under similar conditions 2,4,6-heptanetrione (2) reacts with the same isocyanates to afford pyridinone and pyranone derivatives resulting from the cyclisation of unstable 1:1 and 1:2 adducts.     

Complexation Studies of N,N′-ethylenedi-L-cysteine with Some Metal Ions

As part of a search for environmentally friendly metal chelating ligands, the stability constants of N, N′-ethylenedi-L-cysteine (EC) complexes with Ca(II), Cu(II), Mg(II) and Mn(II) were determined by potentiometry with a glass electrode in aqueous solutions containing 0.1 mol⋅L⁻¹ KCl at 25 °C. Final models are proposed. For the Ca(II)–EC system, the overall stability constants are log ₁₀ β _CaHL=14.53±0.03, log ₁₀ β _CaL=4.79±0.01 and log ₁₀ β _CaL2=8.38±0.04. For the M(II)–EC systems, where M=Cu(II) or Mg(II), the overall stability constants are log₁₀ β _CuHL=31.19±0.02 and log ₁₀ β _CuL=27.02±0.06 for Cu(II), and are log ₁₀ β _MgHL=14.84±0.02 and log ₁₀ β _MgL=6.164±0.008 for Mg(II). For the Mn(II)–EC system, the overall stability constant is log ₁₀ β _MnL=10.12±0.01. Metal–chelate speciations simulations showed that EC is an efficient chelating agent for Cd(II), Co(II), Cu(II), Ni(II), Pb(II) and Zn(II) for pH≥7.     

Stable Operation of Lithium Metal Batteries with Aggressive Cathode Chemistries at 4.9 V

High-voltage lithium metal batteries (LMBs) pose severe challenges for the matching of electrolytes with aggressive electrodes, especially at low temperatures. Here, we report a rational modification of the Li⁺ solvation structure to extend the voltage and temperature operating ranges of conventional electrolytes. Ion-ion and ion-dipole interactions as well as the electrochemical window of solvents were tailored to improve oxidation stability and de-solvation kinetics of the electrolyte. Meanwhile, robust and elastic B and F-rich interphases are formed on both electrodes. Such optimization enables Li||LiNi_0.5Mn_1.5O₄ cells (90.2 % retention after 400 cycles) and Li||LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cells (74.0 % retention after 200 cycles) to cycle stably at an ultra-high voltage of 4.9 V. Moreover, NCM622 cells deliver a considerable capacity of 143.5 mAh g⁻¹ at −20 °C, showing great potential for practical uses. The proposed strategy sheds light on further optimization for high-voltage LMBs.     

Isoreticular Linker Substitution in Conductive Metal–Organic Frameworks with Through-Space Transport Pathways

The extension of reticular chemistry concepts to electrically conductive three-dimensional metal–organic frameworks (MOFs) has been challenging, particularly for cases in which strong interactions between electroactive linkers create the charge transport pathways. Here, we report the successful replacement of tetrathiafulvalene (TTF) with a nickel glyoximate core in a family of isostructural conductive MOFs with Mn²⁺, Zn²⁺, and Cd²⁺. Different coordination environments of the framework metals lead to variations in the linker stacking geometries and optical properties. Single-crystal conductivity data are consistent with charge transport along the linker stacking direction, with conductivity values only slightly lower than those reported for the analogous TTF materials. These results serve as a case study demonstrating how reticular chemistry design principles can be extended to conductive frameworks with significant intermolecular contacts.