Synthesis of Branched Polyethylene via Bulky α-Diimine Nickel(II)-Catalyzed Ethylene Chain-Walking Polymerization

The catalysis of olefin polymerization through the chain-walking process is a subject of great interest. In this contribution, the successful synthesis of a Brookhart-type unsymmetrical α-diimine nickel catalyst Ni, which contains both dibenzhydryl and phenyl groups, was determined by X-ray crystallography. The compound has a pseudo-tetrahedral geometry at the Ni center, showing pseudo-C2-symmetry. Upon activation with modified methylaluminoxane (MMAO), Ni1 exhibits high catalytic activity up to 1.02 × 107 g PE (mol Ni h)−1 toward ethylene polymerization, enabling the synthesis of high molecular weight branched polyethylene. The molecular weights and branching densities could be tuned over a very wide range. The polymerization results indicated the possibility of precise microstructure control, depending on the polymerization temperature. The branching densities were decreased with increasing the polymerization temperature.

Environmentally Friendly Room Temperature Synthesis of 1-Tetralone over Layered Double Hydroxide-Hosted Sulphonato-Salen-Nickel(II) Complex

1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.

Synthesis, Crystal Structure and DNA Binding Studies of a Nickel(II) Complex with 2-Aminomethylbenzimidazole and Demethylcantharate

A new mixed-ligand nickel（Ⅱ） complex, [Ni（L）（DCA）（H2O）]·2H2O （L = C8H9N3, 2-aminomethyl-benzimidazole, DCA2- = 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, demethylcantharate, C8H8O5）, has been synthesized and characterized. The structure of the complex was determined by single-crystal X-ray diffraction. It is of monoclinic system, space group P21/c with a = 7.7211（7）, b = 12.0799（12）, c = 19.7867（19）, β = 100.390（6）°, V = 1815.2（3） nm3, Dc = 1.625 g·cm-3, Ζ = 4, F（000） = 928, R = 0.0314 and wR = 0.0822. In addition, the interaction between the complex and DNA was studied by means of fluorescence spectra and viscosity. The results indicate that the complex binds to DNA by the mode of partial intercalation with the Stern-Volmer constants Ksv of 3.81 × 104 mol·L-1.

Synthesis and Crystal Structure of a New Nickel(II) Complex with Unsymmetric Quadridentate Schiff Base Containing Oxime

The title complex, C18H15N3NiO3, has been prepared and characterized by X-ray diffraction analysis. It crystallizes in the monoclinic system, space group Cc with a = 10.939(2), b = 22.909(5), c = 6.907(1) ?, β = 116.75(3)°, V = 1545.7(5) ?, Z = 4, Mr = 380.04, F(000) = 784, Dc = 1.633 g/cm3 and μ(MoKα) = 1.279 mm–1. The structure was refined to R = 0.0472 and wR = 0.0893 for 2571 observed reflections with I > 2σ(I). The absolute structure Flack parameter X is 0.01(2). In this crystal structure, strong face-to-face π-π stacking interactions between adjacent molecules lead to a one-dimensional chain structure.

Synthesis, Crystal Structure and Thermal Stability of (Diacetylacetone)(diimidazole)Nickel(II) Complex

The title compound, [Ni(acac)2(Im)2] (acac = acetylacetone), has been obtained by the reaction of Ni(acac)2 with imidazole ligand in the ethanol solvent. The blue crystal is of triclinic, space group Pi with a = 7.472(2), b = 9.456(2), c = 13.823(3) ? a = 85.55(3), = 89.03(3), ? = 80.63(3)o, C16H22N4NiO4, Mr = 393.09, V = 960.7(3) 3, Z = 2, Dc = 1.359 g/cm3, F(000) = 412, = 1.036 mm-1, R = 0.0549 and wR = 0.1615. The crystal structure consists of two disconnected structural units. Each Ni atom coordinated by two N atoms from two imidazole ligands and four O atoms from two acetylactone ligands adopts a slightly distorted octahedron. The structure characterization was performed by means of IR, UV, TG, elemental analysis and single-crystal X-ray analysis. The thermal gravity (TG) data indicate that thermal decomposition of the title compound takes place in two steps, and the residue is NiO.

Synthesis and Characterization of Nickel(II) Complex Bearing 2,9-di-tert-butyl-1,10-phenanthroline Ligand

The complex DtbpNiCl2（Dtbp = 2,9-di-tert-butyl-1,10-phenanthroline） was synthe- sized and characterized by X-ray single-crystal structure analysis. For the complex： C20 H24 Cl2 N2 Ni CH2 Cl2, Mr = 506.95, monoclinic, space group P21 /c, a = 9.5905（3）, b = 13.7587（3）, c = 17.3364（5）, β = 94.244（2）°, V = 2281.31（11）3, Z = 4, Dc = 1.476 g/cm3, λ = 1.54184, μ = 5.606 mm-1, F（000） = 1048, S = 1.079, R = 0.0402 and wR = 0.1010 for 3223 observed reflections with I 〉 2σ（I）. In complex DtbpNiCl2, the nickel adopts a distorted tetrahedral geometry coordinated by two nitrogen atoms of Dtbp and two chlorine ions. The complex is connected by intermolecular C–H…Cl hydrogen bonds to form a 1D structure in the solid state.

Crystal Structure and Characterization of 2-N-(2-Hydroxy-benzylidene) Furanmethanoamine Nickel(II) Complex

The Ni（Ⅱ） complex with ligand 2-N-（2-hydroxy-benzylidene） furanmethanoamine has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C2/c with a = 2.0280（4）, b =0.57700（12）, c = 1.7340（4） nm, β = 94.74（3）°, Z = 4, Dc = 1.508 g/cm^3, the final R = 0.0434 and wR = 0.1112 for 1843 observed reflections with 1 〉 2σ（I）. X-ray analysis revealed that the Ni（Ⅱ） ion is coordinated by two nitrogen atoms of Schiff base and two oxygen atoms of salicylaldehyde in the equatorial plane, and the coordination geometry can be described as a square.

Synthesis, Crystal Structure and Electrochemistry Properties of a (N,N'-Ethylene-bis(salicylaldiminato)) Nickel(II) Complex, [Ni_2(salen)_2]·NCS·NH_4

A new Ni（Ⅱ） complex [Ni2（salen）2]·（NCS）·NH4 （salen = N,N＇-bis（salicylideneamino）ethanato） has been prepared and structurally characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 16.8725（13）, b = 19.0046（15）, c = 20.0583（16）A, Z = 8, V = 6431.8（9）A^3, C33H32N6Ni2O4S1, Mr = 726.13, Dc = 1.500 g/cm^3, F（000） = 3008, μ = 1.284 mm^-1, the final R = 0.0394 and wR = 0.0767 for 4449 observed reflections with I 〉 2σ（I）. The complex involves a N,N＇-ethylene-bis（salicylaldiminato） Schiff base, an isothiocyanato anion and an ammonium cation. The nickle（II） ion adopts a distorted square coordination geometry with N2O2 set of Schiff base ligand. The complexes are linked into a dimmer via intermolecular hydrogen bonds and the [Ni（salen）] moieties are connected together to form a 2-D layer structure by intermolecular N-H…O hydrogen bonds and π-π stacking. Cyclic-voltammetry method was used to characterize electrochemically the complex.

Synthesis and Structure of L-Aspartato- nickel(II) Complex with Benzimidazole

The title complex Ni(C4H5NO4)(C7H6N2)31.75(H2O) (C25H26.5N7NiO5.75, Mr = 575.74) has been prepared and its crystal structure was determined by X-ray diffraction method. The crystal of this chiral complex belongs to monoclinic, space group P21 with a = 13.208(1), b = 10.741(1), c = 19.398(1) ? b = 104.39(1)o, V = 2665.8(4) 3, Z = 4, Dc = 1.435 g/cm3, m(MoKa) = 0.780 mm-1 and F(000) = 1198. The final R = 0.0504 and wR = 0.1267 for 9159 observed reflections (I > 2s(I)), and R = 0.065 and wR = 0.1299 for 11006 independent reflections. The complex assumes a distorted octa- hedral coordinate geometry formed by one aspartate dianion and three benzimidazole ligands. The aspartate chelates to the Ni atom as a tridentate ligand. The lattice water molecules are hydrogen- bonded to the Ni complex molecule.

Synthesis and Crystal Structure of a New Ternary Complex of Nickel(II) with L-Aspartic Acid and 1,10-Phenanthroline

A new ternary complex of nickel(II) with L-aspartate (L-Asp) and 1, 10-phenan- throline(Phen), [Ni3(L-Asp)(Phen)5(H2O)3](ClO4)4?4.75H2O, has been synthesized in a mixed sol- vent of H2OC2H5OH at the pH value of 3. It crystallizes in triclinic, space group P1 with a = 11.861(2), b = 18.384(4), c = 19.746(3) ?, α = 107.68(1), β = 105.94(1), γ = 103.41(2)°, V = 3703.6(11) ?3, Mr = 1745.66, Z = 2, Dc =1.565 g/cm3, μ = 0.989 mm-1, F(000) = 1791, R = 0.0643 and wR = 0.1611. The complex contains two cations, binuclear [Ni2(L-Asp)(Phen)3(H2O)]2+ and mononu- clear [Ni(Phen)2(H2O)2]2+. All the nickel ions in the complex are six-coordinated with a distorted octahedral geometry, but the coordination environments for them are different. There exist hydrogen bonds and π-π stacking interactions in the complex.

Nickel catalysts with asymmetric steric hindrance for ethylene polymerization

α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.

Elimination of GGTA1,CMAH,β4GalNT2 and CIITA genes in pigs compromises human versus pig xenogeneic immune reactions

Background:Pig organ xenotransplantation is a potential solution for the severe organ shortage in clinic,while immunogenic genes need to be eliminated to improve the immune compatibility between humans and pigs.Current knockout strategies are mainly aimed at the genes causing hyperacute immune rejection(HAR)that occurs in the first few hours while adaptive immune reactions orchestrated by CD4 T cell thereafter also cause graft failure,in which process the MHCⅡmolecule plays critical roles.Methods:Thus,we generate a 4-gene(GGTA1,CMAH,β4GalNT2,and CIITA)knockout pig by CRISPR/Cas9 and somatic cell nuclear transfer to compromise HAR and CD4 T cell reactions simultaneously.Results:We successfully obtained 4KO piglets with deficiency in all alleles of genes,and at cellular and tissue levels.Additionally,the safety of our animals after gene editing was verified by using whole-genome sequencing and karyotyping.Piglets have survived for more than one year in the barrier,and also survived for more than 3 months in the conventional environment,suggesting that the piglets without MHCⅡcan be raised in the barrier and then gradually mated in the conventional environment.Conclusions:4KO piglets have lower immunogenicity,are safe in genomic level,and are easier to breed than the model with both MHCⅠandⅡdeletion.

Solubility of iron(Ⅲ) and nickel(Ⅱ) acetylacetonates in supercritical carbon dioxide

As a common precursor for supercritical CO_(2)(scCO_(2))deposition techniques,solubility data of organometallic complexes in scCO_(2)is crucial for the preparation of nanocomposites.Recently,metal acetylacetonates have shown great potential for the preparation of single-atom catalytic materials.In this study,the solubilities of iron(Ⅲ)acetylacetonate(Fe(acac)3)and nickel(Ⅱ)acetylacetonate(Ni(acac)2)were measured at the temperature from 313.15 to 333.15 K and in the pressure range of 9.5–25.2 MPa to accumulate new solubility data.Solubility was measured using a static weight loss method.The semi-empirical models proposed by Chrastil and Sung et al.were used to correlate the solubility data of Fe(acac)3 and Ni(acac)2.The equations obtained can be used to predict the solubility of the same system in the experimental range.

SYNTHESIS AND CHARACTERIZATION OF BIS-[2-[[(2-ALKOXYPHENYL)IMINO]METHYL]-PHENOLATO-O,N,O]NICKEL(II)COMPLEXES AND THEIR NORBORNENE POLYMERIZATION

A series of salicylaldimines, synthesized in high yield via microwave-assisted condensation of salicylaldehyde and 2-alkoxyaniline were allowed to react with nickel chloride to form six-coordinated nickel complexes. These nickel complexes were carefully characterized, and the solid structure of la was elucidated by X-Ray diffraction. Activated with MAO, the nickel complexes showed good activity for homopolymerization of norbornene. Reaction parameters, such as the ratio of nickel precursor to MAO, monomer concentration, reaction time and the reaction temperature, as well as the nature of the ligands were found to have significant effects on the catalytic activity and some properties of the resulting polynorbornene.

Structure Studies on New Types of Macrocyclic Compounds Part V．Crystal Structure of Nickel（II） Complex of 5，12－Diphenyl－7，14－dimethyl－1，4，8，11－tetraazacyclotetradecane－N＇，N－diacetic Acid

Crystal structure of nickel（II） complex with a new 14 membered tetraazamacrocyclic ligand 5,12-diphenyl-7,14-dimethyl-1,4,8,11-tetraazacyclotetradecane-N’,N-diacetic acid,Ni[N4C10（CH2COO）2（C6H5）2]·2H2O, Mr= 589. 38 is reported.It crystallizes in monoclinic P21/c space group with a=12.949（6）,b=16.373（3）,c=14.232（16）,β=98.68（6）°,V=2982.9（7）,Z=4,Dc=1.312 gcm-3,μ=6.953 cm-1,F（000）=1256.0.Finally,the structure was refined to R=0.080,Rw=0.065 for 2952 reflections.The central nickel ion of the complex forms an octahedron with four nitrogen atoms of the macrocycle and two oxygen atoms of the appended carboxylate groups.Two phenyl planes of the ligand are almost parallel to each other.

Characterization and Crystal Structure of Bis(N'-ethyl-N-piperazinly-carbodithioato-S,S') Nickel(II) Complex:Ni(S_2CNC_4H_8NC_2H_5)_2

The title compound has been prepared and characterized by elemental analysis, infrared and FT-Raman spectra, and thermal analysis. The crystal and molecular structures of bis（N＇-ethyl-N-piperazinly-carbodithioato-S,S＇） nickel（Ⅱ） complex （Ni（S2CNC4H8NC2H5）2） were determined by X-ray diffraction methods. The crystal crystallizes in the triclinic system, space group PI^- with a = 0.66770（15）, b = 0.85066（12）, c = 0.8973（2） nm,α= 84.97（2）, β =78.71（2）,γ= 80.12（2）°, Mr = 437.34, V= 0.49160（17） nm^3, Z = 1, Dc = 1.477 g/cm^3, F（000） = 230, R = 0.0422 and wR = 0.1290. In the structure, the central Ni atom is coordinated in a slightly distorted square plane by four S atoms from two bidentate S2CNC4H8NC2H5 ligands with the four Ni-S bond distances in the range of 0.22065（10）～0.22076（9） nm. The IR and FT-Raman spectral data are in agreement with the structural data. Thermal analysis indicates that the title compound decomposes completely at the temperature of 799.88℃, leaving NiS.

Synthesis and Structure of (Oxydiacetato)-nickel(II) Complex with Diaminobithiazole

The title complex [Ni(C4H4O5)(C6H6N4S2)(H2O)]2.5H2O has been prepared and its crystal structure was determined by X-ray diffraction method. The crystal belongs to monoclinic, space group P21/n with a = 16.499(2), b = 10.132(1), c = 11.177(2) , b = 109.76(1)o, V = 1758.4(4) 3, Mr = 452.11, Z = 4, Dc = 1.708 g/cm3, m = 1.391 mm-1, F(000) = 932, R = 0.0424 and wR = 0.1088 for 2341 observed reflec- tions (I>2s(I)). The complex assumes a distorted octahedral coordination geometry formed by one oxydiacetate dianion, one diaminobithiazole and one coordinated water molecule. The parallel thiazole rings of adjacent complex molecules overlap to each other, and the separation of 3.458(7) ?suggests the existence of - stacking.

Synthesis and Characterization of Nickel(II) and Copper(II) Complexes with Schiff Base (1R,2R)-(-)-Diaminocyclohexane-N,N'-bis(3-tert-butyl-5-(4'-benzoic acid)-salicylidene)

Two homochiral metallosalen complexes, Ni（salen） （salen = （1R,2R）-（-）-diamino- cyclohexane-N,N′-bis（3-tert-butyl-5-（4′-benzoic acid）-salicylidene） 1 and Cu（salen） 2, have been synthesized and characterized by IR, microanalysis, TGA, powder and single-crystal X-ray crystallography. Both 1 and 2 crystallize in orthorhombic space group P21212 with Z = 4. For 1, a = 12.082（2）, b = 15.447（3）, c = 18.784（4）A^°, V= 3505.7（12）A^°3, Mr = 731.50, Dc = 1.386 g/cm^3, μ = 0.606 mm^-1, F（000） = 1544, the final GOOF = 1.043, R = 0.0496 and wR = 0.1248 for 4791 observed reflections with I 〉 2σ（I）. For 2, a = 12.181（2）, b = 15.501（3）, c = 18.877（4） A^°, V = 3564.3（12）A^°3, Mr = 736.33, Dc = 1.372 g/cm^3, μ = 0.665 mm^-1, F（000） = 1548, the final GOOF = 1.062, R = 0.0575 and wR = 0.1508 for 4562 observed reflections with I 〉 2σ（I）. The crystal structures of 1 and 2 are isostructural with very similar supramolecular structures. An infinite two-dimensional network is generated by hydrogen bonding interactions and intermolecular π…π interactions.

Synthesis and Crystal Structure of an Indenylnickel(II) NHC Complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene)

The complex （Ind）NiBr（1,3-bisbenzylimidazol-2-ylidene） （Ind = indenyl） 1 has been prepared in ca. 65% yield via the reaction of （Ind）2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072（1）, b = 11.264（2）, c = 14.541（3）°A, α = 102.21（3）,β = 93.44（3）,γ = 90.81（3）°, V = 1129.7（4）°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F（000） = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections （I〉 2σ（I））. The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane.

Synthesis and Determination of Stability Constants of a New Bis-1,2,4-triazole Ligand for Complexation with Zinc(II), Copper(II) and Nickel(II) in Acetonitrile

In this work, the synthesis and complexation properties of a new compound, 1,3-bis[5-(2-hydroxyphenyl)-4-phenyl- 1,2,4-triazole-3-yl-thio]propane (BTP), towards certain transition metal ions, (M(II) where M = Zn, Cu, Ni) in acetonitrile is reported. A hard-modeling strategy was applied to UV-Visible spectroscopy data obtained from monitoring the reaction between BTP and the selected metal ions to determine the concentration profiles of each species and the corresponding stability constant(s) of the complex(es). The stability constants of complexes are always defined in terms of their free metal, free ligand and complexed forms. These constants are influenced by parameters such as the type of metal, ligand, counterion or solvent. In this study, the formation constants of the complexes were determined for the synthesized ligand with several metallic cations in acetonitrile solvent by UV-Vis spectrophotometry.