Synthesis and Structures of 3,5-disubstituted 1,2,4-triazole Head Units and Incorporation of 3,5-dibenzoyl-1,2,4-triazolate into New [2 + 2] Schiff-Base Macrocyclic Complexes

The synthesis and characterization of sodium 3,5-diacetyl-1,2,4-triazolate (4 ^Me ) and sodium 3,5-dibenzoyl-1,2,4-triazolate (4 ^Ph ), both of which can be used as head unit building blocks in Schiff-base reactions, are reported. The crystal structures of sodium 3,5-diacetyl-1,2,4-triazolate, as [4 ^Me (H₂O)]_∞, and sodium 3,5-dibenzoyl-1,2,4-triazolate, as [4 ^Ph (CH₃OH)₂]₂, have been determined. The former is a helical polymer whilst the latter is a methanol-bridged dimer. The lead(II) templated cyclization reaction of sodium 3,5-dibenzoyl-1,2,4-triazolate (4 ^Ph ) with 1,3-diaminopropane or 1,4-diaminobutane, respectively, leads to the formation of two new [2 + 2] Schiff-base macrocycles as their lead(II) complexes, [Pb₂ L ^3Ph (μ-OH)]ClO₄ (5) and [Pb₂ L ^4Ph (μ-OH)]ClO₄ (6), respectively. Transmetallation of 5 with nickel(II) ions yields a novel, structurally characterized, dinickel(II) macrocyclic complex, [Ni₂ L ^3Ph (NCS)₂] (7), which features double triazolate bridging of the two five-coordinate nickel(II) ions.     

Planar Chiral and Achiral Arenido(triphenylphosphane)nickel(II) Complexes Containing N,O Bidentate Ligands: 19F, 1H,and 31P NMR Studies

Abstract

Planar chiral and achiral arenido(triphenylphosphane)nickel(II) complexes (arenido = mesitylenido, 2-toluenido) comprising electronically delocalised N,O chelating ligands were studied by ¹H and ¹⁹F NMR using 1D and 2D techniques. Results from complexes and corresponding ligands are discussed in the light of molecular structures obtained from X-ray diffraction.

GRAPHICAL ABSTRACT      

SrMoO4:Sm3+,Na+红色荧光粉的形貌调控和发光性能

以Sm³⁺为激活剂,Na⁺为电荷补偿剂,柠檬酸为配位剂,乙二醇作为辅助配位剂,采用溶胶-凝胶法合成前驱体,然后在800℃下焙烧,成功制备了一系列SrMoO₄：Sm³⁺,Na⁺红色荧光粉。用X射线衍射仪、扫描电镜、荧光光谱和傅里叶变换红外光谱等手段对样品的物相、形貌、组成、发光性能和量子效率等进行测试和表征。分析结果表明：制备的SrMoO₄：Sm³⁺,Na⁺荧光粉均为四方晶系结构,掺杂离子的加入对基质晶体结构影响不大。在403 nm近紫外光激发下,产物有4个发射峰,分别位于563、600、647和707 nm处,归属于⁵G_5/2→⁶H_J（J=5/2,7/2,9/2,11/2）的电子跃迁,其中位于647 nm处的主发射峰的相对发光强度最大。当Sm³⁺的掺杂物质的量分数为1%~3%时,发光强度最好,当浓度超过1%~3%时,会发生荧光猝灭。对实验数据进行分析,确定荧光猝灭机理是由于钐离子间交换作用引起的,并计算了能量传递的临界距离为1.77~2.56 nm。此外,还详细研究了乙二醇对SrMoO₄：Sm³⁺,Na⁺荧光粉形貌的影响,研究结果表明：乙二醇加入量为5 mL时,产物形貌均匀,呈球形或椭球形;且分散性较好;荧光强度最大。     

纯相和镍取代的Co_3O_4尖晶石催化剂用于N_2O直接分解(英文)

A series of NixCo1-xCo2O4(0 ≤ x ≤ 1) spinel catalysts were prepared by the co-precipitation method and used for direct N2O decomposition. The decomposition pathway of the parent precipitates was characterized by thermal analysis. The catalysts were calcined at 500 °C for 3 h and characterized by powder X-ray diffraction, Fourier transform infrared, and N2 adsorption-desorption. Nickel cobaltite spinel was formed in the solid state reaction between NiO and Co3O4. The N2O decomposition measurement revealed significant increase in the activity of Co3O4 spinel oxide catalyst with the partial replacement of Co2+ by Ni2+. The activity of this series of catalysts was controlled by the degree of Co2+ substitution by Ni2+, spinel crystallite size, catalyst surface area, presence of residual K+, and calcination temperature.     

Al2O3基Ni-Cu双金属催化剂上乙酰丙酸氢解（英）

Inexpensive γ-alumina-based nickel-copper bimetallic catalysts were studied for the hydrogenolysis of levulinic acid,a key platform molecule for biomass conversion to biofuels and other valued chemicals,into γ-valerolactone as a first step towards the production of 2-methyltetrahydrofurane.The activities of both monometallic and bimetallic catalysts were tested.Their textural and chemical characteristics were determined by nitrogen physisorption,elemental analysis,temperature-programmed ammonia desorption,and temperature-programmed reduction.The monometallic nickel catalyst showed high activity but the highest bγ-product production and significant amounts of carbon deposited on the catalyst surface.The copper monometallic catalyst showed the lowest activity but the lowest carbon deposition.The incorporation of the two metals generated a bimetallic catalyst that displayed a similar activity to that of the Ni monometallic catalyst and significantly low bγ-product and carbon contents,indicating the occurrence of important synergetic effects.The influence of the preparation method was also examined by studying impregnated- and sol-gel-derived bimetallic catalysts.A strong dependency on the preparation procedure and calcination temperature was observed.The highest activity per metal atom was achieved using the sol-gel-derived catalyst that was calcined at 450 ℃.High reaction rates were achieved;the total levulinic acid conversion was obtained in less than 2 h of reaction time,yielding up to 96%γ-valerolactone,at operating temperature and pressure of 250 ℃ and 6.5 MPa hydrogen,respectively.     

Carbon–Carbon Cross‐Coupling Reactions Catalyzed by a Two‐Coordinate Nickel(II)–Bis(amido) Complex via Observable NiI,NiII, and NiIII Intermediates

Recently, the development of more sustainable catalytic systems based on abundant first‐row metals, especially nickel, for cross‐coupling reactions has attracted significant interest. One of the key intermediates invoked in these reactions is a Ni^III–alkyl species, but no such species that is part of a competent catalytic cycle has yet been isolated. Herein, we report a carbon–carbon cross‐coupling system based on a two‐coordinate Ni^II–bis(amido) complex in which a Ni^III–alkyl species can be isolated and fully characterized. This study details compelling experimental evidence of the role played by this Ni^III–alkyl species as well as those of other key Ni^I and Ni^II intermediates. The catalytic cycle described herein is also one of the first examples of a two‐coordinate complex that competently catalyzes an organic transformation, potentially leading to a new class of catalysts based on the unique ability of first‐row transition metals to accommodate two‐coordinate complexes.     

A d10 Ni–(H2) Adduct as an Intermediate in H?H Oxidative Addition across a Ni?B Bond

Bifunctional E H activation offers a promising approach for the design of two‐electron‐reduction catalysts with late first‐row metals, such as Ni. To this end, we have been pursuing H₂ activation reactions at late‐metal boratranes and herein describe a diphosphine–borane‐supported Ni—(H₂) complex, [(^PhDPB^iPr)Ni(H₂)], which has been characterized in solution. ¹H NMR spectroscopy confirms the presence of an intact H₂ ligand. A range of data, including electronic‐structure calculations, suggests a d¹⁰ configuration for [(^PhDPB^iPr)Ni(H₂)] as most appropriate. Such a configuration is highly unusual among transition‐metal H₂ adducts. The nonclassical H₂ adduct is an intermediate in the complete activation of H₂ across the Ni B interaction. Reaction‐coordinate analysis suggests synergistic activation of the H₂ ligand by both the Ni and B centers of the nickel boratrane subunit, thus highlighting an important role of the borane ligand both in stabilizing the d¹⁰ Ni—(H₂) interaction and in the H—H cleavage step.     

Accurate Structure and Bonding Description of the Transition Metal‐Disulfur Monoxide Complexes [(PMe3)2M(S2O)] (M = Ni,Pd, Pt): Grimme Dispersion Corrected DFT Study

Geometry and bonding energy analysis of M–S₂O bonds in the metal‐disulfur monoxide complexes [(PMe₃)₂M(S₂O)] of nickel, palladium, and platinum were investigated at DFT, DFT‐D3, and DFT‐D3(BJ) methods using three different functionals (BP86, PBE, and TPSS). The TPSS/DFT‐D3(BJ) yields better geometry, while the BP86 geometry is least accurate for studied complexes. The geometry of platinum complex optimized at TPSS/DFT‐D3(BJ) level is in excellent agreement with the available experimental values. The M–S bonds are shorter than the M–S(O) bonds. The Mayer bond orders suggest the presence of M–S and M–S(O) single bonds. Both the M–S and M–S(O) bond lengths vary with the density functionals as TPSS‐D3(BJ) < TPSS < PBE < BP86. The Hirshfeld charge distribution indicates that the overall charge flows from metal fragment to [S₂O]. The Ni–S₂O bond has greater degree of covalent character than the ionic. The contribution of dispersion interactions is large in computing accurate bond dissociation energies between the interacting fragments. The BDEs are largest for the functional TPSS and smallest for the functional BP86. The DFT‐D3 dispersion corrections to the BDEs between the metal fragments [(PMe₃)₂M] and ligand fragment [(S₂O)] for the TPSS functional are in the range 7.1–7.3 kcal · mol^–1, which are smaller than the corresponding DFT‐D3(BJ) dispersion corrections (9.4–10.6 kcal · mol^–1).     

Study on the toxic interactions of Ni with DNA using neutral red dye as a fluorescence probe

The interaction between Ni²⁺ and calf thymus DNA (ctDNA) was investigated in simulated physiological buffer (pH 7.4) using the Neutral Red (NR) dye as a spectral probe by UV-vis absorption and fluorescence spectroscopy, as well as CD spectra. The experimental results showed that the conformational changes in DNA helix induced by Ni²⁺ are the reason for the fluorescence quenching of the DNA-NR system. From the experimental results, conclusion can be drawn that Ni²⁺ can cause structural changes of ctDNA and bind with DNA by electrostatic interaction. At the same time, the paper proved that conformation changes of DNA can also lead to the fluorescence decrease of DNA-probe systems.