Rapid determination of Pu isotopes for decommission concrete samples by inductively coupled plasma mass spectrometry

Journal of Radioanalytical and Nuclear Chemistry - Plutonium is one of the key radionuclides in nuclear decommission. In this study, a rapid method was developed to analyze Pu for concrete samples...     

High performance of N,P co-doped metal-free carbon catalyst derived from ionic liquid for oxygen reduction reaction

Journal of Solid State Electrochemistry - One-pot strategy to fabricate N, P co-doping carbon was developed based on the functional ionic liquid (IL) as the N, P, and C precursors. The IL featuring...     

Ligand Steric Effects on Naphthyl-α-diimine Nickel Catalyzed α-Olefin Polymerization

Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane(MMAO), were tested in the polymerization of higher α-olefin(1-hexene, 1-decene and 1-hexadecene) under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers(42-88/1000 C) with high molecular weights(M_n:(4.3-15.2) × 10~4 g·mol~(-1)) and narrow molecular weight distribution(M_w/M_n = 1.13-1.29, RT), which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction.     

A novel Pt/C‐catalyzed transfer hydrogenation reaction of p‐benzoquinone to produce p‐hydroquinone using cyclohexanone as an unexpectedly effective hydrogen source

A new method for the production of p‐hydroquinone via a Pt/C‐catalyzed reduction of p‐benzoquinone is developed. Different from the conventional transfer hydrogenation reactions that usually use secondary alcohols such as isopropanol as the hydrogen source, in this work, it is unexpectedly found that cyclohexanone is a more effective hydrogen source than secondary alcohols, even cyclohexanol. This reaction affords acceptable yields of p‐hydroquinone with very high turnover number (1109) of the Pt/C catalyst. A mechanism of this interesting reaction is proposed on the basis of the results of a series of control experiments, GC–MS analysis as well as dynamic studies.     

Dinuclear Cu(II) complexes based on p‐xylylene‐bridged bis(1,4,7‐triazacyclononane) ligands: Synthesis,characterization, DNA cleavage abilities and evaluation of superoxide dismutase‐ and catalase‐like activities

Three new dinuclear Cu(II) complexes with the formulas [Cu₂(pxdmbtacn)Cl₄] ( 1 ), [Cu₂(pxdmbtacn)Cl_0.7(NO₃)_1.3(OH)₂(H₂O)_1.3]?6H₂O ( 2 ) and [Cu₂(pxdiprbtacn)Cl₄] ( 3 ) together with one previously reported complex, [Cu₂(pxbtacn)Cl₄] ( 4 ), were obtained from Cu(II) salts with three p‐xylylene‐bridged bis‐tacn ligands bearing pendant alkyl substituents or without pendant group. Complex 2 was structurally characterized as a centrosymmetric dinuclear molecule with each metal center being coordinated to some labile ligands in addition to one tacn ring. Based on the results of mass spectrometry and UV–visible spectroscopy, complexes 1 and 3 are capable of existing in aqueous solution as dinuclear species but 4 can partially form a dimer of the original dinuclear motif. Complexes 1 , 3 and 4 can all effectively cleave supercoiled DNA oxidatively in the presence of hydrogen peroxide. The superoxide dismutase (SOD) activities of 1 and 3 measured under physiological conditions are comparable to that of the native CuZnSOD enzyme but the enzymatic activity of 4 is about three‐ to fourfold lower. Furthermore, complexes 1 , 3 and 4 demonstrate moderate scavenging effect on hydrogen peroxide and their catalase activities are in the decreasing order of 3 > 1 > 4 .     

针对连续变化法测定络合物稳定常数实验中可能出现的设计缺陷的讨论

连续变化法测定络合物组成和稳定常数是大学化学中的经典学生实验。但针对1：2和1：3的络合反应，实验教科书的设计中可能出现数据点过少也就是溶液配制过少的问题。如果按照要求配制溶液，由于没有完全反应的混合溶液，而其他混合溶液给出的数据又都呈良好的线性，就缺少了用来估算曲线的数据点，结果是，将没有足够的数据对稳定常数进行估算。对这种可能出现的数据点过少的实验设计的原因、结果和解决方法进行了探讨。     

α‐Diamine Nickel Catalysts with Nonplanar Chelate Rings for Ethylene Polymerization

A series of novel α‐diamine nickel complexes, (ArNH‐C(Me)‐(Me)C‐NHAr)NiBr₂, 1 : Ar=2,6‐diisopropylphenyl, 2 : Ar=2,6‐dimethylphenyl, 3 : Ar=phenyl), have been synthesized and characterized. X‐ray crystallographic analysis showed that the coordination geometry of the α‐diamine nickel complexes is markedly different from conventional α‐diimine nickel complexes, and that the chelate ring (N‐C‐C‐N‐Ni) of the α‐diamine nickel complex is significantly distorted. The α‐diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α‐diimine nickel catalyst. Increasing the steric hindrance of the α‐diamine ligand by substitution of the o‐methyl groups with o‐isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1 /Et₂AlCl at 35 °C or 2 /Et₂AlCl at 0 °C. The bulky α‐diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure.