Strong Ligand Stabilization Based on π-Extension in a Series of Ruthenium Terpyridine Water Oxidation Catalysts

The substitution behavior of the monodentate Cl ligand of a series of ruthenium(II) terpyridine complexes (terpyridine (tpy)=2,2′:6′,2′′-terpyridine) has been investigated. ¹H NMR kinetic experiments of the dissociation of the chloro ligand in D₂O for the complexes [Ru(tpy)(bpy)Cl]Cl ( 1 , bpy=2,2’-bipyridine) and [Ru(tpy)(dppz)Cl]Cl ( 2 , dppz=dipyrido[3,2-a:2′,3′-c]phenazine) as well as the binuclear complex [Ru(bpy)₂(tpphz)Ru(tpy)Cl]Cl₃ ( 3 b , tpphz=tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine) were conducted, showing increased stability of the chloride ligand for compounds 2 and 3 due to the extended π-system. Compounds 1 – 5 ( 4 =[Ru(tbbpy)₂(tpphz)Ru(tpy)Cl](PF₆)₃, 5 =[Ru(bpy)₂(tpphz)Ru(tpy)(C₃H₈OS)/(H₂O)](PF₆)₃, tbbpy=4,4′-di-tert-butyl-2,2′-bipyridine) are tested for their ability to run water oxidation catalysis (WOC) using cerium(IV) as sacrificial oxidant. The WOC experiments suggest that the stability of monodentate (chloride) ligand strongly correlates to catalytic performance, which follows the trend 1 > 2 > 5 ≥ 3 > 4 . This is also substantiated by quantum chemical calculations, which indicate a stronger binding for the chloride ligand based on the extended π-systems in compounds 2 and 3 . Additionally, a theoretical model of the mechanism of the oxygen evolution of compounds 1 and 2 is presented; this suggests no differences in the elementary steps of the catalytic cycle within the bpy to the dppz complex, thus suggesting that differences in the catalytic performance are indeed based on ligand stability. Due to the presence of a photosensitizer and a catalytic unit, binuclear complexes 3 and 4 were tested for photocatalytic water oxidation. The bridging ligand architecture, however, inhibits the effective electron-transfer cascade that would allow photocatalysis to run efficiently. The findings of this study can elucidate critical factors in catalyst design.     

Shape and structure of N=Z 64Ge: electromagnetic transition rates from the application of the recoil distance method to a knockout reaction

Transition rate measurements are reported for the 2(1)+ and 2(2)+ states in N=Z 64Ge. The experimental results are in excellent agreement with large-scale shell-model calculations applying the recently developed GXPF1A interactions. The measurement was done using the recoil distance method (RDM) and a unique combination of state-of-the-art instruments at the National Superconducting Cyclotron Laboratory (NSCL). States of interest were populated via an intermediate-energy single-neutron knockout reaction. RDM studies of knockout and fragmentation reaction products hold the promise of reaching far from stability and providing lifetime information for excited states in a wide range of nuclei.     

含Dawson结构杂多钨磷(砷)酸电荷转移配合物的合成、结构与性质

近年来,有机多金属氧酸盐电荷转移配合物由于有特殊的光、电、磁性质在催化、功能材料及药物化学等领域受到研究者的广泛关注［１］。自从１９８８年法国的Ｌ．Ｏｕａｈａｂ［２］首次报道（ＴＴＦ）６ＰＷ１２Ｏ４０（Ｅｔ４Ｎ）２的合成以来,已见报道的多金属氧酸盐仅限于ＡｎｄｅｒｓｏｎＥｖａｎｓｅ、ｌｉｎｄｑｕｉｓｔ和Ｋｅｇｇｉｎ结构的多阴离子,对它们功能性质的系统研究也未见文献报道。为了研究阴离子的大小和形状对标题化合物功能性质的影响,作者在以前工作的基础上［３,４］,首次以Ｄａｗｓｏｎ结构杂多钨磷（砷）…     

金诃脑血康胶囊中微量、宏量元素的测定分析

文章采用火焰原子吸收分光光度法测定了5批藏成药金诃脑血康胶囊中镉、铬、钴、铜、铁、镁、锰、镍、铅、锌等10种微量、宏量金属元素的含量,并对其结果进行了分析。结果表明,金诃脑血康胶囊中含有丰富的宏量元素Mg和有益的微量元素Cu,Zn,Fe,Mn,Ni等,有毒元素Pb,Cd含量较低,金属元素的含量高低顺序为：Fe＞Mg＞Zn＞Mn＞Cu＞Ni＞Cr＞Pb＞Co＞Cd。测定结果为探讨藏成药中微量、宏量元素与治疗心脑血管疾病功效的关系提供了有用的数据。     

Time-of-flight mass measurements for nuclear processes in neutron star crusts

We present results from time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory that are relevant for neutron star crust models. The masses of 16 neutron-rich nuclei in the scandium-nickel range were determined simultaneously, with the masses of (61)V, (63)Cr, (66)Mn, and (74)Ni measured for the first time with mass excesses of -30.510(890) MeV, -35.280(650) MeV, -36.900(790) MeV, and -49.210(990) MeV, respectively. With these results the locations of the dominant electron capture heat sources in the outer crust of accreting neutron stars that exhibit super bursts are now experimentally constrained. We find the experimental Q value for the (66)Fe→(66)Mn electron capture to be 2.1 MeV (2.6σ) smaller than predicted, resulting in the transition occurring significantly closer to the neutron star surface.     

Clifford分析中Isotonic柯西型积分的边界性质

本文主要刻画了定义于偶数维欧氏空间中光滑曲面而取值于复Clifford代数的isotonic柯西型积分的边界性质.对具有H(o|¨)lder密度函数的isotonic柯西型积分,得到了Privalov定理和Sokhotskii-Plemelj公式,并证明了多复变函数论中经典Bochner-Martinelli型积分的Privalov定理和Sokhotskii-Plemelj公式为其特殊情形.     

机械设计在CAD中图表资料的处理

机械设计中，有许多复杂的数据信息需要处理，本文主要探讨了齿轮传动中有关数据，表格和线圈的程序化处理方法。     

Survival probabilities in coherent exciton transfer with trapping

In the quest for signatures of coherent transport we consider exciton trapping in the continuous-time quantum walk framework. The survival probability displays different decay domains, related to distinct regions of the spectrum of the Hamiltonian. For linear systems and at intermediate times the decay obeys a power law, in contrast with the corresponding exponential decay found in incoherent continuous-time random walk situations. To differentiate between the coherent and incoherent mechanisms, we present an experimental protocol based on a frozen Rydberg gas structured by optical dipole traps.     

定容燃烧弹内压力振荡机理研究

本文基于一种具有较好发展前景的醚类汽油添加剂异丙醚(DIPE),在定容燃烧弹内研究了该燃料在不同初始压力下随当量比变化的压力振荡特性。实验结果表明,压力振荡强度随当量比增加呈先增大后减小的趋势,且在当量比1.4附近达到最大值;随初始压力增大,压力振荡的强度也增强。本文通过利用He和CO₂以不同掺混比替代N₂作为稀释气体,验证了定容燃烧弹内的压力振荡主要由压力波与火焰相互影响引起,火焰自加速和混合气能量密度对压力振荡有至关重要的作用。