The self-assembly mechanism of the Lindqvist anion [W(6)O(19)](2-) in aqueous solution: a density functional theory study

The formation mechanism is always a fundamental and confused issue for polyoxometalate chemistry. Two formation mechanisms (M1 and M2) of the Lindqvist anion [W(6)O(19)](2-) have been adopted to investigate it's self-assembly reaction pathways at a density functional theory (DFT) level. The potential energy surfaces reveal that both the mechanisms are thermodynamically favorable and overall barrierless at room temperature, but M2 is slightly dominant to M1. The formation of the pentanuclear species [W(5)O(16)](2-) and [W(5)O(15)(OH)](-) are recognized as the rate-determining steps in the whole assembly polymerization processes. These two steps involve the highest energy barriers with 30.48 kcal mol(-1) and 28.90 kcal mol(-1), respectively, for M1 and M2. [W(4)O(13)](2-) and [W(4)O(12)(OH)](-) are proved to be the most stable building blocks. In addition, DFT results reveal that the formation of [W(3)O(10)](2-) experiences a lower barrier along the chain channel.     

Critical behavior of higher cumulants of order parameter in the 3D-Ising universality class

QCD deconfinement phase transition is supposed to be the same universality class as the 3D-Ising model. According to the universality of critical behavior, the Binder-like ratios and ratios of higher cumulants of order parameter near the critical temperature in the 3D-Ising model are studied. The Binder-like ratio is shown to be a step function of temperature. The critical point is the intersection of the ratios of different system sizes between two platforms. The normalized cumulant ratios, like the Skewness and Kurtosis, do not diverge with correlation length, contrary to the corresponding cumulants. Possible applications of these characters in locating critical point in relativistic heavy ion collisions are discussed.     

Photocatalytic hydrogen production from a simple water-soluble [FeFe]-hydrogenase model system

Combined with a simple water soluble [FeFe]-hydrogenase mimic 1, Ru(bpy)(3)(2+) and ascorbic acid enable hydrogen production photocatalytically. More than 88 equivalents of H(2) were achieved in water, which is much better than that obtained in an organic solvent or a mixture of organic solvent and water.     

Imaging source with Gaussian proper time distribution

Making use of the maximum entropy method, we study the most probable source function in heavy ion collisions. An anisotropic Gaussian source is deduced by simply assuming that the particles are emitted within a finite proper-time. The general relations between the most probable source function and the minimal assumptions are discussed, which are instructive in constructing a self-consistent source function from observed Hanbury-Brown/Twiss(HBT) correlations.     

水滑石基材料在长波长光催化CO_2还原中的应用

正化石燃料的不断消耗和温室气体CO_2的持续排放使温室效应和能源危机日益严峻。受自然界植物的光合作用的启发,光催化CO_2还原受到人们广泛关注,将大气中的CO_2还原成为高附加值碳氢化合物,成为有效缓解温室效应和能源危机的有效方式1。然而,一方面由于CO_2分子中C=O具有较大的键能(750 kJ·mol~(-1)),使其难以活化;另一方面,以水为还原剂的体系中,光激发所产生的质子     

Nafion-Induced Metal-Metal Interactions in a Platinum(II) Terpyridyl Acetylide Complex:a Luminescent Sensor for Detection of Volatile Organic Compounds

Introduction The design of new solid-state sensor materials that can selectively adsorb volatile organic compounds (VOC) and produce measurable color and/or lumines-cence changes is of potential significance in the sense of environmental and public safety control.1-5 The use of metal complexes as optical sensors for VOC detection has been reported, and most of them are based on the susceptibility of metal-to-ligand charge transfer (MLCT) and/or metal-metal-to-ligand charge transfer (MMLC…     

D2EHDTPA-TOA反协同萃取镉的速率方程

以恒界面池法研究了D2EHDTPA（二（2-乙基己基）二硫代磷酸）-TOA（三辛胺）反协同萃取镉的界面反应速率方程.萃取历程由若干个相转移（在本体相与界面相之间的物质转移）过程和若干个反应组成.萃取的速率方程为 r=1.42*10^-7[Cd²⁺]^0.42[BHA]^0.47/[B]^0.85[H⁺]^0.21 （mol•m^-2•s^-1） 探讨了萃取速率方程中非整数反应物级数的物理意义.Freundlich因子n越大,物质在界面层所受排斥力越大.萃取过程的表观活化能E=44.2 kJ•mol－1,萃取反应的焓变ΔH=72.9 kJ•mol－1.讨论了由不同的界面模型而导致不能通融的萃取动力学机理的问题.     

放氢交叉偶联反应

过渡金属催化的脱氢偶联反应是一类高效的化学键构筑方式，但通常需要当量甚至过量的氧化剂以移除脱氢过程产生的电子及质子，其氧化剂残渣对环境有一定的污染.放氢交叉偶联（CCHE）反应摒弃了传统脱氢反应中当量氧化剂的使用，在温和条件下实现碳-氢或杂-氢键直接交叉偶联且唯一副产物为氢气，不仅避免了因原料或产物对氧化剂敏感而发生的副反应，而且在规模化生产中具有很高的附加值，是一种更加绿色的合成策略.本综述从放氢交叉偶联反应机理、化学键构筑类型以及反应延伸等角度归纳并介绍了近年来放氢交叉偶联反应的研究进展，并对该领域的发展前景进行了展望.     

Geometry of Quantum Coherence for Two Qubit X States

The geometry of the structure of entanglement and discord for Bell-diagonal states is depicted by Lang and Caves (Phys. Rev. Lett. 105, 150501, 2010). In this paper, we investigate the geometry with respect to several distance-based quantifiers of coherence for Bell-diagonal states. We find that as both l₁ norm and relative entropy of coherence vary continuously from zero to one, their related geometric surfaces move from the region of separable states to the region of entangled states, a fact illustrating intuitively that quantum states with nonzero coherence can be used for entanglement creation. We find the necessary and sufficient conditions that quantum discord of Bell-diagonal states equals to its relative entropy of coherence, and depict the surfaces related to the equality. We give surfaces of relative entropy of coherence for X states. We show the surfaces of dynamics of relative entropy of coherence for Bell-diagonal states under local nondissipative channels and find that all coherences under local nondissipative channels decrease.

     

Mechanistic and dual-level direct dynamics studies on the reaction Cl + CH2FCl

Theoretical investigations are carried out on the reaction Cl + CH₂FCl by means of direct dynamics method. The minimum energy path (MEP) is obtained at the MP2/6-311G(d, p) level. The energetic information is further improved by single-point energy calculations using QCISD(T)/6-311++G(d, p) method. The kinetics of this reaction are calculated by canonical variational transition state theory incorporating with the small-curvature tunneling correction over a wide temperature range of 220–3,000 K, and rate constant expression are found to be k(T) = 1.48 × 10^?17 T ^2.04exp(?913.91/T). For the title reaction, H-abstraction reaction channel is the major channel at the lower temperatures. At higher temperatures, the contribution of Cl-abstraction reaction channel should be taken into account.