基于[LnMo12]二十面体的三维稀土钼酸盐骨架的合成、结构及荧光性能

通过缓慢蒸发溶剂法合成了2例新的三维稀土钼酸盐：[Ln (H₂O)₃]₃[LnMo₁₂O₄₂]·xH₂O,其中Ln=Eu (1)、Tb (2),x=7(1),10.17(2)。这2种稀土钼酸盐中都含有新颖的二十面体[LnMo₁₂O₄₂]构建单元,该单元通过与{LnO₉}多面体进一步连接形成三维网络。光致发光测试表明,化合物1和2显示出明显不同的发射特征,这与Eu³⁺和Tb³⁺离子的不同能级跃迁密切相关。化合物1表现出较强的红色发射(CIE色度坐标为(0.66,0.33))、高发光强度、较大的荧光量子产率(约60%),对应于从⁵D0到⁷F_J (J=4、3、2、1、0)的跃迁;化合物2表现出浅绿色发射(CIE色度坐标为(0.34,0.60)),对应从⁵D₄到⁷F_J (J=6、5、4、3)的能级跃迁,其发光强度较弱和荧光量子产率较低(约20%)。有趣的是,一定量的Tb³⁺引入和大量溶剂分子的存在导致化合物2发生部分荧光猝灭,但对化合物1的荧光几乎没有影响。     

经济研究中的物理学

当前的金融危机再次表明,传统经济学作为一门学科缺乏解释力和预测力.造成这个令人失望的状况的根本原因是由于经济学家没有按照科学的范式来发展这个学科.经济学的现状吸引了一群物理学家进入这个学科并形成了一个新的交叉学科——经济物理学,人们期望它在促进经济学科学化的进程中起决定性作用.文章首先简要介绍了经济学的主要内容,说明经济学理论是建立在理性和均衡假定基础之上的;接着论述了为什么经济学还不是一门科学,指出经济学研究不是基于逻辑实证主义原则来开展的;文章还分析了物理学家是如何研究经济问题的,介绍了经济物理学的主要研究内容和研究方法;文章最后提出经济学范式的转变必须从观察和实验出发,经济学理论必须建立在一个合理设计的量纲体系和对实际经济运行过程的正确理解基础之上.     

不对称(口片)呐醇偶联反应新进展

综述了近年来不同催化体系的不对称合成呐醇的方法,并总结了不同的催化效率和对映选择性的差异.     

A Chain Structure Based on Homodinuclear Scandium Units: [Sc(μ-OH)(2,5-pydc)(H2O)]n

The reaction of pyridine-2,5-dicarboxylic acid with Sc2O3 under hydrothermal con-dition yields a new complex [Sc(μ-OH)(2,5-pydc)(H2P)]n 1 which has a chain structure based on homodinuclear scandium units. Crystal data for 1: space group P1, a = 6.7192(13), b = 7.6131(13),c= 8.9313(14) A, α = 95.976(6), β = 101.663(6),γ,= 108.151(5)°, V = 418.26(13) A3, Z = 2, Dc =1.946 g/cm3,μ = 0.889 mm-1, F(000) = 248, C7H6NO6Sc, M, = 245.09, the final R = 0.0429 and wR = 0.1086.     

A Chain Structure Based on Homodinuclear Scandium Units： [Sc（μ-OH）（2,5-pydc）（H2O）]n

The reaction of pyridine-2,5-dicarboxylic acid with Sc2O3 under hydrothermal con- dition yields a new complex [Sc（μ-OH）（2,5-pydc）（H2O）]n 1 which has a chain structure based on homodinuclear scandium units. Crystal data for 1： space group P^-1, a = 6.7192（13）, b = 7.6131（13）, c = 8.9313（14） A, α = 95.976（6）, β = 101.663（6）, γ = 108.151（5）^o, V= 418.26（13） A^3, Z = 2, Dc = 1.946 g/cm^3, g = 0.889 mm^-1, F（000） = 248, C7H6NO6Sc, Mr = 245.09, the final R = 0.0429 and wR = 0.1086.     

Syntheses and Crystal Structures of Two Complexes with 3-（3-Pyridyl）acrylic Acid

1 INTRODUCTION A recent feature in the development and progress of chemical research is the concern for molecular assemblies, ensembles, and all of structural aggre- gates[1]. The self-assembly of transition metal ions and N-containing organic ligands has been proven a popular approach for the construction of supramo- lecular architecture[2～7]. 3-(3-Pyridyl)acrylic acid is an excellent ligand, not only due to its prolific coor- dination sites but also to its potential hydrogen bon- ding…     

Power-Law Tail in the Chinese Wealth Distribution

We analyse the data from the recently published lists of the richest Chinese from the year 2003 to 2005. The results confirm that in these years the wealth is distributed according to a power law with exponents between 1.758 and 2.285 in the high end. The power distribution is found to be quite robust although the persons in the list change drastically and the wealth increases rapidly. The relation between the wealth and the absolute change of wealth rejects the notion that the wealth evolution is a multiplicative stochastic process.     

Synthesis,Structure and Property of One Bis (benzimidazolin-2-ylidene) Arene-mercury(Ⅱ) Complex

Reaction of a N-heterocycliccarbene(NHC) containing an anthracene unit and two N-picolyl moieties with Hg(OAc)2 yielded a novel mercury(Ⅱ) complex(1). X-ray studies, UV-vis and fluorescence spectroscopy confirmed that a strong interaction exists between the mercury atom and anthracene unit.     

Cobalt-lanthanide coordination polymers constructed with metalloligands: a ferromagnetic coupled quasi-1D Dy3+ chain showing slow relaxation

Four types of cobalt-lanthanide heterometallic compounds based on metalloligand Co(2,5-pydc)(3) (3-) (2,5-H(2)pydc=pyridine-2,5-dicarboxylate acid), [Ln(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n) 2n H(2)O (1) (Ln=Tb, Dy for 1 a, 1 b respectively), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n)3n H(2)O (2), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(9)](n)4n H(2)O (3), and [LaCo(2,5-pydc)(3)(H(2)O)(2)](n)2n H(2)O (4) have been synthesized. Compound 1 has a layer structure with well-isolated carboxylate-bridged Ln(3+) chains, compound 2 is a three-dimensional (3D) porous network with Tb(3+) chains that are also well isolated and carboxylate bridged, 3 is a layer structure based on dinuclear units, and 4 is a 3D network with boron nitride (BN) topology. DC magnetic studies reveal ferromagnetic coupling in all the carboxylate-bridged Ln(3+) chains in 1 a, 1 b, and 2. Compared to the silence of the out-of-phase ac susceptibility of 2, above 1.9 K the magnetic relaxation behavior of both 1 a and 1 b is slow like that of a single-chain magnet.