Solvolthermal Syntheses and Crystal Structures of Three Linear Trinuclear Schiff Base Complexes of Zinc(II) and Cadmium(II)

Three linear trinuclear Schiff base complexes, {Zn[Zn(CH₃COO)(C₁₇H₁₆N₂O₂)]₂} ( 1 ), {Zn[Zn(CH₃COO)(C₂₅H₂₀N₂O₂)]₂} ( 2 ), and {Cd[Cd(CH₃COO)(C₁₈H₁₈N₂O₂)]₂} ( 3 ), were synthesized for the first time under solvolthermal conditions. Their structures have been characterized by elemental analyses, X-ray single crystal determinations, and infrared spectroscopy. There are three bridges across the M-M atom pairs (M is Zn for 1 and 2 , or Cd for 3 ) in each complex, involving two O atoms of a Schiff base ligand (N,N′-bis(salicylidene)-1, 3-propanediaminate (SALPD^2-) for 1 , N, N′-bis(2-hydroxy-naphthalmethenylimino)-1, 3-propanediaminate (NAPTPD^2-) for 2 , and N,N′-bis-(salicylidene)-1,4-butanediaminate (SALBD^2-) for 3 ), and an O-C-O moiety of a μ-acetato group. In each of the complexes, the central M²⁺ ion is located on an inversion center and has a distorted octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and one O atom from each bridging acetate group in the axial positions. The coordination around the terminal M²⁺ ions is irregular square pyramidal, with two O atoms and two N atoms of the Schiff base ligand in the basal plane and one O atom from an acetate group in the apical position. The acetate bridges linking the central and terminal M²⁺ ions are mutually trans. The M…M distances are 3.050(3) Å in 1 , 3.139(2) Å in 2 , and 3.287(6) Å in 3 .     

Measurements and Utilization of Consistent Gibbs Energies of Transfer of Single Ions: Towards a Unified Redox Potential Scale for All Solvents

Utilizing the “ideal” ionic liquid salt bridge to measure Gibbs energies of transfer of silver ions between the solvents water, acetonitrile, propylene carbonate and dimethylformamide results in a consistent data set with a precision of 0.6 kJ mol⁻¹ over 87 measurements in 10 half-cells. This forms the basis for a coherent experimental thermodynamic framework of ion solvation chemistry. In addition, we define the solvent independent - and the values that account for the electronating potential of any redox system similar to the value of a medium that accounts for its protonating potential. This scale is thermodynamically well-defined enabling a straightforward comparison of the redox potentials (reducities) of all media with respect to the aqueous redox potential scale, hence unifying all conventional solvents′ redox potential scales. Thus, using the Gibbs energy of transfer of the silver ion published herein, one can convert and unify all hitherto published redox potentials measured, for example, against ferrocene, to the scale.     

The complete multi-ζ electric dipole moment matrix of π-(C6H6) Cr(CO)3 and tests of semi-empirical MO models

First, we evaluated the complete electric dipole moment matrixeZ using a multi- AO basis on Cr, C, and O centers fortheimportant, parent organometallic molecule -C₆H₆Cr(CO)₃. Second, we generated ground state LCAO-MO eigenvectors employing five commonly used semi-empirical procedures for molecules of this size which contain transition metals. Transformation of operator matrixeZ into the MO space of each of the five methods then leads us to conclude that the empirical input of Basch, Viste and Gray is most suitable. Finally, we compare the merits of several single- basis orbitals with the multi- metal orbitals.[/p]     

富氧条件下Ag/LaMn1-xPdxO3催化剂直接分解NO研究

分别使用柠檬酸络合法和浸渍法制备了钙钛矿型复合氧化物催化剂LaMn1-xPdxO3(x=0,0.01,0.02,0.03,0.04)和不同Ag负载量的Ag/LaMn0.99Pd0.01O3催化剂.使用XRD,BET手段对各催化剂进行了表征,同时在反应条件:NO 0.1%,O2 8%,H2O 0或10%,SO2 0或0.008%,N2为平衡气体,接触时间为0.03g·s·ml-1(GHSV=30000h-1)下对催化剂的活性进行了考察.实验结果发现,当贵金属Pd在B位部分替代Mn时,替代量x=0.01时的催化剂对于催化氧化分解NO反应具有最高活性.另外,在LaMn0.99Pd0.01O3催化剂上负载2%Ag也明显提高了催化剂的活性.而且LaMn0.99Pd0.01O3和2%Ag/LaMn0.99Pd0.01O3催化剂尽管抗水性能不好,但却具有较强的抗SO2性能.     

小分子荧光探针在蛋白质标记与成像分析中的应用

小分子荧光探针由于其体积小、合成简单等特点在蛋白质成像技术中扮演着越来越重要的角色。此领域的研究融合了生物化学、有机合成、分析化学等相关学科,是当今化学发展的一个重要方向,有着广阔的前景。目前,能够专一性地与目标蛋白质(POI)结合的小分子探针较少,设计和合成方法的缺乏已经成为制约该领域进一步发展的瓶颈。本文概括地介绍了近年来出现的一些小分子荧光探针,关注它们在活体标记中的应用。     

Induced circular dichroism and structural assignment of the cyclodextrin inclusion complexes of bicyclic azoalkanes

The stoichiometries and binding constants of the host-guest complexes between the bicyclic azoalkanes 1-6 and alpha-, beta-, and gamma-cyclodextrins (CDs) and the induced circular dichroism (ICD) of the complexes were analyzed. Assisted by proximity relationships obtained from 2D ROESY NMR spectra, the signs and intensities of the ICD spectra are interpreted in terms of the solution structures (co-conformations) of the CD complexes. The ICD assignments are based on the orientation-intensity ICD rules of Harata and Kodaka, which relate the ICD signs and intensities to the relative orientation of the electric dipole transition moment of the n,pi azo chromophore to the CD axis. The influence of the size of the guest and the host is discussed and the effect of introducing an additional chromophore (either a phenyl or a second azo group) on the ICD spectra is demonstrated.     

Molekulare Zusammensetzung von flüssigem Schwefel. Teil: 3 Quantitative Analyse im Bereich 115–350°C

Molecular Composition of Liquid Sulfur. Part 3: Quantitative Analysis in the Temperature Region 115–350°C Relative concentrations of S₆, S₇, S₈, S_x (x > 8) and S_μ (insoluble sulfur) in equilibrium melts of elemental sulfur have been determined from i. r. and Raman spectra. At the freezing point (115°C) the melt consists of 0.6% S₆, 2.8% S₇, 1.5% S_x, and 95.1% S₈. – The solubility of S₇ in CS₂ has been determined at −77 to −26°C; the solubilities of both S₇ and S₈ in CS₂ are considerably enhanced by the presence of S_x. The thermal decomposition of S₈ and S_μ formation from S₆, S₇, and S_x has been investigated.