混合三聚双席夫碱与过渡金属离子的反应及ESR研究

本文发现混合三聚双席夫碱与过渡金属离子Cu(Ⅱ)、Ni(Ⅱ)、VO(Ⅱ)作用时,配体发生碳氮单键断裂后形成亚胺配合物。用室温及低温下ESR对反应进行了跟踪研究。所出现的活性中间体被Job＇s法确定其组份Cu:L为1:1,分子内溶剂轴向配位催化导致碳氮单键断裂。     

长链烷氧基取代金属卟啉／H2O2体系催化烯烃环氧化反应研究

长链烷氧基取代金属卟啉／Ｈ_２Ｏ_２体系催化烯烃环氧化反应研究肖友发，游劲松，余孝其，虞小华，蓝仲薇（四川大学化学系成都６１００６４）关键词长链烷氧基金属卟啉，过氧化氢，烯烃，环氧化反应具有疏水结合部位的金属卟啉，如甾体一金属卟啉［１］、环糊精一金属卟...     

表面对纳米微粒中稀土离子光谱性质的影响

对于稀土和过渡金属这样的离子中心,由于电子轨道的半径小，纳米尺度的限域对能级位置和跃迁速率的影响并不显著，表面效应成为这类材料与相应体材料光谱性质出现差异的主要因素。把使稀土离子光谱性质产生可测量变化的环境用一个以其为中心、半径为D的作用球表示，可以定义纳米材料厚度为D的表面层。用完整晶格的晶体场和一个补偿电荷的场近似描述表面层中稀土离子的晶体场。本文用这个模型分析了纳米微粒中稀土离子光谱的非均匀宽化，激光选择激发下发射光谱随激发波长的变化，非选择激发下发射光谱随温度的变化以及跃迁分支比的变化等实验现象。     

Crystal structures,spectroscopic and nonlinear optical properties of metal complexes of Schiff-base ligands containing nitrogen and sulfur donors

ML2 type CuII chelates with the Schiff base ligands R-C6H4CHNNHC(S)SCH2Ph (R=NMe2 or -OMe) have been prepared and characterized. Spectroscopic data suggest that the Schiff bases act as singly charged anionic bidentate ligands, forming stable neutral metal complexes. Magnetic and e.s.r. data support a square-planar coordination geometry for both complexes. Single crystal X-ray diffraction analysis of the complexes has established that the Schiff base ligand is deprotonated to give the thiol tautomer, coordinated via the thiolato sulfur and β-nitrogen. The geometry around the metal is square-planar with two equivalent Cu-N and Cu-S bonds; the two phenyl rings and the donor atoms are in one plane forming an extensive electronic delocalization system. Third-order optical nonlinearity measurements show that the complexes exhibit fairly large second-order hyperpolarizabilities. This revised version was published online in June 2006 with corrections to the Cover Date.     

Total synthesis of dendroamide a: oxazole and thiazole construction using an oxodiphosphonium salt

The total synthesis of dendroamide A (1), a multidrug-resistance reversing bistratamide-type peptide-derived macrocycle, has been accomplished in 19% yield. Fmoc-protected amino acids were condensed into appropriately protected dipeptides which were treated with bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate to afford oxazoles and thiazolines (oxidized to thiazoles) with high chemo- and stereoselectivity. The convergent condensation of three heterocyclic amino acids followed by macrocyclization afforded the natural product.     

Water reduction and oxidation on Pt-Ru/Y2Ta2O5N2 catalyst under visible light irradiation

Y(2)Ta(2)O(5)N(2) is presented as a novel photocatalyst with high activity for water splitting under visible-light irradiation in the presence of appropriate sacrificial reagents; the activity for reduction to H(2) is increased by the incorporation of Pt or Ru as a co-catalyst, with a significant increase in production efficiency when both Pt and Ru are present.     

Supramolecular self-assembly of conjugated diblock copolymers

This paper describes the synthesis and characterization of a novel series of copolymers with different lengths of oligo(phenylene vinylene) (OPV) as the rod block, and poly(propylene oxide) as the coil block. Detailed characterization by means of transmission electron microscopy (TEM), atomic force microscopy (AFM), and small-angle neutron scattering (SANS) revealed the strong tendency of these copolymers to self-assemble into cylindrical micelles in solution and as-casted films on a nanometer scale. These micelles have a cylindrical OPV core surrounded by a poly(propylene glycol) (PPG) corona and readily align with each other to form parallel packed structures when mica is used as the substrate. A packing model has been proposed for these cylindrical micelles.     

Simultaneous determination of carvedilol and ampicillin sodium by first-derivative fluorometry in the presence of human serum albumin.

A sensitive and selective method for the simultaneous determination of carvedilol and ampicillin sodium (AS) in the presence of human serum albumin (HSA) is described. The maximum emission wavelengths of carvedilol and AS are at 357 nm and 426 nm with excitation at 254 nm, respectively. The first-derivative peaks of carvedilol and AS were at 337 nm and 398 nm, respectively. The linear-regression equations of the calibration graphs of carvedilol and AS were C = 0.0001H - 0.0063 and C = 1.530H - 43.84; the correlation coefficients were 0.9990 and 0.9986, respectively. The detection limits were 1 ng ml(-1) for carvedilol and 23 microg ml(-1) for AS, respectively. The effects of the pH, the stability of carvedilol and AS and foreign ions on the determination of carvedilol and AS were examined. The recoveries of carvedilol and AS were measured. This method is simple and can be used for the determination of carvedilol and AS in human serum and urine samples with satisfactory results.