亚细胞器诱导的2,4,6-三硝基甲苯阴离子自由基的ESR研究

本文在无氧条件下利用ESR分别观察了肝脏和晶状体的微粒体及线粒体酶在NADPH存在下还原三硝基甲苯(TNT)的过程,检测到参数为g=2.0048±0.0005,A_对位~N=1.215mT,A~N=0.800±0.010mT,A~H=0.122±0.0206mT的自由基信号,并通过电子计算机对ESR谱的模拟证明该自由基信号为TNT硝基阴离子自由基,根据其超精细分裂常数认为,其不配对电子的电子云密度主要分布在对位硝基上。     

A density functional theory computational study of the role of ligand on the stability of CuI and CuII species associated with ATRP and SET‐LRP

Atom transfer radical polymerization (ATRP) and single electron‐transfer living radical polymerization (SET‐LRP) both utilize copper complexes of various oxidation states with N‐ligands to perform their respective activation and deactivation steps. Herein, we utilize DFT (B3YLP) methods to determine the preferred ligand‐binding geometries for Cu/N‐ligand complexes related to ATRP and SET‐LRP. We find that those ligands capable of achieving tetrahedral complexes with Cu^I and trigonal bipyramidal with axial halide complexes with [Cu^IIX]⁺ have higher energies of stabilization. We were able to correlate calculated preferential stabilization of [Cu^IIX]⁺ with those ligands that perform best in SET‐LRP. A crude calculation of energy of disproportionation revealed that the same preferential binding of [Cu^IIX]⁺ results in increased propensity for disproportionation. Finally, by examining the relative energies of the basic steps of ATRP and SET‐LRP, we were able to rationalize the transition from the ATRP mechanism to the SET‐LRP mechanism as we transition from typical nonpolar ATRP solvents to polar SET‐LRP solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4950–4964, 2007     

Protonation constant of salicylidene (N-benzoyl)glycyl hydrazone and its coordination behaviour towards some bivalent metal ions

Protonation constant of an unsymmetrical Schiff base, salicylidene(N-benzoyl)glycyl hydrazone (SalBzGH), and formation constants of its complexes have been determined potentiometrically at different temperatures in aqueous dioxane medium. Complexes of SalBzGH with VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been prepared. Elemental analyses, pH-metric, molar conductance, magnetic susceptibility, electronic, IR, ESR, XRD (powder) and NMR studies have been carried out to study the coordination behaviour of SalBzGH toward these metal ions. pH-metric and 1H NMR studies show the presence of two dissociable protons in the ligand. IR and NMR spectra suggest the tridentate nature of the ligand, coordinating as a uninegative species in the Mn(II) complex and as a dinegative species in all the other complexes. Presence of two different conformers of the ligand at room temperature and stabilization of a single conformer upon complex formation have been established from¹H NMR spectra of the metal-free ligand, Zn(II) and Hg(II) complexes recorded at 296 K. Electronic and ESR spectra indicate highly distorted tetragonal geometry for VO(IV) and Cu(II) complexes. XRD powder patterns of the Zn(II) complexes are indexed for an orthorhombic crystal system.     

Theoretical study of anion carriers based on trifluoroacetophenone

Model calculations on anion carrier ligands related to trifluoroacetophenone were carried out using the semiempirical AM 1 method in order to investigate the factors involved in such anion-ligand complexation. The reaction of halogen derivatives of acetophenone with various nucleophiles such as water, carbonic acid, and bicarbonate anion was studied. By this means, the effect of various structural changes, such as variation of the ring substituents and variation of the degree and type of halogen atom substitution, could be determined. It is shown that in terms of relative stability, fluorine derivatives are preferable to chlorine derivatives for the binding of water and carbonic acid. Monosubstitution of a methoxy group in the ortho position of the trifluoroacetophenone ring also brought about stability in the case of the hydration reaction. An electron-withdrawing ester group in the para position on the trifluoroacetophenone ring brings about stabilization also.     

一维螺旋状3，6-哒嗪二甲酸镉(Ⅱ)配位聚合物的合成与结构

Using the ligand pyridazine-3，6-dicarboxylate (H₂pzdc)， a coordination polymer [Cd₂(pzdc)₂(H₂O)₄] was synthesized and characterized by elemental analysis， thermal analysis， IR and single-crystal X-ray diffraction. The complex crystallizes in the tetragonal system with space group I4₁/a. The crystallographic data are: a=1.470 6(4) nm， c=1.489 8(6) nm， V=3.222 0(19) nm³， Z=16， μ=2.725 mm^-1， D_c=2.594 g·cm^-3， R₁=0.017 8， wR₂=0.044 6. In the complex， the cadmium(Ⅱ) ions with the eight-coordinated dodecahedral geometry are linked by the pzdc ligands to generate one-dimensional chains， which are associated into the three-dimensional architecture via O-H…O hydrogen bonding. CCDC: 658853.     

Multinuclear magnetic resonance studies on intramolecular chalcogen-tin coordination in compounds of the type Me2Sn(X)CH2CH2P(E)Ph2 (X = Halogen, E = Chalcogen)

Multinuclear magnetic resonance data for the title compounds are presented and discussed. The intramolecular coordination observed in the solid state is shown to be retained in solution. The best probes for the presence or absence of pentacoordination at tin are provided by the various tin-element coupling constants, although chemical shifts are in some cases also informative. A selenium-proton correlated spectrum indicated that the coupling constant ¹J(Sn,Se) has a positive sign.     

具有六重穿插非中心对称金刚石网络结构的Cd(Ⅱ)和Zn(Ⅱ)的配位高聚物(英)

利用1，4-二-(4-羧基吡啶基)丁烷(L)合成了两个新的三维配位聚合物{(CdL₂)·4H₂O·2ClO₄}_n 1和{(ZnL₂)·4H₂O·2ClO₄}_n 2。单晶X-射线结构分析表明，1和2具有相同的计量式，但其晶体属于不同的空间群(1属于P4n2，2属于P4₂22)。两种配合物中，每个金属离子分别由配体与四个相邻的金属离子连接，从而形成具有六重穿插的金刚石网络结构，其网络中大的空腔被高氯酸根离子和(H₂O)₄分子簇所占据。