A two-dimensional molybdenum (V) phosphate with covalently bonded transition metal coordination complexes: hydrothermal synthesis and structure characterization of Na-2[{Mn(phen)(2)(H2O)}{Mn(phen)(2)}(3){Mn (Mo12O24)-O-V (HPO4)(6)(PO4)(2)(OH)(6)}] center dot 4H(2)O (phen=1,10-phenanthroline)

An organic-inorganic hybrid molybdenum phosphate, Na-2[{Mn(phen)(2)(H2O)} {Mn(phen)(2)}(3){(MnMo12O24)-O-v (HPO4)(6)(PO4)(2) (OH)(6)}] . 4H(2)O (phen=1,10-phenanthroline), involving molybdenum present in V oxidation state and covalently bonded transition metal coordination complexes, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a=16.581(l)Angstrom, b=18.354(1)Angstrom, c=24.485(2)Angstrom, alpha=80.589(l)degrees, beta=71.279(1)degrees, gamma=67.084(1)degrees, V=6493.8(8)Angstrom(3), Z=2, lambda(MoKalpha)=0.71073Angstrom (R(F)=0.0686 for 29,053 reflections). Data were collected on a Bruker Smart Apex CCD diffractometer at 293 K in the range of 1.76 < theta < 28.06degrees using omega-2theta scans technique. The structure of the title compound may be considered to be based on {Mo6O12(HPO4)(3)(PO4)(OH)(3)} units bonded together with {Mn(phen)(2)} subunits into a two-dimensional network. Two types of tunnels are observed in the solid of the title compound.

Mechanical relaxation time of comblike polymer electrolyte

Using poly(styrene-co-maleic anhydride) as the backbone and poly(ethylene glycol) methyl ether as side chains,three kinds of comblike polymers of different side chain length were synthesized. The Li-salt complexes and their firms were prepared. The dynamic mechanical properties were investigated. It was found that the main chain was rigid and the side chain was flexible in this comblike polymer system. Based on the time-temperature equivalence principle, a master curve was constructed. By selecting T-alpha as reference temperature, Arrhenius plots of shift factor and iso-free-volume plots were attained. The values of WLF parameters C-1 and C-2 increase with increasing salt concentration. By reference to T-0 = 50 degrees C, the relation between the average relaxation time 1g tau(c) and Li-salt concentration C is linear. The master curves are displaced progressively to higher frequencies as the M-w of side chains is increased. The relation between the average relaxation time 1g tau(n) and M-w of side chains is also linear. And the master curves are movable with the change of salts. It shows the effect of different kinds of salt on relaxation time.

Pentamethylcyclopentadienyl halfsandwich rhodium complexes containing 1,1 '-ferrocene dichalcogenido chelate ligands

The heterobimetallic complexes Cp * Rh(CN Bu-t)(EC5H4)(2)Fe [E = S(2),Se(3), Te(4)] have been synthesized by the reaction of halfsandwich rhodium complex Cp * Rh(CNtBu) Cl-2 with Fe(C5H4ELi)(2). 2THF. Oxidation of 2,3 by AgBF4 to give ferrocenium - type salts [Cp * Rh(CNtBu) (EC5H4)(2)Fe] (+) [BF4] (-) [E = S(5),Se(6)] also occurs readily. The new complexes have been characterized by MS IR, H-1 and C-13 NMR spectroscopy and elemental analysis.

环己烷~(13)C NMR化学位移的预测

通过计算机辅助方法对1 3 CNMR化学位移进行预测 .这个方法包括分子拓扑指数和几何参数特征值的计算及对所选特征进行的变量压缩 ,并对所选共振碳的化学位移与其提取的特征进行多元回归分析 ,从而得出其相关数学模型 .本文预测了环己烷中 45个仲碳原子的1 3 C化学位移 ,其标准误差约为 1 .4ppm.

La_2C~n(n=-1,0,+1)团簇的理论研究

用B3LYP/Lan1 2dz方法优化了La2 Cn(n =- 1 ,0 ,+1 )分子的结构 ,计算了La2 C的电子亲和势和离化能 ,并对计算结果进行了讨论。

Electrochemistry and spectroscopy study on the interaction of microperoxidase-11 with lipid membrane

The interaction of microperoxidase-11 (MP11) with cationic lipid vesicles of didodecyldimethylammonium bromide (DDAB) induces an alpha -helical conformation from random coil conformations in solution and this change then makes heme macrocycle more distorted. DDAB-induced MP11 conformations were investigated by cyclic votammetry (CV), circular dichroism (CD) and UV-vis spectrometry. All results indicate that the binding of MP11 in solution to DDAB vesicles and the ordered structure formation are driven by mostly electrostatic interaction between negatively charged residues in the undecapeptide and positively charged lipid headgroups on the membrane surface. Upon binding to DDAB, its half-peak potential was also changed. The mechanism of the interaction between MP11 and DDAB was also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Studies on the structure of tricyclohexyltin-2-(1,2-dithioethylene)methylene-3-oxo-5-aryl-4-pentenicate

Three title compounds were prepared and the structure of title compound 2 was characterized by IR, H-1 NMR, C-13 NMR, Sn-119 NMR spectroscopy and the crystal structure of compound 2a was determined by X-ray analysis with the final R indices[I >2 sigma (I)] R-1 = 0.0350 and R-2,R-omega = 0.0888. The crystal of compound 2a belongs to triclinic system, space group P1 with a = 1.0598(6) nm, b = 1.307 4(10) nm, c = 1.378 6(10) nm, alpha = 62.666(7)degrees, beta = 72.530(2)degrees, gamma = 80. 680(2)degrees, V = 1.618 0 nm(3), D-x = 1. 444 g (.) cm(-3), Z = 1, F (000) = 728. The bond length of Sn1-O1 is 0. 2076 nm and Sn1 . . . O2 distance is 0.301 3 nm. The coordination about the tin atom can be considered as a distorted tetrahedral. The detail values of H-1 NMR, C-13 NMR, Sn-119 NMR, (2)J(119Sn-1H) and J(119Sn-13C) were obtained. delta (119Sn) = 23.836, (2)J(119Sn-1H) = 88.0 Hz, (1)J(119Sn-13C) = 347.1 Hz, (2)J(119Sn-13C) = 45.6 Hz.

三环己基锡-2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸酯的结构研究

合成了 3个三环己基锡 -2 -( 1 ,2 -亚乙二硫 )亚甲基 -3-羰基 -5 -芳基 -4 -戊烯酸酯化合物 .用 IR,1 H NMR,1 3 C NMR和 1 1 9Sn NMR光谱及 X射线衍射对所合成的化合物进行了表征 .结果表明标题化合物为四配位、具有畸变四面体结构的锡酯类化合物

Controlled synthesis of L-lactide-b-epsilon-caprolactone block copolymers using a rare earth complex as catalyst

Well-defined block copolymers of L-lactide-b-epsilon-caprolactone were synthesized by sequential polymerization using a rare earth complex, Y(CF3COO)(3)/Al(iso-Bu)(3), as catalyst system. The compositions of the block copolymers could be adjusted by manipulating the feeding ratio of comonomers. The characterizations by GPC, H-1 NMR, C-13 NMR, and DSC displayed that the block copolymer, poly(epsilon-caprolactone-b-L-lactide) [P(CL-b-LLA)], had a narrow molecular weight distribution and well-controlled sequences without random placement.

Nuclear magnetic resonance spectral assignments of 2,2 '-bis(p-aminobenzoic ester)-1,1 '-binaphthyl

H-1 and C-13 nuclear magnetic resonance (NMR) spectra of 2, 2'-bis(p-aminobenzoic ester)-1,1'-binaphthyl were assigned and confirmed using 2D H-1-H-1 COSY, C-13-H-1 HETCOR and C-13-H-1 long-range HETCOR methods. This provided a basis for NMR characterization of the similar compounds.

La_(1-x)Pr_xP_5O_(14)晶体的发光

Pr~(3+)离子的能级结构丰富,在紫外可见区有很好的荧光发射。因此,以Pr~(3+)为激活离子的发光材料研究工作引起了人们的关注。轻稀土五磷酸盐晶体结构为单斜晶系,空间群为P_(1/2)/C,稀土离子处在隔离的多面体中,离子间的作用减弱,即使在化学计量比的PrP_5O_(14)仍得到激光输出。本文采用水热法生长出La_(1-x)Pr_xP_5O_(14)

The electrochemical study of oxidation-reduction properties of horseradish peroxidase

Oxidation-reduction properties of horseradish peroxidase (HRP) have been investigated by using direct electrochemical methods. Two successive separated distinct one-electron processes of HRP were obtained and the related physiological processes were described. The monolayer coverage of HRP at the electrode surface is about 50 pmol/cm(2). UV-Vis spectrophotometry and stable amperometry prove that the enzyme electrode possesses catalytic activity for H2O2 in the absence of a mediator and it might offer an opportunity to build the third generation of biosensors for analytes, such as H2O2, glucose and cholesterol etc. (C) 1997 Elsevier Science S.A.

Synthesis and characterization of soluble polyimides from 1,1-bis(4-aminophenyl)cyclohexane derivatives

A series of novel aromatic diamines (1-3) containing kinked cyclohexylidene moieties was synthesized by a reaction of excess aniline and corresponding methyl-substituted cyclohexanone derivatives. The structures of (1-3) were identifield by H-1 NMR, C-13 NMR, and FT-IR. The polymers were synthesized from the obtained diamines and various aromatic dianhydrides by the conventional polycondensation reaction followed by chemical imidization as well as high-temperature one-step polymerization. The inherent viscosities and weight-average molecular weights of the resulting polyimides were in the ranges of 0.55-1.58 dL/g and (7.4-15.2) x 10(4) g/mol, respectively. The prepared polyimides showed excellent thermal stabilities and good solubility. All polymers were readily soluble in common organic solvents such as tetrahydrofuran, chloroform, tetrachloroethane, etc., and the glass transition temperatures were observed at 290-372 degrees C.

Cyclic voltammetry of dye-modified supported bilayer lipid membranes (s-BLMs)

The voltammetric behaviour of dye-modified supported bilayer lipid membranes is investigated. (C) 1997 Elsevier Science S.A.

Self-assembled monolayers of thiols on gold electrodes for bioelectrochemistry and biosensors

Monolayers of biological compounds including redox proteins and enzymes, and phospholipids have been immobilized on a gold electrode surface through self-assembling. These proteins and enzymes, such as cytochrome c, cytochrome c oxidase and horseradish peroxidase (HRP), immobilized covalently to the self-assembled monolayers (SAMs) of 3-mercaptopropionic acid on a gold electrode, communicate directly electrons with the electrode surface without mediators and keep their physiological activities. The electron transfer of HRP with the gold electrode can also be mediated by the alkanethiol SAMs with electroactive group viologens on the gold electrode surface. All these direct electrochemistries of proteins and enzymes might offer an opportunity to build a third generation of biosensors without mediators for analytes, such as H2O2, glucose and cholesterol. Monensin and valinomycin have been incorporated into the bilayers on the gold electrode consisting of the SAMs of alkanethiol and a lipid monolayer, which have high selectivity for monovalent ions, and the resulting Na+ or K+ sensor has a wide linear range and high stability. These self-assembly systems provide a good mimetic model for studying the physiological function of a membrane and its associated enzyme. (C) 1997 Elsevier Science S.A.