摘要:

AbstractA new molecule of 3,6‐Bis(1‐methyl‐4‐vinylpyridium iodine)carbazole (BMVC) was synthesized for stabilizing the quadruplex structure of human telomeric sequence of d(T2AG3)4in vitro. MixingBMVCwith the DNA can raise the melting temperature of the d(T2AG3)4by ∼ 13 °C, implying thatBMVCcould be a useful telomerase inhibitor. In addition, the fluorescence of theBMVCincreased significantly upon interacting with the d(T2AG3)4which may be useful as a G‐quadruplex spe

ISSN:0009-4536    

DOI:10.1002/jccs.200300026

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractUsing the hydrazone linker and the self‐assembly, functionalized Ag complexes with a helical structure showed a 2.96 Å distance between metal‐metal bonds, well‐aligned aromatic rings, and the strong affinity towa

ISSN:0009-4536    

DOI:10.1002/jccs.200300027

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractThe stoichiometry of charge‐transfer complexes which ionise in polar media has been studied by conductimetric titration technique in the systems morpholine‐p‐chloranil (CA), piperidine‐CA and pyrrolidine‐CA in three different polar solvents namely N,N‐dimethylformamide, acetonitrile and dimethylsulfoxide at different temperatures of 10, 15, 18, 20, 25 and 30 °C. The stoichiometric ratios of these complexes were found to vary from 1:1 to 1:4 (acceptor: donor) depending on the system, temperature and solvent used. The ασM‐values of these complexes have been reported. The effect of solvents, temperatures and types of electron donors on the σP‐value

ISSN:0009-4536    

DOI:10.1002/jccs.200300028

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractWe report in this article the application of a series of weakly ordered liquid crystal solvents for liquid state nuclear magnetic resonance (NMR) spectroscopy. The solvents are an‐alkyl‐poly(ethylene glycol)/n‐alkyl alcohol non‐ionic liquid crystal system, first proposed by Ruckert and Otting (J. Am. Chem. Soc.2000,122, 7793). The merits of these solvents are further demonstrated by using them with a homogeneous polymer PEO which is one of the most studied polymer electrolyte materials, thus offering an answer to the question of whether the weak anisotropy introduced by liquid crystal solvents has any connection with the large‐scale (≥ one nanometer) heterogeneity (tertiary or higher orders of structure) of the system

ISSN:0009-4536    

DOI:10.1002/jccs.200300029

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractA novel metallocene catalyst was prepared from the reaction of (η3‐pentamethylcyclopentadienyl)dimethylaluminum (Cp*AlMe2) and titanium(IV)n‐butoxide Ti(OBu)4. The resulting titanocene Cp*Ti(OBu)3was combined with methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) to carry out the syndiotactic polymerization of styrene. The resulting syndiotactic polystyrene (sPS) possesses high syndiotacticity according to13C NMR. Catalytic activity and the molecular weight of the resulting sPSs were discussed in terms of reaction temperature, concentration of MAO, amounts of scavenger TIBA added, and the hydrogen pressure applied during polyme

ISSN:0009-4536    

DOI:10.1002/jccs.200300030

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractChemical modification on the stereo‐regular poly(styrene‐co‐4‐methylstyrene) (sPS‐PMS) was attempted in this study. Metallocene copolymerization of styrene (St) and 4‐methylstyrene (MSt) was performed by using η5‐pentamethylcyclopentadienyl‐titanium(IV)tributoxide (Cp*Ti(OBu)3)/methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) catalyst in the bulk state. Cobalt(II) catalyst was then applied to oxidize the benzylic methyl group on the MSt units of the resulting sPS‐PMS copolymer. Both aldehyde and carboxylic acid in the oxidized products were resolved by the FTIR and1H NMR. The oxidized sPS‐PMSs exhibit a low and a high‐temperature Tgand Tmcorresponding to the transitions in the amorphous and the crystalline regions. Hydrogen‐bond and polar interactions between the aldehyde and carboxylic acids tend to interrupt the regular chain packing of the oxidized sPS‐PMS, resulting in the lowering of Tmwith oxidation level. The oxidized sPS‐PMS showed better adhesion to glass fiber than pure sPS‐PMS copolymer as evaluated from the re

ISSN:0009-4536    

DOI:10.1002/jccs.200300031

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractThe dissociation kinetics of the copper(II) complexes of 4‐methyl‐4,7‐diazadecanediamide (4‐Me‐L‐2,2,2), 4,7‐dimethyl‐4,7‐diazadecanediamide (4,7‐N,N′‐Me2‐L‐2,2,2), 4‐ethyl‐4,7‐diazadecanediamide (4‐Et‐L‐2,2,2), and 4‐methyl‐4,8‐diazaundecanediamide (4‐Me‐L‐2,3,2) have been studied at 25.0 °C and μ = 4.0 M (NaClO4+ HClO4) by the stopped‐flow method. These reactions are specific‐acid catalyzed; however, the rate constants of these reactions do not depend on the concentrations of acetic, chloroacetic, and dichloroacetic acids. At pH values below 1.4, both the proton‐assisted and the direct protonation pathways make contributions to the rates. The ratios of the rate constant of dissociation by the direct protonation pathway to the rate constant by the proton‐assisted pathway for

ISSN:0009-4536    

DOI:10.1002/jccs.200300032

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractThree new hetero‐bischelated rhodium (III) complexes ofcis‐[Rh(PA)(L)Cl2]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assig

ISSN:0009-4536    

DOI:10.1002/jccs.200300033

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractBy reactions of Mo2(O2CPrn)X2(PPh3)2(X = Cl,1; X = Br,2) with Ph2PCH2CH2P(Ph)CH2CH2PPh2(etp) in CH2X2, the quadruply bonded complexes containing bridging butyrate and tridentate phosphine ligands of the type Mo2(O2CPrn)X3(η3‐etp) (X = Cl,3; X = Br,4) were prepared. Their UV‐vis and31P{1H}‐NMR spectra have been recorded and the structures of1and2have been determined by X‐ray crystallography. Crystal data for1: space group P21/c, a = 9.708 (2)Å, b = 18.491 (4)Å, c= 12.688 (3)Å, β = 110.76 (3)°, V = 2130 Å3, Z = 2, with final residuals R = 0.0441 and Rw = 0.0519. Crystal data for2: space group P21/c, a = 9.737 (1)Å, b = 18.632(1)Å, c = 12.680(1)Å, β= 110.27 (1)°,V = 2158.2 (3) Å3, Z = 2, with final residuals R = 0.0322 and Rw = 0.0481. The δ → δ* transition energies,31P{1H}‐NMR chemical shifts and the coupling constants are dependent on the natures of the halogen atoms and the carboxylate ligands. The through metal‐metal couplings |3JP‐Mo‐Mo‐P| for complexes of the type Mo2(O2CR)X3(η3‐P3), which contain η3‐polydenta

ISSN:0009-4536    

DOI:10.1002/jccs.200300034

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY

摘要:

AbstractHydrothermal experiments on an andesite have been carried out under the condition of 110 °C, autogeneous pressure, 0.05 M H2SO4solution and renewal of acid solution every 6 hours.The experimental results indicate that the plagioclase and pyroxenes in the treated samples show micropits and microfractures. Small crystals readily suffered from alteration, as compared with large ones, and the susceptibility of the minerals to the acid solution is decreased in the order of plagioclase, augite, hypersthene and opaque minerals. Plagioclase, which is the most reactive mineral in the experiments, shows an increase of SiO2, but a decrease of Al2O3, CaO and Na2O as the experiments proceeded. The chemical change of the treated andesite, it indicates that the relative amounts of SiO2, TiO2, MgO, ΣFeO, MnO and K2O increase, while those of Al2O3, CaO, Na2O and P2O5decrease with an increase of the experimental duration.The relative mobility of chemical elements listed in decreasing order is P, Ca, Al, Na, Si, K, Mg, Fe, Mn and Ti in terms of the K value. It is no wonder that Ca, Al and Na are more mobile than others because these elements are readily released into solution from the more reactive plagioclase, while Mg, Fe etc. still stay in the less reactive pyroxenes and opaque mineral

ISSN:0009-4536    

DOI:10.1002/jccs.200300035

出版商:WILEY‐VCH Verlag    

年代:2003

数据来源: WILEY