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1.
TENGLi-rong WANGYa-jun WUMin HONGShui-sheng CHENJia MengQing-fan LIULan-ying 《高等学校化学研究》2003,19(4):442-445
Superoxide dismutases(SODs) were purified to homogeneity from Allium Sativum by means of ammoni-um sulfate precipitation and column chromatography with DEAE--cellulose (DE52) and Sephadex G-75. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-AGE), Allium Sativum is predicted to contain four SODs. The molecular weights of the native SODs are 41.3 kD, 37. 0 kD, 35.2 kD and 31.0 kD, which consist of subunits of 20. 7 kD, 18. 4 kD, 17. 7 kD and 15.4 kD respectively. Because of their specific sensitivity to hydrogen peroxide, cyanogens potassium and chloroform-alcohol, the SODs in Allium Sativum appear to be Cu, Zn-SOD isoenzymes. The isoelectric analysis indicates that three of the four isoermymes are acidic proteins with isoelectric points at pH 3.5, 3.7 and 4. 0, respectively, and the fourth one is a basic pro-tein with isoeletric point at pH 8. 5. 相似文献
2.
Alex Fragoso Roberto Cao Reynaldo Villalonga 《Journal of carbohydrate chemistry》2013,32(9):1379-1386
Abstract The synthesis of a new β-cyclodextrin derivative containing a dithiocarbamate group (3) by condensation of mono-2-methylamino-2-deoxy-β-CD (2) with CS2 in the presence of NEt3 is reported. SOD-mimetic activity was found for the Mn(II) and Cu(II) complexes of 2 and 3 (IC50 = 0.76-7.4 μ). To study the influence of the cyclodextrin residue on the catalytic activity of these complexes, a comparison was made with diethylamine and diethyldithiocarbamate complexes. Complexes of 2 and 3 resulted in 1.3 to 11 fold higher activities. An explanation for this observation, in terms of a possible cooperation of the cyclodextrin residue with the catalytic center of the complex, is given. 相似文献
3.
Dr. Ziyang Guo Chao Li Jingyuan Liu Prof. Yonggang Wang Prof. Yongyao Xia 《Angewandte Chemie (International ed. in English)》2017,56(26):7505-7509
Lithium–air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li2O2/LiOH/Li2CO3 accumulation in the air electrode. Herein, we present a Li–air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I−/I2 conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li–air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li–air battery that can be operated in ambient air. 相似文献
4.
《Tetrahedron》1986,42(3):849-856
(Aza)1,2- and 1,4-dithiafulvalenes are more difficult to oxidize than tetrathiafulvalenes. Depending on substituents, (aza)dithiafulvalenes react with tetracyano-p-quinodimethane (TCNQ) either in a 1:1 or 2:3 ratio to form heterofulvalenium 7,7,8,8-tetracyano-p-quinodimethanides. The electrical conductivity of these salts strongly depends on substituents. The conductivities of alkylthiofulvalene-TCNQ salts are much higher than those of phenyl-substituted derivatives. 相似文献
5.
Casson LA Muzzioli S Raiteri P Skelton BW Stagni S Massi M Brown DH 《Dalton transactions (Cambridge, England : 2003)》2011,40(44):11960-11967
Two rhenium(I) carbonyl complexes of the type fac-[Re(CO)(3)(N^C)X] where N^C is an N-heterocyclic carbene [3-butyl-1-(2'-pyridyl)benzimidazolin-2-ylidene] and X is either Cl or Br have been synthesised via an in situ method from [Re(CO)(5)X] and a respective benzimidazolium salt. The complexes have been characterised by (1)H and (13)C NMR, infra-red spectroscopy and in the case of the bromo-complex by a single-crystal X-ray diffraction study. The photophysical properties of the complexes have been investigated, revealing similar phosphorescent emission which was attributed to radiative decay from a (3)MLCT state partially mixed with a (3)LLCT state. However, the analysis of excited state lifetime and quantum yield values revealed distinct photophysical behaviour for the two complexes, which was attributed to the more labile nature of the bromo ligand with respect to the chloro one. The explanation was supported by the time-dependent emission profile change in diluted acetonitrile solutions. 相似文献
6.
Martínez-Blanco J Mascaraque A Dedkov YS Horn K 《Langmuir : the ACS journal of surfaces and colloids》2012,28(8):3840-3844
The adsorption of coronene molecules (C(24)H(12)) on the Ge(001) surface has been studied by means of scanning tunnelling microscopy (STM). Upon room temperature deposition, the coronene molecules adsorb in an upright geometry forming compact layers patterned in rows for coverages of one monolayer and less, being the only example investigated so far in which a pure aromatic hydrocarbon forms a well-ordered monolayer on a non-passivated semiconductor surface. At half monolayer, the molecular rows consist of long chains of π-stacked molecules and the distance between molecular planes is 8 ?. This configuration is maintained upon cooling the system below the transition temperature of Ge(001) (~220 K), but the molecular layer experiences also a transition from rows perpendicular to rows parallel to the Ge dimer rows. We interpret our observations in terms of a weak bonging between molecules and substrate, which facilitates the formation of large ordered domains of molecules, revealing Ge(001) as an ideal template for the growth of this and other aromatic hydrocarbons. 相似文献
7.
Ironing it out: Oxoiron(IV) porphyrin π-cation radical complexes serve as models for the oxidation of Cl(-) into an active chlorinating reagent that chlorinates various organic compounds. Evidence suggests that Cl(-) is oxidized to Cl(2) via Cl(.) . The mechanism involving either direct electron transfer or iron(III) hypochlorite formation, and then homolysis of the Cl?O bond is discussed. 相似文献
8.
9.
Joachim STCKIGT 《中国化学快报》2006,(4)
The synthesis of (±)-5, 6, 7-trioxygenated dihydroflavonols was carried out. All synthetic compounds were passed through superoxide radical scavenging activity in vitro. Compounds 1e and 1g exhibited significant bioactivity with the inhibitory rates of 68.1% and 80.9% at 40 μg/mL, respectively. 相似文献
10.
Dr. Naoya Suzuki Tomoya Kubota Dr. Naoki Ando Prof. Dr. Shigehiro Yamaguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103584
We report a new design strategy for an excited-state intramolecular proton transfer (ESIPT) fluorophore that can be used in acidic media. A photobasic pyridine-centered donor-acceptor-donor-type fluorophore is combined with a basic trialkylamine “strap”. In the presence of an acid, protonation occurs predominantly at the amine moiety in the ground state. A single-crystal X-ray diffraction analysis confirmed the formation of a pre-organized intramolecular hydrogen-bonded structure between the resulting ammonium moiety and the pyridine ring. Upon excitation, the intramolecular charge-transfer transition increases the basicity of the pyridine moiety in the excited state, resulting in proton transfer from the amine to the pyridine moiety. Consequently, the fluorophore takes on a polymethine-dye character in the ESIPT state, which gives rise to significantly red-shifted emission with an increased fluorescence quantum yield. 相似文献
11.
Hiroyuki Nishide Naoki Yoshioka Yukoh Saitoh Ritsuko Gotoh Takeshi Miyakawa Eishun Tsuchida 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):775-786
Abstract m- and p Bis(diphenylene)propenylphenylacetylene (m-, p-8) were synthesized and polymerized with WCI6, MoCl5, and Rh catalyst, yielding solvent-soluble poly(phenylacetylene)s bearing a π-conjugated bis(di-phenylene)propenyl groups (m-, p-7a). The polymers gave their polyanion derivatives, which were electrolytically and chemically oxidized to yield the corresponding polyradicals (m-, p-7b). The polyradicals were chemically very stable due to the resonance stabilization of an unpaired electron whose spin concentration could be increased up to ca. 2 × 1023 spins per molar monomer unit. ESR spectroscopy suggested an antiferro-magnetic interaction between unpaired electrons. 相似文献
12.
The oxoiron(IV) porphyrin π-cation radical complex (compound I) has been identified as the key reactive intermediate of several heme enzymes and synthetic heme complexes. The redox properties of this reactive species are not yet well understood. Here, we report the results of a systematic study of the electrochemistry of oxoiron(IV) porphyrin π-cation radical complexes with various porphyrin structures and axial ligands in organic solvents at low temperatures. The cyclic voltammogram of (TMP)Fe(IV)O, (TMP = 5,10,15,20-tetramesitylporphyrinate), exhibits two quasi-reversible redox waves at E(1/2) = 0.88 and 1.18 V vs SCE in dichloromethane at -60 °C. Absorption spectral measurements for electrochemical oxidation at controlled potential clearly indicated that the first redox wave results from the (TMP)Fe(IV)O/[(TMP(+?))Fe(IV)O](+) couple. The redox potential for the (TMP)Fe(IV)O/[(TMP(+?))Fe(IV)O](+) couple undergoes a positive shift upon coordination of an anionic axial ligand but a negative shift upon coordination of a neutral axial ligand (imidazole). The negative shifts of the redox potential for the imidazole complexes are contrary to their high oxygenation activity. On the other hand, the electron-withdrawing effect of the meso-substituent shifts the redox potential in a positive direction. Comparison of the measured redox potentials and reaction rate constants for epoxidation of cyclooctene and demethylation of N,N-dimethylanilines enable us to discuss the details of the electron transfer process from substrates to the oxoiron(IV) porphyrin π-cation radical complex in the oxygenation mechanisms. 相似文献
13.
Iron(III) isoporphyrin, a tautomer of porphyrin with a saturated meso carbon, is one of the isoelectronic forms of oxoiron(IV) porphyrin π-cation radical, which is known as an important reactive intermediate of various heme enzymes. The isoporphyrin has been believed to be incapable of catalyzing oxygenation and oxidation reactions. Here, we report that an oxoiron(IV) porphyrin π-cation radical can be converted to iron(III) meso-chloro-isoporphyrin in the presence of trifluoroacetic acid and chloride ion. More importantly, this study shows the first evidence that iron(III) meso-chloro-isoporphyrin is an excellent reactive agent for chlorinating aromatic compounds and olefins. The results of this study suggest that the mechanism involves electrophilic chlorination of substrate with iron(III) meso-chloro-isoporphyrin. 相似文献
14.
《Journal of Coordination Chemistry》2012,65(12):1433-1439
The preparation, spectroscopic properties and crystal structure of (bis-imidazole)quinoline-copper(II) dichloride [Cu(Im)2(quin)Cl2] (Im = imidazole, quin = quinoline) and tetraimidazole-copper(II)-dichloride [Cu(Im)4Cl2] are reported. Both cocrystallize on the triclinic system, space group P-1, with cell constants a = 8.095(5) Å, b = 12.141(5) Å, c = 13.847(5) Å, α = 108.816(5)°, β = 104.173(5)°, γ = 94.965(5)° and Z = 2. In the [Cu(Im)2(quin)Cl2] complex the copper(II) ion is coordinated to two imidazole molecules, to one quinoline and two chlorine ions, with the copper(II) ion in a distorted trigonal bipyramidal coordination geometry. In the [Cu(Im)4Cl2] complex, the copper(II) ion has a distorted octahedral coordination geometry. The superoxide dismutase mimetic activity of the complexes was investigated using the indirect xanthine-xanthine oxidase-nitroblue tetrazolium method and compared to that of the native enzyme. 相似文献
15.
ZHUANG Hui-Sheng WANG Qiong-E ZHANG FanDepartment of Chemistry Fuzhou University Fuzhou Fujian China.HUANG Qiao-Jia TANG Yu-ChaiFuzhou General Hospital Nanjing Military Region Fuzhou Pujian China 《中国化学》1997,15(2):123-129
A new chemilurninescence label N-(β-carboxypropionyl)luminol (CPL) was used to label sheep anti-human IgG (SaHIgG).The labeled antibody was stable and could be detected at least down to 10-17~10-16 mol.The molar incorporation ratio was estimated to be 0.26 mol of CPL per mol of SaHIgG.There were no apparent changes in the immunoreactivity of the labeled SaHIgG and in the quantum efficiency of the CPL after labeling. 相似文献
16.
《Tetrahedron letters》1986,27(11):1273-1276
In cage substrates (15/16) with specifically designed and favourable geometry (X-ray), no [6+2]-photocycloaddition between benzo/azo(azoxy) chromophors could be effected. 相似文献
17.
Youngsuk Kim Dr. Liu Leo Liu Prof. Dr. Douglas W. Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7110-7113
N-Heterocyclic carbene (NHC) derived 3-azabutadienes 1 and 2 have been prepared by a single-step reaction of the corresponding NHC with cyclohexyl isocyanide. Compound 1 features π-basic, delocalized nucleophilic sites over the 3-azabutadiene moiety, therefore allowing for coordinating with small Lewis acids, such as AlCl3, GaCl3, and Me2SAuCl, to form diverse classic Lewis adducts 3 – 5 . Combination of 1 with B(C6F5)3 or [Ph3C][B(C6F5)4] resulted in single-electron transfer and the obtained radical cation was detected by EPR. In addition, a frustrated Lewis pair comprised of the π-basic 1 and BPh3 effects the splitting of the O−H bond of phenol and the N−H bond of imidazole to give 7 and 8 , respectively. An intrinsic bond orbital (IBO) analysis of the pathway leading to 8 showcases the transformation of the delocalized π-electrons of 1 to a newly formed C−H localized σ-bond. 相似文献
18.
Maher TR Meyers JJ Spaeth AD Lemley KR Barybin MV 《Dalton transactions (Cambridge, England : 2003)》2012,41(26):7845-7848
Three synthetic routes to the unusual supramolecular complex ([Cp(2)Co](2)[{(OC)(5)V}(2)(μ-1,4-CNC(6)Me(4)NC)])(∞), which was crystallographically characterized, are presented. The dianion [{(OC)(5)V}(2)(μ-1,4-CNC(6)Me(4)NC)](2-) constitutes the first subvalent organometallics featuring a diisocyanoarene linker. 相似文献
19.
A. B. Nikol’skii Yu. S. Varshavsky T. G. Cherkasova I. S. Podkorytov V. A. Gindin 《Russian Chemical Bulletin》2012,61(4):813-820
The complex trans-[RuPy4(CN)2] cleaves chloride bridges in the binuclear rhodium(i) and palladium(ii) complexes [Rh(CO)2Cl]2, [Rh(η4-C8H12)Cl]2, [(η4-C8H12)Rh(μ-Cl)2Rh(CO)2], [Pd(η3-C3H5)Cl]2, and [(η3-C3H5)Pd(μ-Cl)2Rh(CO)2] to form heterometallic triad complexes [(CO)2ClRh(NC)RuPy4(CN)RhCl(CO)2] (1), [(η4-C8H12)ClRh(NC)RuPy4(CN)RhCl-(η4-C8H12)] (2), [(CO)2ClRh(NC)RuPy4(CN)RhCl(η4-C8H12)] (3), [(η3-C3H5)ClPd(NC)-Ru(Py)4(CN)PdCl(η3-C3H5)] (4), and [(CO)2ClRh(NC)Ru(Py)4(CN)PdCl(η3-C3H5)] (5), respectively. In solutions, complex 3 coexists with equilibrium amounts of compounds 1 and 2; complex 5 is in the equilibrium with compounds 4 and 1. In both cases, the ratio of concentrations is close to binomial. Complexes 2 and 5 treated with [Rh(CO)2Cl]2 are converted into 1 with the simultaneous formation of [Rh(η4-C8H12)Cl]2 and [Pd(η3-C3H5)Cl]2, respectively. The δH and δC values for the ligands η4-C8H12, η3-C3H5, and CO are sensitive to the nature of the remote triad unit. The ligand effects are shown to be transmitted along the chain L′-M′-(NC)-Ru-(CN)-M″-L″. 相似文献
20.
Castellano M Fortea-Pérez FR Stiriba SE Julve M Lloret F Armentano D De Munno G Ruiz-García R Cano J 《Inorganic chemistry》2011,50(22):11279-11281
Self-assembly of the rigid rodlike ligand N,N'-4,4'-diphenylethynebis(oxamate) (dpeba) and Cu(2+) ions affords a novel dinuclear copper(II) metallacyclophane (nBu(4)N)(4)[Cu(2)(dpeba)(2)]·4MeOH·2Et(2)O (1) featuring a very long intermetallic distance (r = 15.0 ?). Magnetic susceptibility measurements for 1 reveal a moderately weak but nonnegligible intramolecular antiferromagnetic coupling between the two metal centers across the double para-substituted diphenylethynediamidate bridge (J = -3.9 cm(-1); H = -JS(1)S(2), where S(1) = S(2) = S(Cu) = (1)/(2)). Density functional electronic structure calculations on 1 support the occurrence of a spin polarization mechanism. 相似文献