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1.
Benzimidazolium-based receptors 1-3 were designed and synthesized. On the basis of fluorescence, UV-Vis, and 1H NMR spectroscopic studies, and X-ray single crystal structure analysis, it was confirmed that the receptor 1 displays strong (C-H)+···X, N-H···X hydrogen bonds and charge-charge interactions with anions. More importantly, these investigations demonstrated that the charged (C-H)+ benzimidazolium and urea moieties play a synergistic role in anion recognition. 相似文献
2.
WANGFa-jun LIUShun-ying HULing LIUXin HEYong-bing 《武汉大学学报:自然科学英文版》2004,9(6):952-956
A novel anion receptor 2 bearing anthracene flurophore and thiourea was synthesized and identified by ^1H NMR,MS,IR and elemental analysis. The interaction between receptor 2 and various α,ω-dicarboxylate anions was studied by fluorescence spectrum. The obtained fluorescence data indicate that 1:1 stoichiometry complex is formed between receptor 2 with diferent dicarboxylate anions through a hydrogen-bonging interaction. The selectivity of 2 for recognition of different dicarboxylates deponds on chain length of the anionic species. 相似文献
3.
The results of research on the effects of anions on the biosorption of microelement cations by the edible marine macroalga Enteromorpha prolifera in singleand multi-metal systems are discussed in this paper. It was shown that the maximum biosorption capacity (qmax) in a single-metal system of Co(II) ions decreased in the following sequence: Cl- (46.0 mg g-1) > SO42- (42.8 mg g-1) > NO3- (41.9 mg g-1). In multi-metal systems, in which the ratios of Cl-, NO3-, and SO42- were 0:0:4, 1:1:2, 3:0:1, and 4:0:0, there were clear differences among the biosorption capacities. In all the examined systems (other than the 0:0:4 system), inhibition of the binding of microelement cations by the macroalga was observed. In all the systems, the highest value of qmax was obtained for Cu(II) cations; the value ranged from 31.9 mg g-1 in 0:0:4 (SO42- only) to 18.2 mg g-1 in 4:0:0 (Cl-only). 相似文献
4.
Meso-tetrahydroxylphenyl chlorin (m-THPC) is one of the most efficient prospective sensitizers used in photodynamic therapy (PDT). ESR spectroscopy, fluorescence quenching experiments and cyclic voltammogram measurement were used to study its redox properties. The results showed that the ability of m-THPC generating superoxide radical anions was very strong, and the rate constant of m-THPC fluorescence quenching by oxygen kq (O2)=1.46×1010 mol-1·s-1. The values of fluorescence quen- ching rate constant of m-THPC by some other electron acceptors, such as methyl viologen (MV2+) and anthraquinone (An), were also measured. And they were kq (MV2+)=5.51×109 mol-1·s-1, kq (An)=7.81×109 mol-1·s-1. The oxidation potential of m-THPC was examined to be +0.62 V (vs. NHE) in acetonitrile. All these suggested that m-THPC should be a much stronger electron donor than photofrin, the currently used in clinical photodrug, and may react easily through electron transfer with biological matter to yield various radicals. So it seemed reasonable that the type Ⅰ reaction may play an important role in the high activity of m-THPC-PDT. 相似文献
5.
Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe2(N-Et-HPTB){O2P(OPh)2}](Cl- O4)2 (1) and [Fe2(N-Et-HPTB) {O2P(Ph)2}] (ClO4)2 (2) with O2 have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O2 adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H¹ = 85.62 kJ·mol-1, ?S¹ = 19.43 J·mol-1·K-1 for compound (1) and ?H¹ = 97.97 kJ·mol-1, ?S¹ = 55.68 J·mol-1·K-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH). 相似文献
6.
Precipitation variability in central Himalayas and its relation to Northern Hemisphere temperature 总被引:3,自引:0,他引:3
DUAN Keqin & YAO Tandong . Cold Arid Regions Environmental Engineering ResearchInstitute Chinese Academy Sciences Lanzhou China . National Laboratory of Western China抯 Environmental Systems Lanzhou University Lanzhou China 《科学通报(英文版)》2003,48(14):1480-1482
Agriculture, industry and hydroelectric power in south Asia are heavily dependent on the performance of the summer (June to September) monsoon rainfall, which provides 75—90% of the annual rainwater over most parts of the area. A weak monsoon year generally corresponds to low crop yields. And strong monsoon usually produces abundant crops, although too much rainfall may produce devastating floods. However, modeling efforts to forecast the monsoon have met with only moderate success[1]. Prev… 相似文献
7.
The synergistic effect of tetrabutylammonium cation (TBA+) or N-hexadecylpyridinium cation (HDP+) and SCN− or I− in 0.5 mol·L−1 H2SO4 solution on the corrosion inhibition of Armco iron was investigated by potentiodynamic polarization and polarization resistance
measurements. The results show that the synergistic effect of HDP+ containing π-electron and anion is stronger than that of TBA+ and anion. The joint adsorption models of cation and anion at electrode-solution interface are related to the structure and
property of both ions by analyzing the desorption behaviours of both ions when the electrode is polarized anodically.
Supported by the national scientific foundation of China
Zou Jinyun: born in Aug. 1936. Prof. 相似文献
8.
Zhenrong Sun Shenyi Wang Yanping Huang Jiyun Lin Liangen Ding Zugeng Wang 《科学通报(英文版)》1998,43(5):399-402
The nonlinear refractive indexesn
2 for the ethanol solutions of 1, 10-phenanthroline (2.0 × 10−3 mol · L−1), [bis(l, 10-phenanthroline) lanthanum (III)] nitrate (1.0 × 10−3 mol · L−1), and [nitrato-fluoracil-bis (1, 10-phenanthroline) lanthanum (III) ] nitrate (1.0 × 10−3 mol · L−1) are first measured, the third-order nonlinear optical susceptibilities χ(3) and 〈γ〉 are calculated, and the mechanisms of the third-order optical nonlinearities enhanced by lanthanum (III) are discussed
preliminarily. 相似文献
9.
Magnetic properties of heteropolyoxometalates 总被引:1,自引:0,他引:1
The progress of the study on the magnetic properties of heteropolyoxometalates during the late decade is reviewed. Some anions of heteropolyoxometalates containing magnetic atoms, such as [M4(H2O)4(PW9O34)2]10- and[M4(H2O)4(P2W15O56)2]16-[M = Co(Ⅱ), Zn( Ⅱ ), Cu( Ⅱ ), Mn(Ⅱ ), Ni(Ⅱ)], and [GaW9O37M3(H2O)3]n-[M = Fe(Ⅲ), Cu(Ⅱ), Co(Ⅱ)] showed ferromagnetic and antiferromagnetic properties. The combination of heteropoly anions and organic π-donor of TTF+ (te-trathiofulvalene cation) results in a variety of magnetic properties. Furthermore, there is an interaction between the inorganic and organic components. The electrocrystallization technique can prepare the organic-inorganic salts of this kind, which will become the new member of molecular magnetic materials. Heteropoly blue is a kind of the mixed-valence complexes and its reduction electrons can be delocalized over anionic framework. The further study on the magnetic properties of heteropolyoxometalates will provide important information for the design of molecular materials. 相似文献
10.
The electronic properties and stabilities of five [Nb2W4O18OCH3]3− isomers have been investigated using a density functional theory method. The results show that the isomer with the methoxy
group occupying a bridging position between two tungsten atoms (two tungsten atoms in the plane that contains two niobium
atoms) in the [Nb2W4O18OCH3]3− framework is the most stable isomer in acetonitrile. The stability of the one-electron-reduced isomers changes little. The
most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4− framework. The M-Ob (M = Nb, W; b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy
group are longer than those in [Nb2W4O19]4−. The highest occupied molecular orbitals (HOMO) in [Nb2W4O19]4− mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,
and the bridging oxygen atoms on the axial surface. The lowest unoccupied molecular orbitals (LUMO) of [Nb2W4O19]4− are mainly concentrated on the tungsten atoms and antibonding oxygen atoms. Methoxy substitution modifies the electronic
properties of the [Nb2W4O18OCH3]3− isomers. The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms, which are distant from the surface
containing the methoxy group and four metal atoms. The LUMOs delocalize over the d-shells of the four metal atoms that are
close to the methoxy group, and the p-orbitals of oxygen. One-electron reduction occurred at the tungsten atoms, not the niobium
atoms. 相似文献
11.
The interaction of Ru(phen)2(dppz)2+(phen=1,10-phenanthroline,dppz=dipyrido[3,2−1:2′,3′−c]phenazine) and the calfthymus DNA were studied with fluorescence and
ultraviolet visible absorption spectroscopy. The ultraviolet visible absorption spectrum of Ru(phen)2(dppz)2+ calfthymus DNA, and their interaction demonstrated that Ru(phen)2(dppz)2+ intercalated into the double helix of DNA via the ligand dppz. Fe(CN)6
4− and NaCl can not quench the fluorescence of Ru(phen)2(dppz)2+-DNA, which was in agreement with the intercalation mode.
Foundation item: Supported by National Natural Science Foundation of China
Biography: LING Lian-sheng (1972-), male, PhD, candidate. 相似文献
12.
Yong Yi Dong Cai Zhonghong Gao Xiangliang Yang Anlian Qu Huibi Xu Xiaomin Wang Songping Han 《科学通报(英文版)》1998,43(20):1727-1727
The mechanism of peroxynitrite (ONOO−)-induced [ca2+]i increase in single MN9D cell (Dopaminergic neuroblastoma cell line) was studied by using Fura-2 microfluorometric technique.
The results show that ONOO− caused a rapid increase of [Ca2+]i when ONOO− was puffed to the cell. Removing Ca2+ from the bath or using calcium channel antagonist (CdCl2, Nifedipine) greatly inhibited the [Ca2+]i increase induced by ONOO−1, suggesting that the opening of L-Ca2+ channel makes a great contribution to the [Ca2+]i increase. The effect of sulfhydryl reductive agent (DTT) on ONOO−-induced [Ca2+]i increase suggests that ONOO−-activating L-Ca2+ channel is partly related to its oxidative speciality. 相似文献
13.
Keggin-type phenylimido-polyoxometalates α-[PM12O39NPh]3− (M = W and Mo) have been systematically investigated on the electronic structures, redox as well as nonlinear optical (NLO)
properties by density functional theory (DFT). The strong M≡N bond confirmed by natural bond orbital (NBO) analysis comprises
one s bond and two π bonds, the same as Mo≡N in [Mo6O18NPh]2−. Furthermore, phenylimido segment effectively modifies the electronic properties of α-[PM12O39NPh]3−. On one hand, when enlarging the inorganic cluster from {Mo6O18} to {PMo12O39}, the energy gap between HOMO and LUMO in α-[PMo12O39NPh]3− decreased, resulting in enormously anodic shift for the reduction potential, while the excitation energy is less and the
total second-order polarizability β
0 is up to 438-3×10−30 esu, which is nearly 10 times larger than that of [Mo6O18NPh]2−. On the other hand, when metal W in α-[PM12O39NPh]3− is substituted by Mo, the interaction between Mo and N is enhanced and the redox ability becomes stronger. The β
0 value for α-[PMo12O39NPh]3− is more than 5 times higher than that of α-[PW12O39NPh]3−. It indicates that changing appropriate metal or enlarging the inorganic cluster will improve the redox properties and second-order
nonlinear response. Moreover, the electron transition for three compounds mentioned above occurred mainly from organoimido
segment (as the electron donor) to polyanion cluster (as the acceptor). As a result, α-[PMo12O39NPh]3− may be a promising candidate for oxidant and nonlinear optical material.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
Supported by National Natural Science Foundation of China (Grant No. 20573016), Training Fund of NENU’s Scientific Innovation
Project (Grant No. NENUSTC07017), Science Foundation for Young Teachers of Northeast Normal University (Grant No. 20070304)
and Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT) 相似文献
14.
Fluxes of carbon dioxide and methane from swamp and impact factors in Sanjiang Plain,China 总被引:16,自引:0,他引:16
SONG Changchun YAN Baixing WANG Yuesi WANG Yiyong LOU Yanjing & ZHAO Zhichun . Northeast Institute of Geography Agricultural Ecology Chinese Academy of Sciences Changchun China . Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Correspondence should be addressed to Song Changchun 《科学通报(英文版)》2003,48(24):2749-2753
Incomplete decomposition of organic matter results in the accumulation of the carbon and other nutriments in wetlands. The wetland ecosystem gains a large amount of carbon from atmosphere CO2 by photosynthesis, and it loses much of which back into the atmosphere as CO2 and CH4 emission through the decomposition and respiration. Climate change, such as global warming and reduction of precipitation could drive the wetlands from carbon sink to source[1,2]. Wetland plays an important role in car… 相似文献
15.
A series of Fe(Ⅲ)-containing imidazolium-based ionic liquids containing ether substituents,including[C3OMim][FeCl4](1,[C3OMim]=1-(2-methoxyethyl)-3-methylimidazolium),[C3OiPim][FeCl4](2,[C3OiPim]=1-isopropyl-3-(2-methoxyethyl)imidazolium),[C3OBim][FeCl4](3,[C3OBim]=1-butyl-3-(2-methoxyethyl)imidazolium),[(C3O)2im][FeCl4](4,[(C3O)2im]=1,3-bis(2-methoxyethyl)imidazolium),[C3OMim][FeBr4](5)and[(C3O)2im][FeBr4](6),were prepared and characterized by elemental analysis,Raman spectroscopy and electrospray ionization mass spectrometry.The catalytic performances of 1–6 and related Fe(III)-based catalysts in the cross-coupling of aryl Grignard reagents with alkyl halides bearing-hydrogens were studied,revealing that mono(ether)functionality improves the catalytic activity and that bis(ether)functionality improves the reusability.After simply decanting the product contained in the ethereal layer,complex 4,which containing bis(ether)-functionalized imidazolium cation,could be successfully recycled seven times. 相似文献
16.
Synthesis and crystal structure of new supramolecular adducts of [PtCl6]2− with cucurbit [7] uril: [(H3O)2 (PtCl6)]3 (C42H42N28O14)2·H2O 总被引:1,自引:0,他引:1
A novel supramolecular adduct [(H3O)2 (PtCl6)]3 (C42H42N28O14)2·H2O (1) was synthesized by mixing [PtCl6]2− and cucurbit [7] uril in solution of hydrochloric acid. The crystal structure was determined by single crystal X-ray diffraction
analysis. The crystal belongs to orthorhombic system and space group F dd2 with cell dimensions:a=4. 705 33 (5) nm,b=7. 153 80 (6) nm,c=1. 894 61 (2) nm,Z=16,V=63, 7744 (11) nm3,D
c
=1.534 g/cm3, μ=3. 007 mm−1,F(000)=29 120,R
1=0.070 7,wR
2=0. 169 2. In crystal, the cucurb [7] uril molecules from two zig-zag chains.
Foundation item: Supported by the National Natural Science Foundation of China (20172040)
Biography: Yan kun (1977-), female, Master, research direction: macrocyclic chemistry. 相似文献
17.
Weiguo Zhu Hongsen Xie Jian Xu Wei Hou Yueming Zhang Jie Guo Zhuming Xu 《科学通报(英文版)》1999,44(5):461-466
A series of melting experiments was carried cut at 1 650°C and 1.00–3.00 GPa using alkaline basalt as starting material. The
cornpitions of quenched basaltic glasses in the products were detected by electron micro probe. Their CIPW norms were calculated
and their refractive indices were determined by the oil-infused method. The Raman spectrum of the quenched basaltic glasses
indicates that their main structural species are monomer [Si2O4]14−, chain [Si2O6]14- and sheet [Si2O5]12-. The relationship at the same temperature between the proportions of integrated areas of structural species, and compositions
and pressures was discussed. 相似文献
18.
[Li(NTO)(H2O)2] was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one (NTO) and lithium hydroxide. The crystal structure
of [Li(NTO)(H2O)2] was determined by single crystal diffraction analysis. The crystal is monoclinic, space group P21/n with crystal parameters of a = 0.742 0(2) nm, b = 0.344 9(1) nm,c = 2.490 6(3) nm, β= 94.89(1)°, Z = 4,D
c
, = 1.799 g cm−3,V = 0.635 nm3, μ = 1.591 cm−1, F(000) = 392. The finalR is 0.051. The MNDO MO calculation shows that the coordinate bonds of title compound possess certain extent of covalent character.
O2 atom of NTO anion is bonded to Li atom; the nitro group will be lost first when NTO is decomposed. 相似文献
19.
Chen Zhenhua Chen Xinlan Tian Bingshou He Jiping Lei Peng Yu Naiteng Zhang Lun 《武汉大学学报:自然科学英文版》1997,2(2):201-204
The Raman and IR spectra of LnTPPTS·10H2O [Ln=La,Sm, TPPTS=P(m-C6H4SO3)
3
3−
] complexes are reported. Based on the observed Raman and IR characteristic frequencies, a vibrational assignments has been
made for these complexes. Coordination induces a lengthening of the S−O bonds and a shortening of the C−S bond. The C−S stretching
frequencies should therefore increase while the position of the
should move to a lower wavenumber. Vibrational modes of metal-oxygen polyhedron V
(La-O) at 146, 168,253 cm−1 are the structural charactrization for coordinate bond of LnTPPTS complexes.
Chen Zhenhua: Born in 1938, Professor 相似文献
20.
An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon
paste electrode (CPE) has been developed. Pb2+ and Cd2+ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix[6]arene, and reduced
at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping
peaks appeared at about −0.60 V and −0.84 V. Compared with a bare carbon paste electrode, the calix[6]arene modified CPE greatly
improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration
of Pb2+ 3.0×10−8–8.0×10−6 mol·L−1 and with that of Cd2+ 6.0×10−8–1.0×10−5 mol ·L−1. The detection limits of Pb2+ and Cd2+ are found to be 8.0×10−9 mol·L−1 and 2.0×10−8 mol·L−1, respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples.
Comparing with that of atomic absorption spectrometry, the results suggests that the calix[6]arene modified CPE has great
potential for the practical sample analysis.
Foundation item: Supported by the National Natural Science Foundation of China (60171023)
Biography: JI Xiao-bo (1980-), male, Master, research direction: electroanalytical chemistry. 相似文献