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991.
992.
《Analytica chimica acta》2002,459(2):229-234
The ligand 1,4,8-tri(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1) containing pendant octyl groups has been synthesised. L1 is a tetraazamacrocycle derived from the well-known cyclam unit, and the Ni2+ and Co2+ complexes, [Ni(L1)]2+ and [Co(L1)]2+, have been isolated and characterised. The ability of the nickel(II) and cobalt(II) complexes to act as anion receptors has been studied by using them as ionophores in membrane-based ion-selective electrodes (ISEs). The PVC membrane containing the complex [Ni(L1)]2+ and 2-nitrophenyloctylether as plasticizer shows a Nernstian response against iodide in a concentration range from 1×10−1 to 4×10−5 M I− with a detection limit of 1.6×10−5 M I− and a slope of 58.6 mV/pI− at pH 7 (25 °C). In comparison, the electrode containing [Co(L1)]2+ as ionophore gave a sub-Nernstian slope and a low lifetime. A comparison between the iodide-selective electrode containing [Ni(L1)]2+ and other reported iodide-selective electrodes is also reported. 相似文献
993.
在过去二十年间,高分子的单链弹性已经得到了广泛的研究.然而由于环境和高分子之间往往有着复杂的相互作用,实验中很难得到高分子在严格无扰状态下的单链弹性(即本征弹性).为此,利用单分子力谱技术研究了高真空条件下聚乙二醇(PEG)的单链弹性.结果表明,由于高真空条件下溶剂分子的干扰被消除,PEG在这一准无扰状态下呈现其本征弹性.在非极性有机溶剂中,由于溶剂分子和PEG之间只有微弱的范德华力作用,PEG表现出和高真空中基本一致的弹性.然而,在不同环境中,力曲线的低力区(F<100 pN)存在着细微的差异.这一现象可归因于不同条件下基底与PEG链之间的吸附力不同.采用的高真空力谱可用于研究其他高分子单链在准无扰状态下的本征弹性. 相似文献
994.
The title compound crystallizes in the orthorhombic space group P212121 with 4 molecules in the unit cell (cell dimensions: a 9.778(2), b 10.639(2) and c 12.423(4) Å). The structure was solved by means of the heavy atom method. The rhodium atom is linked to both olefinic double bonds. The terpene carbonyl group does not participate in coordination to rhodium. Unlike the endocyclic olefinic group, which is approximately perpendicular to the coordination plane of rhodium, the exocyclic Cz.sbnd;C double bound shows a considerable deviation from this arrangement. The π-complexation of carvone with rhodium proceeds diastereospecifically. The absolute configuration of (+)-carvone is 4S in agreement with the assignment derived by indirect chemical correlation. 相似文献
995.
Alternative Ligands. XXII. Rhodium(I) complexes with Donor/Acceptor Ligands of the Typs Me2PCH2CH2SiXnMe3?n(X = F, Cl, OMe) Donor/acceptor ligand of the type Me2PCH2SiXnMe3?n react with [Rh(CO)2Cl]2 ( 1 ) to give the mononuclear complexes RhCl(CO)(PMe2CH2CH2SiXnMe3?n)2 ( 2-6 , Table 1) with planar geometry of the donor atoms, one exception being Me2PCH2CH2CH2SiCl3, yielding the crystalline RhIII-complex RhCl2(CO)(PMe2CH2CH2SiCl2)(PMe2CH2CH2SiCl3) ( 7 ) by oxidative addition of one of the SiCl bonds to the Rh1 precursor. Structures with Rh → Si interaction between the basic central atoms and the acceptor group SiXnMe3?n could be detected in the isolated products neither spectroscopically nor by X-ray diffraction of the two representatives RhCl(CO)(PMe2CH2CH2SiF3)2 ( 2 ) and RhCl(CO)[PMe2CH2CH2siF3]2 ( 2 ) and RhCl(CO) [PMe2CH2CH2Si(OMe3]2 ( 6 ). The presence of such acid/base adducts in the reaction mixture is indicated for the more acidic acceptor groups SiXnMe3?n byvco values near 1990cm?1, (see Table 3). The complex RhCl(CO)PMe3)(PMe2CH2CH2SiF3 ( 8 ) is obtained by the reaction of RhCl(CO)(PMe3)2 ( 9 ) with Me2PCH2SiF3 and has been identified spectroscopically in a mixture with 2 and 9 . 相似文献
996.
Yu. V. Tomilov I. V. Kostyuchenko E. V. Shulishov O. M. Nefedov 《Russian Chemical Bulletin》1997,46(3):511-518
The reaction of diazocyclopropane generatedin situ with acrylonitrile or methyl acrylate to give 1∶1, 1∶2, and 2∶1 cycloadducts was carried out. The products resulting from
1,3-dipolar cycloaddition and subsequent isomeriation,viz., 3-cyano- and 3-methoxycarbonylspiro(2-pyrazoline-5,1′-cyclopropanes), isolated in the first step in ∼70% yield, react in
an alkaline solution with the above acrylates or diazocyclopropane as C(3)-nucleophiles to give the corresponding 3-(2′-cyanoethyl)-,
3-(2′-methoxycarbonylethyl)-, or 3-(cyclopropylazo)-1-pyrazolines. The thermal deazotization of these pyrazolines to spiropentane
derivatives was investigated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 532–539, March, 1997. 相似文献
997.
An electrochemical method for the simultaneous determinations of HgII concentration and total AsIII and AsV concentration has been developed. The method does not require the additional preliminary step of the chemical reduction of AsV to AsIII, or oxidation of AsIII to AsV before stripping analysis takes place. Also, the method for the simultaneous determination of HgII concentration and AsIII concentration is described. Measurements were performed in 0.1 M HCl using a gold-plated graphite electrode as sensor. Detection limits for both methods are below 0.4 ppb. Relative standard deviation did not exceed 15%. The possible interference by other trace metals was investigated. Analyses of natural water and industrial solutions were made using proposed methods and AAS. The t-test demonstrates that there was no significant difference between the results obtained with these methods. Proposed methods decrease the time of analysis because concentrations of the HgII and arsenic ions were measured simultaneously. Also, the removal of the additional step of chemical reduction of AsV to AsIII or oxidation of AsIII to AsV decreases analysis time, and also reduces the chance of contamination due to the use of additional reagents. 相似文献
998.
999.
The conditions of formation and some properties of yttrium and lanthanide benzohydroxamates were studied.
Simultaneous TG-DTG-DTA studies under non-isothermal conditions were carried out in air atmosphere in the temperature range
20-1000°C. The IR spectra and X-ray patterns of some thermal decomposition products were recorded.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
1000.
The kinetics of the reaction between organocobaloximes, RCo(DH)2H2O, and iodine have been investigated. They reveal the participation of an RCo(DH)2H2O · I2 intermediate which undergoes intramolecular transalkylation and acts as an electrophile towards a second organocobaloxime molecule. The trend in reactivity as the R group is varied is discussed. 相似文献