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1.
A. N. Bovin V. I. Evreinov Z. V. Safronova E. N. Tsvetkov 《Russian Chemical Bulletin》1993,42(5):912-916
A number of monopodands havingo-diphenylphosphinyl terminal groups were synthesized by alkylating sodium derivatives of oligoethylene glycols witho-(bromomethyl)phenyldiphenylphosphine. The stability constants of the complexes of these ligands with alkali metal cations at 25 °C were determined conductometrically in a THF—chloroform solution (41, v/v). The complexing ability of monopodands with respect to the cations studied increases monotonically as the number of electron-donating sites increases (from 3 to 8) for all of the cations except Li+ and, to some extent, Na+. In the case of Li+ a smooth decrease in the stability of the complexes is observed. The monopodands obtained in this work differ drastically in this regard from their structural isomers, bis[o-(diphenylphosphinylmethyl)phenyl] ethers of oligoethylene glycols, which had been studied previously.For part 10, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 952–956, May, 1993. 相似文献
2.
Nedjla Zehani Rochdi Kherrat Sergei V. Dzyadevych 《International journal of environmental analytical chemistry》2015,95(5):466-479
Organophosphate pesticides (OPs) have been intensively used as insecticides in agriculture; after entering the aquatic environment, they may affect a wide range of organisms. A conductometric enzymatic biosensor based on lipase extracted from Candida rugosa (CRL) has therefore been developed for the direct and rapid quantitative detection of organophosphate pesticides: diazinon, methyl parathion and methyl paraoxon in water. The biosensor signal and response time were obtained under optimum conditions, the enzyme being immobilised in the presence of gold nanoparticles. Under these conditions, the enzymatic biosensor was able to measure concentrations as low as 60 µg/L of diazinon, 26 µg/L of methyl parathion and 25 µg/L of methyl paraoxon very rapidly (response time: 3 min). Moreover, this CRL biosensor was not sensitive to interferences such as carbamates. It presented good storage stability for 21 days when kept at 4°C and it was successfully applied to real samples. 相似文献
3.
Yvon Pointud Claude Bernard Sébastien Touzain Lionel Astier Béatrice Sabatier Jean Juillard 《Journal of solution chemistry》1997,26(5):479-495
The standard Gibbs functions, enthalpies, and entropies for the formation of the complexes of monensin acid with monovalent
metal cations in acetonitrile were obtained using various methods (conductometry, potentiometry, and calorimetry). Complexation
is appreciable (from 2.0 to 4.5 in terms of association constant logarithm) and controlled mainly by the enthalpic effect.
Comparison with formation of the corresponding neutral complexes permits a comparison to the process of monensin mediated
transport of cation in membranes. A two-step process involving first the formation of the acidic complex is suggested. 相似文献
4.
B. A. Ananchenko L. A. Kalinina Yu. N. Ushakova E. G. Fominykh E. V. Koshurnikova 《Russian Journal of Electrochemistry》2009,45(6):684-692
The CaYb2S4 compound and the phases based on it are fabricated. The ranges of solid solutions of CaS and Yb2S3 in calcium thioytterbiate are determined using the methods of x-ray diffraction analysis and conductometry. Average ionic, electronic, cationic, and anionic transport numbers and the coefficients of self-diffusion and diffusion of majority carrier in the Yb2S3 solid solution based on CaYb2S4 are determined by the modified emf method, the polarization Hebb-Wagner method, and potentiostatic chronoammetry. To discuss the mechanism of ionic transfer, the data on the pycnometric and X-ray densities are compared. 相似文献
5.
Formation of higher ion aggregates mainly by hydrogen bonding in solutions of diethylcyclohexylammonium chloride (c-Hex(Et)2NHCl) has been examined by conductometry in nearly isodielectric mixed solvents: nitrobenzene-acetonitrile (35) and benzonitrile-ethanol (25) at 25°C. At lower acetonitrile content (less than ca. 10% by volume) in mixtures with nitrobenzene the salt gave minimum in the molar conductivities over the concentration range 4x10–3 to 0.12 mol-dm–3 which were explained by ion pair (MX), triple ion (M2X, MX2), and quadrupole (M2X2) formation in the solvent mixtures. The formation constants of the ion aggregates decreased with increasing content of acetonitrile. In benzonitrile-ethanol mixtures, the degrees of ion aggregate formation also decreased with increasing content of ethanol; triple ion formation could not be observed at more than 20% ethanol. 相似文献
6.
Gholam Hossein Rounaghi Razyeh Sanavi Khoshnood Mohammad Hossein Arbab Zavvar 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):247-252
The complexation reactions between Mg2+, Ca2+, Ag+ and Cd2+ metal cations with N-phenylaza-15-crown-5 (Ph-N15C5) were studied in acetonitrile (AN)–methanol (MeOH), methanol (MeOH)–water (H2O) and propanol (PrOH)–water (H2O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stochiometry of all of the complexes with Mg2+, Ca2+, Ag+ and Cd2+ cations is 1:1 (L:M). The stability of the complexes is sensitive to the solvent composition and a non-linear behaviour was observed for variation of log K
f of the complexes versus the composition of the binary mixed solvents. The selectivity order of Ph-N15C5 for the metal cations in neat MeOH is Ag+>Cd2+>Ca2+>Mg2+, but in the case of neat AN is Ca2+>Cd2+>Mg2+>Ag+. The values of thermodynamic parameters (ΔH
c
o
, ΔS
c
o
) for formation of Ph-N15C5–Mg2+, Ph-N15C5–Ca2+, Ph-N15C5–Ag+ and Ph-N15C5–Cd2+ complexes were obtained from temperature dependence of stability constants and the results show that the thermodynamics of complexation reactions is affected by the nature and composition of the mixed solvents. 相似文献
7.
G. H. Rounaghi F. Mofazzeli 《Journal of inclusion phenomena and macrocyclic chemistry》2005,51(3-4):205-210
The complexation reactions between Mg2+,Ca2+,Sr2+ and Ba2+ metal cations with macrocyclic ligand, dicyclohexano-18-crown-6 (DCH18C6) were studied in methanol (MeOH)–water (H2O) binary mixtures at different temperatures using conductometric method . In all cases, DCH18C6 forms 1:1 complexes with these metal cations. The values of stability constants of complexes which were obtained from conductometric data show that the stability of complexes is affected by the nature and composition of the mixed solvents. While the variation of stability constants of DCH18C6-Sr 2+ and DCH18C6-Ba2+versus the composition of MeOH–H2O mixed solvents is monotonic, an anomalous behavior was observed for variations of stability constants of DCH18C6-Mg2+ and DCH18C6-Ca2+ versus the composition of the mixed solvents. The values of thermodynamic parameters (ΔHc°, ΔSc°) for complexation reactions were obtained from temperature dependence of formation constants of complexes using the van’t Hoff plots. The results show that in most cases, the complexation reactions are enthalpy stabilized but entropy destabilized and the values of thermodynamic parameters are influenced by the nature and composition of the mixed solvents. The obtained results show that the order of selectivity of DCH18C6 ligand for metal cations in different concentrations of methanol in MeOH–H2O binary system is: Ba2+>Sr2+>Ca2+> Mg2+. 相似文献
8.
Ali Jabbari Masoumeh Hasani Mojtaba Shamsipur 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(4):329-340
The complexation reactions between Tl+ and Ag+ ions and several crown ethers have been studied conductometrically in acetonitrile, acetone and dimethylformamide solutions at 25°C. The stability constants of the resulting 1:1 complexes were determined, and found to decrease in the order DA18C6>DC18C6>DB30C10>18C6>DB21C7>DB24C8>DB18C6>B15C5 >12C4, in the case of Tl+ complexes, and in the order DA18C6>DC18C6>18C6>DB18C6 >DB24C8>DB30C10B15C5>DB21C7 for Ag+ complexes. There is an inverse relationship between the stabilities of the complexes and the Gutamnn donicity of the solvents. The influence of a number of atoms in the macrocycle and of substituents in the polyether ring on the stability of the complexes is discussed. 相似文献
9.
10.
The protonation of aminoalkyl groups covalently bonded on the silica surface was studied by the conductometric titration method.
Porous varieties of silica can adsorb HCl from an aqueous solution. Conductometric titration was proposed for the determination
of concentrations and constants of protolytic equilibrium of grafted amino groups. During HCl chemisorption the effect of
temperature on the electric conductivity of suspensions of the modified silicas was studied.
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Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1789–1793, August, 2005. 相似文献