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1.
The kinetics of ligand substitution between aquapentacyanoruthenate(II) ion, [Ru(CN)5H2O]3− and 4-cyanopyridine (4-CNpy) has been investigated spectrophotometrically in the presence of anionic surfactant micelle,
namely sodium dodecylsulphate (SDS) at 400 nm (λmax of the intense yellow product [Ru(CN)54-CNpy]3−) under pseudo-first-order conditions using at least 10% excess of 4-CNpy over [Ru(CN)5H2O]3−. The reaction was studied as a function of [Ru(CN)5H2O3−], [4-CNpy], [SDS], pH, ionic strength and temperature, by varying each of these variables one at a time. The reaction exhibited
overall second-order kinetics, being first order each in [4-CNpy] and [Ru(CN)5H2O3−] over a wide concentration range. Variation of ionic strength of the medium had a significant negative effect on the rate.
The SDS micelle, being negatively charged, does not reveal any regular effect except at or near its critical micelle concentration
(c.m.c). The rate of reaction was measured at different temperatures, and the activation parameters were computed using Arrhenius
and Eyring plots. A plausible mechanism consistent with the experimental results has been proposed. 相似文献
2.
María Goncalves José Daniel Martínez Mary Lorena Araujo Felipe Brito Giuseppe Lubes Mildred Rodríguez Vito Lubes 《Journal of solution chemistry》2011,40(9):1517-1527
The complex species formed in aqueous solutions (25 °C, I=3.0 mol⋅dm−3 KCl ionic medium) between the V(III) cation and the ligands 6-methylpicolinic acid (MePic, HL), salicylic acid (H2Sal, H2L) and phthalic acid (H2Phtha, H2L) have been studied by potentiometric and spectrophotometric measurements. Application of the least-squares computer program
LETAGROP to the experimental emf(H) data, taking into account the hydrolytic species and hydrolysis constants of V(III), indicates
that under the employed experimental conditions the complexes [VL]2+, [V(OH)L]+, [V(OH)2L], [V(OH)3L]−, [VL2]+, [VL3] and [V2OL4] form in the vanadium(III)–MePic system. Were observed the complexes [VL]+, [VL2]−, [V(OH)L2]2− and [VL3]3− in the vanadium(III)–H2Sal system, and the species [VHL]2+, [VL]+, [V(OH)L], [VHL2], [VL2]−, [V(OH)L2]2−, [V(OH)2L2]3− and [VL3]3− in the vanadium(III)–H2Phtha system. The stability constants of these complexes were determined by potentiometric measurements, and spectrophotometric
measurements were made in order to perform a qualitative characterization of the complexes formed in aqueous solution. 相似文献
3.
Alexander P. Boichenko Le Thi Kim Dung Lidia P. Loginova 《Journal of solution chemistry》2011,40(6):968-979
The apparent dissociation constants of 1-propanoic, 1-butanoic, 1-pentanoic and 1-hexanoic acids were obtained for the first
time in Brij 35 micellar solutions with concentration from 0.03 to 0.20 mol⋅L−1 and sodium dodecyl sulfate (SDS) micellar solutions with concentrations from 0.01 to 0.30 mol⋅L−1. A pronounced effect of Brij 35 micelles on the acid-base properties of aliphatic acids was observed. The binding constants,
K
b, of carboxylic acids to micellar pseudophases of SDS and Brij 35 were estimated within the framework of the pseudophase model.
The dependences of Gibbs energies of transfer from water to the micellar pseudophases were constructed, and Gibbs energies
were evaluated for methylene and carboxylic group transfers into Brij 35 and SDS micelles. Comparison of the Gibbs energies
of methylene group transfer from water to Brij 35 and SDS suggests that the mechanisms of hydrocarbon group transfer into
the core of nonionic and anionic micelles involving the same monomer hydrophobic tail length are similar. 相似文献
4.
R. Gup 《Russian Journal of Coordination Chemistry》2006,32(2):99-108
A new vic-dioxime, N-{4-[[(2-hydroxyphenyl)methylene]hydrazinecarbonyl]phenyl}aminoglyoxime (H3L), was prepared by the reaction of anti-chloroglyoxime with salicylaldehyde 4-aminobenzoylhydrazone. The reaction of H3L with Cu(II) salts and an appropriate simple ligand gave only homotrinuclear complexes [Cu3(HL)2X2], whereas the reaction of H3L with Ni(II) salts gave mono-and homotrinuclear complexes [Ni(H2L)2 and Ni3(HL)2X2]. Also, heterotrinuclear complexes of H3L were prepared by the reaction of Ni(H2L)2 with Cu(II) salt and an appropriate simple ligand, [NiCu2(HL)2X2], X = Cl−, NO
3
−
, SCN−, CN−, and N
3
−
. The new vic-dioxime and its complexes were identified by elemental analyses, IR, 1H NMR, UV-VIS, magnetic susceptibility, and mass spectral data. The elemental analyses and spectral data indicated that the
hydrazone side of H3L acted as monobasic tridentate and the fourth position was occupied by simple ligands, such as Cl−, NO
3
−
, SCN−, CN−, and N
3
−
.
The text was submitted by the author in English. 相似文献
5.
Hui-fang Du An-you Zhang Zhu-xian Yang Zu-ming Zhou 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):241-243
The solvent extraction of U(VI) by p-tert-butylcalix[n]-arene acetate (H
n
L) (n=4, 6, 8) has been studied. The effects of acidity in aqueous phase and concentration of extractant in organic phase on the
distribution ratio were examined. It has been found that the distribution ratio is proportional to [H+]−2 and [H
n
L](O) and the extracted complex species is UO2H
n
−2L. The equilibrium constants of the extraction reactions have been determined. The reaction mechanism is discussed. 相似文献
6.
The quenching of fluorescence of the free-base tetraphenylporphyrin, H2TPP, and its metal derivatives, MgTPP and ZnTPP by diverse iron(III) complexes, [Fe(CN)6]3−, Fe(acac)3, [Fe(mnt)2]−, Fe(Salen)Cl, [Fe4S4(SPh)4]2−·, FeTPPCl and [Fe(Cp)2]+ has been studied both in homogeneous medium (CH3CN) and micellar media, SDS., CTAB and Triton X-100. The quenching efficiencies are analysed in terms of diffusional encounters
and it has been possible to separate static quenching components. The quenching constants are dependent on the nature of the
ligating atoms around iron(III) and also on the extent of π-conjugation of the ligands. The quenching mechanism has been investigated
using steady-state irradiation experiments. Evidence for oxidative quenching by iron(III) complexes was obtained, though the
spin multiplicities of the excited electronic states of iron(III) complexes permit both energy and electron transfer mechanisms
for quenching of the singlet excited state of the porphyrins. 相似文献
7.
The polyoxyethylene chain of non-ionic surfactant Triton X-100 [4-(1,1,3,3-tetramethylbutyl) phenyl polyethylene glycol,TX-100] was degraded by permanganate in the presence of HClO4. The oxidative degradation rate and cloud point have been obtained as a function of [surfactant], [permanganate], [HClO4], and temperature. Dependence of the reaction rate on adding inorganic salts (Na4P2O7, NaF and MnCl2) was also examined. The oxidation rate increased with increase in [TX-100] and [H+]. The higher order kinetics with respect to [TX-100] at lower [H+] shifted to lower order at higher [H+]. The cloud point of TX-100 (67°C) shifted to lower temperature (23±0.5°C) after oxidative degradation of the polyoxyethylene chain. Evidence of complex formation between TX-100 and MnO
4
−
was obtained spectrophotometrically. Presence of the primary alcoholic (–OH) group in the TX-100 skeleton is responsible for the degradation of oxyethylene chain. Both monomeric and aggregated TX-100 molecules are oxidized by permanganate. A catalytic oxidation mechanism is proposed on the basis of the experimental findings. 相似文献
8.
Dai-Zheng Liao Li-Cun Li Zong-Hui Jiang Shi-Ping Yan Peng Cheng Geng-Lin Wang Xin-Kan Yao Hong-gen Wang 《Transition Metal Chemistry》1992,17(4):356-359
Three novel heterobinuclear complexes have been prepared and identified as [Cu(oxap)Ni(L)2](ClO4)2·ξH2O, where oxap denotes theN,N′-bis(2-aminopropyl)oxamido dianion and L denotes 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) or 5-nitro-1,10-phenanthroline
(NO2-phen). The crystal structure of [Cu(oxap)Ni(phen)2]-(ClO4)2·2H2O has been determined. Crystal data: triclinic, space group
, a=12.079 (6), b=12.409 (4), c=17.261 (8) ?, α=70.91 (2), β=86.72 (4), γ=89.19 (3)o. At room temperature, Z=2. The CuII is in a square planar environment and the NiII is in an octahedral environment. The Cu−Ni distance is 5.292 ?. The temperature dependences of the magnetic susceptibilities
of [Cu(oxap)Ni(phen)2]-(ClO4)2·2H2O and [Cu(oxap)Ni(bipy)2](ClO4)2 have been studied in the 4.2–300 K range, giving the exchange integral J=−92.4 cm−1 for bipy and J=−94.3 cm−1 for phen. These results are commensurate with antiferromagnetic interactions between the adjacent metal ions. 相似文献
9.
Joanna Wiśniewska 《Transition Metal Chemistry》2007,32(6):811-815
The kinetics of the electron-transfer reactions between promazine (ptz) and [Co(en)2(H2O)2]3+ in CF3SO3H solution ([CoIII] = (2–6) × 10−3
m, [ptz] = 2.5 × 10−4
m, [H+] = 0.02 − 0.05 m, I = 0.1 m (H+, K+, CF3SO
3
−
), T = 288–308 K) and [Co(edta)]− in aqueous HCl ([CoIII] = (1 − 4) × 10−3
m, [ptz] = 1 × 10−4
m, [H+] = 0.1 − 0.5 m, I = 1.0 m (H+, Na+, Cl−), T = 313 − 333 K) were studied under the condition of excess CoIII using u.v.–vis. spectroscopy. The reactions produce a CoII species and a stable cationic radical. A linear dependence of the pseudo-first-order rate constant (k
obs) on [CoIII] with a non-zero intercept was established for both redox processes. The rate of reaction with the [Co(en)2(H2O)2]3+ ion was found to be independent of [H+]. In the case of the [Co(edta)]− ion, the k
obs dependence on [H+] was linear and the increasing [H+] accelerates the rate of the outer-sphere electron-transfer reaction. The activation parameters were calculated as follows:
ΔH
≠ = 105 ± 4 kJ mol−1, ΔS
≠ = 93 ± 11 J K−1mol−1 for [Co(en)2(H2O)2]3+; ΔH
≠ = 67 ± 9 kJ mol−1, ΔS
≠ = − 54 ± 28 J K−1mol−1 for [Co(edta)]−. 相似文献
10.
Zhao Song Zixia Zhao Xia Qin Jiadong Huang Haibin Shi Baoyan Wu Qiang Chen 《Frontiers of Chemistry in China》2007,2(2):146-150
A novel amperometric choline biosensor has been fabricated with choline oxidase (ChOx) immobilized by the sol-gel method on
the surface of multi-walled carbon nanotubes (MWCNT) modified platinum electrode to improve the sensitivity and the anti-interferential
property of the sensor. By analyzing the electrocatalytic activity of the modified electrode by MWCNT, it was found that MWCNT
could not only improve the current response to H2O2 but also decrease the electrocatalytic potential. The effects of experimental variables such as the buffer solutions, pH
and the amount of loading enzyme were investigated for the optimum analytical performance. This sensor shows sensitive determination
of choline with a linear range from 5.0 × 10−6 to 1.0 × 10−4 mol/L when the operating pH and potential are 7.2 and 0.15 V, respectively. The detection limit of choline was 5.0 × 10−7 mol/L. Selectivity for choline was 9.48 μA·(mmol/L)−1. The biosensor exhibits excellent anti-interferential property and good stability, retaining 85% of its original current
value even after a month. It has been applied to the determination of choline in human serum.
Translated from Chinese Journal of Analytical Chemistry, 2006, 34(7): 910–914 (in Chinese) 相似文献
11.
The octahedral complex, [CoIII(HL)]·9H2O (H4L = (1,8)-bis(2-hydroxybenzamido)-3,6-diazaoctane) incorporating bis carboxamido-N-, bis
sec-NH, phenolate, and phenol coordination has been synthesized and characterized by analytical, NMR (1H, 13C), e.s.i.-Mass, UV–vis, i.r., and Raman spectroscopy. The formation of the complex has also been confirmed by its single
crystal X-ray structure. The cyclic voltammetry of the sample in DMF ([TEAP] = 0.1 mol dm−3, TEAP = tetraethylammonium perchlorate) displayed irreversible redox processes, [CoIII(HL)] → [CoIV(HL)]+ and [CoIII(HL)] → [CoII(HL)]− at 0.41 and −1.09 V (versus SCE), respectively. A slow and H+ mediated isomerisation was observed for the protonated complex, [CoIII(H2L)]+ (pK = 3.5, 25 °C, I = 0.5 mol dm−3). H2Asc was an efficient reductant for the complex and the reaction involved outer sphere mechanism; the propensity of different
species for intra molecular reduction followed the sequence: [{[CoIII(HL)],(H2Asc)}–H]− <<< {[CoIII(H2L)],(H2Asc)}+ < {[CoIII(HL)],(H2Asc)}. A low value (ca. 3.7 × 10−10 dm3 mol−1 s−1, 25 °C, I = 0.5 mol dm−3) for the self exchange rate constant of the couple [CoIII(HL)]/[CoII(HL)]− indicated that the ligand HL3− with amido (N-) donor offers substantial stability to the CoIII state. HSO3− and [CoIII(HL)] formed an outer sphere complex {[CoIII(HL)],(HSO3−)}, which was slowly transformed to an inner sphere S-bonded sulfito complex, [CoIII(H2L)(HSO3)] and the latter was inert to reduction by external sulfite but underwent intramolecular SIV → CoIII electron transfer very slowly.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
M. V. Muftakhov R. V. Khatymov V. A. Mazunov V. N. Odinokov I. V. Galyautdinov 《Russian Chemical Bulletin》2000,49(4):713-716
The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative
ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by
the elimination of H2O and H2 molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH2O].− (n=1–3) and [M−H2−nH2O].− (n=0−3) ions that are generated exclusively by the rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000. 相似文献
13.
N. Kumaraguru K. Santhakumar S. Kalyanasundharam 《Journal of solution chemistry》2011,40(10):1673-1686
The critical micelle concentration (CMC) of surfactant–Cr(III)–dodecylamine complexes of the type cis-α-[Cr(trien)(C12H25NH2)X]2+ (where trien = triethylenetetramine; X = F−, Cl−, Br−) has been studied in n-alcohol and in formamide at different temperatures, by electrical conductivity measurements. From the CMC values as a function
of temperature, various thermodynamic properties have been evaluated: standard Gibbs energy changes (Δmic
G
0), standard enthalpy changes (Δmic
H
0) and standard entropy changes (Δmic
S
0) for micellization. Critical micelle concentrations have also been measured as a function of the percentage composition of
alcohol added. The solvent composition dependences of these thermodynamic parameters were determined. It is suggested that
alcohol addition leads to an increase in formamide penetration into the micellar interface that depends on the alcohol’s chain
length. The results are discussed in terms of an increased hydrophobic effect, dielectric constant of the medium, the chain
length of the alcohols, and the surfactant in the solvent mixture. 相似文献
14.
Two multiamide calix[4]arenes (5, 6) were synthesized and characterized by NMR, MS and elemental analysis. The binding properties
of receptors with some anions (π-O2NPhOPO32−, π-O2NPhO−, H2PO4−, Ac−, Cl−, Br− and I−) were studied by UV-Vis spectra. The results indicate that the tetraamide calix[4]arenes (5, 6) have a good selectivity to
the anions containing aromatic ring (π-O2NPhOPO3
2−, π-O2NPhO−). The 1 : 1 complexes between host and guest were formed through multiple hydrogen bonding and π-π interactions. The hosts
5 and 6 also show a definite binding ability for the anions (H2PO4−, Ac−, Cl−) that have no ultraviolet absorption, which provides a simple method of spectrum detection for these anions. 相似文献
15.
V. N. Kirichenko L. A. Glinskaya R. F. Klevtsova T. G. Leonova S. V. Larionov 《Journal of Structural Chemistry》1994,35(2):242-247
We have synthesized high-spin mixed-ligand Mn2+ complexes Mn(S2COR)2L where R=i−C3H7, i−C4H9; [L=1,10-phenanthroline (Phen), 2,2′-bipyridyl (2,2′-Bipy), 4,4′-bipyridyl (4,4′-Bipy)]. As solids, the compounds are stable
to oxidation by atmospheric oxygen. An X-ray structural study of the [Mn(S2COC3H7−i)2(2,2′-Bipy)] complex was carried out. The structure is composed of discrete monomeric molecules. The corrdination polyhedron
of the Mn atom is a distorted [4S+2N] octahedron. The molecules are bonded by van der Waals interactions.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 2, pp. 106–111, March–April, 1994.
Translated by T. Yudanova 相似文献
16.
Reaction of hydrated electrons with safranine T (SF+), a phenazine dye useful as sensitizer in photogalvanic cell and the transient semireduced species formed by this reaction
have been studied in SDS micellar medium using the technique of pulse radiolysis. Thee
aq
−
reaction with SF+ in the micellar environment was only marginally slower (5.1 × 109 dm3 mol−1 s−1) as compared to that in homogeneous aqueous medium (2.2 × 1010 dm3 mol−1 s−1) explicable on the basis of our finding that although a large fraction of the dye gets localized near the micelle Stern layer
where the molecule experiences a dielectric.constant of ≈40, a small but significant concentration of the dye exists in the
aqueous bulk as charge pair complex with the anionic surfactant monomer (association constant for the formation of the complex
being 2.8 × 104 dm3 mol−1). The transient semireduced absorption band observed in the micellar medium showed a red shift of ≈ 50 nm and also the decay
of the transient, which was very fast with 2k = 1 × 109 dm3 mol−1 s−1 in aqueous medium, was stable in the SDS micellar medium over a few tens of milliseconds suggesting that the radical is incorporated
deeper than the parent molecule in the SDS micelle. The effect of this stability on the photogalvanic conversion needs to
be examined. 相似文献
17.
Effect of dicationic gemini surfactants C16H33(CH3)2N+-(CH2)
s
-N+(CH3)2C16H33, 2Br− (where s = 4, 5, 6) on the reaction of ninhydrin with L-isoleucine has been investigated spectrophotometrically as a function of [gemini],
[L-isoleucine], [ninhydrin], and pH. The reaction follows first- and fractional-order kinetics, respectively, in [L-isoleucine]
and [ninhydrin]. The gemini surfactant micellar media are found more effective for the reaction than their conventional monomeric
counterpart CTAB. Furthermore, whereas typical rate constant (k
ψ) increase and leveling-off regions are observed with CTAB and geminis, the latter produce a third region of increasing k
ψ at concentrations ≥ 60 cmc’s. 1H NMR studies reveal that this unusual third-region effect of the geminis is due to changes in their micellar morphologies.
Quantitative kinetic analysis has been performed on the basis of modified pseudo-phase model. 相似文献
18.
The kinetics of nucleophilic substitution of pyridine in bis-cationic [Pt(L)(py)]2+ complexes (L=SNS, NNN, NSN) [SNS=bis(methylthiomethyl)pyridine, NNN=bis(2-pyridylmethyl)amine, NSN=bis(2-pyridylmethyl)sulphide]
by a series of nucleophiles (Cl−, Br−, I−, N3−, (C2H5)2S, NH3, thiourea (tu), NO2−, C5H10NH, SeCN−, SCN−, CN− when L=SNS; Cl−, Br−, I−, N3−, (C2H5)2S, SCN−, NH3, NO2− when L=NNN; Br−, N3−, NO2−, NH3, C5H10NH when L=NSN) have been measured in MeOH at 25 °C, μ =0.1 mol dm−3 (LiClO4 or LiCF3SO3). The logarithms of the second-order rate constants calculated at μ=0, log k° 2, do not follow the dependence upon the n° Pt scale. In particular, the reactivity of the biphilic reagents tu, SeCN−, SCN− and, to a lesser extent, NO− 2, towards these doubly charged substrates is largely lower than expected on the basis of the n° Ptscale. There are good linear relationships between logk° 2 for the bis-cationic substrate [Pt(SNS)(py)]2+, chosen as the standard, and log k° 2 for the same reactions with [Pt(NNN)(py)]2+, [Pt(NSN)(py)]2+ and other double charged complexes previously studied. A new wide nucleophilicity scale based on [Pt(SNS)(py)]2+, that is appropriate to all the bis-cationic substrates, is here proposed 相似文献
19.
The effects of a substrate additive, H+ and solvents (water and acetone), on the micelle-catalyzed aquation of tris-(4,7-diphenyl-1, 10-phenanthroline)iron(II),
Fe(Ph2Phen)3
2+, have been investigated using#Triton X-100 micelles. The k0
vs. [TX-100] profiles at fixed [H2O] are structured, exhibiting maxima. Catalytic factors of 46.6–171.7 are observed for 5.56×10−2≤[H2O] 55.60×10−2 mol dm−3. On the other hand, at fixed [H+], the k0
vs. [TX-100] exhibit broad maxima. The aquation reaction is inhibited by H+ and catalytic factors decrease rapidly and exponentially from 422.5 to 20.9 for 0.20×10−3≤[H+]≤2.00×10−3 mol dm−3. The aquation is found to be faster (ca. 160–1200 fold) in acetone than in the aqueous medium depending on the added [H2O]. These observations are rationalized on the basis of a proposed modified lamellar structure for the Triton X-100 (TX-100)
micelles in which direct substitution of water molecules into the coordination sphere of the complex occurs. 相似文献
20.
Sodium (3-dodecanoyloxy-2-hydroxy-propyl) succinate (SLGMS) is a conjugated anionic surfactant in which a glycerol residue
connects with a hydrophilic sodium succinate and dodecanoate. Aqueous micellar phase (Wm), hexagonal (H1), bicontinuous cubic (V1), and lamellar (Lα) phases are successively formed with increasing the surfactant concentration in a binary SLGMS-water system. The Krafft point
is below 0 °C. The effective cross sectional area per surfactant molecule, a
s, in the H1 phase is almost constant, 0.5 nm2, and the shape of cylindrical micelle is almost unchanged with surfactant concentration. The cmc value of SLGMS measured
by means of surface tension, electrical conductivity, and fluorescence probe methods is in the range of 4∼9 × 10−5 mol/l that is much lower than that of sodium dodecanoate, 2 × 10−2 mol/l, or SDS, 8 × 10−3 mol/l. Hence, it is considered that the polar glycerol part in the SLGMS acts as a hydrophobic part. The solubilization of
oil in the SLGMS solution is much higher than that in the SDS solution and this also suggests that the glycerol and succinic
units act as lipophilic moieties.
Received: 15 June 2000/Accepted: 27 July 2000 相似文献