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1.
Yoon-Ki Joung Hak Soo Choi Tooru Ooya Nobuhiko Yui 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):323-328
We have previously prepared a stimuli-responsive inclusion complex between PEG–b-PEI–g-dextran graft copolymer (PEG–PEI–dex) and γ-cyclodextrin (γ-CD) in order to investigate unique inclusion phenomena, double-axle
inclusion. For further study, a γ-CD derivative, mono-6-O-(2-sulfonato-6-naphthyl)-γ-CD (SN-γ-CD) was additionally synthesized for 1H NMR titration study, which is expected to induce the competition of pendant naphthyl group with external polymer guests.
Consequently, 1H NMR titration results of the inclusion complex of PEG–PEI–dex with SN-γ-CD showed stoichiometric changes, temperature-dependence,
and reversibly pH-responsive properties of the inclusion complexes in terms of chemical shift variation. 相似文献
2.
The equilibrium in the system water—electrolyte—cross-linked polymer containing immobilized 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octahydroxycalix[4]arene
was studied. Immobilized calixarene 1 was shown to form 1∶1, 1∶2, 1∶3, and 1∶4 compounds with inorganic cations (Na+, Cs+, and NH4
+), and with organic cations (hexamethylen-tetramine and β-diethylaminoethylp-aminobenzoate) 1∶1 compounds are formed. The affinity of immobilized calixarene1 increases in the series of cations: hexamethylenetetramine <Na+, Cs+, NH4
+<β-diethylaminoethylp-aminobenzoate.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2214–2216, November, 1998. 相似文献
3.
Yu. V. Fedorov N. E. Shepel E. Yu. Chernikova O. A. Fedorova E. N. Gulakova V. G. Avakyan G. Jonusauskas 《Russian Chemical Bulletin》2008,57(11):2385-2393
The reversible photochemical E—Z-isomerization of crown-containing 4-styrylpyridine was studied. The reaction was carried out in the presence of alkaline-earth
metals capable of forming complexes with the crown-ether fragment and heavy metal perchlorates (Hg2+, Cd2+) that are able to coordinate the nitrogen atom of the heterocyclic residue. The influence of complex formation on the E—Z-photoisomerization was determined by electronic spectroscopy and 1H NMR spectroscopy. The studies performed confirm that the E—Z-photoisomerization can be controlled using supramolecular complex formation. 相似文献
4.
N. Sh. Lebedeva R. S. Kumeev G. A. Al’per E. V. Parfenyuk A. S. Vashurin T. V. Tararykina 《Journal of solution chemistry》2007,36(6):793-801
For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C6H4—OC11H23)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods.
It has been found that in o-xylene at concentrations of Zn(4—O—CO—C6H4—OC11H23)Pc higher than 6×10−4 mol⋅L−1
π–π dimers species are formed (λ
max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C6H4—OC11H23)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes.
Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C6H4—OC11H23)Pc—DABCO—Zn(4—O—CO—C6H4—OC11H23)Pc sandwich dimers (λ
max= 675 nm). 相似文献
5.
Summary A clean method without use of organic solvents has been developed for isolation and high-performance liquid chromatographic
(HPLC) determination of oxytetracycline (OTC) and sulphadimidine (SDD) in cow's milk. Isolation is rapid and simple—homogenization
with an inorganic acid solution by means of a handy ultrasonic homogenizer, which is easy-to-use and portable, followed by
centrifugation. Reversed-phase HPLC was performed on a C4 column, with 1.25 mmol L−1 succinic acid solution as mobile phase, and identification was by means of a photodiode-array detector. Separation of the
analytes was achieved in less than 8 min. Significant linearity was established over the concentration range of 0.1–1.0 μg
mL−1 for both target compounds (r>0.99,P<0.01). Average recoveries of OTC and SDD (each spiked at 0.1–1.0 μg mL−1) were ≥88.8, and inter- and intra-assay variability was ≤2.8%. The total time required for analysis of one sample was <20
min. The limits of quantitation of the method (μg mL−1 in milk) were 0.044 for OTC and 0.023 for SDD. No organic solvent was used at any stage of the analysis. 相似文献
6.
R. S. B. Reddi V. S. A. Kumar Satuluri U. S. Rai R. N. Rai 《Journal of Thermal Analysis and Calorimetry》2012,107(1):377-385
Solid–liquid phase equilibrium data of three binary organic systems, namely, 3-hydroxybenzaldehyde (HB)—4-bromo-2-nitroanilne
(BNA), benzoin (BN)—resorcinol (RC) and urea (U)—1,3-dinitrobenzene (DNB), were studied by the thaw–melt method. While the
former two systems show the formation of simple eutectic, the third system shows the formation of a monotectic and a eutectic
with a large immiscibility region where two immiscible liquid phases are in equilibrium with a liquid of single phase. Growth
kinetics of the pure components, the monotectic and the eutectics, studied by measuring the rate of movement (v) of solid–liquid interface in a thin U-tube at different undercoolings (ΔT) suggests the applicability of the Hillig–Turnbull’s equation: v = u (ΔT)
n
, where v and n are the constants depending on the nature of the materials involved. The thermal properties of materials such as heat of
mixing, entropy of fusion, roughness parameter, interfacial energy, and excess thermodynamic functions were computed from
the enthalpy of fusion values, determined by differential scanning calorimeter (Mettler DSC-4000) system. The role of solid–liquid
interfacial energy on morphologic change of monotectic growth has also been discussed. The microstructures of monotectic and
eutectics were taken which showed lamellar and federal features. 相似文献
7.
I. S. Ryzhkina A. P. Timosheva A. V. Chernova R. R. Shagidullin A. A. Gazizova W. D. Habicher T. Krause L. I. Vagapova A. I. Konovalova 《Russian Chemical Bulletin》2007,56(3):475-483
Aggregation of amphiphilic calix[4]resorcinarenes (CRA) modified by carboxymethyl (1), 2-hydroxyethyl (2), methylamino acetal (3), and aminomethyl (4) fragments and their interaction with some synthetic (5, 6) and natural (7, 8) surfactants in the low-polarity solvent (chloroform) were studied by permittivity measurements and FT-IR spectroscopy. Compounds
1–4 and surfactants form aggregates at critical micelle concentrations (CMC) of 2.0·10−5–7.5·10−5 and 1.7·10−5–2.0·10−3 mol L−1, respectively. The CMC values of CRA—surfactant mixed aggregates depend on the surfactant structure and the structure and
concentration of CRA. Analysis of the IR spectra of solutions of a series of amphiphilic CRA (2–4, 9, 10) and their mixtures with the cationic surfactant N-cetyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bromide (5) showed that an increase in the concentration of the solutions in individual and mixed systems is accompanied by a decrease
in the molar integral intensities and intensities in the maxima of the absorption bands of the O—H and C—H bonds down to the
CMC point, after which these values change slightly. The discovered effect, which is differently pronounced for all systems
studied, indicates that both the polar “head” groups and nonpolar fragments of CRA and surfactant are involved in the formation
of supramolecules of the reverse micelle type in all cases.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 459–466, March, 2007. 相似文献
8.
Raman scattering spectra and molecular conformations of bis(quaternaryammonium bromide)-water systems 总被引:1,自引:0,他引:1
The dimeric bis(quaternaryammonium bromide) surfactants, [Br−(CH3)2N+(C
m
H2
m
+1)—(CH2)
s
—(C
m
H2
m
+1)N+(CH3)2Br−, s = 2, 3 and m = 4, 6, 10 and 12, s = 6 and m = 8, 10, 12], have been synthesized and the phase maps of the sm6-8-water, sm6-10-water and sm6-12-water binary systems have
been determined (sm6-8 implies s = 6, m = 8). In order to examine the molecular structures of these solid samples and of their dimeric surfactant-water binary systems,
Raman spectra of the simple dimeric surfactants, sm2-4 and sm3-4, in which crystal structures of the trans- and cis-type conformations
have been determined by single-crystal X-ray diffraction analysis, have been investigated, and Raman bands characteristic
of these skeletal structures were found in the skeletal deformation region. On the basis of these characteristic Raman bands
for the two conformations, it has been concluded that the dimeric surfactants, sm6-8, sm6-10 and sm6-12 also take up a cis-type
conformation in the crystalline state. Furthermore, it has been found that the Raman bands in the C—H stretching, skeletal
stretching and CH2 scissoring regions are sensitive to phase structure.
Received: 21 July 1998 Accepted in revised form: 9 November 1998 相似文献
9.
The enthalpies of combustion for five noncyclic and cyclic phosphites in the condensed state were calculated from the derived
equation ΔHcomb/kJ mol-1 = —860.7 — 107.0(N — n), where N is the number of bonding valent electrons, and c is the number of lone electron pairs of heteroatoms. The dependence presented was used to calculate the combustion enthalpy
of five phosphorylated carbohydrates, because these thermochemical values are often difficult to determine by reaction calorimetry.
The enthalpies of formation of carbohydrate cyclophosphites were calculated by Hess’s law for the first time. 相似文献
10.
The initiation of ethylene polymerization on L2MMe+ cations (M = Ge, Sn; L = alkoxy, alkyl, phenoxyiminate, β-diketonate) was studied by the PBE/TZ2P density functional method.
It was found that ethylene insertion into the M—C bond of the L2MMe+ cations is energetically favorable (ΔG
0 = −7.6—−13.6 kcal mol−1). The calculated energy barriers to reactions lie in a wide range 39.8 to 75.6 kcal mol−1. The lowest energy barriers were obtained for tin cations bearing hexa- and heptafluoroacetylacetonate substituents.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1338–1347, July, 2008. 相似文献
11.
M. S. Afanasyeva P. A. Purtov M. B. Taraban T. V. Leshina C. B. Grissom 《Russian Chemical Bulletin》2006,55(7):1132-1136
The photoinitiated oxidation of β-NADH catalyzed by horseradish peroxidase (Per3+) was studied by time-resolved photoinitiated chemically induced dynamic nuclear polarization (CIDNP). The polarization observed
on protons at the C(4) atom of the β-NADH molecule is evidence for the reversible one-electron transfer between the radical
cation NADH+· and the ferroperoxidase intermediate (Per2+). A new approach based on electron transitions in the (NADH+· Per2+) pair was proposed to describe the formation of CIDNP effects in systems including quartet (Q)—doublet (D) electron transitions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1090–1094, July, 2006. 相似文献
12.
Dumitru Condrat Cristina Mosoarca Alina D. Zamfir Florin Cri?an Maria R. Szabo Alfa X. Lupea 《Central European Journal of Chemistry》2010,8(3):530-535
This study presents the results obtained from qualitative and quantitative analysis of gallic acid from hydro-alcoholic extracts
(methanol, ethanol) of plants from Plantae regnum. Plant qualitative analysis was performed using a novel mass spectrometric (MS) method based on fully automated chip-nanoelectrospray
ionization (nanoESI) high capacity ion trap (HCT) while quantitative analysis was carried out by high performance liquid chromatography
(HPLC). These methods were applied to Alchemilla vulgaris — common lady’s-mantle (aerial part), Allium ursinum — bear’s garlic (leaves), Acorus calamus — common sweet flag (roots), Solidago virga-aurea — goldenrod (aerial part). Obtained results indicated that methanol extracts (96%, 80%) have a gallic acid content ranging
between 0.0011–0.0576 mg mL−1 extract while the ethanol extracts (96%, 60%) exhibit a gallic acid concentration that varies between 0.0010–0.0182 mg mL−1 extract.
相似文献
13.
The results of MNDO/PM3 calculations of η5-π-C60R5M complexes (R=H and Ph; M=Tl and In) are reported. Local energy minima and geometric parameters as well as the heats of formation
and ionization potentials were determined for all systems in question. The nature of chemical M—pent bonding (pent is the pentagonal face) is discussed. The results of calculations are compared with experimental data that confirm our predictions
about the possibility of existence of stable cyclopentadienyl type η5-π-complexes of C60 fullerence derivatives. The stability of the C60In12 complex with theI
h
symmetry, in which the In atoms are coordinated to each of 12 pentagonal faces of C60 fullerene, was estimated. The energy of the In—pent bond (62.4 kcal mol−1) is close to that in C60H5In (64.5 kcal mol−1).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1935–1940, November, 1997. 相似文献
14.
M. O. Talismanova A. A. Sidorov G. G. Aleksandrov V. N. Charushin S. K. Kotovskaya V. P. Ananikov I. L. Eremenko I. I. Moiseeva 《Russian Chemical Bulletin》2008,57(1):47-55
The reactions of palladium(II) salts with 2-mercaptobenzimidazole (HL) and its 5,6-difluorinated derivative (HLF) were investigated. In the presence of hydrochloric acid, PdCl2 and K2PdCl4 react with HL and HLF in the ethanol—water and acetonitrile—water systems to form the mono-nuclear dicationic complexes [Pd(HL)4]Cl2 (1) and [Pd(LF)4]Cl2 (2). In the absence of HCl, the reactions afford the tetranuclear complex Pd4[(L)2(μ3-S,N-(L))2(μS,N-(L))4] (3). The reaction of triethylamine with an ethanolic solution of 3 leads to degradation of 3 and the formation of the lantern-type dinuclear complex Pd2[(μ2-(L)4] (4), in which the palladium atoms are in the nonequivalent coordination environment, PdN4 and PdS4. The reaction of K2PdCl4 with HL or HLF in the THF—water or acetonitrile—water systems (for the reaction with HLF) in the presence of Et3N produces the lantern-type dinuclear complexes Pd2[(μS,N′-(L3))4] and Pd2[(μ-S,N′-(LF))4] (5), in which the metal atoms are in the equivalent coordination environment (cis-PdN2S2).
Dedicated to Academician G. A. Tolstikov on the occasion of his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 45–52, January, 2008. 相似文献
15.
Ivanka Antovic Nevenka M. Antovic 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):31-37
226Ra activity concentration in the mullet (Mugilidae) species Mugil cephalus whole individuals, and some organs (gills, gastrointestinal system, fins, muscle and bones), was measured by the γ-coincidence
spectrometer PRIPYAT-2M. 226Ra transfer parameters [concentration factors (CFs)] from seawater, sediment and mud with detritus to fish tissues, and annual
intake by humans consuming this fish species, have been estimated. Minimum detected radium activity concentration in whole
M. cephalus individuals was found to be 0.89 ± 0.42 to 3.09 ± 0.41 Bq kg−1, with arithmetic mean of 1.65 ± 0.39 Bq kg−1. An average concentration in muscles is found to be 2.28 ± 0.84 Bq kg−1, in gills—5.02 ± 1.85 Bq kg−1, in gastrointestinal system—12.88 ± 1.71 Bq kg−1, and in bones—14.72 ± 3.75 Bq kg−1. No one fins showed radium activity above minimum detectable one. Annual intake of 226Ra by human consumers of this fish species is estimated to provide an effective dose of 0.006 mSv year−1. CFs for 226Ra indicating transfer from seawater to whole individuals ranged from 8.9 to 30.9, and those indicating transfer from the
sediment and mud with detritus—from 0.11 to 0.39 and from 0.08 to 0.3, respectively. The seawater to bones CFs varied from
97.9 to 197.3, to gastrointestinal system—from 59 to 178.8, to gills—from 22.5 to 68.3, to muscles—from 17 to 30.8. 相似文献
16.
A. V. Teplukhin 《Russian Chemical Bulletin》1998,47(11):2106-2109
Monte Carlo simulation of the hydration of metal ion—DMP− and metal ion—9-methylguanine complexes was performed. A comparative analysis of the results for Na+ and K+ ions was carried out. The main stages of dissociation were revealed. The energy effects of dissociation were evaluated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2174–2177, November, 1998. 相似文献
17.
Arsenic-speciation analysis in marine samples was performed by high-pressure liquid chromatography (HPLC) with ICP–MS detection.
Separation of eight arsenic species—AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+—was achieved on a C18 column with isocratic elution (pH 3.0), under which conditions AsIII and MMA co-eluted. The entire separation was accomplished in 15 min. The HPLC–ICP–MS detection limits for the eight arsenic
species were in the range 0.03–0.23 μg L−1 based on 3σ for the blank response (n=5). The precision was calculated to be 2.4–8.0% (RSD) for the eight species. The method was successfully applied to several
marine samples, e.g. oysters, fish, shrimps, and marine algae. Low-power microwave digestion was employed for extraction of
arsenic from seafood products; ultrasonic extraction was employed for the extraction of arsenic from seaweeds. Separation
of arsenosugars was achieved on an anion-exchange column. Concentrations of arsenosugars 2, 3, and 4 in marine algae were
in the range 0.18–9.59 μg g−1.
This paper was presented at the European Winter Conference 2005 相似文献
18.
The temperature dependences of the equilibrium constants of two chain reversible reactions in quinonediimine (quinonemonoimine)—2,5-dichlorohydroquinone
systems in chlorobenzene were studied. The enthalpy of equilibrium of the reversible reaction of quinonediimine with 4-hydroxydiphenylamine
was estimated from these data (ΔH = − 14.4±1.6 kJ mol−1) and a more accurate value of the N-H bond dissociation energy in the 4-anilinodiphenylaminyl radical was determined (D
NH = 278.6±3.0 kJ mol−1). A chain mechanism was proposed for the reaction between quinonediimine and 2,5-dichlorohydroquinone, and the chain length
was estimated (ν = 300 units) at room temperature. Processing of published data on the rate constant of the reaction of styrylperoxy
radicals with 2,5-dichlorohydroquinone in the framework of the intersecting parabolas method gave the O-H bond dissociation
energy in 2,5-dichlorohydroquinone: D
OH = 362.4±0.9 kJ mol−1. Taking into account these data, the O-H bond dissociation energy in the 2,5-dichlorosemiquinone radical was found: D
OH = 253.6±1.9 kJ mol−1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1661–1666, October, 2006. 相似文献
19.
Solutions of 1-adamantanol in sulfuric acid at T < 100 °C interact with alkanes (RH, [H2SO4] > 85%) and arenes (ArH, [H2SO4] > 59%). The data on the kinetics, kinetic isotope effect (KIE), effects of the structure of RH and ArH and acidity of the
medium, and the observation of 1,4-cis-dimethylcyclohexane isomerization indicate that adamanyl cations (Ad+) serve as reactive species. In the reactions with alkanes, the Ad+ cation abstracts the hydride ion from RH in the rate-determining step. Compensation dependences appear between the activaion
parameters for the KIE and “effect 5/6” (ratio of the rate constants for the C–H bond cleavage in cyclopentane and cyclohexane)
in the reactions of cycloalkanes with Ad+ and other electrophilic reagents, such as “anthracene” (An2)H+ and hydroxymethyl (CH2OH)+ cations and HgII ions, including the points of the lower selectivity limit (k
H/k
D) = 1.4, (“5/6”) = 1. In the reactions with the Ad+ cation, the bond selectivity 30: 20 of alkanes is higher, while 20: 20 is lower compared to other reagents. In the first case, the selectivity is probably determined predominantly by the energies
of the cleaved C–H bonds, whereas in the second case it is determined by steric hindrances. Judging by the kinetic and selectivity
data in the series benzene—toluene—o-xylene—m-xylene and the absence of the reaction with p-xylene, mesitylene, and pseudocumene, it can be concluded that the main contribution to the Ad+ + ArH interaction is made by adamantylation to the para- and meta-positions of the benzene ring, whereas the ortho-positions are inaccessible to the attack because of steric hindrances.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1581–1596, August, 2008. 相似文献
20.
Krisztina Kurin-Cs?rgei Viktor Horváth Miklós Orbán 《Reaction Kinetics and Catalysis Letters》2007,90(2):405-411
The BrO
3
−
— BrAc — Ru(bpy)
3
2+
subsystem is shown to represent the core oscillator that serves as source of the long lasting temporal and spatial periodic
behaviors observed in the BrO
3
−
— H2PO
2
−
— acetone — Mn2+ — Ru(bpy)
3
2+
— acid “double substrate-double catalyst” oscillatory batch system. The BrAc — the substrate of the core oscillator — is
formed and accumulated in the reactions taking place in the six-component system. BrAc was produced in a separate experiment
with bromide, acetone, acid and excess bromate and the mixture was used for bringing about patterns in the thin solution layer
after adding the Ru(bpy)
3
2+
catalyst. The two-dimensional reaction-diffusion patterns that appear in the subsystem and its parent system are very similar
in wave speed, wavelength, color and in the duration of the pattern evolution, therefore a common chemical origin is supposed
to exist in their formation. The role that the BrAc may play in the mechanism of the BrO
3
−
— reductant — acetone — catalyst type oscillators (∼ 30 variants) is also pointed out. 相似文献