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1.
S. P. Meenakshisundaram S. Parthiban G. Madhurambal R. Dhanasekaran S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2008,94(1):15-20
1,10-Phenanthroline (Phen) as a new additive was added into the solutions of KH2PO4 (KDP) and NH4H2PO4 (ADP) in a small amount (∼2.5·10−3 M L−1). The crystals were grown from the aqueous solutions of pH ∼4.5 at constant temperature by solvent evaporation technique.
It leads to an increase in metastable zone width and assists the bulk growth process. The growth rate of crystals in the presence
of Phen decreases considerably with an increase in impurity concentration (∼2.5·10−2 M L−1). Not much variation is observed in FTIR and XRD of pure and doped ADP/KDP. It appears that the growth promoting effect (GPE)
of Phen is caused by the adsorption of the organic additive on the prism faces of ADP/KDP crystals. Higher optical transmittance
is observed in the presence of the dopant. Detailed microhardness studies of ADP crystals reveal the anisotropy in the hardness
behaviour. Scanning electron microscope (SEM) photographs exhibit the effectiveness of the impurity in changing the surface
morphology of ADP/KDP crystals. Contrary to expectations, Phen depresses the NLO efficiency of ADP/KDP, suggesting that the
molecular alignments in the presence of Phen results in cancellation effects disturbing the non-linearity. 相似文献
2.
S. P. Meenakshisundaram S. Parthiban R. Kalavathy G. Madhurambal G. Bhagavannarayana S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2010,100(3):831-837
The influence of heteroaromatic N-base (1,10-phenanthroline) (Phen), a new additive as complexing agent on tris(thiourea)zinc(II)sulphate (ZTS) crystals from aqueous solutions at 30 °C is investigated. Crystals were grown using low concentration of the dopant (0.005 M L?1) in the aqueous growth medium and the growth promoting effect (GPE) is much greater because of an increase in the metastable zone width. High dopant concentration decreases GPE. The crystalline perfection of the grown crystals is quite good both in doped and undoped crystals as evaluated by high-resolution X-ray diffractometry (HRXRD). The diffraction curve of a typical Phen doped as-grown ZTS crystal was observed to contain a single peak indicating that the crystal does not contain any epitaxial layer on the surface or internal structural grain boundaries. Not much variation is observed in FT-IR and XRD of pure and doped ZTS. Phen depresses the NLO efficiency of ZTS. It could be ascribed due to the disturbance of charge transfer in the presence of the dopant. The grown crystals were also characterized by UV–Vis, SEM and TG–DTA techniques. 相似文献
3.
S. Meenakshisundaram S. Parthiban G. Bhagavannarayana G. Madhurambal S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2009,96(1):125-129
It was observed that the addition of a very small quantity (5·10−3 M L−1) of an organic solvent, benzene (C6H6) in the aqueous growth medium (pH ∼5.9) of tristhioureazinc(II)sulphate (ZTS) markedly influences the SHG efficiency. The
measurements using Nd:YAG laser source reveal that second harmonic generation (SHG) conversion efficiency which is one of
the most important nonlinear optical (NLO) properties is enhanced by benzene dopant by a factor of nearly 1.5 times. The crystalline
perfection of the grown crystals was evaluated by high-resolution X-ray diffractometry (HRXRD). The full width at half maximum
(FWHM) of the diffraction curve (which gives an estimate for the degree of crystalline perfection) for undoped and benzene
doped specimen crystals are 26 and 15 arc sec, respectively.
The reduction in FWHM due to the benzene solvent indicates the significant improvement in crystalline perfection. This very
much suggests that the dissolution of trace impurities in the presence of benzene prevents the entry of impurities into the
crystal lattice and at the same time enhances the growth promoting effect (GPE). Not much variation is observed in XRD, FTIR
and TG-DTA of ZTS in the presence and absence of benzene in the aqueous growth medium. 相似文献
4.
Development of a cloud point extraction and preconcentration method for silver prior to flame atomic absorption spectrometry 总被引:1,自引:0,他引:1
The possibility was investigated of using 2-mercaptobenzothiazole (MBT) for Ag(I) concentration by micellar extraction at
cloud point (CP) temperature and subsequent determination by flame atomic absorption spectrometry (FAAS). The method is based
on the complexation of Ag(I) with 2-mercaptobenzothiazole (MBT) in the presence of non-ionic micelles of Triton X-114. The
effect of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and
time on cloud point extraction was studied. Under the optimum conditions, the preconcentration of 10 mL of water sample in
the presence of 0.1% Triton X-114 and 2 × 10−4 mol L−1 2-mercaptobenzothiazole permitted the detection of 2.2 ng mL−1 silver. The calibration graph was linear in the range of 10–200 ng mL−1, and the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Ag(I) in water samples. 相似文献
5.
A copper(I) thiocyanate coordination polymer [Cu(Phen)(μ-NCS)]n (I) (Phen = 1,10-phenan-throline) has been synthesized by the low-temperature solid-state reaction. Single-crystal X-ray analyses
reveal that compound I possesses a type of one-dimensional (1D) framework structure. Polymer I was characterized by elemental analyses, IR spectra, and UV-visifele spectra. The third-order nonlinear optical properties
were also investigated, and they exhibit good nonlinear absorption and self-defocusing performance with modulus of the hyperpolarizability
4.94 × 10−30 esu for I in a 6.35 × 10−4 mol dm−3 DMF solution. 相似文献
6.
Jonathan F. Ojo Jide Ige Grace O. Ogunlusi Olanrewaju Owoyomi Esan S. Olaseni 《Transition Metal Chemistry》2006,31(3):337-339
The reactions between Fe(Phen)32+[phen = tris-(1,10) phenanthroline] and Co(CN)5X3− (X = Cl, Br or I) have been studied in aqueous acidic solutions at 25 °C and ionic strength in the range I = 0.001–0.02 mol dm−3 (NaCl/HCl). Plots of k2 versus √I, applying Debye–Huckel Theory, gave the values −1.79 ± 0.18, −1.65 ± 0.18 and 1.81 ± 0.10 as the product of charges (ZAZB) for the reactions of Fe(Phen)32+ with the chloro-, bromo- and iodo- complexes respectively. ZAZB of ≈ −2 suggests that the charge on these CoIII complexes cannot be −3 but is −1. This suggests the possibility of protonation of these CoIII complexes. Protonation was investigated over the range [H+] = 0.0001 −0.06 mol dm−3 and the protonation constants Ka obtained are 1.22 × 103, 7.31 × 103 and 9.90 × 102 dm6 mol−3 for X = Cl, Br and I, respectively. 相似文献
7.
L. M. Doubova 《Russian Journal of Electrochemistry》2010,46(4):450-460
The kinetics of Ru[(NH3)6]3+ reduction in 1 M NaNO3 solution at Ag(210) and Ag(111) singlecrystal electrodes modified by n-decanthiol monolayer is studied by electrochemical impedance spectroscopy and cyclic voltammetry. By using these two methods,
standard rate constants of the redox reaction involving Ru[(NH3)6]3+/2+ redox couple in the absence and in the presence of the n-decanthiol film were estimated. The equivalent circuit describing the experimental data in the presence of the self-assembled
organic monolayer and in the absence of redox reaction is an electrical circuit comprising a large resistance (∼106 Ω) connected in parallel with a capacitance (∼10−8 F). Analysis of kinetic data and extrapolation of Tafel lines resulted in the determination of the rate constant at unmodified
Ag-electrode, which is characteristic of very fast heterogeneous electron transfer. The calculated rate constants for n-decanthiol-modified silver singlecrystal faces (210) and (111) in 1 M NaNO3 solution (pH 6.3) equal 4.63 × 10−5 and 3.05 × 10−5 cm/s, respectively. The results are compared with the data at hand reported by different authors for gold electrodes in indifferent
electrolyte solution in the absence and in the presence of self-assembled monolayer. 相似文献
8.
Jinzhang Gao Dongyu Lv Wu Yang Xiaoxia Wei Jie Qu Hua Chen Hongxia Dai Jie Ren 《Central European Journal of Chemistry》2007,5(2):581-589
A convenient and sensitive method for determination of sulfanilamide (SNA) was described based on the Mn(II)-catalyzed oscillating
chemical reaction. Under optimum conditions, a linear relationship existed between the changes of oscillating period or amplitude
and the negative of logarithm of SNA concentration in the range of 4.27 × 10−8 mol ·L−1 ∼ 7.41 × 10−6 mol ·L−1 (RSD, 0.85%) and 9.33 × 10−8 mol ·L−1 ∼ 3.02 × 10−6 mol ·L−1 (RSD, 1.08%), respectively. The lower limit of detection was found to be 2.69 × 10−8 mol ·L−1 and 6.03 × 10−8 mol ·L−1, respectively.
相似文献
9.
The interaction of the clinically used 1,2-dimethyl-3-hydroxypyrid-4-one with trivalent europium Eu(III), was investigated
by using potentiometric and spectroscopic methods. The stability constants of the EuLn
(3−n)+ complexes determined by spectroscopic and potentiometric measurements were found to be log β11 = 6.5±0.3 and log β12 = 12.0±0.5. However, at pH ≥ 5, hydrolysis of the Eu-L complexes starts, resulting in the formation of needle-type, yellow
crystals. The low solubility of the Eu-L complexes in the neutral pH range is disadvantageous with respect to the use of deferiprone
as chelating agent for decorporation of trivalent f-elements. 相似文献
10.
G. I. Romanovskaya A. Yu. Olenin S. Yu. Vasil’eva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(2):274-278
The ability of silver nanoparticles stabilized by cetyltrimethylammonium bromide (CTAB) to concentrate polycyclic aromatic
hydrocarbons (PAHs) from aqueous solutions was shown. It was found that fixed PAH molecules are capable of acting as electronic
energy donors and of generating sensibilized fluorescence of silver nanoparticles. It was shown by spectral-luminescent investigations
of dilute PAH solutions (5 × 10−10−1 × 10−6 g/ml) in the presence of silver nanoparticles (∼0.7 vol %) that the concentration of PAH molecules from solutions occurs
due to its sorption on hydrocarbon CTAB radicals in close contact to the surface of metallic silver. On the basis of the spectral
data, the sorption isotherms were obtained and the values of extraction degree and partition coefficients for naphthalene,
phenanthrene, anthracene, chrysene, pyrene, and 3,4-benzopyrene were calculated. It was found that the degree of extraction
values of the investigated PAHs fall within the range of 73–98%, the partition coefficients (logD) ∼ 6, and the concentration coefficients ∼105. 相似文献
11.
The impedance spectra of CeF3/CeF3 bicrystal (two single crystals separated by a single intercrystalline boundary) between Ag-electrodes are studied over a
135 to 410 K temperature interval (including temperatures below room temperature). The bicrystal was prepared by thermal-diffusion
welding under a pressure of 1.5 × 107 Pa at 1473 K in vacuum (∼10−2 Pa). It is shown that the intercrystalline boundary affects but insignificantly the bicrystal bulk impedance. The CeF3/CeF3 ionic conductivity is 3 × 10−6 S/cm at 293 K; it is mainly determined by transfer processes in the single crystal bulk. 相似文献
12.
N. V. Platonova Yu. O. Punin V. D. Franke E. N. Kotelnikova 《Journal of Structural Chemistry》1994,35(5):634-641
In the ammonium chloride crystallization region of the NH4Cl−CuCl2−H2O−CH3ON system, cocrystallization of the impurity with the main substance occurs by epitaxial adsorption of complexes of varying
composition. In NH4Cl crystals, the Cu2+ impurity forms oriented interlayers (ingrowths) simultaneously at the macro-and microlevels. The ratio between the two trapping
forms depends on the growth conditions.
St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 70–78, September–October, 1994.
Translated by L. Smolima 相似文献
13.
Won-Sik Han Jang-Ki Kim Koo-Chun Chung Joo-Yeon Hong Jong-Ki Hong Jeong-Hoon Kim Tae-Kee Hong 《Journal of Analytical Chemistry》2010,65(10):1035-1040
Udenafil is an oral agent for treating male erectile dysfunction. The poly(aniline) solid contact selective electrodes for
udenafil have been fabricated from PVC cocktail solutions with three ion selective ion pairs. This solid contact electrode
contains three layers of Pt/electro-conductive poly(aniline) polymer/PVC film with an ionophore with a thickness of 2.5 ±
0.1 mm. We compared the slopes of EMF responses and the response range of a solid contact electrode based on Udenafil-TmCIPB
ion pair with those based on Udenafil-PMA and Udenafil-TPB ion pairs and showed that the response slopes were influenced by
plasticizers. The EMF response slopes of Udenafil-TmCIPB-based solid contact electrodes equalled 58.0 mV/decade (at 20 ± 0.2°C)
and their linear response dynamic ranges were 1.0 × 10−2∼1.0 × 10−5.85 M (r
2 = 0.9984). When electrodes with 6 different plasticizers based on Udenafil-TmCIPB were compared, as the dielectric constant
of PVC plasticizer increased, so was the response slope at the same time. Having applied the electrodes to artificial serum
directly, we could get same satisfactory results [Nernstian slope: 60.3 mV/decade, dynamic range: 1.0 × 10−2∼1.0 × 10−5.78 M (r
2 = 0.9978) in artificial serum]. Solid contact electrodes with Udenafil-TmCIPB have shown the best selectivity, reproducibility
of EMF, long-term stability, and short response time (< 20 s). 相似文献
14.
Effect of pH and ionic strength on the interaction of humic acid with aluminium oxide 总被引:4,自引:0,他引:4
E. Tombácz Á. Dobos M. Szekeres H. D. Narres E. Klumpp I. Dékány 《Colloid and polymer science》2000,278(4):337-345
The effect of pH and neutral electrolyte on the interaction between humic acid/humate and γ-AlOOH (boehmite) was investigated.
The quantitative characterization of surface charging for both partners was performed by means of potentiometric acid–base
titration. The intrinsic equilibrium constants for surface charge formation were logK
a,1
int=6.7±0.2 and logK
a,2
int = 10.6±0.2 and the point of zero charge was 8.7±0.1 for aluminium oxide. The pH-dependent solubility and the speciation of
dissolved aluminium was calculated (MINTEQA2). The fitted (FITEQL) pK values for dissociation of acidic groups of humic acid were pK
1 = 3.7±0.1 and pK
2 = 6.6±0.1 and the total acidity was 4.56 mmol g−1. The pH range for the adsorption study was limited to between pH 5 and 10, where the amount of the aluminium species in the
aqueous phase is negligible (less than 10−5 mol dm−3) and the complicating side equilibria can be neglected. Adsorption isotherms were determined at pH ∼ 5.5, ∼8.5 and ∼9.5,
where the surface of adsorbent is positive, neutral and negative, respectively, and at 0.001, 0.1, 0.25 and 0.50 mol dm−3 NaNO3. The isotherms are of the Langmuir type, except that measured at pH ∼ 5.5 in the presence of 0.25 and 0.5 mol dm−3 salt. The interaction between humic acid/humate and aluminium oxide is mainly a ligand-exchange reaction with humic macroions
with changing conformation under the influence of the charged interface. With increasing ionic strength the surface complexation
takes place with more and more compressed humic macroions. The contribution of Coulombic interaction of oppositely charged
partners is significant at acidic pH. We suppose heterocoagulation of humic acid and aluminium oxide particles at pH ∼ 5.5
and higher salt content to explain the unusual increase in the apparent amount of humic acid adsorbed.
Received: 20 July 1999 /Accepted in revised form: 20 October 1999 相似文献
15.
B. A. Trofimov T. A. Skotheim L. N. Parshina M. Ya. Khil'ko L. A. Oparina I. P. Kovalev A. B. Gavrilov 《Russian Chemical Bulletin》1999,48(3):463-469
The hydrosilylation of vinyl methyl and divinyl ethers of oligoethylene glycols with polyhydridosiloxanes in the presence of chloroplatinic acid is accompanied by side processes, namely, polymerization of vinyl ethers and homodehydrocondensation of polyhydridosiloxanes. The electrical conductivity of ∼1M solutions of lithium triflate or bis(trifluoromethylsulfonyl) imide in the resulting hydrosilylation products is ∼10−5 S cm−1. 相似文献
16.
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
17.
S. Meenakshisundaram S. Parthiban U. R. Pisipaty G. Madhurambal S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2010,100(3):821-826
The influence of the highly fluorescent dopant, anthracene (over a concentration range from 5 × 10?4 to 1.2 × 10?2 mol dm?3) on the nonlinear optical properties and fluorescence intensity of potassium hydrogen phthalate (KHP) single crystals grown at 30 °C by a slow evaporation solution growth technique (SEST) has been investigated. Powder XRD and FTIR spectral analyses confirm the slight distortion of the structure of crystal because of doping. UV–Visible study shows that the transparency is not affected much by the dopant. The SEM investigation reveals that KHP suffers from crack development. Thermal analysis indicates that there is no decomposition of the crystal up to the melting point. It is interesting to observe that additions of small quantity anthracene to KHP results in the enhancement of fluorescence intensity. The fluorescence intensity dependence on dopant concentration is observed. Interestingly, second harmonic generation (SHG) efficiency of KHP is dramatically improved by doping with small quantities of anthracene. 相似文献
18.
A simple galvanic cell was developed to produce rod-shaped PbS crystals with lead and gold as negative and positive electrodes. The electrolyte solution contains sodium thiosulfate, sodium sulfate, and 1-thioglycerol (TG). It was found out that lead dissolved spontaneously and produced PbS crystals in the electrolyte solution immediately after assembling the cell. Further study shows that TG catalyzes the oxidation of lead into Pb2+ and the reduction of thiosulfate into S2−. The produced rod-shaped PbS crystals are 140∼350 nm in diameter and 1∼3 μm in length after 4 h of reaction. 相似文献
19.
T. N. Solomoichenko Yu. S. Sadovskii T. M. Prokop’eva E. A. Karpichev I. V. Kapitanov Zh. P. Piskunova V. A. Savelova A. F. Popov 《Theoretical and Experimental Chemistry》2006,42(6):364-370
We have studied the nucleophilicity of the hydroperoxide anion relative to 4-nitrophenyl diethyl phosphonate (NPDEPS) in the
presence of cetyltrimethylammonium bromide (water, 25 °C) while varying the acidity of the medium and the hydroperoxide anion
concentration over a broad range. The increase in the reaction rate when the reaction is transferred to a micellar pseudophase
is as high as ∼10-fold, which is explained by concentration effects. In CTAB micelles, as in water, the hydroperoxide ion
is one of the most effective α-nucleophiles, and the size of the α-effect, characterized by the ratio of the second-order rate constants for reactions of HOO− and OH− anions with NPDEPS, remains practically constant and reaches a value of ∼50-fold.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 6, pp. 357–363, November–December, 2006. 相似文献
20.
S. V. Larionov R. F. Klevtsova E. A. Sankova L. A. Glinskaya T. E. Kokina 《Russian Journal of Inorganic Chemistry》2008,53(9):1417-1425
Heteroligand complexes [Pb(Phen)2(iso-Bu2PS2)2] (I) and [Pb(4,4′-Bipy(iso-Bu2PS2)2]
n
(II) were synthesized, and their crystal structures were determined. The crystals of complex I are monoclinic: a = 17.2011(9) ?, b = 14.1695(7) ?, c = 19.8727(12) ?; β = 115.644(1)°, V = 4366.5(4) ?3, Z = 4, ρcalcd = 1.500 g/cm3, space group C2/c. The crystals of complex II are triclinic: a = 11.9283(2)?, b = 12.3814(2) ?, c = 14.0917(3) ?; α = 74.705(1)°, β = 87.240(1)°, γ = 61.448(1)°, V = 1755.86(6) ?3, Z = 2, ρcalcd = 1.479 g/cm3, space group P
. The structure of complex I consists of mononuclear molecules. The coordination polyhedron of the Pb atom is a distorted tetragonal antiprism N4S4 formed by the bidentate chelating ligands Phen and iso-Bu2PS2−. Continuous zigzag ribbons along the c axis are formed through contacts of the peripheral atoms of the Phen molecules of the adjacent complexes. Polynuclear complex
II has a chain structure. The coordination polyhedron of the Pb atom is a distorted octahedron N2S4 formed by the bidentate chelating iso-Bu2PS2− ligands and bidentate bridging 4,4′-Bipy molecules. Short intermolecular contacts between the Pb and S atoms of the adjacent
chains in structure II result in the formation of supramolecular two-chain assemblies as volume columns parallel to the b axis. The environment of the Pb atoms in the assembly is formed by pentagonal bipyramids N2S4 + 1.
Original Russian Text ? S.V. Larionov, R.F. Klevtsova, E.A. Sankova, L.A. Glinskaya, T.E. Kokina, 2008, published in Zhurnal
Neorganicheskoi Khimii, 2008, Vol. 53, No. 9, pp. 1516–1524. 相似文献