共查询到20条相似文献,搜索用时 31 毫秒
1.
Vytautas Getautis Albina Stanisauskaite Tadas Malinauskas Jolanta Stumbraite Valentas Gaidelis Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2006,137(11):1401-1409
Summary. Hydrazones containing 1-phenyl-1,2,3,4-tetrahydroquinoline units were synthesized starting from diphenylamine. These compounds
were found to constitute novel hole transporting materials and were characterized by the time of flight method. The hole drift
mobility in these compounds exceeds 10−6 cm2 V−1 s−1 at an electric field of 106 V cm−1. 相似文献
2.
Jolanta Stumbraite Maryte Daskeviciene Rimgaile Degutyte Vygintas Jankauskas Vytautas Getautis 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1243-1248
Summary. Novel glass-forming 2-(1-phenyl-1,2,3,4-tetrahydroquinoline-6-ylmethylene)-1,3-indandione derivatives were synthesized and
their thermal properties were studied. The results of a preliminary investigation of the photoelectric properties of amorphous
films of the title compounds are briefly reported. The ionization potential of these molecular glasses is ca. 5.6 eV and the hole drift mobility exceeds 10−8 cm2 V−1 s−1 at strong electric fields. 相似文献
3.
Vida Peciuraite Violeta Vaitkeviciene Saulius Grigalevicius Juozas V. Grazulevicius Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2006,137(8):1053-1062
Summary. Star-shaped molecules of di(9-alkylcarbazol-3-yl)arylamines were synthesized and found to constitute new glass-forming materials
with glass transition temperatures ranging from 40 to 147°C. The electron photoemission spectra of the molecular glasses were
recorded and ionisation potentials of 4.9–5.0 eV were established. Room temperature time of flight hole drift mobilities of
the di(9-alkylcarbazol-3-yl)phenylamines molecularly dispersed in polycarbonate-Z approached 5 · 10−6 cm2/Vs at high electric fields. Some of the compounds were converted to cross-linkable derivatives, which are potential components
for insoluble charge transport layers. 相似文献
4.
Vida Peciuraite Violeta Vaitkeviciene Saulius Grigalevicius Juozas V. Grazulevicius Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2006,18(4):1053-1062
Star-shaped molecules of di(9-alkylcarbazol-3-yl)arylamines were synthesized and found to constitute new glass-forming materials
with glass transition temperatures ranging from 40 to 147°C. The electron photoemission spectra of the molecular glasses were
recorded and ionisation potentials of 4.9–5.0 eV were established. Room temperature time of flight hole drift mobilities of
the di(9-alkylcarbazol-3-yl)phenylamines molecularly dispersed in polycarbonate-Z approached 5 · 10−6 cm2/Vs at high electric fields. Some of the compounds were converted to cross-linkable derivatives, which are potential components
for insoluble charge transport layers. 相似文献
5.
Selective Indicator Reaction for Kinetic Determination of Traces of Manganese(II), Ribavirin and Tiazofurin 总被引:1,自引:0,他引:1
Gordana A. Milovanović Mira M. Čakar Nevenka B. Vučić Milan Jokanović 《Mikrochimica acta》2000,135(3-4):173-178
In this work it was established that, in the presence of ammonium carbonate, traces of manganese(II) catalyse the oxidation
of Nile Blue A by hydrogen peroxide, which enables its kinetic determination in the concentration range from 6.6 to 65.9 ng
cm−3, the detection limit being 8.0 × 10−2 ng cm−3. Antiviral/antitumour substances modify the catalytic activity of manganese(II): 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide,
ribavirin, increases the catalytic effect of manganese(II), while 2-β-D-ribofuranosyl-thiazole-4-carboxamide, tiazofurin,
acts as an inhibitor. On the basis of these effects, a kinetic method for determining ribavirin concentrations from 0.5 × 10−1 to 4.0 × 10−1 μg cm−3 and tiazofurin concentrations from 0.3 to 2.6 μg cm−3 is proposed. The kinetics of the indicator reaction were studied in the presence of the substances examined, the kinetic
equations established, and the constants of the corresponding reaction rates calculated. The effect of temperature on these
reactions was also investigated. The method was applied to the determination of manganese(II) in mineral water and ribavirin
in pharmaceutical preparations.
Received December 16, 1999. Revision June 6, 2000. 相似文献
6.
Razika Brahimi Mohamed Trari Aïssa Bouguelia Yassine Bessekhouad 《Journal of Solid State Electrochemistry》2010,14(7):1333-1338
The delafossite CuAlO2 single crystal, prepared by the flux method, is a low mobility p-type semiconductor with a hole mobility of 1.2 × 10−5 cm−2 V−1 s−1. The chronoamperometry showed an electrochemical O2− insertion with a diffusion coefficient D
303K of 3.3 × 10−18 cm2 s−1. The thermal variation of D in the range 293–353 K gave an enthalpy of diffusion (ΔH) of 44.7 kJ mol−1. CuAlO2 is photoactive, and the Mott–Schottky plot indicates a flat band potential of +0.42 V vs saturated calomel electrode and
a holes density (N
A) of 1016 cm−3. The photocurrent spectra have been analyzed by using the Gartner model from which the absorption coefficients and diffusion
lengths were determined. An optical transition at 1.66 eV, indirectly allowed, has been obtained. The spectral photoresponse
provides a high absorption at 480 nm. The low quantum yield (η) is attributed to a small depletion length (440 nm) and a hole diffusion width (271 nm) compared to a very large penetration
depth (12 μm). 相似文献
7.
Summary. A new simple, rapid, sensitive, and selective method is proposed for the microdetermination of mercury. Mercury(II) forms
insoluble complexes with 2,3-dichloro-6-(2-hydroxy-3,5-dinitrophenylazo)-quinoxaline (1), 2,3-dichloro-6-(5-amino-3-carboxy-2-hydroxy-phenylazo)-quinoxaline (2), 2,3-dichloro-6-(2,7-dihydroxynaphth-1-ylazo)-quinoxaline (3), and 2,3-dichloro-6-(3-carboxy-2-hydroxy-naphth-1-ylazo)-quinoxaline (4) in aqueous acidic medium; the complexes can be made soluble by the action of an anionic surfactant. The solution of the
pink coloured compounds is stable for at least 24 h. Beer’s law is obeyed over the concentration range from 0.1 to 2.8 μg · cm−3 of mercury. For a more accurate analysis, Ringbom optimum concentration ranges were found to be 0.25–2.5 μg · cm−3. The molar absorpitivity, Sandell sensitivity, and relative standard deviations were also calculated. A slight interference from Pd2+ and Cd2+ is exhibited by the first three ligands, whereas the last one is only negligibly affected by these metal ions. Strong interference
from Ag(I) is evident for all ligands, whereas alkali, alkaline earth, and other transition metals tested posed negligible
interference. 15 μg · cm−3 of Cd2+ and Pd2+ or 10 μg · cm−3 of Ag+ can be tolerated if 1.0 mg of potassium bromide and 2.0 mg of citrate as masking agents are added for the determination of
1.5 μg · cm−3 of mercury(II). The method was applied to the determination of methyl- and ethylmercury chloride and the analysis of environmental
water samples.
Received August 7, 2000. Accepted (revised) October 18, 2000 相似文献
8.
Jun Yue Bai Liang Wang Hong Jing Wang Peng Fei Huang Yu Qing Zhao Sheng Di Fan 《Mikrochimica acta》2006,156(3-4):321-326
The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode
was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry.
The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10−6 cm2 s−1. In 0.1 mol L−1 phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the
concentration of EP in the range of 1.0 × 10−5–2.0 × 10−4 mol L−1 and 1.0 × 10−7–1.0 × 10−6 mol L−1. The detection limit is 5 × 10−8 mol L−1. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The
method is simple, quick, sensitive and accurate. 相似文献
9.
Yuri Pleskov Alik Tameev Valentin Varnin Irina Teremetskaya 《Journal of Solid State Electrochemistry》1998,3(1):25-30
The drift mobility of nonequilibrium holes injected in undoped polycrystalline diamond films was determined, by a transit-time
technique, as ca. 10−3 cm2/(V s). This hole mobility is three orders of magnitude lower than the “equilibrium” mobility in boron-doped diamond films
[0.1–1 cm2/(V s)], determined from the films' dc conductivity. This difference is explained by the effect of a nonequilibrium charge
carrier trapping during the carrier transport in polycrystalline diamond.
Received: 3 December 1997 / Accepted: 9 April 1998 相似文献
10.
Heli Hossein Faramarzi F. Sattarahmady N. 《Journal of Solid State Electrochemistry》2010,14(12):2275-2283
The electrochemical behavior of sodium alendronate on copper microparticle- and copper nanoparticle-modified carbon paste
electrodes was investigated. In the voltammograms recorded using microparticles, a single anodic oxidation peak appeared,
while using nanoparticles, two anodic peaks appeared. The anodic currents were related to the electrocatalytic oxidation of
alendronate via the active species of Cu(III). The catalytic rate constant for the electrocatalytic oxidation process and
the diffusion coefficient of alendronate were obtained to be 1.57 × 103 cm3 mol−1 s−1 and 2.44 × 10−6 cm2 s−1, respectively. A sensitive and time-saving detection procedure was developed for the analysis of alendronate, and the corresponding
analytical parameters were reported. Alendronate was determined with a limit of detection of 11.26 μmol L−1 with a linear range of 50–6,330 μmol L−1. The proposed amperometric method was applied to the analysis of commercial pharmaceutical tablets, and the results were
in good agreement with the declared values. 相似文献
11.
Zirconium (IV) was determined spectrophotometrically by reaction with quercetin as primary ligand and oxalate as secondary
ligand. Polyvinylpyrrolidone (PVP) was used as protective colloid to solubilize the formed zirconium quercetin oxalate ternary
complex. The molar absorptivity of the 1:3:1 (zirconium–quercetin–oxalate) complex is 7.31 × 104 L·mol−1 cm−1 at 430 nm with a stability constant of 8.2 × 1020 and its detection limit is 0.16 mg/L. Beer’s law is rectilinear up to 1.46 mg/L of zirconium (IV). The sensitivity index
is 1.25 ng cm−2.
The reaction of aluminium (III) with quercetin in presence of PVP as a surfactant has been studied spectrophotometrically.
The molar absorptivity of the 1:3 (aluminium–quercetin) complex is 8.09 × 104 × L·mol−1·cm−1 at 433 nm, its stability constant is 2.6 × 1013 with sensitivity index of 0.33 ng·cm−2 and its detection limit is 0.08 mg/L. The optimal conditions for the quantitative determination of zirconium and aluminium
were studied. The proposed methods are examined by statistical analysis of the experimental data. The methods are free from
interference of most cations and anions. The proposed methods have been used to determine zirconium and aluminium in industrial
waste water.
Received May 30, 2001; accepted November 2, 2001; published online July 15, 2002 相似文献
12.
Graham A. Bowmaker Paul A. Kilmartin Graham A. Wright 《Journal of Solid State Electrochemistry》1999,3(3):163-171
Stable, yellow anodic films of parathiocyanogen (SCN)
x
were formed on a platinum electrode from 2.8 M KSCN in methanol at 45 °C at a constant current of 20–40 mA cm−2 for 15–30 min. Loosely bound orange crystals of a more amorphous character were removed by rinsing to leave an adherent yellow
film with sharp Raman bands under 647.1 nm laser excitation at 627 cm−1 (vCS), 1152 cm−1 and 1236–1261 cm−1 (vNN and vCN). The lack of electroactivity and short-lived photocurrents pointed to an insulating film at potentials up to 1.0 V (SHE).
At more positive potentials, longer-lasting photocurrents were obtained, consistent with breakdown of the insulating film.
XPS scans confirmed N:C:S ratios close to 1:1:1, with a deficiency of S of some 10% due to S lost as sulfate at the film surface.
Oxidation of SeCN− in neutral aqueous solution led to the formation of a less-stable orange paraselenocyanogen film with a Raman band at 1256–1267 cm−1, which decomposed within a day to grey selenium.
Received: 12 December 1997 / Accepted: 23 March 1998 相似文献
13.
Jolita Ostrauskaite Viktoras Voska Juozas V. Grazulevicius 《Monatshefte für Chemie / Chemical Monthly》2002,29(9):599-607
A series of new glass-forming hydrazones containing bicarbazolyl units were synthesized starting from 9-(2-(9H-carbazol-9-yl)-cyclobutyl)-9H-carbazole and 9-(6-(9H-carbazol-9-yl)-hexyl)-9H-carbazole, and their thermal properties were studied. The correlation between their inclination to form glasses and their chemical structures are discussed. The results of a preliminary investigation of the photoelectric properties of amorphous films of the title compounds are briefly reported. The highest hole drift mobility was observed for 9-(2-(9H-carbazol-9-yl)-cyclobutyl)-9H-carbazole-3-carbaldehyde N,N-diphenylhydrazone; at high electric fields, it approaches 1 · 10−3 cm2/Vs. 相似文献
14.
Konstantin L. Mutaftchiev 《Mikrochimica acta》2001,136(1-2):79-82
The catalytic effect of manganese(II) on the oxidation of Naphthol Blue Black, with potassium periodate in the presence of
1,10-phenanthroline in weakly acidic media is studied. The reaction is followed spectrophotometrically by measuring the decrease
in the absorbance of the dye at 618 nm. Under the optimum conditions (3 × 10−5 mol dm−3 Naphthol Blue Black, 6 × 10−4 mol dm−3 potassium periodate, 1 × 10−4 mol dm−3 1,10-phenanthroline, 0.1 mol dm−3 acetate buffer – pH 4.0, 60 °C, 5 min) manganese(II) in the range 0.08–4 ng cm−3 can be determined by the fixed-time method with a detection limit of 0.025 ng cm−3. The influence of foreign ions on the accuracy of the results is investigated. The developed method is highly sensitive,
selective, and simple. The method was applied successfully to the determination of manganese in cucumbers, garlic cloves and
parsley leaves.
Received June 12, 2000. Revision December 12, 2000. 相似文献
15.
Krzysztof Miecznikowski James A. Cox Adam Lewera Pawel J. Kulesza 《Journal of Solid State Electrochemistry》2000,4(4):199-204
We describe a sol-gel approach by which iron hexacyanoferrate is immobilized in silica in a manner suited to investigation
by electrochemistry in the absence of a contacting liquid phase. Such physicochemical parameters as concentration of redox
sites (C
o) and apparent (effective) diffusion coefficient (D
app) are estimated by performing cyclic voltammetric and potential step experiments in two time regimes, which are characterized
by linear and spherical diffusional patterns, respectively. Values of D
app and C
o thereby obtained are 2.0 × 10−6 cm2 s−1 and 1.4 × 10−2 mol dm−3. The D
app value is larger than expected for a typical solid redox-conducting material. Analogous measurements done in iron(III) hexacyanoferrate(III)
solutions of comparable concentrations, 1.0 × 10−2 and 5.0 × 10−3 mol dm−3, yield D
app on the level of 5–6 × 10−6 cm2 s−1. Thus, the dynamics of charge propagation in this sol-gel material is almost as high as in the liquid phase. The residual
water in the silica, along with the pore structure, are important to the overall mechanism of charge transport, which apparently
is limited by physical diffusion rather than electron self-exchange. Under conditions of a solid state voltammetric experiment
which utilizes an ultramicroelectrode, encapsulated iron hexacyanoferrate redox centers seem to be in the dispersed colloidal
state rather than in a form of the rigid polymeric film.
Received: 8 April 1999 / Accepted: 13 August 1999 相似文献
16.
Functionalized polypyrrole films were prepared by incorporation of Fe(CN)6
3− as doping anion during the electropolymerization of pyrrole at a glassy carbon electrode from aqueous solution. The electrochemical
behavior of the Fe(CN)6
3−/Fe(CN)6
4− redox couple in polypyrrole was studied by cyclic voltammetry. An obvious surface redox reaction was observed and dependence
of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole film with ferrocyanide incorporated
was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer. The catalytic effect for mediated
oxidation of ascorbic acid was 300 mV and the bimolecular rate constant determined for surface coverage of 4.5 × 10−8 M cm−2 using rotating disk electrode voltammetry was 86 M−1 s−1. Furthermore, the catalytic oxidation current was linearly dependent on ascorbic acid concentration in the range 5 × 10−4–1.6 × 10−2 M with a correlation coefficient of 0.996. The plot of i
p versus v
1/2 confirms the diffusion nature of the peak current i
p.
Received: 12 April 1999 / Accepted: 25 May 1999 相似文献
17.
Bolade O. Agboola Sibulelo L. Vilakazi Kenneth I. Ozoemena 《Journal of Solid State Electrochemistry》2009,13(9):1367-1379
Electrochemistry of water-soluble cobalt(II) tetrasulfophthalocyanine (CoTSPc) electrodeposited on glassy carbon nanotube
pre-modified with acid-functionalized multi-walled carbon nanotubes (MWCNT) is described. Both charge transfer resistances
toward [Fe(CN)6]3−/4− redox probe and electrocatalytic responses toward epinephrine (EP) detection follow the trend: bare GCE < GCE-MWCNT < GCE-CoTSPc < GCE-MWCNT-CoTSPc.
EP analysis was then carried out in details using GCE-MWCNT-CoTSPc. The catalytic rate constant value k
ch = 2.2 × 107 (mol cm−3)−1 s−1 was obtained from rotating disk electrode experiment. Interestingly, GCE-MWCNT-CoTSPc efficiently suppressed the detection
of ascorbic acid (the natural interference of neurotransmitters in physiological conditions) showing good sensitivity (0.132 ± 0.003 A
l mol−1), limit of detection (4.517 × 10−7 mol l−1), and quantification (15.056 × 10−7 mol l−1). In addition, GCE-MWCNT-CoTSPc was conveniently used to determine EP in epinephrine hydrochloric acid injection with recovery
of 101.1 ± 2.2%. 相似文献
18.
Patel II Trevisan J Singh PB Nicholson CM Krishnan RK Matanhelia SS Martin FL 《Analytical and bioanalytical chemistry》2011,401(3):969-982
Vibrational spectroscopy techniques can be applied to identify a susceptibility-to-adenocarcinoma biochemical signature. A
sevenfold difference in incidence of prostate adenocarcinoma (CaP) remains apparent amongst populations of low- (e.g. India)
compared with high-risk (e.g. UK) regions, with migrant studies implicating environmental and/or lifestyle/dietary causative
factors. This study set out to determine the biospectroscopy-derived spectral differences between risk-associated cohorts
to CaP. Benign prostate tissues were obtained using transurethral resection from high-risk (n = 11, UK) and low-risk (n = 14, India) cohorts. Samples were analysed using attenuated total reflection Fourier-transform infrared (FTIR) spectroscopy,
FTIR microspectroscopy and Raman microspectroscopy. Spectra were subsequently processed within the biochemical cell region
(1,800−1–500 cm–1) employing principal component analysis (PCA) and linear discriminant analysis (LDA) to determine whether wavenumber–absorbance/intensity
relationships might reveal biochemical differences associated with region-specific susceptibility to CaP. PCA-LDA scores and
corresponding cluster vector plots identified pivotal segregating biomarkers as 1,582 cm−1 (Amide I/II trough); 1,551 cm−1 (Amide II); 1,667 cm−1 (Amide I); 1,080 cm−1 (DNA/RNA); 1,541 cm−1 (Amide II); 1,468 cm−1 (protein); 1,232 cm−1 (DNA); 1,003 cm−1 (phenylalanine); 1,632 cm−1 [right-hand side (RHS) Amide I] for glandular epithelium (P < 0.0001) and 1,663 cm−1 (Amide I); 1,624 cm−1 (RHS Amide I); 1,126 cm−1 (RNA); 1,761, 1,782, 1,497 cm−1 (RHS Amide II); 1,003 cm−1 (phenylalanine); and 1,624 cm−1 (RHS Amide I) for adjacent stroma (P < 0.0001). Primarily protein secondary structure variations were biomolecular markers responsible for cohort segregation
with DNA alterations exclusively located in the glandular epithelial layers. These biochemical differences may lend vital
insights into the aetiology of CaP. 相似文献
19.
Liang Wang Jun Yue Bai Peng Fei Huang Hong Jing Wang Xiao Wei Wu Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):73-78
The electrochemical behaviors of uric acid (UA) at the penicillamine (Pen) self-assembled monolayers modified gold electrode
(Pen/Au) have been studied. The Pen/Au electrode is demonstrated to promote the electrochemical response of UA by cyclic voltammetry
(CV). The diffusion coefficient D of UA is 6.97 × 10−6 cm2 s−1. In differential pulse voltammetric (DPV) measurements, the Pen/Au electrode can separate the UA and ascorbic acid (AA) oxidation
potentials by about 120 mV and can be used for the selective determination of UA in the presence of AA. The detection limit
was 1 × 10−6 mol L−1. The modified electrode shows excellent sensitivity, good selectivity and antifouling properties. 相似文献
20.
Sayed Medhi Ghoreishi Mohsen Behpour Mohammad Hassan Motaghedi Fard 《Journal of Solid State Electrochemistry》2012,16(1):179-189
In this work, we investigate the electrochemical activity of dopamine (DA) and uric acid (UA) using both a bare and a modified
carbon paste electrode as the working electrode, with a platinum wire as the counter electrode and a silver/silver chloride
(Ag/AgCl) as the reference electrode. The modified carbon paste electrode consists of multi-walled carbon nanotubes (>95%)
treated with α-cyclodextrine, resulting in an electrode that exhibits a significant catalytic effect toward the electro-chemical
oxidation of DA in a 0.2-M Britton–Robinson buffer solution (pH 5.0). The peak current increases linearly with the DA concentration
within the molar concentration ranges of 2.0 × 10−6 to 5.0 × 10−5 M and 5.0 × 10−5 to 1.9 × 10−4 M. The detection limit (signal to noise >3) for DA was found to be 1.34 × 10−7 M, respectively. In this work, voltammetric methods such as cyclic voltammetry, chronoamperometry, chronocuolometry, differential
pulse and square wave voltammetry, and linear sweep and hydrodynamic voltammetry were used. Cyclic voltammetry was used to
investigate the redox properties of the modified electrode at various scan rates. The diffusion coefficient (D, cm2 s−1 = 3.05 × 10−5) and the kinetic parameters such as the electron transfer coefficient (α = 0.51) and the rate constant (k, cm3 mol−1 s−1 = 1.8 × 103) for DA were determined using electrochemical approaches. By using differential pulse voltammetry for simultaneous measurements,
we obtained two peaks for DA and UA in the same solution, with the peak separation approximately 136 mV. The average recovery
was measured at 102.45% for DA injection. 相似文献