The effect of surfactants on the acid-base behaviour of methyl red. Part I. A spectrophotometric comparison of the effect of CPB and SDS

1990 ◽  
Vol 55 (6) ◽  
pp. 1491-1499 ◽  
Author(s):  
Jana Jirasová ◽  
Jiří Bílý ◽  
Ludmila Čermáková
Keyword(s):  
Absorption Spectra ◽  
Dissociation Constants ◽  
Methyl Red ◽  
Acid Base ◽  
Absorption Bands ◽  
Gaussian Shape ◽  
The Individual ◽  
Sds Surfactant

The effect of a cationic (CPB) and an anionic (SDS) surfactant on the bands in the absorption spectra of methyl red was studied. The interactions of methyl red with the two surfactants were monitored on the basis of the changes in the absorption curves that were mathematically deconvoluted into Gaussian shape absorption bands. The methyl red dissociation constants were determined in the presence of the two surfactants at sub- and supercritical micelle concentrations. The methyl red conditional dissociation constants changed by ΔpKa = -1.47 for c(CPB) = 5 mmol l-1 and ΔpKa = 0.81 for c(SDS) = 4 mmol l-1. The contributions of the individual forms of methyl red to the interactions with CPB and SDS were discussed.

The Effect of Surfactants on the Acid-Base Behaviour of Methyl Red. Part II. A Spectrophotometric Comparison of the Effect of Triton X-100 and β-Cyclodextrin

1994 ◽  
Vol 59 (2) ◽  
pp. 322-329
Author(s):  
Jana Jirasová ◽  
Jiří Bílý ◽  
Ludmila Čermáková
Keyword(s):  
Dissociation Constant ◽  
Dissociation Constants ◽  
Methyl Red ◽  
Acid Base ◽  
Absorption Bands ◽  
Triton X

The effect of the non-ionogenic surfactant Triton X-100 (TX) and β-cyclodextrin (CD) on the absorption bands of methyl red was examined. The interactions of methyl red with the both substances were studied based on changes in the absorption curves after their resolution into Gaussian bands. The conditional dissociation constants of methyl red were determined at various concentrations of the additives (in the case of TX, both below and above its cmc value). At cTX = 0.06 mol l-1 the change in the conditional dissociation constant of methyl red was ∆pKa = -0.58 and at cCD = 6 mmol l-1 the ∆pKa value was identical.

Ultraviolet Absorption Spectra and Dissociation Constants of Diamino-1,3,5-triazines

2002 ◽  
Vol 67 (4) ◽  
pp. 429-438 ◽  
Author(s):  
Rafael Pérez ◽  
Rafael Marín Galvín ◽  
José M. Rodríguez Mellado
Keyword(s):  
Normal Distribution ◽  
Absorption Spectra ◽  
Dissociation Constants ◽  
Ultraviolet Absorption ◽  
Amino Groups ◽  
Individual Bands ◽  
Ring Nitrogen ◽  
Log Normal ◽  
The Individual ◽  
Log Normal Distribution

This paper presents ultraviolet absorption spectra of two diamino-1,3,5-triazines, namely 1,3,5-triazine-2,4-diamine (DT) and 6-chloro-1,3,5-triazine-2,4-diamine (ClDT). The spectra were fitted to the log-normal distribution. In the more energetic zone of the spectrum both compounds presented common bands, placed around 204-205 and 223-226 nm (depending on the pH of the medium). At higher wavelengths the spectra were different, with bands appearing in the range 235-267 nm. From variations of the maximum absorbances of the individual bands, the pKb values 3.5 ± 0.2 and 1.2 ± 0.1 were obtained for protonation of the ring nitrogen placed between the amine radicals of DT and ClDT, respectively, and 9.35 ± 0.2 and 11.5 ± 0.1 for dissociation of the amino groups of DT and ClDT, respectively.

The optical and acid-base properties of chromatographically pure Chromazurol S, Eriochromazurol B and Eriochromcyanine R

1981 ◽  
Vol 46 (2) ◽  
pp. 354-367 ◽  
Author(s):  
Naděžda Pollaková-Mouková ◽  
Dagmar Gotzmannová ◽  
Vlastimil Kubáň ◽  
Lumír Sommer
Keyword(s):  
Aqueous Medium ◽  
Dissociation Constants ◽  
Absorption Coefficients ◽  
Acid Base ◽  
Chromazurol S ◽  
Base Transition ◽  
The Individual ◽  
Mixed Water ◽  
Base Properties

The positons of the absorption maxima and the values of the molar absorption coefficients of all the acid-base forms and the dissociation constants of the individual acid-base transition of chromatographically pure Chromazurol S, Eriochromazurol B and Eriochromcyanine R were found by graphical and numerical interpretation of the absorbance curves measured in aqueous medium and mixed water-ethanol and water-DMF medium. These values were compared with the values given in the literature.

Acid-base properties of 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan

1982 ◽  
Vol 47 (11) ◽  
pp. 2882-2889
Author(s):  
Nadezhda Likhareva ◽  
Ladislav Šůcha ◽  
Miloslav Suchánek
Keyword(s):  
Computer Program ◽  
Dissociation Constants ◽  
Acid Base ◽  
New Compounds ◽  
Base Properties

Two new compounds from the formazan series, viz. 1,3-diphenyl-5-(1H-tetrazol-2-yl)formazan and 1,3-diphenyl-5-(2H-1,2,4-triazol-3-yl)formazan, were prepared, and the dissociation constants and molar absorptivities of all of their acid-base species were determined spectrophotometrically employing the SPEKTFOT computer program.

Mechanism of anionic coordination dimerization of isoprene

1981 ◽  
Vol 46 (7) ◽  
pp. 1600-1606 ◽  
Author(s):  
Jan Bartoň ◽  
Karel Volka ◽  
Miroslav Kašpar ◽  
Vlastimil Růžička
Keyword(s):  
Gas Chromatography ◽  
Alkali Metal ◽  
Absorption Spectra ◽  
Visible Radiation ◽  
Absorption Bands ◽  
Absorption Spectrophotometry ◽  
Spectrophotometric Data ◽  
Oligomeric Forms

The mechanism of controlled anionic coordination dimerization of isoprene (i.e. 2-methyl-1,3-butadiene) in the system tetrahydrofuran-isoprene-alkali metal-dialkylamine was investigated by using absorption spectrophotometry in the range of visible radiation and gas chromatography. The effect of the alkali metal (Li, Na, K) and dialkylamine (dicyclohexylamine, N-isopropylcyclohexylamine, N-methylisopropylamine) on the absorption spectra was tested. By comparing chromatographic and spectrophotometric data, the absorption bands in the range of visible radiation were identified with the existence of π-complexes between oligomeric forms of isoprene and alkali metal dialkylamide.

scholarly journals Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Wiebeler ◽  
Joachim Vollbrecht ◽  
Adam Neuba ◽  
Heinz-Siegfried Kitzerow ◽  
Stefan Schumacher
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Absorption Bands ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Hartree Fock ◽  
Tauc Plot ◽  
Electrochemical Approach

AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands.

Characterization of bulk crystals of transition metal doped ZnO for spintronic applications

2003 ◽  
Vol 799 ◽  
Author(s):  
M. H. Kane ◽  
R. Varatharajan ◽  
Z. C. Feng ◽  
S. Kandoor ◽  
J. Nause ◽  
...  
Keyword(s):  
Transition Metal ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Growth Technique ◽  
Undoped Material ◽  
Doped Zno ◽  
Metal Doped ◽  
The Individual

ABSTRACTIn this work, we report on the material properties of ZnO doped with Mn, Co, and Fe grown by a modified melt growth technique. X-ray diffraction measurements show that transition metals can be incorporated on Zn sites; an increase in the lattice parameter is apparent with increasing doping level. UV-visible transmission and reflectance measurements have also been performed. Absorption bands in the visible regime are distinctive to the individual transition metal dopants. A noticeable shift in the optical band edge has been observed from these Mn/Co/Fe-doped ZnO crystals in comparison with the undoped material. ZnO may also provide a suitable platform for the incorporation of transition metal elements through high temperature near equilibrium growth processes; however, further work is required in order to employ these materials for spintronic applications.

scholarly journals III. A contribution to the study of the yellow colouring matter of the urine

1894 ◽  
Vol 55 (331-335) ◽  
pp. 394-407 ◽  
Keyword(s):  
Absorption Spectra ◽  
Spectroscopic Properties ◽  
Yellow Pigment ◽  
Chemical Methods ◽  
Distinctive Character ◽  
Yellow Coloration ◽  
Normal Urine ◽  
The Individual

The uncertainty which still surrounds the origin of a phenomenon so familiar as the yellow coloration of the urine bears eloquent testimony to the difficulties which beset the investigation, by ordinary chemical methods, of such substances as the urinary pigments, and to the importance of the part which the spectroscope has played in the acquisition of such knowledge of them as we possess. Indeed, our acquaintance with the individual pigments is proportional to the distinctive character of their absorption spectra, rather than to the time which has elapsed since they first attracted attention; and in not a few modern works doubt is thrown upon the very existence of a distinct yellow pigment, having negative spectroscopic properties, but to which normal urine owes its characteristic tint, the chief part in the coloration of the excretion being assigned to urobilin.

Excitonic Bands in the Optical Absorption Spectra of A3MX6 and A3M2X9 (A = MeNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I)

1994 ◽  
Vol 49 (6) ◽  
pp. 849-851 ◽  
Author(s):  
G. C. Papavassiliou ◽  
I. B. Koutselas
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Visible Spectral Region ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Uv Visible ◽  
Low Dimensional

The title compounds (natural low-dimensional semiconductors) show strong excitonic optical absorption bands in the UV-visible spectral region, because of the dielectric confinement of excitons. as in the cases of other similar systems based on PbX2-4, SnX2-4. PtI - X - PtIV-X , Cdx,Sy-clusters etc

scholarly journals ACID-BASE PROPERTIES OF -UNSATURATED KETONES OBTAINED FROM REACTION OF 5-FORMYL-8-HYDROXYQUINOLINE WITH P-SUBSTITUTED ACETOPHENONES

2019 ◽  
Vol 16 (31) ◽  
pp. 755-764
Author(s):  
Roberto FERNANDEZ-MAESTRE ◽  
Alonso J MARRUGO-GONZÁLEZ
Keyword(s):  
Electron Donor ◽  
Opposite Effect ◽  
Dissociation Constants ◽  
Phenyl Group ◽  
Hydroxyl Group ◽  
Ultraviolet Spectroscopy ◽  
Acid Base ◽  
Unsaturated Ketones ◽  
Ph Values ◽  
Phenyl Fragment

Chalcones (α,β-unsaturated ketones) containing aromatic or heterocyclic radicals are highly reactive, allowing the synthesis of novel organic compounds. In this study, the dissociation constants (pKa) of seven chalcones derived from 8-hydroxyquinoline were determined and the influence on dissociation of substituents in the phenyl group (-CH3, -OCH3, -N(CH3)2, -Cl, -Br, and -NO2) was analysed. pKa values are important because they determine the pH at which ligands are fully deprotonated -when they show their maximum chelating properties- and determine the ligands interactions at different pH values. The chalcones’ pKa’s were calculated by visible ultraviolet spectroscopy in a water-ethanol (1:1) mixture using the Henderson-Hasselbach equation. It was shown that the 8-hydroxyquinolinic fragment has a large electron donor effect on the π system of the chalcones. The introduction of substituents (R) in the phenyl fragment of the chalcones slightly affected the dissociation of the hydroxyl group and the protonation of the nitrogen in the hydroxyquinoline fragment. The acceptor substituents (Cl, Br, NO2) increased the polarity of OH- and its acidity. Nitrogen protonation decreased electron donor properties of this fragment, and deprotonation of the hydroxyl caused the opposite effect. Substituents introduction in the phenyl fragment slightly affected hydroxyl group dissociation and nitrogen protonation.

Sign in / Sign up

Export Citation Format

Share Document