Electrochemical behaviour and ESR spectra of nitro substituted mono- and dibenzoylmethylenebenzthiazolines and selenazolines

1979 ◽  
Vol 44 (5) ◽  
pp. 1540-1551 ◽  
Author(s):  
Jaro Komenda ◽  
Jiří Huzlík
Keyword(s):  
Electron Transfer ◽  
Esr Spectroscopy ◽  
Electrochemical Behaviour ◽  
Spectroscopic Studies ◽  
Esr Spectra ◽  
Slow Electron

Compounds of the type of 2-(4'-nitrobenzoyl)methylene-3-ethylbenzothiazoline (I) and 2-bis-(p-nitrobenzoyl)methylene-3-ethylbenzothiazoline (II) were studied polarographically and by ESR spectroscopy to obtain informations about their electrochemical and follow-up reactions and their conformation. Whereas with compounds of the type I the conjugation in their molecules is preserved, with type II the coplanarity of the molecules is disturbed, which is manifested in the values of the splitting constants of the ESR spectra and a slow electron transfer between both nitrophenyl substituents. These conclusions are supported by NMR spectroscopic studies.

Association of radical anion with alkali cations. IV. ESR study of the 4-nitrobenzophenone radical anion

1980 ◽  
Vol 45 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ
Keyword(s):  
Hyperfine Splitting ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Supporting Electrolyte ◽  
Esr Spectra ◽  
Proton Donor ◽  
Alkali Cations

The 4-nitrobenzophenone radical anion prepared by electrolysis was studied by ESR spectroscopy. On the basis of the interpretation of ESR spectra, the conformation of this system was estimated. The effect of the concentration of supporting electrolyte and of the presence of a proton-donor agent (C2H5OH) was examined. It is assumed that changes in hyperfine splitting constants are caused by association.

Electron transport in clay-modified electrodes: study of electron transfer between electrochemically oxidized tris (2,2′-bipyridyl) iron cations and clay structural iron(II) sites

1992 ◽  
Vol 70 (6) ◽  
pp. 1833-1837 ◽  
Author(s):  
Yan Xiang ◽  
Gilles Villemure
Keyword(s):  
Electron Transfer ◽  
Modified Electrodes ◽  
Quantitative Relation ◽  
Cyclic Voltammograms ◽  
Slow Electron ◽  
Cathodic Current ◽  
Peak Current ◽  
Scan Speed ◽  
Anodic Peak Current ◽  
Structural Iron

The cyclic voltammograms of tris (2,2′-bipyridyl) iron(II) ([Fe(bpy)3]2+) adsorbed in clay-modified electrodes made from a range of different smectites were recorded. In all cases, at low scan speed (1 mV/s), the initial anodic peak current was much larger than the initial cathodic peak current. Partial reduction of the clay structural iron further increased the initial anodic to cathodic current ratio, suggesting that the discrepancy between the charge transferred in the anodic and cathodic scans was due to a slow electron transfer between the clay structural Fe(II) and the oxidized bipyridyl cations. However, no clear quantitative relation was found between the measured FeO contents of the different clays and the observed excess anodic currents. In fact, of all the clays tested only one, montmorillonite SWy-1, contained enough Fe(II) for it to account for all of the excess anodic charge transferred in the initial scan.

Darstellung und Redoxverhalten aller bindungsisomeren Hexakis(thiocyanato(N)-thiocyanato(S))-osmate(III) und (IV), [Os(NCS)n(SCN)6-n]3-/2-, n = 0—6, einschließlich der Stereoisomeren / Preparation and Electrochemical Behaviour of All Bond-Isomeric Hexakis(thiocyanato(N)-thiocyanato(S))osmates(III) and (IV), [Os(NCS)n(SCN)6-n]3-/2-, n = 0—6, Including Stereoisomers

1988 ◽  
Vol 43 (4) ◽  
pp. 382-388 ◽  
Author(s):  
K. Bütje ◽  
W. Preetz
Keyword(s):  
Electron Transfer ◽  
Electrochemical Behaviour ◽  
Deae Cellulose ◽  
Transfer Reactions ◽  
Cyclic Voltammograms ◽  
Geometric Isomers ◽  
Cellulose Oxidation ◽  
Half Wave ◽  
Complete Series ◽  
Back Donation

AbstractThe first two complete series of all 10 possible linkage and geometric isomers of the general formula [Os(NCS)n(SCN)6-n]3-/2- have been obtained. The Os(III) complexes, some of which have been previously known, are prepared from the reactions of K2[OsX6], X = Cl. Br. I, and K2[OsO2(OH)4] with excess aqueous or methanolic KSCN solution and subsequent chromato­graphic separation on DEAE cellulose. Oxidation with Ce(IV) in acetone or methanol yields the corresponding Os(IV) compounds without changes in the ligand sphere except for n = 0, but pure salts of [Os(SCN)6]2“ are isolated by repeated recrystallization. S-bonding is less favoured in Os(IV) than in Os(III), proving that Os(IV) is the harder Lewis acid. Cyclic voltammograms of all isomers show two waves, a mainly irreversible Os(II)/Os(III) couple and a reversible Os(III)/Os(IV) couple. Characteristic shifts of the half-wave potentials of both electron transfer reactions within the series give strong evidence of π-back donation to -NCS.

Electrochemistry of Redox Active Centres Encapsulated by Non-Covalent Methods

2010 ◽  
Vol 63 (2) ◽  
pp. 184 ◽  
Author(s):  
Suresh Gadde ◽  
Elizabeth K. Batchelor ◽  
Angel E. Kaifer
Keyword(s):  
Electron Transfer ◽  
Direct Electron Transfer ◽  
Electrochemical Behaviour ◽  
Research Work ◽  
Transfer Reactions ◽  
Molecular Receptors ◽  
General Terms ◽  
Redox Active ◽  
Wide Range ◽  
Active Centres

This manuscript presents a summary of recent research work on the electrochemical behaviour of redox active guests fully or almost fully encapsulated by suitable molecular receptors or molecular capsules. From the standpoint of their voltammetric behaviour the cyclodextrins have been shown to be very dynamic hosts, which hamper the observation of direct electron transfer to/from their inclusion complexes. Therefore, this Review is essentially concerned with research work on cucurbituril and cavitand-type hosts, which was mostly done in the author’s laboratory. In general terms, the observed voltammetric behaviour for encapsulated guests covers a wide range of possibilities. Cucurbituril and cavitand-type hosts afford more kinetically stable complexes, whose direct electrochemical behaviour is observable and tends to be kinetically slower than that of the free guests. However, the degree of kinetic attenuation varies over a wide range and, in some cases, challenges our ability to rationalize the data. Clearly, more variation in the host structures and more research work are required to improve our understanding of encapsulation effects on these electron transfer reactions.

scholarly journals Statistical detection of a tidal stream associated with the globular cluster M68 using Gaia data

2019 ◽  
Vol 488 (2) ◽  
pp. 1535-1557 ◽  
Author(s):  
Carles G Palau ◽  
Jordi Miralda-Escudé
Keyword(s):  
Globular Cluster ◽  
Milky Way ◽  
Spectroscopic Studies ◽  
Dark Halo ◽  
General Catalogue ◽  
Tidal Stream ◽  
Statistical Detection ◽  
Tidal Streams ◽  
North Galactic

ABSTRACT A method to search for tidal streams and to fit their orbits based on maximum likelihood is presented and applied to the Gaia data. Tests of the method are performed showing how a simulated stream produced by tidal stripping of a star cluster is recovered when added to a simulation of the Gaia catalogue. The method can be applied to search for streams associated with known progenitors or to do blind searches in a general catalogue. As the first example, we apply the method to the globular cluster M68 and detect its clear tidal stream stretching over the whole North Galactic hemisphere, and passing within 5 kpc of the Sun. This is one of the closest tidal streams to us detected so far, and is highly promising to provide new constraints on the Milky Way gravitational potential, for which we present preliminary fits finding a slightly oblate dark halo consistent with other observations. We identify the M68 tidal stream with the previously discovered Fjörm stream by Ibata et al. The tidal stream is confirmed to contain stars that are consistent with the HR-diagram of M68. We provide a list of 115 stars that are most likely to be stream members, and should be prime targets for follow-up spectroscopic studies.

An ESR and calorimetric study of iron oolitic samples from the Northampton ironstone

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 303-311 ◽  
Author(s):  
A. U. Gehring ◽  
R. Karthein
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Esr Spectroscopy ◽  
Thermal Conversion ◽  
Esr Spectra ◽  
Calorimetric Study ◽  
Calorimetric Methods ◽  
Mineral Phases ◽  
Spin Resonance

AbstractElectron spin resonance (ESR) spectroscopy and calorimetric methods were used to characterize conversion processes in multimineral samples from the Northampton ironstone (NIS) at temperatures between 25°C and 800°C. The beginning of the thermal conversion processes can be determined by the formation of asymmetric ESR spectra with g ≈ 2 at 250°C. The breakdown of the berthierine structure between 250°C and 520°C is indicated by the disappearance of the hyperfine splitting in the Mn2+ spectrum and the formation of magnetite. The decomposition of siderite and calcite was found by calorimetric methods at 580°C and 700°C, respectively. The hematite formation between 550°C and 800°C is explained by the decomposition of siderite but also by the oxidation of previously formed magnetite. The occurrence of hematite as the dominant ferric oxide at 800°C signifies the end of the conversion process of the major mineral phases in the NIS samples.

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