Error Analysis of the Determination of Spin Concentration with the Electron Spin Resonance Method

Casteleijn, G.; Bosch, Jeroen; Smidt, J.

doi:10.1063/1.1656979

Cited by 33 publications

(18 citation statements)

References 11 publications

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“…For longer samples, L Å 40 and 50 mm, B). The agreement between theory and experiment is good in all cases and any deviations can be attributed to the pres-optimized values for I pp correspond to the sample center, S c (L/2), being shifted below the physical center of the ence of the sample access holes (17, 24), the compression field effect (5,19), and nonuniformity of both the micro-cavity. wave and the modulation fields (13,17,18) which were not Some of the above experiments were repeated using the included in the theoretical function.…”

Section: Resultsmentioning

confidence: 95%

“…cavity (5,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and serious systematic errors may be in-(3) The sample was inserted at the bottom of the active curred in quantitative EPR spectroscopy if samples with difpart of the cavity, S L (L) å P out , and then moved up to the ferent lengths or internal diameters are compared. These upper boundary of the cavity, S 0 (0) å P in .…”

Section: Resultsmentioning

confidence: 99%

“…See, for point-like samples were prepared by making cylindrical samples with a material column length 1.3 mm and i.d. 1.3 mm example, (5,13,17,18).…”

Section: Rectangular Cavitymentioning

confidence: 97%

“…Howlengths from 5 to 20 mm; (ii) a plateau, over which the EPR signal ever, in practice, experimental analysis of the same sample intensity remained constant within experimental errors of 0.26-in different laboratories produced results which in the worst tary cavity of the double TE 104 cavity caused an additional defor-the microwave cavity. These criteria are in practice only mation of the signal intensity for a 30-mm sample which was fulfilled for a point-like sample (4,5,(13)(14)(15)(16)(17)(18)(19). However, moving in the first cavity.…”

mentioning

confidence: 99%

“…), which is filled by the liquid, or powdered material to Cylindrical samples to be compared should be of identical length produce column lengths varying from 5 to 50 mm or more. (2,5,(17)(18)(19) In quantitative EPR it is sometimes necessary to compare the unknown cylindrical sample (with a variable length) …”

mentioning

confidence: 99%

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Analysis of the Movement of Line-like Samples of Variable Length along theX-Axis of a Double TE104and a Single TE102Rectangular Cavity

Mazúr

Morris

Valko

1997

Journal of Magnetic Resonance

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

“…See, for point-like samples were prepared by making cylindrical samples with a material column length 1.3 mm and i.d. 1.3 mm example, (5,13,17,18).…”

Section: Rectangular Cavitymentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Analysis of the Movement of Line-like Samples of Variable Length along theX-Axis of a Double TE104and a Single TE102Rectangular Cavity

Mazúr

Morris

Valko

1997

Journal of Magnetic Resonance

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Tripyrrindione as a Redox‐Active Ligand: Palladium(II) Coordination in Three Redox States

et al. 2015

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The tripyrrin-1,14-dione scaffold of urinary pigment uroerythrin coordinates divalent palladium as aplanar tridentate ligand. Spectroscopic,structural and computational investigations reveal that the tripyrrindione ligand binds as ad ianionic radical, and the resulting complex is stable at room temperature.O ne-electron oxidation and reduction reactions do not alter the planar coordination sphere of palladium(II) and lead to the isolation of two additional complexes presenting different redox states of the ligand framework. Unaffected by stability problems common to tripyrrolic fragments,t he tripyrrindione ligand offers arobust platform for ligand-based redox chemistry.Redox-active (or redox non-innocent) ligands in coordination compounds can act as electron reservoirs,t hereby extending opportunities for multi-electron transformations beyond the redox chemistry of the metal center(s). Thedesign and study of such ligands is key to the engineering of new catalytic systems featuring additional pathways for redox reactivity.[1-4] Within biological catalysts,t he storage and release of redox equivalents on tetrapyrrolic ligands is critical in numerous heme enzymes including catalases and cytochrome P450 monooxygenases.S ynthetic tetrapyrroles,s uch as porphyrins, [5] corroles, [6][7][8] and bilins, [9,10] as well as expanded porphyrin macrocycles [11][12][13][14][15] and tetradentate bis(phenolate)-dipyrrins, [16] display rich ligand-based redox chemistry.Incontrast, the stabilization of unpaired electrons is not well documented for smaller dipyrrolic and tripyrrolic fragments.H erein, we describe the one-electron redox chemistry of astable tripyrrindione framework in palladium-(II) complexes.Conjugated tripyrroles are attractive ligand platforms, likely inheriting the exquisite electronic tunability of porphyrins while allowing access to the metal center for additional coordination in the plane of the ligand. Thec oordination chemistry of tripyrroles,h owever, suffers from limited stability of the ligands and complicated redox chemistry in the presence of transition metals (often leading to ligand deterioration).[17] Fori nstance,t ripyrrins (Scheme 1) are typically stable as protonated salts in neat trifluoroacetic acid, but decompose rapidly in the presence of nucleophiles. [18] In addition, tripyrrane [19] and tripyrrin-1-one [20] scaffolds,a sw ell as pyrrolyldipyrrin prodigiosin [21,22] (Scheme 1), undergo oxidative ligand degradation in the presence of Cu II ions. Atripyrrolic motif is found in the structure of ubiquitous urinary pigment uroerythrin (Scheme 1), which was first isolated in 1975 from the pool of pigments excreted in human urine and generically known as urochrome. [23,24] We reasoned that the tripyrrin-1,14-dione scaffold of this physiological product of heme degradation could serve as astable platform for metal coordination. In addition, the ability of tetrapyrrolic bilindione (i.e., an analog of heme metabolite biliverdin) to stabilize ligand-based radicals [9,25] prompted us to cons...

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Tripyrrindione as a Redox‐Active Ligand: Palladium(II) Coordination in Three Redox States

et al. 2015

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Error Analysis of the Determination of Spin Concentration with the Electron Spin Resonance Method

Cited by 33 publications

References 11 publications

Analysis of the Movement of Line-like Samples of Variable Length along theX-Axis of a Double TE104and a Single TE102Rectangular Cavity

Analysis of the Movement of Line-like Samples of Variable Length along theX-Axis of a Double TE104and a Single TE102Rectangular Cavity

Tripyrrindione as a Redox‐Active Ligand: Palladium(II) Coordination in Three Redox States

Tripyrrindione as a Redox‐Active Ligand: Palladium(II) Coordination in Three Redox States

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