Nitroxides. LII. Synthesis and electron spin resonance studies of N,N'-dioxy-2,6-diazaadamantane, a symmetrical ground state triplet

Dupeyre, Rose-Marie; Rassat, A.; Ronzaud, Jacques

doi:10.1021/ja00828a004

Cited by 70 publications

(25 citation statements)

References 3 publications

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“…That leaves either the distant nitrogen or the protons on the distant bridgehead carbons as unresolved contributions to the linewidths. Rassat and co-workers prepared the closely-related radical 4 as a precursor to a diradical and commented on the extensive well-resolved hyperfine splitting [7]. They assigned the hyperfine couplings based on the symmetry of the molecule and by integration of the peaks in the paramagnetic NMR spectrum.…”

Section: Resultsmentioning

confidence: 99%

Azaadamantyl nitroxide spin label: complexation with β-cyclodextrin and electron spin relaxation

Rajca

Yang

Eaton

2017

Free Radical Research

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An iodoacetamide azaadamantyl spin label was studied in fluid solution and in 9:1 trehalose:sucrose glass. In 9:1 toluene:CH2Cl2 solution at 293 K the isotropic nitrogen hyperfine coupling is 19.2 G, T1 is 0.37 μs and T2 is 0.30 to 0.35 μs. Between about 80 and 150 K 1/Tm in 9:1 trehalose:sucrose is approximately independent of temperature demonstrating that the absence of methyl groups decreases 1/Tm relative to that which is observed in spin labels with methyl groups on the alpha carbons. Spin lattice relaxation rates between about 80 and 293 K in 9:1 trehalose:sucrose are similar to those observed for other nitroxide spin labels, consistent with the expectation that relaxation is dominated by Raman and local mode processes. Although complexation of the azaadamantyl spin label with β-cyclodextrin slows tumbling in aqueous solution by about a factor of 10, it has little impact on 1/T1 or 1/Tm in 9:1 trehalose:sucrose between 80 and 293 K.

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Section: Resultsmentioning

confidence: 99%

Azaadamantyl nitroxide spin label: complexation with β-cyclodextrin and electron spin relaxation

Rajca

Yang

Eaton

2017

Free Radical Research

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“…The suggestion that organic ferromagnets may be obtained from ground-state triplets [4] projects some light on the situation. Assuming that Hund's rule is still valid at the molecular level, it becomes clear that any system with two electrons in a degenerate shell should be a triplet ground state [5]. Dioxygen is a well-known example, and diatomic molecules with 12 valence electrons behave in the same way [6].…”

Section: Introductionmentioning

confidence: 99%

Chirality and spin density: Ab initio and density functional approaches

Fluekiger

Weber

Chiarelli

et al. 1993

Int J of Quantum Chemistry

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The spin distribution in a stable nitroxide biradical that shows ferromagnetic interactions in the solid phase has been studied at three levels of theory: First, at the UHF level; then, including correlation effects in U M P~ calculations; and finally, the results are compared with the spin density obtained using the local density functional (LDF) approximation. It is shown that LDF spin densities are closer to U M P~ than to UHF predictions; the difference between the UHF and the ( U M P~, LDF) results points to a redistribution of the spin repartition between N and 0 due to electronic correlation. For planar conformations of the NO group, there is symmetric distribution ( D u ) of the spin density on the adamantane skeleton. For nonplanar nitroxides, the molecule is chiral ( C * ) , which results in a breakdown of the spin transmission on part of the adamantane cage. 0 1993 John Wiley & Sons, Inc.

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“…The methods of calculating the zero-field splitting are reported in the literature [4][5][6][7][8]. Taking into account delocalization of spin density the component D is calculated by using the expression for the element of the dipole-dipole interaction matrix [5,7] :…”

Section: Introductionmentioning

confidence: 99%

Calculation of the geometry of the complex of spatially hindered quinones and phenols from E.S.R. spectra of radical pairs

et al. 1978

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Geometry of the binary complex of 3,6-di-t-butyl-o-quinone and 2,4,6-tri-t-butyl phenol is investigated. Photolysis of this system produces two types of radical pairs with unequal zero-field splitting tensors. The values of the components, D and E, for each type of radical pair were calculated by diagonalizing the dipole-dipole interaction matrix; the elements of this matrix were calculated by using spin density distributions, either known from the experiment or obtained theoretically. The four parameters (three coordinates of the centre of the benzene ring in the phenoxy radical, and one Euler angle) were found by variational search techniques, through comparing the experimental and calculated values of the zero-field splittings. It is shown that benzene rings of the two radicals are displaced with respect to one another by approximately 1'6 .~ and rotated relative to one another by 86"5 ~ . This configuration is interpreted in terms of interaction between the t-butyl groups, hydroxyl and carbonyl groups.

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Nitroxides. LII. Synthesis and electron spin resonance studies of N,N'-dioxy-2,6-diazaadamantane, a symmetrical ground state triplet

Cited by 70 publications

References 3 publications

Azaadamantyl nitroxide spin label: complexation with β-cyclodextrin and electron spin relaxation

Azaadamantyl nitroxide spin label: complexation with β-cyclodextrin and electron spin relaxation

Chirality and spin density: Ab initio and density functional approaches

Calculation of the geometry of the complex of spatially hindered quinones and phenols from E.S.R. spectra of radical pairs

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