Spectroscopic Splitting Factors in Aromatic Radicals

McConnell, Harden M.; Robertson, Richard E.

doi:10.1021/j150553a048

Cited by 198 publications

(146 citation statements)

References 7 publications

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“…Nitrogen heterocycle radicals likewise have the typically small wx-radical g shifts, bgiI < 0.01 (21). Moreover, one expects AgdI > bg I I I 0 for a planar -r radical, contrary to observation for ES (22). Finally, through calulations such as those of Schulz et al (23) one may show that spin-coupling between the S = 1 heme and a radical cannot produce the observed g values.…”

Section: Methodsmentioning

confidence: 81%

Electron-nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase: identification of the free radical site with a methionyl cluster.

Hoffman¹,

Roberts²,

Brown³

et al. 1979

Proc. Natl. Acad. Sci. U.S.A.

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The results of electron-nuclear double resonance and electron paramagnetic resonance (EPR) studies on the hydrogen peroxide compound of yeast cytochrome c peroxidase are inconsistent with previous proposals for the source of the EPR signal in this compound, in particular with its identification with an aromatic amino acid radical such as would arise by oxidation of a tryptophanyl side chain. The present observations lead us to propose that the EPR signal is associated with a cluster containing at least one methionine and in which proximate side chains share the charge created by loss of one electron.

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Section: Methodsmentioning

confidence: 81%

Electron-nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase: identification of the free radical site with a methionyl cluster.

Hoffman¹,

Roberts²,

Brown³

et al. 1979

Proc. Natl. Acad. Sci. U.S.A.

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“…The synthetic pathway which furnished the target compounds is shown in Scheme 1. 2,6-Diarylpiperidin-4-ones 1-10 were prepared by the method of Noller and Baliah 27 while their corresponding chloroacetyl derivatives (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) were prepared by adopting our earlier report. 3 General procedure for the synthesis of compounds 21-30 The compounds were prepared by adopting the earlier method.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, structural and antimicrobial studies of some 1-[2-(1H-benzimidazol-1-yl)acetyl]-2,6-diarylpiperidin-4-ones

Aridoss¹,

Amirthaganesan²,

Kim³

et al. 2008

Arkivoc

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A series of 1-[2-(1H-benzimidazol-1-yl)acetyl]-2,6-diarylpiperidin-4-ones (21-30) has been synthesized under mild conditions in good yield. Structural assignments and conformational analysis of the compounds were established through one-( 1 H and 13 C) and two-dimensional (NOESY and HSQC) NMR studies. A significant upfield shift of proton and carbon at position 'g' of the benzimidazole moiety and phenyl ortho protons of the piperidone system is considered to originate from the anisotropic influence of the suitably positioned π bond containing amide carbonyl group. Dynamic NMR studies proved the existence of restricted rotation and coplanarity of the amide N-C=O carbonyl group and was further confirmed by X-ray crystallographic study of 20. Besides, the rotomers resulting from restricted rotation undergo fastest interconversion on NMR time scale at ambient temperature while at low temperatures, slow exchange occurs leading to a set of signals corresponding to cis and trans rotomers with perfectly equal intensity. The possible factors for the non-broadening of the benzimidazole signals even at very low temperature is explained through dynamic NMR studies. Mass spectral studies indicate a common mode of cleavage among the symmetrically and unsymmetrically substituted analogues. Measurement of antimicrobial activity showed that compounds 23, 24 and 25 exhibited a better activity profile towards the tested microbial strains.

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“…In particular, pseudocontact chemical shifts (PCS) induced by lanthanide complexes are commonly described by McConnell's long-range relation (SI units), [2]   22 3 1 3cos 1 3 sin cos 2 12…”

Section: Beyond Bleaney's Theory: Experimental and Theoretical Analysmentioning

confidence: 99%

Beyond Bleaney's Theory: Experimental and Theoretical Analysis of Periodic Trends in Lanthanide‐Induced Chemical Shift

et al. 2017

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A detailed analysis of paramagnetic NMR shifts in a series of isostructural lanthanide complexes relavant to PARASHIFT contrast agents reveals unexpected trends in the magnetic susceptibility anisotropy that cannot be explained by the commonly used Bleaney's theory. Ab initio calculations reveal that the primary assumption of Bleaney's theory—that thermal energy is larger than the ligand field splitting—does not hold for the lanthanide complexes in question, and likely for a large fraction of lanthanide complexes in general. This makes the orientation of the magnetic susceptibility tensor differ significantly between complexes of different lanthanides with the same ligand: one of the most popular assumptions about isostructural lanthanide series is wrong.

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Spectroscopic Splitting Factors in Aromatic Radicals

Cited by 198 publications

References 7 publications

Electron-nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase: identification of the free radical site with a methionyl cluster.

Electron-nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase: identification of the free radical site with a methionyl cluster.

Synthesis, structural and antimicrobial studies of some 1-[2-(1H-benzimidazol-1-yl)acetyl]-2,6-diarylpiperidin-4-ones

Beyond Bleaney's Theory: Experimental and Theoretical Analysis of Periodic Trends in Lanthanide‐Induced Chemical Shift

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