Related Experiment Video
Updated: May 20, 2025

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow
Published on: April 24, 2014
X-band electron spin relaxation times for four aromatic radicals in fluid solution and comparison with other organic
Virginia Meyer1, Sandra S Eaton1, Gareth R Eaton1
1Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208.
Abstract:
X-band electron spin relaxation times of BDPA (1:1 α,γ-bisdiphenylene-β-phenylallyl), galvinoxyl 2,6-di-tert-butyl-α-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy, DPPH (2,2-diphenyl-1-picrylhydrazyl) and thianthrene radicals in fluid solution were measured by electron spin echo and inversion recovery at ambient temperature. Tumbling correlation times are estimated to be in the range of 20 to 30 ps. In this fast tumbling regime T 1 ~ T 2. Relaxation times are compared with previously reported values for symmetrically-substituted triarylmethyl, semiquinone, and nitroxide radicals. The concentration dependence of spin lattice relaxation for neutral BDPA in toluene is about 103 greater than for anionic trityl radicals in water. T 1 decreases in the order carbon-center BDPA > galvinoxyl > DPPH > thianthrene. The dominant relaxation mechanisms are proposed to be a local mode for BDPA, spin rotation, local mode and modulation of anisotropic proton hyperfine coupling for galvinoxyl, modulation of anisotropic nitrogen hyperfine for DPPH, and spin rotation plus modulation of anisotropic proton hyperfine coupling for thianthrene.
More Related Videos
08:01Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
Published on: September 26, 2016
09:25Author Spotlight: Exploring Intrinsically Disordered Protein Dynamics Through NMR Relaxation Experiments
Published on: November 1, 2024
Related Concept Videos
Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Radical Reactivity: Overview
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
Radical Reactivity: Steric Effects
Along with electronic...