Rate constant measurements for radical addition reactions with C60 by means of time-resolved EPR and spin-echo detected pulsed EPR spectroscopy

[Display omitted] •Time-resolved EPR spectra of adducts were measured in C60 and radical reactions.•Addition reaction rate constants of C60 were measured by spin-echo detected EPR.•It was confirmed that C60 is a good radical scavenger with large rate constants.•Semi-empirical analysis on the reaction rates was made. C60 fullerene shows high reactivity with free radicals and is considered as a radical trapping agent. Addition reaction of radicals to C60 was investigated by time-resolved Electron Paramagnetic Resonance (TR-EPR) and pulsed EPR methods. The structures of adduct radicals were determined by TR-EPR, and the reaction mechanism was clarified. Addition rate constants, k's of radicals to C60 were measured by the electron spin echo detection method utilizing pulsed EPR. The measured k values were remarkably high and the reactions are diffusion-controlled. We discussed activation energy on the basis of the charge transfer effect and enthalpy change.