What Fullerene Is More Reactive Toward Peroxyl Radicals? A Comparative DFT Study on ROO^• Addition to C₆₀ and C₇₀ Fullerenes

Abstract

The structures of transition states and activation parameters of radical addition of ^tBuOO^• and Ph(CH₃)₂COO^• to the C₆₀ and C₇₀ fullerenes have been found by density functional theory method PBE/3ζ. Calculated by Eyring equation, the rate constants of the ^tBuOO^• addition to C₆₀ and C₇₀, equal to 100 and 18.9 L mol⁻¹ s⁻¹, respectively; in the case of the Ph(CH₃)₂COO^• addition, these are 14.5 and 17.7 L mol⁻¹ s⁻¹ (all reactions are in gas phase). The estimated inhibitor capacity of C₆₀ equals to 3.7–5.3. According to calculated rate constants, C₆₀ is more sensitive toward the structure of the peroxyls added. The calculated values agree with available experimental data on the reactions of these radicals with fullerenes. As follows from the calculated data, rate constants depend both on the nature of the fullerene and radical. The obtained data may be applied as reference values to the analysis of fullerene inhibition effect on the oxidation of organic compounds.

Keywords:

• fullerenes
• peroxyl radicals
• radical addition
• density functional theory
• rate constants

Acknowledgements

The work was supported by Russian Foundation for Basic Researches (project code 14-03-97050 r_povolzh'e_a).