Fullerene C60 conjugated with N,N-dimethylaniline - a hybrid antioxidant acting at high temperature

Fullerene derivative, N-methyl-2-[4-(dimethylamino)phenyl]-3,4-[60]fulleropyrrolidine (F-DMA), was prepared and its antioxidant activity was tested by means of Differential Scanning Calorimetry during non-isothermal oxidation of stearic acid (STA) as a model of saturated lipid. Temperature of the start of oxidation and the overall Arrhenius kinetic parameters (activation energy Ea, pre-exponential factor Z, and rate constants k) of oxidative decomposition indicate that F-DMA is effective antioxidant a cting at temperatures above 150°C, with temperature of start of oxidation 12-19C higher and with smaller k (two-fold and three-fold at 150 and 200C, respectively) than for oxidation of noninhibited pure STA. On the other hand, the experiments with peroxidation of cumene at 30C indicate that F-DMA is not efficient trap for peroxyl radicals (no inhibition or retardation effect). We suggest that F-DMA is able to inhibit high temperature STA autoxidation due to trapping alkoxyl radicals by C60 core, with additional participation of tertiary amine moieties as chain-breaking agents, whereas autoxidation of cumene is mediated by peroxyl radicals that are not effectively scavenged by any part of F-DMA.