Theoretical Structural and Spectral Analyses of TEMPO Radical Derivatives of Fullerene

The spectroscopic properties of the 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) radicalderivatives of the fullerene (C60) were theoretically investigated. The ground state optimizedstructures of the radical adducts of the fullerene were calculated by using DFT (B3LYP) with 6-31G(d) level. It was concluded that a 6-6 ring junction of C60 moiety generally covalently links to thepiperidine ring of the TEMPO derivatives, directly. The optimization characteristics of all thefullerene radical derivatives indicate generally a annulene structure while C60+TEMPO indicate acyclopropane structure which is formed by the link of the carbon of the piperidine ring doubly to a 6-6 ring junction of C60. The calculated isotropic hyperfine coupling constants, vibrational frequenciesand UV- Vis transition energies of all the radical adducts were seen to be in good agreement with thecorresponding experimental data. The UV-Vis transitions and their energies were determined withcorresponding to the experimental values. In the IR analysis the shifts of vibrational frequencies havebeen commented by comparison with those belonged to the pure C60. Also the some selectedgeometrical parameters with together the cage width and the cage length for the ground stateoptimized structures of all the radical adducts were listed, and the binding energies of the radicalswere obtained.