La@C82 as a spin-active filling of SWCNTs: ESR study of magnetic and photophysical properties

Electron microscopy (TEM) and electron spin resonance (ESR) were applied to characterize lanthanum metallofullerence (La@C-82)-filled peapods. The peapods were prepared by encapsulation of La@C-82 in SWCNTs, which were obtained by laser ablation technique in the presence of non-magnetic catalysts Pt : Rh : Re. Empty fulerenes, C-60, were used as separators for the spin-active La@C-82. TEM analysis confirmed filling of peapods with both C-60 and La@C-82 molecules. ESR spectra acquired in the temperature range from 5 K to 295 K provided indirect evidence of encapsulation of the spin-active La@C-82 in carbon nanotubes and pointed to marked differences in magnetic properties of peapods as a function of the relative concentration of La@C-82. Preliminary ESR studies of the photo-physical properties of La@C-82 in CS2 revealed that, under illumination with white light, La@C-82 neither generated singlet oxygen nor was photoactive against a paramagnetic target, nitroxide (TEMPO). (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim