Fullerene magnetic properties

Volume 3 contains 16 chapters dealing with photoelectron spectroscopy, spectroelectrochemistry, crystallography scanning force microscopy, optically detected magnetic resonance studies of conductive polymers and fullerenes, magnetic properties, microwave properties, electrochemistry, electrocatalytic properties, metallic properties of conductive polymers due to dispersion, thin film properties of oligothiophenes, electrochromism, thermochromism, solvatochromism, degradation and stability of conductive polymers. 

Also, novel magnetic properties have been reported in mixed fullerene composites, in which the fullerene is limited... 

In particular for fullerenes, antioxidant properties and photodynamic activity are presented in detail, together with the analysis of gadolinium endohedrals as magnetic resonance imaging (MRI) contrast agents. Moreover, drag delivery based on carbon nanomaterials has been illustrated. 

It was discovered, however, that the spherical aromaticity of the icosahedral fullerenes C20, Cjq and CgQ depends on the filling of the Jt-sheUs with electrons [107]. As pointed out in Section 14.3.1 no distortion of the cage structure is expected in these fullerenes if their shells are fully filled. Closed-shell situations are realized if the fullerene contains 2(N -1-1) Jt electrons. This is closely related to the stable noble-gas configuration of atoms or atomic ions [108]. In this case the electron distribution is spherical and all angular momenta are symmetrically distributed. Correlation of the aromatic character determined by the magnetic properties is shown in Table 14.3. 

Rare earth endohedral metallofullerenes are an interesting class of full-erenes because electron transfer from the encaged metal atom to the carbon cage has been known to occur and this dramatically alters electronic and magnetic properties of the fullerenes. 

La Cs2 was 0.38 (iB, equivalent to 0.22 of an electron spin per fullerene molecule. This is quite different from the value of 1.0 which would be expected for S = 1/2 La Cs2- A similar magnetic property for Gd Cs2 has been obtained by Dunsch et al. (1988b) the susceptibility follows a Curie law and the magnetization can be described by a Brillouin fimction. They also reported that the two Eu fullerenes, Eu C74 and Eu Cs2/ show the same M H/T) magnetic behavior as that of Gd Cs2 if all magnetization values are normalized to the saturation magnetization at high fields. 

An interesting offshoot in the context of carbon-based nanomaterials is the role of external perturbations in modulating their physical and chemical characteristics. These perturbations can include cations or neutral atoms. In this context, we examined the magnetic properties of exohedral fullerenes of alkali metal fullerides (Aj,-C6o. A = Na, K, Rb, Cs) [148-150] and the spin properties of endohedral fullerenes (A C6o, A = N, P, As, O, S) [128,151] (Fig. 34.11). The most interesting aspect of the experimental... 

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