Fullerene-type compounds

Another important group of fullerene-related compounds are the carbon nanotubes, the reference compounds of the carbon nano-science. They may be obtained by convenient variations of the preparation procedure mentioned. These are long tubular fullerenes with a concentric shell structure a few nanometres wide and often capped with C60-like hemisphere or faceted tips. They are mechanically very strong and either metallic conducting or semiconducting types have been obtained. 

The compounds with the highest electron mobility are currently fullerene C60 [81, 82] and N,N4-dialkyl-3,4,9,10-perylene tetracarboxylic diimide derivatives [83, 84], with values up to 0.5 cm2 V 1 s 1. A major problem with these compounds is their high sensitivity to ambient conditions, especially oxygen and moisture. A small number of air-stable n-type compounds have been reported [85-88]. All are perfluorinated and their mobility does not exceed a few tenths of 1 cm2 V 1 s 1. 

In the case of Vaska-type compounds, (Ir(CO)(PR3)2Cl), it has proved possible to form different adducts by varying either the fullerene or phosphine used [Eqs. (5)-(7)] U3,14, 28,29, 33) ... 

As immense pi systems, fullerenes were recognized early as ligands to transition metals. Fullerene-metal compounds have been prepared for a variety of metals. These compounds fall into several structural types ... 

It is possible to place electrochemi-cally active transition metal centers in the branches of the dendrimers, and many researchers have investigated dendritic macromolecules with organic redox-active moieties in the dendritic branches. Some of the redox-active organic species that have been incorporated include quinone and quinone-type compounds, TTF, fullerenes, and others. The wide variety of organic groups that can be used in such dendrimers makes this a growing area of investigation. 

Bis(zinc porphyrin)-oxoporphyrinogen [(ZnTPP)2-OxP] is an example of a donor-acceptor-type triad. Excitation of the zinc porphyrin gronps leads to an efficient energy or electron transfer in the triad and this process depends on the polarity of the solvent used. Further elaboration of this system was accomplished by complexing this compound and other derivatives with fullerene-containing compounds capable of coordinating at the porphyrin zinc metal ions. The structures of the complexes are shown in Figure 14. 

FIGURE P.6 Fullerene Cg type compounds crystal (up) and a sample from a nanotube (down). ... 

Now and then, projectiles from outer space cause excitement and surprises, as in January 2000, when a meteorite impacted the frozen surface of Lake Targish in Canada. It was a new type of C-chondrite with a carbon concentration of 4-5%, and probably came from a D-type asteroid (Hiroi et al., 2001). More exact analysis of the Targish meteorite showed the presence of a series of mono- and dicarboxylic acids as well as aliphatic and aromatic hydrocarbons (Pizzarello et al., 2001). Aromatic compounds and fullerenes were detected in the insoluble fraction from the extraction this contained planetary helium and argon, i.e., the 3He/36Ar ratio was... 

Cycloaddition with nitrile oxides occur with compounds of practically any type with a C=C bond alkenes and cycloalkenes, their functional derivatives, dienes and trienes with isolated, conjugated or cumulated double bonds, some aromatic compounds, unsaturated and aromatic heterocycles, and fullerenes. The content of this subsection is classified according to the mentioned types of dipolarophiles. Problems of relative reactivities of dienophiles and dipoles, regio- and stereoselectivity of nitrile oxide cycloadditions were considered in detail by Jaeger and... 

Lattice parameter determination, diffractometers in, 26 428 Lattice polymers, fullerene, 12 250, 251 Lattice-type inclusion compounds,... 

Silylmethylation of fullerenes can be achieved by Grignard reaction of Cjq with Me2Si(0 Pr)MgCl (Scheme 3.4). Two different types of silylmethylated 1,2-fullerene adducts are formed [8]. The use of different solvents leads either to the 1,2-product 12 or to the unprecedented 1,4-addition product 13. These compounds react easily with various alcohols or phenols, which makes silylmethylated fullerenes a versatile starting material for regioselectively defined fullerene compounds [10]. Some examples are shown in Scheme 3.4. 

A multicomponent approach for synthesizing ionic fullerene compounds Di Dn (fuUerene) is very effective in developing various functional and structural fullerene CT solids, including a- and re-type dimers of fullerenes and an ry-type... 

---