Natural Fullerene-based Self-assemblies
aNanotechnology Department, Kaunas University of Technology, LITHUANIA
bSt Petersburg State University
cLithuanian Textile Institute
This is an abstract
for a presentation given at the
Foresight Conference on Molecular Nanotechnology
Shungite (Sh) are the black Precambrian rocks of Karelia (Russia) where the first natural occurrence of fullerenes was found. Carbon-rich Sh - a natural composite with a submicronic degree of uniformity in distribution carbon and mineral components that allows to consider them as metastable solid solutions. Presence of fullerenes and aluminosilicate components in such Sh supposes a wide spectrum of catalytic transformations of substance. Various types of the substance organization during concentrating of the water - carbon disulfide shungite-extracts are considered. The organization of fullerene-like quasi-crystall particles from icosahedral composite molecules of type a core C60 - shell S42 structure is shown in . At a final stage of such particle origin the stress crack are formed and the recrystallization of substance as a film polycrystal (the upper optical micrograph) by account of high concentration CS2 inside a shell is possible.
The globular organization of aluminosilicate component alsow is possible. The result of crystallization of the body-porous globules in the form of foam-like particles is expressed on the lower optical micrograph. Such formations were observed for water-soluble zeolites. C60 extracting from foam particles as well as difference between volumes of initial and final phases allow to assume, that such globules are constituted from supramolecular centres of a core - shell type. The metastability of the foam particles stucture with carbon adsorbate (change of their form and decrease of fractal dimensionality) corresponds to mutual influence of adsorbate and adsorbent structures.
One of results of concentrating the colloidal solution received by anode etching of Sh with carbon more of 95 wt. % is a formation of threadlike particle with characteristic attributes vapor-liquid-solid (VLS) crystallization, but with vitreous shearing cut in orthogonal section ( the middle optical micrograph). Dissolution of the fullerene-containing cathodic deposit and the presence in a colloid solution essentially grafite-like particles with the linear sizes about 3x3 nm allows to assume, that the element of self-similarity of a threadlike particle is a composite macromolecule from dimer C60 with twisted on it a graphite-like claster. Plural thickenings along of a threadlike particle axis testify to inclusion and following diffusion concentrating of carbon black, that is possible only for linear molecules. Thus, the cathodic deposit represents the aggregate of composite molecules of a core-shell type. Such model is coordinated with catalityc synthesis of varible composition carbon monosulfides  directly on a fullerene surface at presence of labile sulfur.
Also the other forms of substance organization are demonstrated, in particular, threadlike carbon, carbon monosulfide and metal crystals, which formations is possible only at participation of a molecular sorbent and the catalytic agent.
Thus, the general property of observably types of substance organization is the VLS mechanism of the growth of new phases and the basic role of fullerenes in selective molecular self-assembly.
- Osipov EV, Reznikov VA, Carbon, 2002; 40, Issue 6, p.961-5.
Eduard V. Osipov
Nanotechnology Department, Kaunas University of Technology
Musninku 5-9, Vilnius LT-2010 LITHUANIA
Phone: +370-5-412466 Fax: +370-7-308668