Polarizability of C60 fullerene dimer and oligomers: the unexpected enhancement and its use for rational design of fullerene-based nanostructures with adjustable properties

Abstract

The high polarizabilities of fullerene and its derivatives cause peculiarities in various physical and chemical processes in fullerene-containing systems. Their polarizabilities have been found to be efficient parameters for the design of nanostructures with desirable behavior. Unfortunately, the appropriate experimental data are scarce for most of the fullerene derivatives, due to their low availability or possible dissociation. At the same time, such information may be useful for C₆₀-based nanotechnologies. We point our attention to the fullerene dimer and oligomers, which are novel and very promising compounds for nano-applications. We have performed the first density-functional theory study on the polarizability of fullerene derivatives (C₆₀)_n (n = 1–5) to elucidate how their structure affects the polarizability. In contrast to the concept of additivity, common in physical chemistry, the mean polarizability of (C₆₀)_n nonlinearly depends on the number of fullerene cores in their molecules, i.e. it violates the additivity. Similar to the other positive deviations from additive schemes, it has been called exaltation of polarizability. This effect is a result of the interaction of the π-electronic systems of fullerene cores in (C₆₀)_n and increases with their maximal remoteness. Experimental evidence of the exaltation is discussed. Thus, it agrees well with the enhancement of the polarizability of crystalline forms of C₆₀ compared to molecular ones measured previously. Also, we have found a strong correlation between the calculated exaltations and the chemical properties of isomeric (C₆₀)₃, (C₆₀)₂ and its derivatives observed experimentally. The predicted enhancement has not been described previously and may be widespread among various nanostructures (for example, dimers of bowl-shaped hydrocarbons or other fullerenes). Insights into possible applications of the polarizability and its anisotropy to the molecular design and molecular machinery have been provided.