Structural and electronic properties of radialenes and related systems

The discovery of new allotropic forms of carbon gives rise to a great interest in carbon compounds as building blocks for novel nanostructure materials. Radialenes are homologous series of compounds with a cycloalkane nucleus bound to methylene side groups, with molecular formula CnHn. The series of expanded radialenes of molecular formulae C2nHn and C3nHn are obtained by inserting acetylene or diacetylene groups between each pair of methylene units. This paper is a report on the theoretical study of structural, electronic and spectroscopic properties of radialenes, expanded radialenes and related molecular systems. Using semiempirical methods we explore the behavior of π-electrons along the carbon-rich skeleton. The results for structural parameters are in a good agreement with the available experimental data. The calculated electronic gaps and spatial distribution of frontier orbitals indicate to interesting electrical and nonlinear optical properties of the explored compounds, which may be useful for technological applications.