The tunability of the electronic structures for poly(carbosilylsilanes): a theoretical study

Abstract

To tune purposefully the electronic structures of poly(carbosilylsilanes), a theory study has been investigated using the density functional theory combined with AM1 method. Attentions were paid to the dependence of molecular geometries and absorption spectra on the backbone conformation and the various substituting groups. The strong electronegative substituents can more effectively tune the geometries and spectra of the polysilanes than the alkyl ones. Their main-chain substitutions can induce the great red-shift of the absorption spectra, and the side-chain substitutions can induce the blue-shift. The length of methylene chain in the carbosilyl groups exerts the small effect on the absorption spectra, but with the lengthening of side chain, poly(carbosilylsilanes) have a preference for the all-trans conformation with the loose helix backbone. Different from the alkyl side chain in poly(alkylsilanes), the lengthening of carbosilyl chain leads to the decrease of the positive charges of silicon backbone.

Interplay of thermochemistry and Structural Chemistry, the journal (volume 21, 2010) and the discipline

“…Geometric and electronic changes of a series of poly(carbosilysilanes) induced by varying the size and species of the substituting groups was investigated by Ding et al [156] using DFT combined with AM1 method. While the bias-trans conformation is preferred if the side chain contains fewer than three carbons, the all-trans conformation with a loose-helix backbone is a preference with more than four carbons in side chain.…”

Effect of skeleton conformation on the electronic structure of 50% Ti substituted polysilanes from density functional calculations

“…The close relationship between the structural and the optical property of polysilane is evident from a number of experimental and theoretical studies devoted to tailoring the bandgaps of polysilanes by manipulating the backbone conformations or the side-chain substitutions [22][23][24][25][26][27]14,28]. It has been shown that the bandgap of polysilanes and their derivatives increase as the Si backbone conformation becomes more twisted.…”