Electronic spectra and third-order nonlinear properties of new structures in carbon family

New molecular chains of the carbon family were constructed with sym-tribenzotridehydro annulene. The UV/Vis absorption spectra and the second hyperpolarizabilities were investigated through the semiempirical INDO/S and AM1 molecular orbital methods. The transition wavelengths were estimated to be shorter than 350 nm for long enough molecular chains and the increase of second hyperpolarizabilities with the addition of molecular units manifest nonlinear effects. These results imply that these materials are promising third-order nonlinear optical materials with high hyperpolarizability and good transparency.