Electronic structures of the electron donor-acceptor complexes of fullerenes C60 and C70 with azulene and some of its derivatives employing ab initio and DFT methods

Quantum mechanical calculations have been carried out to determine the structural and electronic properties of the electron donor-acceptor complexes of C60 and C70 with azulene and some of its derivative, viz, 1,3-dichloroazulene, 2-hydroxyazulene and 4,6,8-trimetrhyl azulene. The molecules studied are optimized first with semi-empirical molecular orbital theory at the third parametric level, and, then further optimized by Hartree Fock method. The optimized geometries, calculated energies, spatial distribution, HOMO and LUMO energies along with the electrostatic potential maps of the individual molecules and the electron donor-acceptor complexes are obtained by ab initio and density functional theory methods. The results suggest that the LUMO state of these complexes is localized on the fullerene moiety whereas the HOMO state is positioned on the azulenes. The energy difference of localized LUMO levels strongly depend on the functional group attached to the azulene and the structure of the fullerene-azulene molecular complexes.