Electronic structures of quinizarin complexed with TiO_(2) clusters

摘要

Electronic structure calculations using the semiempirical method PM3 were performed on quinizarin complexed with TiO_(2) clusters. At first, electronic structure calculations of quinizarin complexed with small TiO_(2) clusters were performed to check a reliability of the parameters. The calculated transition energies were correlated to the observed absorption spectra. Then, TiO_(2) cluster was expanded into rutile type cluster which contained 11 Ti~(4+) ions. The LUMO of quinizarin complexed with the cluster was greater than the CB of the matrix. The replacements of Ti~(4+) ions by Si~(4+) ions changed the densitiy of states of the matrix. The increase of Si~(4+) sites shifted the CB to larger energy, and a change of relative energy level of the CB to the LUMO of the dye was observed. This result was consistent with a consideration from the TiO_(2) content dependence of the fluorescence lifetimes of quinizarin.