Theoretical studies on cyclometalated platinum complexes with long chain β-diketonate ancillary ligands have been carried out at B3LYP/LanL2DZ(6-31＋＋G**) level to obtain electronic absorption spectra and second-order nonlinear optical properties. The results indicate that a large conjugated system was formed by Pt atom, benzene, pyridine and β-diketonate ancillary ligands, which makes the electronic transition from the ground state to the first excited state (p→p* and n→p*) with MLCT transition. The maximal absorption wavelength was obtained at around 406 nm, belonging to near UV. The structure and electronic spectra were little influenced by the length of β-diketonate ancillary alkyl, which is in good agreement with experimental results. The cyclometalated platinum complexes with long chain β-diketonate ancillary ligand molecules display good nonlinear optical properties.

Key words: cyclometalated platinum complex, electronic spectra, second-order nonlinear optical property, density functional theory