Synthesis of novel luminescent cyclometallated platinum (IV) complexes with a quinoline Schiff bases ligand and their photophysical properties

Abstract

The synthesis, characterization, electro and photophysical properties of eight cyclometallated platinum (IV) complexes 6a–6d and 7a–7d derived from quinoline Schiff base ligands are reported. Spectral studies revealed that nonparticipation of nitrogen atom and participation of carbon atom of the quinoline ring in the bond formation through [NN′C] mode of coordination for complex 6, whereas [N S O] mode of coordination with octahedral geometry for complex 7. The absorption and emission spectra studied in acetonitrile medium at room temperature showed that the ligand charge transitions within the quinoline Schiff base ligands with Metal Ligand Charge Transfer (MLCT) character. The broad band appeared in the range of 460–502 nm is attributed to the higher emission intensities of cyclometallated platinum (IV) compounds. The HOMO, LUMO and energy gap of the synthesized complexes was found to be − 2.60 eV, −4.75 eV and 2.15 eV through Density Functional Theory (DFT).