Tuning the NLO response of bis-cyclometalated iridium(iii) complexes by modifying ligands: experimental and structural DFT analysis

Density functional theory (DFT) calculations have been carried out to investigate two synthesized iridium(iii) complexes with substituted Phbd (1-phenyl-2-(pyridin-2-yl)-1H-benzo[d]imidazole) and Crbd (9-(4-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)phenyl)-9H-carbazole) as ancillary ligands. The aim of this paper is to study the effect of the substituent on the geometrical structures, electronic and second-order nonlinear optical (NLO) properties, and UV-vis absorption spectra. It is found that the first hyperpolarizabilities can be easily modulated by the introduction of Phbd and Crbd units. The complex with Phbd possesses larger first hyperpolarizability values compared to the complex with Crbd as an ancillary ligand. Significantly, the changes in the first hyperpolarizabilities can be qualitatively explained by means of the charge transfer pattern. It is anticipated that the theoretical investigation of these iridium(iii) complexes will be helpful for designing high performance and versatile NLO materials.

Automated summary

Density functional theory calculations were employed to investigate the geometric structures, electronic properties, and second-order nonlinear optical (NLO) properties of two synthesized iridium(iii) complexes with different substituted ancillary ligands. The first hyperpolarizabilities were found to be easily modulated by the introduction of different units, and the changes in properties could be qualitatively explained by means of the charge transfer pattern. The theoretical investigation of these complexes is expected to aid in designing high-performance and versatile NLO materials.