Synthesis, photophysical properties and DFT calculation of four novel iridium(III) complexes based on dibenzothiophene

To investigate the DR/NIR luminescent properties of iridium complexes enlarging by the conjugation of 2-phenylpyridine (ppy), and to assess the substituent effects on the characteristics of iridium complexes, we employed 5-R-2-(dibenzo[b,d]thiophen-3-yl)pyridine (R = -H, F, -CF₃, and -CH₃) as the primary ligand in the design and synthesis of four novel iridium(III) complexes. Single-crystal X-ray structures verified the definitive coordination geometry as well as the intramolecular and intermolecular interactions present in Ir2-Ir4. Subsequent to the incorporation of dibenzothiophene into the primary ligand, Ir1(H) exhibits a redshift compared to Ir(ppy)₂tmd. It is proposed that the slight redshift may be attributed to changes in the electron cloud distribution resulting from structural modifications to the ligand. Besides, Ir3 (-CF₃) and Ir2 (F) show a bathochromic relative to Ir1 (H), while Ir4 (-CH₃) leads to a minor blueshift. These results are in consistent with density functional theory (DFT) calculations. This study highlights the crucial role of ligand structure in influencing the photophysical properties of iridium(III) complexes, potentially offering new avenues for their design and synthesis.