Enhancement of the Photofunction of Phosphorescent Pt(II) Cyclometalated Complexes Driven by Substituents: Solid-State Luminescence and Circularly Polarized Luminescence.

Ligand functionalization is an attractive strategy for enhancing the performance of metal-based phosphorescent emitters. Here, we report the synthesis and characterization of cyclometalated Pt(II) complexes and containing organosilyl-substituted (2-(2-thienyl)pyridine) ligands and compare their properties with those of (no substituent) and (organocarbon substituent). The photophysical characteristics of these molecules, including their absorption and phosphorescence spectra, phosphorescence quantum yield and lifetime, were investigated. The molecular structures were revealed by X-ray diffraction analysis. Under UV light irradiation, emitted intense orange phosphorescence in the solid state because of the bulkiness of their side chains (up to Φ: 0.49). Optically pure (-)-()- and (+)-()- were prepared using the optically active ligands (+)- and (-)-, respectively. The chiroptical properties of (+)-()-, which has an asymmetric silicon atom, were investigated. Circular dichroism and circularly polarized luminescence measurements showed that these structural motifs are suitable for applications in chiroptical phosphorescent materials.