Design and synthesis of axially chiral platinum(II) complex and its CPL properties in PMMA matrix

A pair of axially chiral platinum(II) complex was synthesized via Sonogashira coupling and subsequent coordination of a pincer ligand to a precursor. The complex exhibited a broad absorption band ranging from 250 to 700 nm in the UV–vis spectrum, with TD-DFT calculations indicating mixed ligand-to-ligand charge transfer (LL′CT) and metal-to-ligand charge transfer (MLCT) character. Photoluminescence measurements in CH ₂ Cl ₂ solution revealed dual emission peaks at 427 nm and 596 nm, with a quantum yield of 3%. In PMMA matrix, the emission peaks were blue-shifted to 408 nm and 558 nm, and the quantum yield slightly increased to 4%. CD spectra showed distinct Cotton effects in the MLCT region, and CPL signals were observed only in the PMMA matrices, with a dissymmetry factor ( g _lum ) of |0.4 × 10⁻³|. These results demonstrate that axial chirality can be effectively transferred to the metal center and induce CPL activity under restricted molecular motion, providing a promising strategy for designing chiral phosphorescent materials.