Circularly\nPolarized Phosphorescence Properties of\nBinuclear Cyclometalated Platinum(II) Complexes Bearing Axially Chiral\nSchiff-Base Ligands

The\nsynthesis, structure, and circularly polarized phosphorescence\n(CPP) properties of axially chiral cyclometalated binuclear platinum(II)\ncomplexes were described. A series of optically pure binuclear platinum(II)\ncomplexes were synthesized in five steps from commercially available\n(<i>R</i>)- or (<i>S</i>)-1,1′-bi-2-naphthol\n(BINOL) as starting materials. Their three-dimensional molecular structures\nand square-planar coordination geometries were elucidated from X-ray\ndiffraction and 2D NMR analysis. The complexes were found to exhibit\nred- to near-infrared photoluminescence in solution and in the solid\nstate. Furthermore, dilute DMSO solutions of the enantiopure samples\nshowed red CPP with relatively high luminescence dissymmetry factor\n(<i>g</i><sub>lum</sub>) values. Density functional theory\n(DFT) calculations were conducted to examine their three-dimensional\nmolecular conformations and photophysical properties.