Pyrrole‐Based π‐System–Pt II Complexes: Chiroptical Properties and Excited‐State Dynamics with Microsecond Triplet Lifetimes

Metal-Induced Distally Axial Chirality of Vertical Binuclear Platinum(II) Complexes: Chirality Self-Sorting and Chiral Stability/Phosphorescence Enhancement

Chirality is a fundamental property of nature. Herein, we demonstrate a straightforward strategy to build a new kind of metal-induced distally axial chirality based on vertical binuclear platinum(II) complexes. The strong and balanced steric hindrance between the four methyl substituents of sym-tetraacetylethane bridging ligand causes the two Pt-containing hexatomic rings in these binuclear Pt(II) complexes to be orthogonally linked by a C-C single bond. Although the two heterobidentate 2-phenylpyridine (C N) ligands are spatially distant from the C-C single bond, they are strictly orthogonal to each other, resulting in metal-induced distally axial chirality. Moreover, such distally axial chirality can reduce the synthesis difficulty of asymmetric bridging ligands, extend axially chiral plane without distorting the coordination configuration, and enhance rotational barriers for high phosphorescent quantum yield and racemization energy barrier. The enantiomers of complexes can be separated by chiral high-performance liquid chromatography (HPLC) and their absolute configurations were confirmed by X-ray diffraction, circular dichroism, and density functional theory calculation. Furthermore, without the use of chiral HPLC, enantiopure complexes can be prepared using chiral binaphthalene- and estrone-based C N ligands through chirality self-sorting. The estrone groups can also facilitate the formation of supramolecular gels by self-assembly.

Rational Design of Axially Chiral Platinabinaphthalenes with Aggregation-Induced Emission for Red Circularly Polarized Phosphorescent Organic Light-Emitting Diodes

Circularly polarized luminescent (CPL) materials have received a lot of interest due to their potential applications in next-generation displays. However, the development of easily accessible red circularly polarized phosphorescent emitters for practical organic light-emitting diodes fabrication remains a grand challenge. In this paper, we report a new family of CPL-active platinum complexes based on the binaphthalene chiral platform. These axially chiral platinabinaphthalenes were facile synthesized by directly incorporating platinum(II) into the π-conjugated backbone of a commercially available enantiopure binaphthalene derivate. These complexes exhibit aggregation-induced circularly polarized phosphorescence enhancement with high quantum yields of up to 66% and luminescence dissymmetry factors of around 2.6 × 10^-3. Moreover, solution-processable circularly polarized organic light-emitting diodes (CPOLEDs) using these complexes as emitters show good performance with the maximum luminance of up to 3500 cd m^-2 and dissymmetry factor values of around 1.0 × 10^-3. These findings by the rational design of axially chiral platinabinaphthalenes are important for the development of high-performance CPL complexes for CPOLEDs.