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

Abstract

Heteroleptic Pt II complexes comprising p-extended dipyrrins and 2-phenylquinoline were prepared. Single-crystal X-ray analysis disclosed the stepped conformations of two ligand moieties in these Pt II complexes. The enantiomers could be separated by HPLC and their configurations were determined from CD spectroscopy results and TD-DFT calculations. Transient absorption measurements revealede xcited-state dynamics characterized by fast intersystem crossing and microsecond-order triplet-statelifetimes.[a] Dr.

Highly Phosphorescent Planar Chirality by Bridging Two Square-Planar Platinum(II) Complexes: Chirality Induction and Circularly Polarized Luminescence

“…In contrast to other well-known octahedral phosphorescent d 6 Ir­(III) complexes (e.g. Ir­(ppy) 3 , ppy = 2-phenylpyridine) that have an intrinsic metal-induced Λ/Δ chirality, − the chirality of square-planar d 8 Pt­(II) complexes is mainly introduced by chiral ligands. − There are limited examples of chiral Pt­(II) complexes with achiral ligands. − However, their CPL has seldom been reported before, mainly due to not only the weak chirality but also the low emission quantum yield (Φ) (Figure S1) of the distorted-square-planar coordination configuration of the Pt­(II) ion. For the same reason, they have not been applied in circularly polarized OLEDs (CP-OLEDs) before, even though CP-OLEDs can emit CPL directly and have extensive applications in 3D displays, optical data storage, and optical spintronics. − Up to now, just a few Pt­(II) complexes with chiral ligands have been used for applications in CP-OLEDs. ,− For example, Jiang et al used chiral binaphthalene (BINA)-based mononuclear Pt­(II) complexes to fabricate solution-processed CP-OLEDs, which have an external quantum efficiency (EQE) and an asymmetry factor ( g EL ) of up to 2.15% and 1.1 × 10 –3 , respectively.…”

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

“…Beside rare examples of circularly polarized thermally activated delayed fluorescence emitters, − ,− most of the reported fluorescent polymers and SOMs are not suitable for fabricating highly efficient CPOLEDs because of their theoretically maximum 25% internal quantum efficiency. In contrast, transition metals such as platinum, iridium, or copper­(I) complexes with strong spin–orbit coupling property are preferred to generate circularly polarized phosphorescence (CPP) in CPOLED based on their immense success achieved in OLEDs. − However, only a few CPL-active platinum/iridium complexes have been reported, ,,− and even fewer of these have been applied as luminescent dopants in CPOLED due to their poor performance in terms of quantum yield (Φ) and/or luminescence dissymmetry factor ( g lum ). ,,,− Besides, phosphors with efficient CPP are highly required to satisfy the development of red–green–blue (RGB) CPOLEDs. Although red emissive CPOLEDs based on chiral europium complexes have been reported by Di Bari et al, their total luminescence is very low (3–20 cd m –2 ). , …”