Platinum Complexes of Tetradentate NCCN -Coordinating Ligands: Structures and Photophysical Properties of Pt II , Pt 2 III and Pt IV Compounds
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Tetradentate proligands based on biphenyl appended at the 3 and 3′ positions with pyridin-2-yl rings (H 2 L 1 ), quinoline-8-yl (H 2 L 3 ) heterocycles, or one such pyridine and quinoline (H 2 L 2 ), have been synthesized by palladium-catalyzed cross-coupling. These compounds were expected to undergo cyclometalation with K 2 PtCl 4 to generate Pt(II) complexes, PtL 1–3, featuring NCCN -coordinated ligands. For H 2 L 2 and H 2 L 3, the corresponding Pt(IV) compounds PtL 2–3 Cl 2 were initially isolated, from which PtL 2–3 could be obtained by reduction with zinc. In contrast, H 2 L 1 gave an unusual Pt(III) dimer, Pt 2 L 1 2 Cl 2, and subsequently PtL 1 upon reduction. All of the complexes have been structurally characterized in the solid state by X-ray diffraction. The quinoline-containing complexes of L 2 and L 3 feature one or two 6-membered chelates, respectively, with an accompanying twisting of the quinoline ring(s) relative to the biphenyl unit to allow the metal ion to achieve its preferred square-planar coordination. PtL 1 displays intense green phosphorescence in solution at room temperature with a quantum yield of 67%. The deep-red emission of PtL 2–3 is weaker due to suppressed triplet radiative rate constants as well as faster nonradiative decay. The Pt(IV) complexes emit only at 77 K, with long lifetimes of around 300 μs, while the Pt(III) dimer shows no detectable emission.
Source: Inorganic Chemistry
Institution: Durham University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funder: Durham University
OpenAlex ID: W4416000283