Platinum(ii ) complexes of benzannulated N∧N−∧O-amido ligands: bright orange phosphors with long-lived excited states
| Autor: | David E. Herbert, Issiah B. Lozada, J. A. Gareth Williams |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
Phenanthridine
010405 organic chemistry Acetylacetone Substituent chemistry.chemical_element 010402 general chemistry Photochemistry 01 natural sciences 3. Good health 0104 chemical sciences Inorganic Chemistry chemistry.chemical_compound chemistry Excited state Singlet state Triplet state Phosphorescence Platinum |
| Zdroj: | Inorganic chemistry frontiers, 2022, Vol.9(1), pp.10-22 [Peer Reviewed Journal] |
| ISSN: | 2052-1553 |
| Popis: | The synthesis, structural characterization and photophysical properties of a series of platinum(II) complexes of benzannulated pincer-type diarylamido ligands are described. The ligands all contain tricyclic phenanthridine (3,4-benzoquinoline) rings as donor arms, which were elaborated into N∧N−∧O-coordinating β-enaminoketonato chelates via partial condensation with acetylacetone. The proligands are easily deprotonated, and metallation can be achieved under mild conditions using simple Pt(II) salts and Ag2O as a base. The resulting Pt(II) complexes exhibit strong metal-to-ligand charge-transfer absorptions in the region of ∼450–575 nm and are phosphorescent in solution at room temperature, emitting bright orange light (λmax ∼ 600 nm) with quantum yields of up to 16% and excited-state lifetimes on the order of ∼20 μs, representing significant improvements to these photophysical properties compared with many previously reported N∧N∧O or N∧N∧N-ligated systems. Computational modelling reveals that the lowest-lying triplet state is populated efficiently thanks to strong coupling between singlet and triplet excited state manifolds, as in cyclometallated compounds of Pt(II). Substituents (CH3, tBu, or CF3) in the 2-position of the phenanthridinyl unit are found to have little influence on the optical properties, but the emission is severely quenched when a methyl substituent is introduced ortho to the coordinating nitrogen. Molecular distortions in the excited state are shown to be primarily responsible for the quenching in this complex. |
| Databáze: | OpenAIRE |
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