Synthesis, Luminescence, and Electrochemistry of Tris-Chelate Platinum(IV) Complexes with Cyclometalated N-Heterocyclic Carbene Ligands and Aromatic Diimines
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Dicationic, C 2 -symmetrical, tris-chelate Pt(IV) complexes of general formula [Pt(trz) 2 (N∧N)](OTf) 2, bearing two cyclometalated 4-butyl-3-methyl-1-phenyl-1 H -1,2,3-triazol-5-ylidene (trz) ligands and one aromatic diimine [N∧N = 2,2′-bipyridine (bpy, 2 ), 4,4′-di- tert -butyl-2,2′-bipyridine (dbbpy, 3 ), 4,4′-dimethoxi-2,2′-bipyridine (dMeO-bpy, 4 ), 1,10-phenanthroline (phen, 5 ), 4,7-diphenyl-1,10-phenanthroline (bphen, 6 ), dipyrido[3,2- a:2′,3′- c ]phenazine (dppz, 7 ), or 2,3-diphenylpyrazino[2,3- f ][1,10]phenanthroline (dpprzphen, 8 )] are obtained through chloride abstraction from [PtCl 2 (trz) 2 ] ( 1 ) using AgOTf in the presence of the corresponding diimine. Complexes 2–4 show long-lived phosphorescence from 3 LC excited states involving the diimine ligand, with quantum yields that reach 0.18 in solution and 0.58 in the solid matrix at room temperature for 3 . Derivatives with more extended aromatic systems show dual phosphorescent/fluorescent emissions ( 5, 6 ) or mainly fluorescence ( 7, 8 ) in solution. Comparisons with similar complexes bearing cyclometalated 2-arylpyridines instead of aryl-N-heterocyclic carbenes indicate that the {Pt(trz) 2 } subunit is crucial to enable efficient emissions from diimine-centered excited states. It is also shown that the introduction of protective bulky substituents on the diimine, such as the tert -butyl groups in 3, is a key strategy to reach higher emission efficiencies. The new compounds represent rare examples of luminescent Pt(IV) complexes that show quasi-reversible one-electron reductions, indicating an unusually high redox stability.
Source: Inorganic Chemistry
Institution: Universidad de Murcia
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G1119358563, G441910153, G8858913034
OpenAlex ID: W4405580865