Iridium(III) Complexes with Fluorinated Phenyl-tetrazoles as Cyclometalating Ligands: Enhanced Excited-State Energy and Blue Emission
| Autor: | Letizia Sambri, Armando Carlone, Filippo Monti, Nicola Armaroli, Andrea Baschieri, Andrea Mazzanti |
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| Přispěvatelé: | Baschieri, A., Sambri, L., Mazzanti, A., Carlone, A., Monti, F., Armaroli, N. |
| Rok vydání: | 2020 |
| Předmět: |
010405 organic chemistry
Ligand Phenanthroline Isocyanide chemistry.chemical_element 010402 general chemistry Photochemistry 01 natural sciences 0104 chemical sciences Cationic iridium(III) complexes photo physical proprieties Fluorinated Phenyl-tetrazoles Cyclometalating Ligands Inorganic Chemistry chemistry.chemical_compound Bipyridine chemistry Excited state Tetrazole Iridium Physical and Theoretical Chemistry Triplet state |
| Zdroj: | Inorganic Chemistry. 59:16238-16250 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | Five cationic iridium(III) complexes with fluorinated cyclometalating tetrazole ligands [Ir(dfptrz)2L]+, where Hdfptrz = 5-(2,4-difluorophenyl)-2-methyl-2H-tetrazole and L = 2,2′-bypiridine (1F), 4,4′-ditert-butyl-2,2′-bipyridine (2F), 1,10-phenantroline (3F), 4,4′-bis(dimethylamino)-2,2′-bipyridine (4F), and tert-butyl isocyanide (5F), were prepared following a one-pot synthetic strategy based on a bis-cyclometalated solvato complex obtained via silver(I)-assisted cyclometalation, which was then reacted with the proper ancillary ligand to get the targeted complexes. The X-ray crystal structures of 2F and 4F were determined, showing that the tetrazole ligands are in a trans arrangement with respect to the iridium center. Electrochemical and photophysical properties, along with density functional theory calculations, allowed a full rationalization of the electronic properties of 1F-5F. In acetonitrile solution at 298 K, complexes 1F-3F, equipped with bipyridine and phenanthroline ligands, exhibit strong vibronically structured luminescence bands in the blue region with photoluminescence quantum yields (PLQYs) in the range 56-76%. This behavior is radically different from the nonfluorinated analogues reported previously, which emits in the green region from 3MLCT excited states. 4F shows relatively strong emission (PLQY = 40%) of charge transfer character centered on the amino-bipyridine ancillary ligand, whereas the emission of 5F is very weak (PLQY = 0.6%), further blue-shifted and attributed to the lowest ligand-centered (3LC) triplet state of the tetrazolyl cyclometalated moiety. A similar photophysical behavior is observed in PMMA at 298 K, whereas in a 77 K matrix, all of the compounds are strong emitters. This novel fluorinated phenyl-tetrazole cyclometalating ligand provides the corresponding iridium(III) complexes with a combination of excited-state energy and redox potentials that make them very promising as photoredox catalysts. |
| Databáze: | OpenAIRE |
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