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Red‐to‐NIR Iridium(III) Emitters: Synthesis, Photophysical and Computational Study, the Effects of Cyclometallating and β‐Diketonate Ligands
Author(s) -
Kuznetsov Kirill M.,
Kritchenkov Ilya S.,
Shakirova Julia R.,
Gurzhiy Vladislav V.,
Pavlovskiy Vladimir V.,
Porsev Vitaly V.,
Sokolov Viktor V.,
Tunik Sergey P.
Publication year - 2021
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.202100189
Subject(s) - bathochromic shift , chemistry , iridium , phosphorescence , excited state , photochemistry , ligand (biochemistry) , pyridine , luminescence , phenanthridine , absorption (acoustics) , fluorescence , stereochemistry , medicinal chemistry , organic chemistry , catalysis , biochemistry , physics , receptor , optoelectronics , quantum mechanics , nuclear physics , acoustics
In this work nine novel heteroleptic Ir(III) complexes of general formulae [Ir(N ∧ C # ) 2 (O ∧ O # )] containing four different cyclometallating and four β‐diketonate ligands were synthesized and fully characterized. Six of them display phosphorescence in the deep red and NIR regions with quantum yields reaching 24.6 % in degassed solution for one of the NIR emitters. Variation in the nature of orthometalating ligands results in dramatic changes in photophysical behavior: the compounds containing 2‐phenylpyridine (N ∧ C 1 ) and 2‐(benzo[b]thiophen‐2‐yl)pyridine (N ∧ C 2 ) ligands give non‐emissive complexes, whereas those with methyl 2‐phenylquinoline‐4‐carboxylate (N ∧ C 3 ) and 6‐(benzo[b]thiophen‐2‐yl)phenanthridine) (N ∧ C 4 ) are luminescent, but display different character of electronic transitions responsible for absorption and emission. Complexes with theN ∧ C 3 ligand luminesce from 3 LC excited state and do not change their emission characteristics upon variations in the nature of β‐diketonates. On the contrary, the compounds based on theN ∧ C 4 cyclometalating ligand emit from the excited state with considerable contribution of 3 MLCT character and show systematic bathochromic shift of absorption and emission bands upon increase in electron donicity ofO ∧ O # ligands. This conclusion was supported by DFT and TD‐DFT calculations and by the analysis of correlations between the 13 C chemical shift of the diketonate C(H) carbon and emission maxima of the compounds under study.