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Comparison of Structural and Optical Properties for N‐Embedded Polycyclic and Non‐Embedded Cationic Phosphorescent Iridium(III) Complexes
Author(s) -
Li Qiuxia,
Shi Chao,
Zhang Xinghua,
Tao Peng,
Zhao Qiang,
Yuan Aihua
Publication year - 2019
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.201900077
Subject(s) - iridium , phosphorescence , chemistry , excited state , ligand (biochemistry) , molecule , cationic polymerization , luminescence , photochemistry , crystallography , bipyridine , intermolecular force , crystal structure , fluorescence , polymer chemistry , materials science , biochemistry , physics , receptor , optoelectronics , organic chemistry , quantum mechanics , nuclear physics , catalysis
We designed and synthesized N‐embedded polycyclic based cationic iridium(III) complex Ir‐NO and non‐embedded complexes Ir‐N and Ir‐O . Single crystal structures indicate that the N‐embedded polycyclic unit in Ir‐NO exhibits a certain planarity and induces two interesting π–π‐stackings between 2,2′‐bipyridine moieties of one molecule and two polycyclic units of the other molecule, and their shortest intermolecular distances are both 3.24 Å, which results in a stronger structural distortion of the 2,2′‐bipyridine ligand with a larger torsion angle (12.70°) in comparison with those of Ir‐N (5.51°) and Ir‐O (8.11°). Unpredictably, both Ir‐N and Ir‐O show deep red emission in solution, whereas Ir‐NO exhibits no emission. However, all complexes show significant luminescence in their respective polystyrene (PS) films, and Ir‐NO displays a longer emission lifetime than those of Ir‐N and Ir‐O . DFT calculations reveal that unusual ligand‐to‐metal charge transfer ( 3 LMCT) excited state character can be found in Ir‐NO and Ir‐N , which is in contrast to the metal‐to‐ligand charge transfer ( 3 MLCT) excited state observed in Ir‐O .