Cationic iridium complexes with intramolecular π-π Interaction and enhanced steric hindrance for solid-state light-emitting electrochemical cells
Journal
Inorganic Chemistry
Journal Volume
51
Journal Issue
22
Pages
12114-12121
Date Issued
2012
Author(s)
Hsiao-Fan Chen
Wen-Yi Hung
Shou-Wei Chen
Ting-Chih Wang
Shih-Wei Lin
Shu-Hua Chou
Chih-Teng Liao
Hai-Ching Su
Hsiao-An Pan
Yi-Hung Liu
Abstract
Cationic iridium complexes incorporated 4,5-diaza-9,9'-spirobifluorene as N(∧)N ancillary ligands, in which one (2) or two (3) phenyl groups were introduced onto 4,5-diazafluorene to afford intraligand π-π interactions. The X-ray crystal structures of complexes 2 and 3 show that the pendant phenyl ring forms strong intramolecular face-to-face π-stacking with the difluorophenyl ring of the cyclometalated ligand with distances of 3.38 Å for complex 2 and 3.40 and 3.46 Å for complex 3. This π-π stacking interaction minimizes the expansion of the metal-ligand bonds in the excited state, resulting in a longer device lifetime in the light-emitting electrochemical cell (LEC) devices.
SDGs
Type
journal article