| 초록 |
To gain new insights into ligand-to-ligand charge-transfer (LLCT) dynamics, we synthesised two heteroleptic Ir3+ complexes: (Ir(dfppy)2(tpphz)) and (Ir(dfppy)2(dpq)), where dfppy, tpphz, and dpq are 2-(4,6-difluorophenyl)pyridine, tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine, and 2,3-bis-(2-pyridyl)-quinoxaline. The LLCT dynamics from dfppy to tpphz (or dpq) was probed using femtosecond transient absorption (TA) spectroscopy after the selective excitation of dfppy. The TA band for the LC/MLCT state of dfppy is observed at 480 nm. The time constants for the LLCT process were 17 ps for Ir(dfppy)2(tpphz) and 5 ps for Ir(dfppy)2(dpq). The MLCT emission of Ir(dfppy)2(tpphz) showed strong temperature dependence, indicating that the LLCT process has a significant energy barrier. In comparison, the temperature weakly influenced the emission of Ir(dfppy)2(dpq), and thus, its LLCT process may have a smaller barrier. |
