| 초록 |
To gain new insights into LLCT dynamics, we synthesised Ir3+ complexes: (Ir(dfppy)2(tpphz)) and (Ir(dfppy)2(dpq)). The excited LC state and the MLCT state of dfppy are higher than tpphz and dpq. The LLCT dynamics from dfppy to tpphz (or dpq) was probed using femtoscond transient absorption (TA) spectroscopy after the selective excitation of dfppy. Because of the LLCT process, the TA bands related to the MLCT states of tpphz and dpq ligands increased, whereas those of dfppy decreased. 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 influenced the emission of Ir(dfppy)2(dpq), and thus, its LLCT process may have a smaller barrier. The anomalous rigidochromism and photodynamic behaviours can be explained in terms of the barrier between cyclometalating and ancillary ligands. |
