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Geometrical Change Induced Intraligand Charge Transfer of N-Heterocyclic Carbene Ir(III) Complexes
나수원,최민수,윤보선,강상욱,손호진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
The phosphorescence properties of fac-Ir(pmp)3, mer-Ir(pmp)3, fac-Ir (dmpmp)3, and mer-Ir(dmpmp)3 (pmp = 3-methyl-1-phenyl-2,3-dihydro- 1H-imidazo[4,5-b]pyridine, dmpmp = 1-(2',6'-dimethylbiphenyl-2-yl) -3-methyl-2,3-dihydro-1H-imidazo[4,5-b]pyridine) in CH2Cl2 were investigated. At 77 K, the fac-isomers showed blue emission with a vibronic structure, while the mer-isomers showed less structured emission. At 300 K, all complexes showed broad and markedly red-shifted emission spectra. The quantum yields of the Ir(dmpmp)3 isomers were low, and their emission lifetimes were short compared to those of Ir(pmp)3. We performed femtosecond time-resolved transient absorption (TA) spectroscopic measurement. The TA spectra of Ir(dmpmp)3 were same as those of Ir(pmp)3 at a short delay time. However, Ir(dmpmp)3 showed a new broad TA band at 720 nm with increasing delay time. The rise time of this band was ca. 10 ps for both isomers.
나수원,윤보선,백창현,이대한,강상욱,손호진 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
We investigated the photophysical properties of fac-Ir(pmp)<sub>3</sub>, mer-Ir (pmp)<sub>3</sub>, fac-Ir(dmpmp)<sub>3</sub>, and mer-Ir(dmpmp)<sub>3</sub> (where pmp = 3-methyl-1-phenyl-2,3-dihydro-1H-imidazo[4,5-b]pyridine and dmpmp = 1-(2',6'-dimethylbiphenyl-2-yl)-3-methyl-2,3-dihydro-1H-imidazo[4,5-b]pyridine). At 77 K, the fac-isomers showed blue emission with a vibronic structure, while the mer-isomers showed less structured emissions. At 300 K, all complexes showed broad and markedly red-shifted emission. The quantum yields of the Ir(dmpmp)<sub>3</sub> isomers were very low, and their emission lifetimes were very short compared to those of Ir(pmp)<sub>3</sub>. In order to understand the large differences between the photodynamic properties of Ir(pmp)<sub>3</sub> and Ir(dmpmp)<sub>3</sub>, we performed femtosecond time-resolved transient absorption (TA) spectroscopic measurements. The TA spectra of Ir(dmpmp)<sub>3</sub> were almost the same as those of Ir(pmp)<sub>3</sub> at a short delay time. However, Ir(dmpmp)<sub>3</sub> showed a new broad TA band at around 720 nm with increasing delay time.
나수원,최민수,김진형,강상욱,손호진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Two isomeric N-heterocyclic carbene Ir(III) complexes, f-Ir-(dbfmi)3 and m-Ir-(dbfmi)<sub>3</sub>, were isolated and their systematic investigation on photophysical and electrochemical properties was carried out. The crystal structure m-Ir-(dbfmi)<sub>3</sub>, is determined. Both isomers, f-Ir- (dbfmi)<sub>3</sub> and m-Ir-(dbfmi)<sub>3</sub>, showed efficient emission in dichloromethane solution with quantum yields of 68% and 53%, due to unusual properties of the N-heterocyclic carbene (NHC) ligand; -that is, the complexes possess a strong metal-ligand bond that destabilizes the non-radiative metal centred ligand-field states. Depending on their configurations, the two isomers showed slightly different excited states. Even though both isomers possess a largely <sup>3</sup>LC character mixed with the <sup>3</sup>MLCT character in their excited states, m-Ir-(dbfmi)3 showed higher <sup>3</sup>MLCT character as evidenced by the solvent polarity dependence emission spectra and emission lifetime.
나수원,김진형,백창현,이대한,김철훈,강상욱,손호진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
We prepared phenylimidazole-based C^N-cyclometalated Ir(III) complexes (DMP, TPF2) and C^C-cyclometalated Ir(III) complex (PMP), and investigated the energy transfer(ET) process by examining the intermolecular interactions between the two cyclometalated Ir(III) complexes. In films doped with 3% PMP and 15% DMP or TPF2, the PMP effectively induced ET to the DMP or TPF2. This intermolecular ET process was investigated using a picosecond time-resolved emission spectroscopic method. In the case of mixing PMP with DMP, where two types of luminescence were observed at 470 nm and 580 nm, the emission at 470 nm was due to DMP, while the emission at 580 nm can be assigned as the intermolecular exciplex emission. By contrast, in the case of mixing PMP with TPF2, the emission at 465 nm corresponding to the PMP emission region decreased for 18.5 ns, while the emission at 530 nm corresponding to TPF2 increased. This emission can be attributed to the ET from PMP to TPF2.
백창현,나수원,김진형,강상욱,손호진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
We investigated the relation between the narrowing of the emission band and structural changes using synthesised tetradentate Pt-complexes. All Pt-complexes showed phosphorescence with high colour performance and the vibronic structure in the emission spectra was measured at 77 and 300 K. The 0-0 vibronic band was significantly more intense compared to the 0-1 vibronic band, due to the structural restriction of the fused tetradentate ligand. The spacing between the 0-0 and 1-0 vibronic bands were 1487 and ca. 1323 cm-1, respectively, which were compared to the vibration modes in the IR and Raman spectra.