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제123회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Effect of Bulkiness and Structural Isomerism of Homoleptic N-Heterocyclic Carbene Iridium(III) Complexes

2019년 2월 14일 14시 58분 49초
IND.P-74 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
4월 19일 (금요일) 11:00~12:30
Industrial Chemistry
저자 및
Bo-Sun Yun, Jeong-Wan Yu, Jin-Hyoung Kim, Min Su Choe, Dae won Cho*, Sang Ook Kang, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, Korea
The phosphorescence properties of fac-Ir(pmp)3, mer-Ir(pmp)3, fac-Ir(dmpmp)3 and mer-Ir(dmpmp)3 in CH2Cl2 were investigated. 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 spectra compared to those at 77 K. The quantum yields of the Ir(dmpmp)3 isomers were very low, and their emission lifetimes were very short compared to those of Ir(pmp)3. In order to understand the large differences between the photodynamic properties of Ir(pmp)3 and Ir(dmpmp)3, we performed femtosecond time-resolved transient absorption (TA) spectroscopic measurements. The TA spectra of Ir(dmpmp)3 were almost the same as those of Ir(pmp)3 at a short delay time. However, Ir(dmpmp)3 showed a new broad TA band at around 720 nm with increasing delay time. The rise time of this band was ca. 10 ps for both isomers, and it may be attributed to the fast migration of localization of excited state via intraligand energy transfer. An electron density displacement takes place in the excited state accompany with the geometrical change of the dimethylphenyl substituent. Actually, Ir(dmpmp)3 showed a strong rigidochromic shift in the emission spectra with varying temperature. To understand the molecular orbitals and the energy levels, theoretical calculations were performed using density functional theory