122nd General Meeting of the KCS

Type Poster Presentation
Area Industrial Chemistry
Room No. Grand Ballroom
Time 10월 19일 (금요일) 11:00~12:30
Code IND.P-22
Subject Understanding the photophysical change of geometric isomers of heteroleptic Ir(III) complexes
Authors So-Yoen Kim, Dae won Cho*, Sang Ook Kang, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, Korea
Abstract We have synthesized heteroleptic Ir(III) complexes showing red phosphorescence, which can be separated as two geometrical isomers. Each isomer showed different absorption and emission spectral behaviours. The phosphorescence of the cis isomer is observed at shorter wavelengths than the trans one. The LUMOs of both isomers are at the same energy level, but the HOMO of the cis isomer is shifted to a significantly lower energy than that of the trans isomer. The red emissions originate from the triplet metal-to-ligand charge transfer (MLCT) state, which is assigned by femtosecond time-resolved transient absorption spectroscopic analysis. The MLCT emission spectra of both isomers show highly structured bands with a vibronic spacing of ca. 1470 cm-1. Observation of vibrational fine structure in the emission spectra is attributed to the limited excited state structural change imposed by the rigidity of metal coordination.
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