121st General Meeting of the KCS

Type Poster Presentation
Area Physical Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code PHYS.P-171
Subject Photoinduced electron transfer in a bis(4-arylphenylamino benzo)-ortho-carborane investigated by time-resolved transient absorption spectroscopy
Authors So-Yoen Kim, Chul Hoon Kim, DAE WON CHO, Sang Ook Kang, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, Korea
Abstract The intramolecular photoinduced electron transfer (PET) processes of three bis(4-arylphenylamino benzo)-ortho-carboranes (ArCbAr, Ar = phenyl (Ph), naphthyl (Np) and pyrenyl (Py)) triads were investigated in CH2Cl2 and n-hexane using the femtosecond time-resolved transient absorption (TA) spectroscopic technique. In CH2Cl2, the transient S1-Sn absorption band of 1ArCbAr* was observed at short delay times. Concomitant with the decay of 1ArCbAr*, the TA bands for cation radical species were detected at around 700 nm for Ph•+, 650 nm for Np•+, and 580 nm Py•+. At the same time, the TA band of the carborane anion radical (Cb•-) was observed at around 430 nm. This implies that the intramolecular PET process occurs from the 1ArCbAr* state. The TA bands of the cationic and anionic radical species can be assigned by comparison to the absorption spectra of an electrochemically generated radical species. The PET process also occurs in n-hexane, as demonstrated by the monitoring of radical species in the TA spectra. In n-hexane, the TA band for At•+ interfered with the aggregation induced emission (AIE) at early delay times. The long lived Ar•+ species can be observed in the TA spectra at long delay times after fading of the AIE. The PET is exergonic in both solvents, as shown with the negative Gibbs energies (ΔG) for the PET processes.
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