So-Yoen Kim
Korea University
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Publication
Featured researches published by So-Yoen Kim.
Journal of Organic Chemistry | 2015
So-Yoen Kim; Ah-Rang Lee; Guo Fan Jin; Yang-Jin Cho; Ho-Jin Son; Won-Sik Han; Sang Ook Kang
We studied electronic change in oligothiophenes by employing o-carborane into a molecular array in which one or both end(s) were substituted by electron-withdrawing dicyano-vinyl group(s). Depending on mono- or bis-substitution at the o-carborane, a series of linear A1-D-A2 (1a-1c) or V-shaped A1-D-A2-D-A1 (2a-2c) oligothiophene chain structures of variable length were prepared; A1, D, and A2, represent dicyano-vinyl, oligothiophenyl, and o-carboranyl groups, respectively. Among this series, 2a shows strong electron-acceptor capability of o-carborane comparable to that of the dicyano-vinyl substituent, which can be elaborated by a conformational effect driven by cage σ*-π* interaction. As a result, electronic communications between o-carborane and dicyano-vinyl groups are successfully achieved in 2a.
Journal of Materials Chemistry C | 2017
Yang-Jin Cho; So-Yoen Kim; Jin-Hyoung Kim; Douglas W. Crandell; Mu-Hyun Baik; Jiwon Lee; Chul Hoon Kim; Ho-Jin Son; Won-Sik Han; Sang Ook Kang
A series of heteroleptic Ir(III) complexes composed of 2-(2,4-difluoro-3-(trifluoromethyl)phenyl)-4-methylpyridine (dfCF3) as the main ligand and such ancillary ligands as acetylacetonate [Ir(dfCF3)2(acac)] (acac), picolinate [Ir(dfCF3)2(pic)] (pic), and tetrakis-pyrazolyl borate [Ir(dfCF3)2(bor)] (bor) were prepared, and their emission behaviors depending on the ancillary ligands were systematically investigated. It was found that the Huang–Rhys factors (SMs) of the emission decrease in the order bor (0.97) > acac (0.87) > pic (0.76), while the nonradiative rate constants (knr/105 s−1) calculated from the quantum yields and lifetimes of emission were in the order acac (4.89) > pic (1.17) > bor (0.28). It was assumed that the large difference of knr for the complexes arose from important contributions of the ancillary ligands to the crossing from an emissive state (3MLCT) to a nonemissive metal-centered state (3MC). The activation energies for the crossing from 3MLCT to 3MC were estimated from the temperature dependencies of the emission lifetime and were found to be 46 meV for acac, 61 meV for pic, and >100 meV for bor. The experimental results were in line with the theoretical calculations based on integrating quantum chemical modeling methods. By the excellent emission behavior, bor was applied as a dopant to prototype deep-blue phosphorescent organic light-emitting diode devices, which revealed high emission efficiency and colour purity.
Journal of Physical Chemistry A | 2018
So-Yoen Kim; Yang-Jin Cho; Ho-Jin Son; Dae Won Cho; Sang Ook Kang
We report the results of photoinduced electron transfer (PET) in a novel dyad, in which a boron dipyrromethene (BODIPY) dye is covalently linked to o-carborane ( o-Cb). In this dyad, BODIPY and o-Cb act as electron donor and acceptor, respectively. PET dynamics were investigated using a femtosecond time-resolved transient absorption spectroscopic method. The free energy dependence of PET in the S1 and S2 states was examined on the basis of Marcus theory. PET in the S1 state occurs in the Marcus normal region. Rates are strongly influenced by the driving force (-Δ G), which is controlled by solvent polarity; thus, PET in the S1 state is faster in polar solvents than in nonpolar ones. However, PET does not occur from the higher energy S2 state despite large endothermic Δ G values, because deactivation via internal conversion is much faster than PET.
Physical Chemistry Chemical Physics | 2015
So-Yoen Kim; Yang-Jin Cho; Guo Fan Jin; Won-Sik Han; Ho-Jin Son; Dae Won Cho; Sang Ook Kang
Physical Chemistry Chemical Physics | 2016
Yang-Jin Cho; So-Yoen Kim; Minji Cho; Won-Sik Han; Ho-Jin Son; Dae Won Cho; Sang Ook Kang
Journal of Organometallic Chemistry | 2015
So-Yoen Kim; Ah-Rang Lee; Yang-Jin Cho; Ho-Jin Son; Won-Sik Han; Sang Ook Kang
Physical Chemistry Chemical Physics | 2017
So-Yoen Kim; Yang-Jin Cho; Ah-Rang Lee; Ho-Jin Son; Won-Sik Han; Dae Won Cho; Sang Ook Kang
Physical Chemistry Chemical Physics | 2016
Yang-Jin Cho; So-Yoen Kim; Minji Cho; Kyung-Ryang Wee; Ho-Jin Son; Won-Sik Han; Dae Won Cho; Sang Ook Kang
Physical Chemistry Chemical Physics | 2017
Yang-Jin Cho; So-Yoen Kim; Ho-Jin Son; Dae Won Cho; Sang Ook Kang
Physical Chemistry Chemical Physics | 2017
Yang-Jin Cho; So-Yoen Kim; Ho-Jin Son; Dae Won Cho; Sang Ook Kang