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| Type |
Poster Presentation |
| Area |
Physical Chemistry |
| Room No. |
Event Hall |
| Time |
4월 20일 (금요일) 11:00~12:30 |
| Code |
PHYS.P-109 |
| Subject |
Ultrafast time-resolved x-ray absorption study of valence tautomerism in Co-Dioxolene complexes |
| Authors |
Rory Ma, YUJIN KIM, TaeKyu Kim*
Department of Chemistry, Pusan National University, Korea
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| Abstract |
Valence tautomeric (VT) metal complexes have the magnetic properties of a suitable switchable material system. At this point, it is possible to be used as the memory or display devices. The well-known VT system is the Co-dioxolene complexes, where the electron transfer take place between cobalt metal and their ligands. Specially, Time-Resolved X-ray Absorption Spectroscopy (TR-XAS) is a significant tool to investigate molecular dynamics like this system. It also has become possible to observe the transient chemical reactions on fundamental timescale. In this study, we investigate the valence tautomerism process on two different Co-dioxolene molecules by using TR-XAS. The molecules which we studied are Co(Cat-N-BQ)(Cat-N-SQ) and Co(tpy)(Cat-N-SQ)PF6, where Cat-N-BQ = 2-(2-hydroxy-3,5-ditert-butylphenyl-imino)-4,6-ditert-butylcyclohexa-3,5-dienone, Cat-N-SQ is the dianionic radical analogue, and tpy = 2,2′-6-2″- terpyridine. 10 mM samples are used with 450 um liquid jet system. To modify their 3d valence orbital, we take XANES measurement in pre-edge region, and for their structural information, EXAFS measurement is performed at Co K-edge at KEK NW 14A beamline. DFT calculation, TD-DFT and FEFF simulation are supported to explain our experimental data. After pumped with 500 nm, the excitation process between low spin state in ground state and high spin state are associate with ligand to metal charge transfer (LMCT) in toluene solution. As a result, in Co(tpy)(Cat-N-SQ)PF6 sample, LMCT is clearly modified in XANES region around 260ps lifetime. In EXAFS data, we find that the difference of bond distance of Co–N(tpy) and Ru–N(SQ) bonds by 0.3 and 0.09 Å, respectively in high spin metastable state. |
| E-mail |
rory6847@gmail.com |
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121st General Meeting of the KCS