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[주태하 교수] Excited State Proton Transfer of Quinone Cyanine 9: Implications on the Origin of Super-Photoacidity

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작성자 최고관리자 댓글 조회 작성일 21-04-14 16:41

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Excited State Proton Transfer of Quinone Cyanine 9: Implications on the Origin of Super-Photoacidity


Dr. Changmin Lee Dr. Seyoung Chung Dr. Hayoung Song Prof. Young Min Rhee Prof. Eunsung Lee Prof. Taiha Joo

 

퀴논 사이아닌 9 (QCy9)은 들뜬 상태에서 양성자를 내놓는 photoacid (PA) 중 가장 강력한 PA로 알려져 있다. 높은 시간 분해능의 시분해 형광을 이용하여 QCy9의 들뜬 상태에서 일어나는 양성자 이동 과정을 연구하였다. 관찰 결과 반응이 매우 빠르고 (40 fs) 완전하게 일어난다는 점과 반응 결과 생성된 짝염기가 용매화에 의해 크게 안정화된다는 점이 QCy9을 강한 PA로 만든다는 것을 알 수 있었다.

 

Quinone cyanine 9 (QCy9) is one of the strongest photoacids known to date. The origin of “super”‐photoacidity was investigated via time‐resolved fluorescence (TF) with high time resolution to accurately resolve the ultrafast dynamics of the excited‐state proton transfer (ESPT) to solvent. The ESPT of QCy9 in water is found to proceed fully by two ultrafast time constants of 40 fs (65 %) and 200 fs (35 %). More importantly, the initially created base form of QCy9 in the excited state undergoes a significant dynamic red shift of over 2700 cm1 by solvation. We suggest that the entirely ultrafast reaction rate and the massive solvation of the conjugate base could make QCy9 a particularly strong photoacid. Quantum chemical calculations show that structural diversity leads to the nonexponential behavior of the ESPT dynamics.

 

https://doi.org/10.1002/cptc.202000254

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