Mechanism of efficient firefly bioluminescence via adiabatic transition state and seam of sloped conical intersection
Mechanism of efficient firefly bioluminescence via adiabatic transition state and seam of sloped conical intersection
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DOI：
10.1021/ja8052464
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发表时间：
2008-10-01
影响因子：
15
通讯作者：
Morokuma, Keiji
中科院分区：
文献类型：
--
作者：
Chung, Lung Wa;Hayashi, Shigehiko;Morokuma, Keiji
萤火虫发光是一种众所周知的高效生物发光。然而，萤火虫中高效热产生电子激发态的谜团仍然没有解开，特别是在原子和分子水平上。我们进行了SA-CASSCF(12，12)/6-31G*和CASPT2(12，12)/6-31G*//SA-CASSCF(12，12)/6-31G*计算，以阐明萤火虫二氧杂环己酮在气相中的生物发光反应机理。对O-O键断裂的绝热过渡态(TS)和最小能量锥交(MECI)进行了定位和表征。MECI独特的拓扑结构特征是萤火虫二氧六甲酮的斜锥形交叉口，这是首次发现的，它沿着反应路径出现，提供了一个广泛扩展的通道，从基态以非绝热的方式访问激发态。
Firefly emission is a well-known efficient bioluminescence. However, the mystery of the efficient thermal generation of electronic excited states in firefly still remains unsolved, particularly at the atomic and molecular levels. We performed SA-CASSCF(12,12)/6-31G* and CASPT2(12,12)/6-31G*//SA-CASSCF(12,12)/6-31G* calculations to elucidate the reaction mechanism of bioluminescence from the firefly dioxetanone in the gas phase. Adiabatic transition state (TS) for the O-O bond cleavage and the minimum energy conical intersection (MECI) were located and characterized. The unique topology of MECI featuring a seam of a sloped conical intersection for the firefly dioxetanone, which was uncovered for the first time, emerges along the reaction pathway to provide a widely extended channel to diabatically access the excited-state from the ground state.