Four Plus Four State Degeneracies in the O−O Photolysis of Aromatic Endoperoxides
Four Plus Four State Degeneracies in the O−O Photolysis of Aromatic Endoperoxides
复制标题
芳香族内过氧化物 O−O 光解中的四加四态简并
DOI：
10.1021/jz100196q
复制
发表时间：
2010
影响因子：
5.7
通讯作者：
L. González
中科院分区：
文献类型：
--
作者：
Doreen Mollenhauer;I. Corral;L. González
使用高级多构型从头计算（CASSCF 和 MS-CASPT2）阐明了芳香氧载体光敏剂蒽-9,10-内过氧化物中的热和光化学 O−O 键解离机制。我们的结果表明，在热和光化学途径中，系统通过四个单线态和四个三线态的简并进行。这种高阶简并性为从最低激发态进行无辐射失活提供了一个有效的漏斗，表明系统不会在激发态流形中解离，而是在电子基态中形成产物。因此，过氧化物基团的均裂产生四加四基态双自由基，它们是实验观察到的重排产物的前体。
The thermal and photochemical O−O bond dissociation mechanisms in the aromatic oxygen carrier photosensitizer anthracene-9,10-endoperoxide have been elucidated using high-level multiconfigurational ab initio calculations (CASSCF and MS-CASPT2). Our results show that in both the thermal and the photochemical pathways, the system proceeds through a degeneracy of four singlet plus four triplet states. This high-order degeneracy provides an efficient funnel for radiationless deactivation from the lowest excited state, indicating that the system does not dissociate in the excited-state manifold but that the products are rather formed in the electronic ground state. Accordingly, the homolysis of the peroxide group leads to four plus four ground-state biradicals, which are the precursors of the experimentally observed rearrangement products.