非血红素铁(Ⅲ)活化氧分子反应的自旋轨道耦合和零场分裂（英文）  

Spin-Orbit Coupling and Zero-Field Splitting in Dioxygen Activation by Non-Heme Iron(Ⅲ)

作　　者：吕玲玲[1] 王小芳[1] 朱元成[1] 刘新文[1] 袁焜[1] 王永成[2] 

机构地区：[1]天水师范学院生命科学与化学学院,甘肃天水741001 [2]西北师范大学化学化工学院,兰州730070

出　　处：《物理化学学报》2013年第8期1673-1680,共8页Acta Physico-Chimica Sinica

基　　金：supported by the National Natural Science Foundation of China(21263022);University Research Fund of Gansu Province Financial Department,China~~

摘　　要：采用密度泛函理论对原儿茶酚3,4-双加氧酶(3,4-PCD)活化O2分子的反应机理进行了探讨.初始复合物,六重态61的超快形成主要归因于电子交换诱导系间穿越(EISC),Fedz2:O2π*(z)是主要的交换通道,在Fe―O键长为0.2487nm处,交换重叠积分Sij=<dz2α|π*(z)β〉=0.3758.从六重态61形成四重态中间体41,有两种效应共存,即电子交换耦合作用和自旋轨道耦合(SOC)作用,且相互竞争.计算结果表明,自旋轨道耦合(SOC)作用起主导因素(SOC=353.16cm-1).至于O―O键的解离主要取决于儿茶酚(PCA)最高占据分子轨道(HOMO)的电子转移,非血红素酶的铁中心仅承担PCA向O2电子转移的缓冲作用.The mechanism of the 02 activation by the protocatechuate 3,4-dioxygenase was investigated using density functional calculations. In the initial complex, the ultrafast formation of the sextet 61 was probably the result of electron-exchange-induced intersystem crossing, and Fe dz2：O2 π＊（Z） was the dominant exchange pathway, with an overlap of Sif=（d,2aITT＊（Z）β 〉=0.3758 at an Fe- O bond length of 0.2487 nm. Two coexisting effects, electron spin exchange coupling and spin-orbit coupling （SOC） in the sextet 61, are responsible for formation of the quartet state 41 from the sextet 61. The exchange interaction competes with the SOC interaction as a driving force for spin conversion. The calculated results show that the latter is the dominant factor, because of the larger SOC constant （353.16 cm-1）. In cleavage of the O-- O bond, electron transfer from the protocatechuate （PCA） highest occupied molecular orbital （HOMO） plays a vital role. The Fe center of the non-heme enzyme is a buffer to transfer an electron pair from the PCA HOMO to O2.

关 键 词：原儿茶酚3 4-双加氧酶 自旋轨道耦合 零场分裂 反应机理 

分 类 号：O643.1[理学—物理化学]