Reversible redox-switchable second-order optical nonlinearity in polyoxometalate:: A quantum chemical study of [PW11O39(ReN)]n- (n=3-7)
Reversible redox-switchable second-order optical nonlinearity in polyoxometalate:: A quantum chemical study of [PW11O39(ReN)]n- (n=3-7)
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DOI：
10.1021/ic8001527
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发表时间：
2008-06-16
影响因子：
4.6
通讯作者：
Su, Zhongmin
中科院分区：
文献类型：
--
作者：
Guan, Wei;Yang, Guochun;Su, Zhongmin
本文采用含时密度泛函理论（TDDFT）结合态求和（SOS）方法，系统地研究了标题系列配合物的可逆氧化还原性质与二阶非线性光学（NLO）响应之间的关系.结果表明，PW_（11）Re_（V）_（VII）（1）→ PW_（11）Re_（VI）（2）→ PW_（11）Re_（V）_（3）→ PW_（11）Re_（V）_（1e）（4）→ PW_（11）Re_（V）_（2e）（5）.此外，它们的电化学性能已被成功地再现。值得注意的是，二阶非线性光学行为可以通过可逆的氧化还原切换目前所研究的配合物。完全氧化构成了关闭二阶极化率（系统1）的方便方式。额外电子的掺入导致二阶NLO活性的显著增强，特别是对于第三还原态（系统4），其静态二阶极化率（beta（vec））比完全氧化的1大约144倍。对应于对β（vec）值的主要贡献的电荷转移转变的特性表明，以金属为中心的氧化还原过程影响分子内供体或受体的特性。因此，这类配合物具有易实现的可逆氧化还原态，有望成为优良的可开关非线性光学材料。
In this paper, the relationship between the reversible redox properties and the second-order nonlinear optical (NLO) responses for the title series of complexes has been systematically investigated by using the time-dependent density functional theory (TDDFT) method combined with the sum-over-states (SOS) formalism. The results reveal that the successive reduction processes of five PW11ReN redox states should be PW(11)Rev(VII) (1) -> PW11ReVI (2) -> PW11ReV (3) -> PW(11)Re(V)1e (4) -> PW(11)Re(V)2e (5). Furthermore, their electrochemical properties have been reproduced successfully. It is noteworthy that the second-order NLO behaviors can be switched by reversible redox for the present studied complexes. Full oxidation constitutes a convenient way to switch off the second-order polarizability (system 1). The incorporation of extra electrons causes significant enhancement in the second-order NLO activity, especially for the third reduced state (system 4), whose static second-order polarizability (beta(vec)) is about 144 times larger than that of fully oxidized 1. The characteristic of the charge-transfer transition corresponding to the dominant contributions to the beta(vec) values indicates that metal-centered redox processes influence the intramolecular donor or acceptor character. Therefore, these kinds of complexes with the facile and reversible redox states could become excellent switchable NLO materials.