Reversible Redox-Switchable Second-Order Optical Nonlinearity in Polyoxometalate: A Quantum Chemical Study of [PW11O39(ReN)]n− (n = 3−7)

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• 作者：Wei Guan ; Guochun Yang ; Chunguang Liu ; Ping Song ; Liang Fang ; Likai Yan ; Zhongmin Su
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：June 16, 2008
• 年：2008
• 卷：47
• 期：12
• 页码：5245 - 5252
• 全文大小：669K
• 年卷期：v.47,no.12(June 16, 2008)
• ISSN：1520-510X

文摘

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 PW₁₁Re^VII (1) → PW₁₁Re^VI (2) → PW₁₁Re^V (3) → PW₁₁Re^V1e (4) → PW₁₁Re^V2e (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 (β_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 β_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.