The comparative investigation on redox property and second-order nonlinear response of Keggin-type α-[PM12O39NPh]3− (M = W and Mo) and Mo6NPh
The comparative investigation on redox property and second-order nonlinear response of Keggin-type α-[PM12O39NPh]3− (M = W and Mo) and Mo6NPh
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DOI：
10.1007/s11434-008-0500-5
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发表时间：
2009-02
影响因子：
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通讯作者：
Ping Song;Likai Yan;W. Guan;Jing-Dong Feng;Chun-Guan Liu;Z. Su
中科院分区：
文献类型：
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作者：
Ping Song;Likai Yan;W. Guan;Jing-Dong Feng;Chun-Guan Liu;Z. Su
利用密度泛函理论（DFT）系统地研究了keggin型苯基氨基多金属氧酸盐α-[PM12O39NPh]3−（M = W和Mo）的电子结构、氧化还原和非线性光学（NLO）性质。自然键轨道（NBO）分析证实的强M≡N键由一个s键和两个π键组成，与[Mo6O18NPh]2−中的Mo≡N相同。此外，苯基限制段有效地修饰了α-[PM12O39NPh]3−的电子性质。一方面，当无机团簇从{Mo6O18}扩大到{PMo12O39}时，α-[PMo12O39NPh]3−中HOMO和LUMO之间的能隙减小，导致还原电位发生了巨大的阳极位移，激发能减小，总二阶极化率β0达到438-3×10−30esu，是[Mo6O18NPh]2−的近10倍。另一方面，当金属W inα-[PM12O39NPh]3−被Mo取代时，Mo与N的相互作用增强，氧化还原能力增强。α-[PMo12O39NPh]3−的β0值比α-[PW12O39NPh]3−的β0值高5倍以上。结果表明，适当改变金属或扩大无机团簇可以改善氧化还原性能和二阶非线性响应。此外，上述三种化合物的电子跃迁主要发生在有机胺段（作为电子供体）到聚阴离子簇（作为电子受体）之间。因此，α-[PMo12O39NPh]3−可能是一种很有前途的氧化剂和非线性光学材料。
Keggin-type phenylimido-polyoxometalatesα-[PM12O39NPh]3−(M = W and Mo) have been systematically investigated on the electronic structures, redox as well as nonlinear optical (NLO) properties by density functional theory (DFT). The strong M≡N bond confirmed by natural bond orbital (NBO) analysis comprises one s bond and twoπbonds, the same as Mo≡N in [Mo6O18NPh]2−. Furthermore, phenylimido segment effectively modifies the electronic properties of α-[PM12O39NPh]3−. On one hand, when enlarging the inorganic cluster from {Mo6O18} to {PMo12O39}, the energy gap between HOMO and LUMO inα-[PMo12O39NPh]3−decreased, resulting in enormously anodic shift for the reduction potential, while the excitation energy is less and the total second-order polarizabilityβ0is up to 438-3×10−30esu, which is nearly 10 times larger than that of [Mo6O18NPh]2−. On the other hand, when metal W inα-[PM12O39NPh]3−is substituted by Mo, the interaction between Mo and N is enhanced and the redox ability becomes stronger. Theβ0value forα-[PMo12O39NPh]3−is more than 5 times higher than that ofα-[PW12O39NPh]3−. It indicates that changing appropriate metal or enlarging the inorganic cluster will improve the redox properties and second-order nonlinear response. Moreover, the electron transition for three compounds mentioned above occurred mainly from organoimido segment (as the electron donor) to polyanion cluster (as the acceptor). As a result,α-[PMo12O39NPh]3−may be a promising candidate for oxidant and nonlinear optical material.