Janjua Muhammad Ramzan Saeed Ashraf, Liu Chun-Guan, Guan Wei, Zhuang Jia, Muhammad Shabbir, Yan Li-Kai, Su Zhong-Min
Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
J Phys Chem A. 2009 Apr 16;113(15):3576-87. doi: 10.1021/jp808707q.
The dipole polarizabilities, dipole moments, density of states, and second-order nonlinear optical (NLO) properties of organoimido derivatives of hexamolybdates have been investigated by using time-dependent density functional response theory. This class of organic-inorganic hybrid compounds possesses remarkably large and eye-catching molecular second-order NLO response, especially Mo(6)O(17)(NC(16)H(12)NO(2))(FeNC(10)H(9)) (7) and Mo(6)O(17)(NC(16)H(12)NO(2))(NC(6)H(2)(NH(2))(3)) (6) with static second-order polarizability (beta(vec)) computed to be 15766.27 x 10(-30) esu and 6299.59 x 10(-30) esu, respectively. Thus, these systems have the possibility to be excellent second-order nonlinear optical materials. Analysis of the major contributions to the beta(vec) value suggests that the charge transfer (CT) from polyanion to organic segment (D-A) along the z-axis plays the key role in NLO response; the polyanion acts as a donor (D) whereas organoimido acts as an acceptor (A) in all the studied systems. The computed beta(vec) values increase by incorporation of an electron acceptor (-NO(2)) at the end of the phenyl ring of the organoimido segment. Furthermore, substitution of amino (-NH(2)) or ferrocenyl (-FeC(10)H(9)) at the outer side of polyanion and an electron acceptor (-NO(2)) at the end of the phenyl ring in organoimido segment simultaneously is more important to enhance the optical nonlinearity. Orbital analysis shows that the degree of CT between the polyanion and organoimido segments was increased when ferrocenyl donor was introduced. The present investigation provides important insight into the remarkably large NLO properties of organoimido-substituted hexamolybdates.
利用含时密度泛函响应理论研究了六钼酸有机亚胺衍生物的偶极极化率、偶极矩、态密度和二阶非线性光学（NLO）性质。这类有机 - 无机杂化化合物具有非常大且引人注目的分子二阶NLO响应，特别是[Mo(6)O(17)(NC(16)H(12)NO(2))(FeNC(10)H(9))](2 - )（7）和[Mo(6)O(17)(NC(16)H(12)NO(2))(NC(6)H(2)(NH(2))(3))](2 - )（6），其静态二阶极化率（β(vec)）经计算分别为15766.27×10(-30) esu和6299.59×10(-30) esu。因此，这些体系有可能成为优异的二阶非线性光学材料。对β(vec)值主要贡献的分析表明，沿z轴从聚阴离子到有机片段（D - A）的电荷转移（CT）在NLO响应中起关键作用；在所有研究体系中，聚阴离子充当供体（D），而有机亚胺充当受体（A）。通过在有机亚胺片段苯环末端引入电子受体（-NO(2)），计算得到的β(vec)值增加。此外，在聚阴离子外侧同时取代氨基（-NH(2)）或二茂铁基（-FeC(10)H(9)）以及在有机亚胺片段苯环末端取代电子受体（-NO(2)）对增强光学非线性更为重要。轨道分析表明，引入二茂铁基供体时，聚阴离子和有机亚胺片段之间的CT程度增加。本研究为有机亚胺取代的六钼酸具有显著大的NLO性质提供了重要见解。
