Bu Kejun, Feng Xin, Wang Dong, Fu Tonghuan, Ma Yiran, Guo Songhao, Luo Hui, Ding Yang, Zhai Tianyou, Lü Xujie
Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China.
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
J Am Chem Soc. 2024 Aug 14;146(32):22469-22475. doi: 10.1021/jacs.4c05927. Epub 2024 Aug 1.
Rational design of structural polarization is vital for modern technologies, as it allows the physical properties of functional materials to be tailored. An effective approach for governing polarization involves the utilization of stereochemical lone-pair electrons (LPEs). However, despite the recognized significance of LPEs in controlling structural polarization, there remains a lack of understanding regarding the quantitative relationship between their expression and the extent of structural polarization. Here, by using pressure to continuously tune the LPE expression, we achieve the precise control and quantification of structural polarization, which brings enhanced second harmonic generation (SHG) of the molecular crystal SbI·3S. We introduce the I-Sb-I angle (α̅) that describes the degree of LPE expression and establishes a quantitative relationship between α̅ and structural polarization. That is, decreasing α̅ shapes LPE expression from delocalization to localization, which repels the bonding pairs of electrons and thus enhances the structural polarization. In addition, we extend this quantified relationship to a series of molecular crystals and demonstrate its applicability to the design of structural polarization by tailoring LPE expression.
结构极化的合理设计对现代技术至关重要，因为它能使功能材料的物理性质得到定制。一种控制极化的有效方法是利用立体化学孤对电子（LPEs）。然而，尽管LPEs在控制结构极化方面的重要性已得到认可，但对于它们的表达与结构极化程度之间的定量关系仍缺乏了解。在此，通过使用压力连续调节LPE表达，我们实现了对结构极化的精确控制和量化，这使得分子晶体SbI·3S的二次谐波产生（SHG）增强。我们引入了描述LPE表达程度的I-Sb-I角（α̅），并建立了α̅与结构极化之间的定量关系。也就是说，减小α̅会使LPE表达从离域变为局域，这会排斥电子的成键对，从而增强结构极化。此外，我们将这种量化关系扩展到一系列分子晶体，并通过定制LPE表达证明了其在结构极化设计中的适用性。
