Theoretical Study on Second Hyperpolarizabilities of Intramolecular Pancake-Bonded Diradicaloids with Helical Scaffolds
Theoretical Study on Second Hyperpolarizabilities of Intramolecular Pancake-Bonded Diradicaloids with Helical Scaffolds
复制标题
螺旋支架分子内饼状双自由基二次超极化率的理论研究
DOI：
10.1021/acsomega.8b03619
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发表时间：
2019
期刊：
影响因子：
4.1
通讯作者：
Nakano Masayoshi
中科院分区：
文献类型：
--
作者：
Takamuku Shota;Nakano Masayoshi
利用自旋无限制密度泛函理论方法，研究了一类新型的具有螺旋骨架的开壳单重态稠环分子，为发展高效的三阶非线性光学(NLO)系统奠定了基础。结果表明，螺旋分子具有中间双自由基性质的煎饼键，因此与闭壳类似物相比，其取向平均二次超极化率γs值(分子尺度上的三阶非线性光学性质)有较大的提高。研究还发现，与没有不对称电荷分布的开壳类似物相比，位于螺旋支架两端环上的界面自由基点之间的不对称电荷分布导致了中间开壳特征区域的γ值进一步提高。这些结果表明，具有中间双自由基性质的螺旋体系是构建高效开壳单重态非线性光学材料的潜在候选者，其性能优于传统的闭壳非线性光学材料。
Using the spin-unrestricted density functional theory method, we have investigated a novel class of open-shell singlet fused-ring molecules with helical scaffolds toward the development of highly efficient third-order nonlinear optical (NLO) systems. It turns out that the helical molecules possess pancake bonding with intermediate diradical character and thereby exhibit large enhancement of orientationally-averaged second hyperpolarizability γsvalues (third-order NLO properties at the molecular scale) as compared to their closed-shell analogues. It is also found that the asymmetric charge distribution between the cofacial radical sites located on both the terminal rings of the helical scaffold leads to further enhancement of the γ value in the intermediate open-shell character region as compared to the open-shell analogues without asymmetric charge distributions. These results indicate that the helical systems with intermediate diradical character are potential candidates for the building block of highly efficient open-shell singlet NLO materials, which are superior to the conventional closed-shell NLO materials.