The State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
Phys Chem Chem Phys. 2014 Jan 28;16(4):1597-606. doi: 10.1039/c3cp53639d.
Using DFT methods, the electronic properties and the first hyperpolarizabilities of boron-heterofullerene-(super)alkali dyads: M3O-BC59 (M = Li, Na and K) and K@n-BC59 (n = 5 and 6) were systematically investigated. It is found that both M3O and K can effectively bind to BC59 with high binding energies (2.50-2.69 eV for K and 4.24-5.14 eV for M3O). The interaction between K and BC59 in K@n-BC59 is identified as primarily ionic in nature, whereas that between the superalkali M3O unit and BC59 becomes much stronger owing to the formation of a strong chemical bond (B-O bond). Moreover, compared with the sole parent cluster BC59 (619 au), both K@n-BC59 (n = 5 and 6) and M3O-BC59 (M = Li, Na and K), possess large first hyperpolarizabilities (β0), which are 3352, 2621 and 4921, 5440 and 7800 au, respectively, where the superalkali doped dyads (M3O-BC59) are much superior to the simple alkali exo-hedral species (K@n-BC59), and heavier superalkali can be more powerful in enhancing the β0 values of M3O-BC59. Clearly, these superalkali doped dyads M3O-BC59, formal donor-acceptor (DA) chromophores, exhibit not only excellent stability but also large first hyperpolarizability; therefore, they are expected to be potential candidates for excellent second-order NLO materials.
利用密度泛函理论（DFT）方法，系统地研究了硼富勒烯-（超）碱金属二聚体：M3O-BC59（M=Li、Na 和 K）和 K@n-BC59（n=5 和 6）的电子性质和第一超极化率。结果表明，M3O 和 K 都可以与 BC59 以高结合能（对于 K 为 2.50-2.69eV，对于 M3O 为 4.24-5.14eV）有效结合。在 K@n-BC59 中，K 与 BC59 之间的相互作用本质上是离子的，而超碱金属 M3O 单元与 BC59 之间的相互作用由于形成强化学键（B-O 键）而变得更强。此外，与单一母体团簇 BC59（619au）相比，K@n-BC59（n=5 和 6）和 M3O-BC59（M=Li、Na 和 K）都具有较大的第一超极化率（β0），分别为 3352、2621 和 4921、5440 和 7800au，其中超碱金属掺杂的二聚体（M3O-BC59）优于简单的碱金属外壳物种（K@n-BC59），并且更重的超碱金属可以更有效地增强 M3O-BC59 的β0 值。显然，这些超碱金属掺杂的二聚体 M3O-BC59 作为形式上的给体-受体（DA）发色团，不仅具有优异的稳定性，而且具有较大的第一超极化率；因此，它们有望成为优异的二阶 NLO 材料的潜在候选材料。
