Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, Jilin, People's Republic of China.
J Phys Chem A. 2011 Mar 17;115(10):2035-40. doi: 10.1021/jp110412n. Epub 2011 Feb 21.
On the basis of the n-acenes (n = 1, 2, 3 and 4), the α-Li@n-acenes and β-Li@n-acenes salts were selected to investigate how increasing the number n of conjugated benzenoid rings affects the linear and nonlinear optical responses. The α-Li@n-acenes and β-Li@n-acenes salts are obtained by a lithium atom substituting the α-H and β-H, respectively. In the present work, both ab initio (HF and MP2) and DFT (B3LYP, BhandHLYP, M05-2X, and CAM-B3LYP) methods are adopted to calculate the polarizability (α(0)) and first hyperpolarizability (β(tot)) of the α-Li@n-acenes and β-Li@n-acenes salts. MP2 results show that the α(0) values of both classes of lithium salts increase with increasing number n of conjugated benzenoid rings. Interestingly, we found that the β(tot) values of α-Li@n-acenes and β-Li@n-acenes salts take on opposite trends: the β(tot) values of α-Li@n-acenes are decreasing slowly (2187 for α-Li@benzene > 1978 for α-Li@naphthalene > 1898 for α-Li@anthrecene > 1830 au for α-Li@tetracene) and inceasing remarkably (2738 for β-Li@naphthalene < 3186 for β-Li@anthrecene < 3314 au for β-Li@tetracene) for β-Li@n-acenes. Furthermore, we found that the β(tot) values (2738-3314 au) of the β-Li@n-acenes are larger than those of the α-Li@n-acenes (1830-2187 au). On the other hand, comparing the results of different methods, the β(tot) values obtained by the M05-2X and CAM-B3LYP methods reproduce the polarizability and first hyperpolarizability of the α-Li@n-acenes and β-Li@n-acenes salts well, which test and verify the results of the MP2 method. Our present work may be beneficial to development of high-performance organic NLO optical materials.
基于 n-并五苯（n = 1、2、3 和 4），选择了α-Li@n-并五苯和β-Li@n-并五苯盐，以研究增加共轭苯环的数量 n 如何影响线性和非线性光学响应。α-Li@n-并五苯和β-Li@n-并五苯盐是通过一个锂原子取代α-H 和β-H 得到的。在本工作中，采用从头算（HF 和 MP2）和密度泛函理论（B3LYP、BhandHLYP、M05-2X 和 CAM-B3LYP）方法计算了α-Li@n-并五苯和β-Li@n-并五苯盐的极化率（α(0)）和一阶超极化率（β(tot)）。MP2 结果表明，两类锂盐的α(0)值随共轭苯环数 n 的增加而增加。有趣的是，我们发现α-Li@n-并五苯和β-Li@n-并五苯盐的β(tot)值呈现相反的趋势：α-Li@n-并五苯的β(tot)值缓慢减小（2187 为α-Li@苯>1978 为α-Li@萘>1898 为α-Li@蒽>1830 au 为α-Li@四并苯），β-Li@n-并五苯的β(tot)值显著增大（2738 为β-Li@萘<3186 为β-Li@蒽<3314 au 为β-Li@四并苯）。此外，我们发现β-Li@n-并五苯的β(tot)值（2738-3314 au）大于α-Li@n-并五苯的β(tot)值（1830-2187 au）。另一方面，通过比较不同方法的结果，M05-2X 和 CAM-B3LYP 方法得到的β(tot)值很好地再现了α-Li@n-并五苯和β-Li@n-并五苯盐的极化率和一阶超极化率，这验证了 MP2 方法的结果。我们的工作可能有助于开发高性能有机 NLO 光学材料。
