Strategy for enhancing second-order nonlinear optical properties of the Pt(II) dithienylethene complexes: substituent effect, π-conjugated influence, and photoisomerization switch.
Strategy for enhancing second-order nonlinear optical properties of the Pt(II) dithienylethene complexes: substituent effect, π-conjugated influence, and photoisomerization switch.
复制标题
DOI：
10.1021/jp4041265
复制
发表时间：
2013-11
期刊：
影响因子：
--
通讯作者：
Mengying Zhang;Cun-Huan Wang;Wen-yong Wang;Nana Ma;Shiling Sun;Y. Qiu
中科院分区：
文献类型：
--
作者：
Mengying Zhang;Cun-Huan Wang;Wen-yong Wang;Nana Ma;Shiling Sun;Y. Qiu
采用密度泛函理论（DFT）结合解析导数方法研究了一系列具有可逆光致变色行为的二噻吩基乙烯（DTE）铂配合物的二阶非线性光学性质.结果表明，随着取代基R（R = H，CF 3，NO2）吸电子能力的增强和噻吩环数目的增加，开环和闭环体系的静态第一超极化率（βtot）均显著增大，增大幅度在2.1-4.5倍之间.此外，从开环系统到相应的闭环系统，βtot值有很大的增强。这种高效的增强归因于π电子系统的离域性更好，电荷转移程度更明显，f（os）/E（gm）（3）更大（f（os）为振子强度和E（gm）是基态和激发态之间的跃迁能）值的封闭形式根据键长交替（BLA）和含时密度泛函理论（TDDFT）计算。此外，在低频区（0.000-0.040 Au），色散对体系的频率依赖的第一超极化率（βtot（ω））影响较小.本文的工作为金属配合物大二阶非线性光学响应的进一步理论和实验研究奠定了基础。
The second-order nonlinear optical (NLO) properties of a series of Pt(II) dithienylethene (DTE) complexes possessing the reversible photochromic behavior have been investigated by density functional theory (DFT) combined with the analytic derivatives method. The results show that the calculated static first hyperpolarizabilities (βtot) of the open-ring and closed-ring systems significantly increase in the range of 2.1-4.5 times through strengthening of the electron-withdrawing ability of the substituent R (R = H, CF3, NO2) and an increase of the number of thiophene rings. Moreover, there is a large enhancement of the βtot values from the open-ring systems to the corresponding closed-ring systems. This efficient enhancement is attributed to the better delocalization of the π-electron system, the more obvious degree of charge transfer, and the larger f(os)/E(gm)(3) (f(os) is the oscillator strength, and E(gm) is the transition energy between the ground and the excited states) values in the closed forms according to the bond length alternation (BLA) and time-dependent density functional theory (TDDFT) calculations. In addition, the dispersion has less influence on the frequency-dependent first hyperpolarizabilities (βtot(ω)) of the studied systems at the low-frequency area ω (0.000-0.040 au). Our present work would be beneficial for further theoretical and experimental studies on large second-order NLO responses of metal complexes.