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First-Order Hyperpolarizability of Triphenylamine Derivatives Containing Cyanopyridine: Molecular Branching Effect
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-01-12 00:00:00 , DOI: 10.1021/acs.jpcc.7b05829
Ruben D. Fonseca 1, 2 , Marcelo G. Vivas 3 , Daniel Luiz Silva 4 , Gwennaelle Eucat 5 , Yann Bretonnière 5 , Chantal Andraud 5 , Leonardo De Boni 1 , Cleber R. Mendonça 1
Affiliation  

In the present work, we report the multibranching effect on the dynamic first-order hyperpolarizability (β(−2ω; ω, ω)) of triphenylamine derivatives containing cyanopyridine one-branch (dipolar structure), two-branch (V-shaped structure), and three-branch (octupolar structure) structures. For this study, we used the hyper-Rayleigh scattering (HRS) technique involving picosecond pulse trains at 1064 nm. Our results show that βHRS increases from 2.02 × 10–28 to 9.24 × 10–28 cm5/esu when an extra branch is added to the molecule, configuring a change from a dipolar to a V-shaped (quadrupolar) molecular structure. When a third branch is added, leading to an octupolar structure, a decrease to 3.21 × 10–28 cm5/esu is observed. Such a significant decrease in βHRS is attributed to a negative contribution presented in the βHRS description by using a three-level energy approach due to their electronic structure and considering a specific combination of the angle between the dipole moments. On the other hand, the enhancement of βHRS found for the quadrupolar structure is associated with the cooperative enhancement due to the electronic coupling between the branches that increases considerably the transition dipole moment and permanent dipole moment change. To explain the βHRS results obtained for different molecules, we employed the HRS figure of merit, FOMHRS = βHRS/Neff3/2, in which Neff is the effective number of π-conjugated bonds, and the few-energy level approach for βHRS within the Frenkel exciton model. To shed more light on the experimental results interpretation, we performed time-dependent density functional theory calculations combined with a polarizable continuum model to confirm the energy and oscillator strength of the electronic transitions assumed in the Frenkel exciton model employed here.

中文翻译:

含氰基吡啶的三苯胺衍生物的一阶超极化性:分子支化效应

在本工作中,我们报告了多支化对含有氰基吡啶一分支(双极性结构),二分支(V形结构)的三苯胺衍生物的动态一阶超极化性(β(-2ω;ω,ω))的影响。 ,以及三分支(八极结构)结构。对于本研究,我们使用了涉及1064 nm皮秒脉冲序列的超瑞利散射(HRS)技术。我们的结果表明,β HRS从2.02×10增加-28到9.24×10 -28厘米5 / ESU当一个额外的分支被添加到分子,配置从一个偶极对的V形(四极)的分子结构的变化。当添加第三个分支时,导致八极结构,减小到3.21×10 –28 cm观察到5 / esu。在β这样的显著减少HRS被归因于β呈现的负贡献HRS通过使用三电平能量的方法的描述,因为它们的电子结构,并考虑偶极矩之间的角度的特定组合。在另一方面,β的增强HRS发现四极结构与合作的增强,由于部门之间的电子耦合关联的大幅增加过渡偶极矩和永久偶极矩的变化。为了解释针对不同分子获得的βHRS结果,我们采用了HRS品质因数FOM HRS = βHRS /Ñ EFF 3/2,其中Ñ EFF是有效数量的π共轭键,且为β的少数能量级方法HRS的弗伦凯尔激子模型内。为了更清楚地解释实验结果,我们进行了时变密度泛函理论计算,并结合了可极化的连续体模型,以确认此处采用的Frenkel激子模型假定的电子跃迁的能量和振荡器强度。
更新日期:2018-01-12
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