Davies Joshua A, Elangovan Arumugasamy, Sullivan Philip A, Olbricht Benjamin C, Bale Denise H, Ewy Todd R, Isborn Christine M, Eichinger Bruce E, Robinson Bruce H, Reid Philip J, Li Xiaosong, Dalton Larry R
Department of Chemistry, University of Washington, 109 Bagley Hall, Box 351700, Seattle, Washington 98195, USA.
J Am Chem Soc. 2008 Aug 13;130(32):10565-75. doi: 10.1021/ja8007424. Epub 2008 Jul 19.
Two new highly hyperpolarizable chromophores, based on N,N- bis-(4-methoxyphenyl) aryl-amino donors and phenyl-trifluoromethyl-tricyanofuran (CF3-Ph-TCF) acceptor linked together via pi-conjugation through 2,5-divinylenethienyl moieties as the bridge, have been designed and synthesized successfully for the first time. The aryl moieties on the donor side of the chromophore molecules were varied as to be thiophene and 1-n-hexylpyrrole. The linear and nonlinear optical (NLO) properties of all compounds were evaluated in addition to recording relevant thermal and electrochemical data. The properties of the two new molecules were comparatively studied. These results are critically analyzed along with two other compounds, reported earlier from our laboratories and our collaborator's, that contain (i) aliphatic chain-bearing aniline and (ii) dianisylaniline as donors, keeping the bridge (2,5-divinylenethienyl-), and the acceptor (CF3-Ph-TCF), constant. Trends in theoretically (density functional theory, DFT) predicted, zero-frequency gas-phase hyperpolarizability [beta(0;0,0)] values are shown to be consistent with the trends in beta HRS(-2omega;omega,omega), as measured by Hyper-Rayleigh Scattering (HRS), when corrected to zero-frequency using the two-level model (TLM) approximation. Similarly, trends in poling efficiency data (r33/E(p)) and wavelength dispersion measured by reflection ellipsometry (using a Teng-Man apparatus) and attenuated total reflection (ATR) are found to fit the TLM and DFT predictions. A 3-fold enhancement in bulk nonlinearity (r33) is realized as the donor subunits are changed from alkylaniline to dianisylaminopyrrole donors. The results of these studies provide insight into the complicated effects on molecular hyperpolarizability of substituting heteroaromatic subunits into the donor group structures. These studies also demonstrate that, when frequency dependence and electric-field-induced ordering behavior are correctly accounted for, ab initio DFT generated beta(0;0,0) is effective as a predictor of changes in r33 behavior based on chromophore structure modification. Thus DFT can provide valuable insight into the electronic structure origin of complex optical phenomena in organic media.
首次成功设计并合成了两种新型的高可超极化发色团，它们基于N，N-双（4-甲氧基苯基）芳基氨基供体和苯基-三氟甲基-三氰基呋喃（CF3-Ph-TCF）受体，通过2,5-二乙烯基噻吩基部分作为桥连基团进行π共轭连接在一起。发色团分子供体侧的芳基部分分别为噻吩和1-正己基吡咯。除记录相关的热学和电化学数据外，还评估了所有化合物的线性和非线性光学（NLO）性质。对这两种新分子的性质进行了比较研究。将这些结果与我们实验室和合作者之前报道的另外两种化合物进行了批判性分析，这两种化合物分别含有（i）带有脂肪族链的苯胺和（ii）二茴香胺作为供体，桥连基团（2,5-二乙烯基噻吩基）和受体（CF3-Ph-TCF）保持不变。理论上（密度泛函理论，DFT）预测的零频率气相超极化率[β(0;0,0)]值的趋势，经双能级模型（TLM）近似校正到零频率后，与通过超瑞利散射（HRS）测量的βHRS(-2ω;ω,ω)趋势一致。同样，发现极化效率数据（r33/E(p)）以及通过反射椭偏仪（使用滕-曼仪器）和衰减全反射（ATR）测量的波长色散趋势符合TLM和DFT预测。当供体亚基从烷基苯胺变为二茴香胺基吡咯供体时，体相非线性（r33）实现了3倍的增强。这些研究结果深入了解了将杂芳族亚基取代到供体基团结构中对分子超极化率的复杂影响。这些研究还表明，当正确考虑频率依赖性和电场诱导的有序行为时，基于发色团结构修饰，从头算DFT生成的β(0;0,0)可有效地预测r33行为的变化。因此，DFT可以为有机介质中复杂光学现象的电子结构起源提供有价值的见解。
