Synthesis and linear/nonlinear optical properties of a new class of ‘RHS’ NLO chromophore
作者:Andrew J. Kay、Anthony D. Woolhouse、Yuxia Zhao、Koen Clays
DOI:10.1039/b315274j
日期:——
Examples of a new class of zwitterionic, âright-hand sideâ merocyanines containing a cyanodicyanomethylidenedihydrofuran electron acceptor have been prepared. As well as allowing for the facile synthesis of these chromophores, our synthetic methodology enables considerable variation in both the donor moiety as well as the extent of conjugation between the donor and acceptor systems. As expected, all of these âright-hand sideâ systems are negatively solvatochromic, with the difference between λmax
(polar vs. nonpolar solvents) increasing with the extent of conjugation. In accord with expectations, hyper-Raleigh scattering (HRS) measurements confirm that molecules with the greatest conjugation pathway (for e.g.21c, 23c) have the largest first hyperpolarisabilites, βo. In addition, our HRS evaluation indicates that the 4-quinolinylidene donor nucleus is superior to both the 4-pyridinylidene and benzothiazolylidene systems. The figures of merit, μ(calc).βo(measured), that we obtain for some of these compounds, are of a similar magnitude to the best âleft hand sideâ examples reported in the literature. In order to demonstrate the versatility of our synthetic technique, representative polymer-tetherable derivatives of these compounds have been prepared, as have the corresponding TDI-based polyurethanes.
已经制备出一种新的双离子型“右侧”梅罗氰胺类化合物,其包含氰基二氰甲基二氢呋喃电子受体。我们的合成方法不仅允许这些色素的简便合成,还能在供体部分及供体与受体系统之间的共轭程度上进行相当大的变化。正如预期的那样,所有这些“右侧”系统都表现出负溶剂色散性,最大波长(极性与非极性溶剂)之间的差异随着共轭程度的增加而增大。符合预期,超拉赖散射(HRS)测量证实,具有最大共轭路径的分子(例如21c、23c)具有最大的首个超极化率βo。此外,我们的HRS评估表明,4-喹啉基腈供体核优于4-吡啶基腈和苯并噻唑基腈系统。我们为一些化合物获得的绩效指标μ(calc)·βo(measured)与文献中报道的最佳“左侧”示例相似。为了展示我们合成技术的多样性,已经制备了这些化合物的代表性聚合物连接衍生物,以及相应的基于TDI的聚氨酯。