Abstract：
Multifluorinated aromatics serve as supramolecular synthons in the research of organic electro-optic (EO) materials by exploiting π-π stacking interaction between the aromatic hydrocarbon and multifluorinated aromatic groups for performance improvement. However, non-classical hydrogen bonding remains largely unexplored in fluorinated EO dendrimers. In this study, three Fréchet-type generation 1 benzyl ether co-dendrons were synthesized by replacing one benzyl group with 2,3,5,6-tetrafluorobenzyl (p-HF4Bz), pentafluorobenzyl (C6F5Bz), and 2,3,4,5-tetrafluorobenzyl (o-HF4Bz) groups, to afford the benzoic acid derivatives D1, D2, and D3, which were further bonded to the donor and π-bridge moieties to afford three co-dendronized push-pull phenyltetraene chromophores EOD1, EOD2, and EOD3, respectively. The weak C-H⋅⋅⋅X (X=O, F) interactions in the crystal structure of D1 cumulatively add to the benzoic acid dimers to form an extended hydrogen-bonded network, while D2 is crystallized into a centric one-dimensional chain with strong intermolecular interactions. The poled films of EOD1 with PMMA exhibited the largest and most stable EO activity with optical homogeneity among the series. The results identify the effectiveness of weak but favorable hydrogen bonds enabled by the enhanced carbon acidity of p-HF4Bz synthon in D1, over the interactions in D2 and D3, for the rational design of supramolecular EO dendrimers.
摘要：
通过利用芳烃与多氟化芳族基团之间的π-π堆叠相互作用来改善性能，多氟化芳族化合物在有机电光（EO）材料的研究中用作超分子合成子。然而,非经典氢键在氟化EO树枝状聚合物中仍未被探索。在这项研究中,通过用2,3,5,6-四氟苄基（p-HF4Bz）取代一个苄基，合成了三个Fréchet型1代苄基醚共树突，五氟苄基(C6F5Bz),和2,3,4,5-四氟苄基(o-HF4Bz)基团，得到苯甲酸衍生物D1、D2和D3，它们进一步键合到供体和π-桥部分，分别得到三个共同树突化的推拉苯基四烯发色团EOD1、EOD2和EOD3。弱C-H·······X(X=O，F）D1晶体结构中的相互作用累积地添加到苯甲酸二聚体中，以形成扩展的氢键网络，而D2结晶成具有强分子间相互作用的中心一维链。具有PMMA的EOD1极化膜表现出最大和最稳定的EO活性，并且在该系列中具有光学均匀性。结果确定了通过D1中p-HF4Bz合成子的碳酸度增强而在D2和D3中的相互作用中，弱但有利的氢键对于超分子EO树枝状聚合物的合理设计的有效性。
