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Hybrid conjugated polymers with alternating dithienosilole or dithienogermole and tricoordinate boron units†
Polymer Chemistry ( IF 4.1 ) Pub Date : 2017-12-18 00:00:00 , DOI: 10.1039/c7py01790a
Yohei Adachi 1, 2, 3, 4, 5 , Yousuke Ooyama 1, 2, 3, 4, 5 , Yi Ren 6, 7, 8, 9 , Xiaodong Yin 6, 7, 8, 9 , Frieder Jäkle 6, 7, 8, 9 , Joji Ohshita 1, 2, 3, 4, 5
Affiliation  

Conjugated polymers composed of tricoordinate boron and π-conjugated units possess extended conjugation with relatively low-lying LUMOs arising from pB–π interactions. However, donor–acceptor (D–A) polymers that feature triorganoboranes alternating with highly electron-rich donors remain scarce. We present here a new class of hybrid D–A polymers that combine electron-rich dithienosiloles or dithienogermoles with highly robust tricoordinate borane acceptors. Polymers of modest to high molecular weight are readily prepared by Pd-catalyzed Stille coupling reaction of bis(halothienyl)boranes and distannyldithienosiloles or -germoles. The polymers are obtained as dark red solids that are stable in air and soluble in common organic solvents. Long wavelength UV-vis absorptions at ca. 500–550 nm indicate effective π-conjugation and pronounced D–A interactions along the backbone. The emission maxima occur at wavelengths longer than 600 nm in solution and experience further shifts to lower energy with increasing solvent polarity, indicative of strong intramolecular charge transfer (ICT) character of the excited state. The powerful acceptor character of the borane comonomer units in the polymer structures is also evident from cyclic voltammetry (CV) analyses that reveal relatively low-lying LUMO levels of the polymers, enhancing the D–A interaction. Density functional theory (DFT) calculations on model oligomers further support these experimental observations.

中文翻译:

具有交替的二噻吩并甲硅烷基或二噻吩并germol和三配位硼单元的杂化共轭聚合物

由三配位硼和π共轭单元组成的共轭聚合物与p B –π相互作用产生的相对较低的LUMO具有扩展的共轭。但是,具有三有机硼烷与高度电子富集的供体交替出现的供体-受体(D-A)聚合物仍然稀缺。我们在这里提出了一种新型的杂化D–A聚合物,它结合了富电子的二噻吩并二噻吩并小分子与高度坚固的三配位硼烷受体。通过双(卤代噻吩基)硼烷与二苯乙烯基噻吩并二萜或-锗烷的Pd催化的Stille偶联反应可以容易地制备中等至高分子量的聚合物。获得的聚合物为深红色固体,在空气中稳定并溶于常见的有机溶剂。长波长紫外可见吸收约为。500–550 nm表示有效的π共轭和沿骨架的明显的DA相互作用。发射最大值出现在溶液中大于600 nm的波长处,并随着溶剂极性的增加而发生进一步转变,以降低能量,这表明激发态具有强大的分子内电荷转移(ICT)特性。循环伏安法(CV)分析也证明了硼烷共聚单体单元在聚合物结构中的强大受体特性,揭示了聚合物相对较低的LUMO含量,增强了D–A相互作用。对模型低聚物的密度泛函理论(DFT)计算进一步支持了这些实验观察。
更新日期:2017-12-18
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