Synthesis and Properties of Dicyanomethylene-Endcapped Thienopyrrole-Based Quinoidal <i>S</i>,<i>N</i>-Heteroacenes
作者:Hua Jiang、Kazuaki Oniwa、Zhanqiang Xu、Ming Bao、Yoshinori Yamamoto、Tienan Jin
DOI:10.1246/bcsj.20170083
日期:2017.7.15
A new series of highly π-extended dicyanomethylene-endcapped quinoidal S,N-heteroacenes (JH-quinoids) fused with thiophene and pyrrole rings have been designed and synthesized. The π-extension of the central S,N-heteroacene cores gives rise to significant red-shifted absorption maxima in solution without being affected by the long alkyl groups. The absorption maximum of JH10 with the longest quinoidal backbone in the thin film significantly red-shifted to the near-infrared region of 1260 nm as compared to that in solution (880 nm), indicating the formation of strong intermolecular interaction in the solid state. JH-quinoids maintain sufficiently low LUMO energy levels in the range of −4.09∼−4.22 eV regardless of the fused ring systems and substituents, while the HOMO energy levels increase with extending the length of S,N-heteroacenes; the highest HOMO energy level of JH10 is as high as −5.18 eV owing to the contributions from the nitrogen atoms and chalcogen. The molecular geometries of JH-quinoids optimized from the DFT calculations indicate their complete planar backbones and the trend of HOMO and LUMO energy levels variation is in good agreement with the cyclic voltammetry results. Consequently, the present JH-quinoids should be promising candidates for ambipolar organic semiconductors.
设计并合成了一系列新的含有噻吩和吡咯环的高π扩展二氰甲叉端基喹喔啉型S,N-杂芳烃(JH-喹喔啉)。其中S,N-杂芳烃核心的π扩展在溶液中产生显著的红移吸收最大值,而不受长链烷基的影响。与溶液相比,具有最长的喹喔啉骨架的JH10在薄膜中的吸收最大值显著红移至近红外区域的1260 nm(溶液中为880 nm),表明在固态中形成了强大的分子间相互作用。JH-喹喔啉保持了足够低的LUMO(最低未占据分子轨道)能级,范围为−4.09至−4.22 eV,无论其融合的环系统和取代基。价轨道(HOMO)能级随着S,N-杂芳烃长度的增加而增加;由于氮和硫的贡献,JH10的HOMO能级最高可达−5.18 eV。从DFT计算优化得到的JH-喹喔啉分子几何结构表明其完全平面的骨架,HOMO和LUMO能级的变化趋势与循环伏安结果一致。因此,目前JH-喹喔啉应该是双极性有机半导体的有希望的候选者。