Yin Xiaodong, Low Jonathan Z, Fallon Kealan J, Paley Daniel W, Campos Luis M
Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China.
Department of Chemistry , Columbia University , New York , New York 10027 , USA . Email:
Chem Sci. 2019 Oct 7;10(46):10733-10739. doi: 10.1039/c9sc04096j. eCollection 2019 Dec 14.
Linear acenes are a well-studied class of polycyclic aromatic hydrocarbons and their established physical properties have led to their widespread application across the field of organic electronics. However, their quinoidal forms - dihydroacenes - are much less explored and exhibit vastly different photophysical and electronic properties due to their non-planar, cross-conjugated nature. In this work, we present a series of difluorenylidene dihydroacenes which exhibit a butterfly-like structure with a quinoidal skeleton, resulting in comparatively higher optical gaps and lower redox activities than those of their planar analogs. We found that these compounds exhibit aggregation induced emission (AIE), activated through restriction of the "flapping" vibrational mode of the molecules in the solid state. Furthermore, anthracene-containing dihydroacenes exhibit thermally activated ground-state spin switching as evidenced by planarization of the acene core and diradical activity recorded by EPR. These two characteristics in this relatively unexplored class of materials provide new insights for the design of multifunctional materials.
线性并苯是一类经过充分研究的多环芳烃，其已确定的物理性质使其在有机电子领域得到了广泛应用。然而，它们的醌式形式——二氢并苯——却较少被研究，并且由于其非平面、交叉共轭的性质，呈现出截然不同的光物理和电子性质。在这项工作中，我们展示了一系列二芴叉基二氢并苯，它们呈现出具有醌式骨架的蝴蝶状结构，与平面类似物相比，具有相对较高的光学带隙和较低的氧化还原活性。我们发现这些化合物表现出聚集诱导发光（AIE），这是通过限制分子在固态中的“摆动”振动模式而激活的。此外，含蒽的二氢并苯表现出热激活的基态自旋切换，这由并苯核心的平面化以及电子顺磁共振记录的双自由基活性所证明。在这类相对未被充分探索的材料中的这两个特性为多功能材料的设计提供了新的见解。
