Dibenzo[a,e]pentalenophanes: Bending a Non-Alternant Hydrocarbon
Dibenzo[a,e]pentalenophanes: Bending a Non-Alternant Hydrocarbon
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DOI：
10.1002/chem.201800322
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发表时间：
2018-05-23
影响因子：
4.3
通讯作者：
Esser, Birgit
中科院分区：
文献类型：
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作者：
Hermann, Mathias;Wassy, Daniel;Esser, Birgit
在环番中，芳族部分被并入（应变）环状结构中。作为弯曲碳纳米结构的模型系统特别感兴趣的是含有多环芳烃的那些。二苯并[a，e]并环戊二烯（DBP）是一种非交替多环碳氢化合物，具有带隙小、光电性质可调等特点。然而，通过弯曲DBP结构来改变这些性质还有待研究。在此，我们报告了四种不同的桥尺寸和DBP单元的弯曲角度的（2，7）二苯并[a，e]并环戊二烯并吡喃的合成，光电和结构性质，并伴有（TD）DFT计算。最后，用Burgess试剂进行菌株诱导脱水反应。HOMO和LUMO能级以及指向环蕃腔内质子的磁屏蔽随环应变的增加而逐步增大。最小的三个衍生物的单晶X-射线结构揭示了一个近半圆和一个弯曲角的DBP单元的几乎88度的最小的衍生物。我们通过改变DBP单元的取代基来证明我们的方法的合成通用性，从而允许进一步调整光电性质。本文提出的合成策略可以为共轭DBP纳米环的合成铺平道路。
In cyclophanes, an aromatic moiety is incorporated into a (strained) cyclic structure. Of particular interest as model systems for bent carbon nanostructures are those containing polycyclic aromatic hydrocarbons. Dibenzo[a,e]pentalene (DBP) is a non-alternant polycyclic hydrocarbon with small band gap and tunable optoelectronic properties. However, changing these properties by bending of the DBP structure has yet to be investigated. Herein, we report the synthesis, optoelectronic, and structural properties of (2,7)dibenzo[a,e]pentalenophanes with four different bridge sizes and bending angles of the DBP unit, accompanied by (TD)DFT calculations. The last, strain-inducing dehydration reaction was accomplished by using Burgess' reagent. The HOMO and LUMO levels and the magnetic shielding of protons pointing inside the cyclophane cavity grew stepwise with increasing ring strain. Single-crystal X-ray structures of the smallest three derivatives revealed a near semi-circle and a bend angle of the DBP unit of almost 88 degrees for the smallest derivative. We demonstrated the synthetic versatility of our approach by varying the substituents at the DBP unit, allowing for further tuning of optoelectronic properties. The synthetic strategy presented herein may pave the way for the synthesis of conjugated DBP nanorings.