Synthesis and Properties of Benzo[d]dithieno[b,f]borepins
Synthesis and Properties of Benzo[d]dithieno[b,f]borepins
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DOI：
10.1021/acs.organomet.7b00844
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发表时间：
2018-03-26
期刊：
影响因子：
2.8
通讯作者：
Ohshita, Joji
中科院分区：
文献类型：
--
作者：
Adachi, Yohei;Ohshita, Joji
Borepin是含有三配位硼的七元不饱和环系统。尽管迄今为止已经报道了许多与芳香系统成环的borepin化合物，但仅合成了一种[B，d，f]-成环四环borepin。本论文合成了一类新型的苯并[d]-二噻吩并[B，f] borepin类化合物，它们具有以下结构特点：（1）二噻吩并[B，f]borepin类化合物具有高的化学稳定性，（2）具有高度共轭的含borepin环的四环体系，（3）具有良好的热稳定性和热稳定性。以及（3）通过在成环苯环上引入官能团而容易调节的电子结构。所制备的borepins在空气中无论是溶液还是固体都是稳定的，并且可以通过改变苯环上的取代基来微调其电子状态。有趣的是，DFT计算表明，LUMO和LUMO+1能级强烈地受到苯并[d]-成环的影响，这取决于稠合噻吩环上的硼桥位置。NICS和HOMA方法证明了苯并[d]二噻吩并[B，f]硼平体系中硼平环的芳香度较小。我们还报告了一个意想不到的红色发射观察到的第一次在borepin化合物的苯并[d]二噻吩并[B，f]borepin在固态。
Borepin is a seven-membered unsaturated ring system containing a tricoordinate boron. Although many borepin compounds annulated with aromatic systems have been reported to date, only one [b,d,f]-annulated tetracyclic borepins has been synthesized. In the present study, we synthesized benzo[d]-dithieno[b,f]borepins as a new class of building blocks for functional materials motivated by the following structural features: (1) the high chemical stability of dithieno[b,f]borepin species; (2) the highly conjugated tetracyclic system with a borepin ring; and (3) electronic structures that are easily tuned by the introduction of functional groups on the annulated benzene ring. The prepared borepins were stable in air both in solution and as solids, and the electronic states could be finely tuned by changing the substituents on the benzene ring. Interestingly, DFT calculations revealed that the LUMO and LUMO+1 energy levels were strongly affected by the benzo[d]-annulation, depending on the boron-bridged positions on the fused thiophene rings. NICS and HOMA methods proved that the aromaticity of the borepin ring in the benzo[d]dithieno[b,f]borepin system is relatively small. We also report an unexpected red emission observed for the first time in borepin compounds for benzo[d]dithieno[b,f]borepin in the solid state.