稳定的硼吡咯烷和硼芴杂环：基于硼氧相互作用的可逆热致变色“开关”。
Stable Borepinium and Borafluorenium Heterocycles: A Reversible Thermochromic "Switch" Based on Boron-Oxygen Interactions.
机构信息
Department of Chemistry, University of Virginia, 409 McCormick Rd./ PO Box 400319, Charlottesville, VA, 22904, USA.
Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, Victoria, Australia.
出版信息
Chemistry. 2019 Sep 25;25(54):12512-12516. doi: 10.1002/chem.201903348. Epub 2019 Sep 3.
The first examples of N-heterocyclic carbene (NHC) and cyclic(alkyl)(amino) carbene (CAAC) stabilized borepinium and borafluorenium heterocycles are reported herein. The optical properties of the heterocyclic borenium cations were tuned by varying the Lewis base and by changing the number of atoms in the ring. More importantly, functionalizing the cationic boron ring system in the NHC-borafluorenium cation affords a temperature-sensitive molecule with reversible colorimetric "turn off/turn on" properties in solution. Notably, this is the first report of thermochromism in these cationic species. This property, which is mediated by an intermolecular boron-oxygen bond equilibrium, was examined in detail by X-ray crystallography, variable temperature-UV/Vis absorption spectroscopy (VT-UV/Vis), and density functional theory (DFT).
本文报道了首例 N-杂环卡宾（NHC）和环状（烷基）（氨基）卡宾（CAAC）稳定的硼并吡咯鎓和硼并芴鎓杂环。通过改变路易斯碱和亲环硼原子环上的原子数，对杂环硼翁阳离子的光学性质进行了调节。更重要的是，在 NHC-硼并芴鎓阳离子中环上的阳离子硼原子系统的功能化提供了一种温度敏感的分子，在溶液中具有可逆比色“关/开”性质。值得注意的是，这是这些阳离子物种中热致变色的首次报道。这种性质是由分子间的硼氧键平衡介导的，通过 X 射线晶体学、变温紫外/可见吸收光谱（VT-UV/Vis）和密度泛函理论（DFT）进行了详细研究。
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