Feng Chieh-Ning, Hsu Wen-Ching, Li Jen-Yi, Kuo Ming-Yu, Wu Yao-Ting
Department of Chemistry, National Cheng Kung University, No.1 Ta-Hsueh Road, 70101, Tainan, Taiwan.
Department of Applied Chemistry, National Chi Nan University, No. 1 University Rd., 54561 Puli, Nantou, Taiwan.
Chemistry. 2016 Jun 27;22(27):9198-208. doi: 10.1002/chem.201600124. Epub 2016 May 31.
The syntheses, structures, and physical properties of a full series of benzannulated tetraphenylenes are reported. The palladium-catalyzed annulation of tetraiodo-substituted 2,3,6,7,10,11,14,15-octamethyltetraphenylene with insufficient di(4-anisyl)ethyne yielded a mixture of per-substituted [8]circulene and its non-planar fragments, including mono-, para-di-, ortho-di-, and triannulated products. Their structures were unambiguously verified by X-ray crystallography. Successive benzannulations significantly affect the molecular geometries, dynamic behaviors, and physical properties of the compounds. In this series of compounds, [8]circulene is the most strained one, as reflected by the significant deplanarization of the phenanthrene moieties (ca. 63° in the bay region) and the fact that it has the highest strain energy (120.6 kcal mol(-1) ). The dynamic behaviors of these compounds were examined both experimentally and theoretically. The ring flipping of per-substituted [8]circulene is confirmed to proceed through pseudorotation with a barrier of around 21 kcal mol(-1) , whereas its non-planar fragments require much more energy for the ring inversion. The photophysical and electrochemical properties of the investigated compounds depend strongly on the extent of efficient π conjugation. The successive benzannulations red-shift both the absorption and the emission bands, and reduce the first oxidation potential.
报道了一系列苯并稠合四亚苯基的合成、结构和物理性质。钯催化四碘代取代的2,3,6,7,10,11,14,15 - 八甲基四亚苯基与不足量的二（4 - 甲氧基苯基）乙炔进行环化反应，得到全取代的[8]环烯及其非平面片段的混合物，包括单环、对二环、邻二环和三环化产物。它们的结构通过X射线晶体学得到明确验证。连续的苯并环化显著影响化合物的分子几何形状、动态行为和物理性质。在这一系列化合物中，[8]环烯是应变最大的，菲环部分明显的非平面化（湾区约63°）以及它具有最高的应变能（120.6 kcal mol⁻¹）都反映了这一点。通过实验和理论研究了这些化合物的动态行为。全取代的[8]环烯的环翻转被证实是通过势垒约为21 kcal mol⁻¹的假旋转进行的，而其非平面片段的环反转需要更多能量。所研究化合物的光物理和电化学性质强烈依赖于有效π共轭的程度。连续的苯并环化使吸收带和发射带都发生红移，并降低第一氧化电位。
