Bai Sha, Wang Li-Feng, Wu Zhen-Wei, Feng Ting, Han Ying-Feng
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Xi'an Key Laboratory of Functional Supramolecular Structure and Materials, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
Dalton Trans. 2022 Jun 7;51(22):8743-8748. doi: 10.1039/d2dt01094a.
Photochemical reactions are vital synthetic means for the synthesis of natural products and highly strained molecules. However, it remains an immense challenge to control the chemo- and regioselectivity in the photoreactions of anthracene derivatives while maintaining high reactivity. Herein, we report the synthesis of two photoactive metallarectangles 1a and 1b by coordination-driven self-assembly of 2,6- and 2,7-bifunctionalized anthracenes with a half-sandwich rhodium template. By taking advantage of the rhodium template, the anthracene groups within the metallarectangles can be preorganized in a parallel fashion and exclusively undergo a photochemical [4 + 4] cycloaddition. As a result, the -photodimers were obtained in quantitative yields under irradiation at 365 nm. The photocycloaddition of metallarectangles 1a and 1b was found to be reversible photo- and thermal cleavage reactions, even after repeating three times. Furthermore, pure organic photodimers 3a and 3b, which are difficult to synthesize by conventional organic methods, can be readily dissociated from the metalloassemblies in high yields.
光化学反应是合成天然产物和高张力分子的重要合成手段。然而，在保持高反应活性的同时，控制蒽衍生物光反应中的化学选择性和区域选择性仍然是一个巨大的挑战。在此，我们报道了通过2,6-和2,7-双官能化蒽与半夹心铑模板的配位驱动自组装合成了两种光活性金属矩形配合物1a和1b。利用铑模板，金属矩形配合物中的蒽基团可以以平行方式预先排列，并仅发生光化学[4 + 4]环加成反应。结果，在365 nm光照下以定量产率获得了光二聚体。发现金属矩形配合物1a和1b的光环加成反应是可逆的光解和热解反应，即使重复三次后也是如此。此外，难以通过传统有机方法合成的纯有机光二聚体3a和3b可以很容易地以高产率从金属组装体中解离出来。
