Guest encapsulation and coronene–C60 exchange in supramolecular zinc porphyrin tweezers, grids and prisms
作者:Soumen K. Samanta、Michael Schmittel
DOI:10.1039/c3ob27481k
日期:——
Using a variant of the HETPHEN concept, heteroleptic 2D and 3D metallosupramolecular structures, such as tweezer T, grid G and tetragonal prism P, were fabricated quantitatively and characterised by 1H NMR, 13C NMR, 1Hâ1H COSY, DOSY as well as ESI-MS. All structures encapsulate C60, with P showing the highest binding affinity (Kassoc = 3.3 Ã 106 Mâ1). The association constant increases along the series T < G < P, most likely due to the enhanced structural rigidity and better coplanarity of the two zinc porphyrin units. In contrast to T and G, the tetragonal prism P shows notable encapsulation of coronene (Kassoc = 1.1 Ã 104 Mâ1). In T and G, on the other hand, complexation of coronene is kinetically inhibited by the bulky mesityl rings at the porphyrin periphery. As illustrated in the facile displacement of coronene by C60 in coronene@P to furnish C60@P, P behaves as a flexible and guest-adaptive host.
利用 HETPHEN 概念的变体,定量制作了异极二维和三维金属超分子结构,如镊子 T、网格 G 和四方棱柱 P,并通过 1H NMR、13C NMR、1Hâ1H COSY、DOSY 以及 ESI-MS 进行了表征。所有结构都能封装 C60,其中 P 的结合亲和力最高(Kassoc = 3.3 Ã 106 Mâ1)。结合常数随着 T < G < P 系列的增加而增加,这很可能是由于两个锌卟啉单元的结构刚性增强,共面性提高所致。与 T 和 G 不同的是,四方棱柱 P 显示出明显的冠烯包裹性(Kassoc = 1.1 Ã 104 Mâ1)。另一方面,在 T 和 G 中,冠烯的络合受到卟啉外围笨重的间苯二酚环的动力学抑制。在冠醚@P 中,冠醚很容易被 C60 置换成 C60@P,这说明 P 是一种灵活的客体适应性宿主。