Guest binding and new self-assembly of bisporphyrins
Guest binding and new self-assembly of bisporphyrins
复制标题
DOI：
10.1021/jo052224b
复制
发表时间：
2006-03-31
影响因子：
3.6
通讯作者：
Fukazawa, Y
中科院分区：
文献类型：
--
作者：
Haino, T;Fujii, T;Fukazawa, Y
在有机介质中，由芳香族连接体连接的双卟啉 1-6 通过范德华力、pi-pi 堆积和 CH/pi 等微妙的力自组装，形成超分子二聚体。利用我们的化学位移模拟讨论了双卟啉二聚体1中心点1的结构，发现1中心点1主要采用自互补结构A。双卟啉的ESI质量实验表明1-4仅形成二聚体；双卟啉1中心点1主要采用自互补结构A。然而，在气相中观察到了5和6的三聚体以及二聚体。因此，双卟啉5和6的组装体应采用结构B，其仍然具有结合位点，另一个双卟啉可以与该结合位点形成寡聚结构。双卟啉 I 的二聚常数取决于溶剂极性：值按甲苯 > 氯仿 > 20% 甲醇-氯仿的顺序减小。二聚过程的热力学研究表明，去溶剂化以及 pi-pi 堆积相互作用在自互补二聚体的形成中发挥着关键作用。双卟啉 1 与多种缺电子芳香族客体 9-17 的结合研究是在氯仿中进行的。 I 的 Soret 和 Q 带显示出随着客体 9-13 和 15 的添加而发生的特征变化，并且在 H-1 NMR 光谱的络合研究中观察到其质子的大高场位移。这些结果表明，缺电子芳香族客体通过电荷转移以及客体与卟啉环之间的 pi-pi 堆积相互作用结合在双卟啉 1 的裂隙内。 1中心点1的二聚化常数远小于1中心点9的缔合常数，表明二聚体1中心点1的解离可以通过裂口内9的结合来调节。将9添加到1个中心点1的溶液中导致二聚体快速解离并形成1个中心点9。
In organic medium, bisprophyrins 1-6 connected by aromatic linkers self-assemble via subtle forces such as van der Waals, pi-pi stacking, and CH/pi to form supramolecular dimers. The structures of bisporphyrin dimer 1 center dot 1 were discussed using our chemical shift simulation, revealing that 1 center dot 1 mainly adopts the self-complementary structure A. ESI mass experiments of the bisporphyrins showed that 1-4 form only the dimers; however, trimers as well as the dimers of 5 and 6 were observed in the gas phase. Thus, the assemblies of bisporphyrin 5 and 6 should adopt structure B, which still has a binding site to which another bisporphyrin can fit to form oligomeric structures. The dimerization constant of bisporphyrin I is dependent on the solvent polarity: the values decrease in the order of toluene > chloroform > 20% methanol -chloroform. The thermodynamic studies of the dimerization processes revealed that desolvation as well as pi-pi stacking interactions play a key role in the formation of the self-complementary dimers. The binding studies of bisporphyrin 1 with a variety of electron deficient aromatic guests 9-17 were carried out in chloroform. Soret and Q-bands of I showed the characteristic changes with the addition of guests 9-13 and 15, and large upfield shifts of their protons were observed in their complexation studies with H-1 NMR spectroscopy. These results suggested that the electron deficient aromatic guests bound within the cleft of bisporphyrin 1 via charge transfer as well as pi-pi stacking interactions between the guests and the porphyrin rings. The dimerization constant of 1 center dot 1 is much smaller than the association constant of 1 center dot 9, suggesting that the dissociation of dimer 1 center dot 1 can be regulated by binding of 9 within the cleft. The addition of 9 into the solution of 1 center dot 1 resulted in the quick dissociation of the dimer and the formation of 1 center dot 9.