Coordination assembled rings of ferrocene-bridged trisporphyrin with flexible hinge-like motion: selective dimer ring formation, its transformation to larger rings, and vice versa.
Coordination assembled rings of ferrocene-bridged trisporphyrin with flexible hinge-like motion: selective dimer ring formation, its transformation to larger rings, and vice versa.
复制标题
DOI：
10.1021/ja0445746
复制
发表时间：
2005-02
影响因子：
15
通讯作者：
O. Shoji;Saori Okada;Akiharu Satake;Y. Kobuke
中科院分区：
文献类型：
--
作者：
O. Shoji;Saori Okada;Akiharu Satake;Y. Kobuke
通过醛与二吡咯甲烷的两步缩合反应合成了二茂铁桥联三卟啉（2），研究了其基于咪唑基卟啉锌（II）互补配位基序的自组装行为，并结合二茂铁连接体自由旋转的双环所赋予的铰链柔性研究了其自组装行为.二茂铁桥连的三孢卟啉（2）在简单的锌（II）插入时自发地和排他地产生二聚环（7），表明自由旋转的铰链连接体有利于最小的环形成。利用二茂铁独特的铰链状的灵活性，我们试图通过重组被吡啶裂解一次的结构，将二聚体环转化为卟啉大环的混合物。用制备凝胶渗透色谱法可将卟啉大环化合物从三聚体到十聚体分离成其组分。所获得的大环在不存在配位溶剂的情况下保持稳定。另一方面，它们在配位溶剂如甲醇的存在下很容易转化为二聚体环，表明这种转化是完全可逆的，并且可以通过溶剂系统的选择来控制。在Grubbs催化剂的作用下，通过复分解反应将两个互补的配位二聚体共价连接，得到了一系列卟啉大环化合物。具有不同间隔基长度的双齿配体对二聚体环的配位行为表明，只有具有与面对的中心卟啉匹配的间隔基长度的双齿配体（15）被选择性地容纳在环内。具有可调腔和多个配位位点的配位组装柔性环将被用作各种各样的客体分子的通用主体。
Ferrocene-bridged trisporphyrin (2) was synthesized by two-steps condensation of corresponding aldehydes and dipyrromethanes, and its self-assembling behavior based on the complementary coordination motif of imidazolylporphyrinatozinc(II) was investigated in conjunction with hinge-like flexibility given by freely rotating cyclopentadienyl rings of ferrocene connector. Ferrocene-bridged trisporphyrin (2) spontaneously and exclusively generated the dimeric ring (7) upon simple zinc(II) insertion, indicating that the freely rotating hinge connector favored the smallest ring formation. Taking advantage of the unique hinge-like flexibility of ferrocene, we attempted to transform the dimer ring into a mixture of porphyrin macrocycles by reorganizing the structure cleaved once by pyridine. A series of porphyrin macrocycles from trimer to decamer can be separated into its components by preparative gel permeation chromatograms. Macrocycles obtained are kept stable in the absence of coordinating solvents. On the other hand, they were easily transformed to the dimer ring in the presence of coordinating solvents such as methanol, showing that the transformation is completely reversible and can be controlled by the choice of the solvent system. A series of porphyrin macrocycles was confirmed via covalent linking of each complementary coordination dimer pair by metathesis reaction in the presence of Grubbs's catalyst. The coordination behavior of the bidentate ligands with different spacer lengths toward the dimer ring revealed that only the bidentate ligand (15) with a spacer length that matched the facing central porphyrins was selectively accommodated inside the ring. Coordination assembled flexible rings with tunable cavities and multiple coordination sites will be used as versatile hosts for a wide variety of guest molecules.