A self-locking molecule operative with a photoresponsive key.
A self-locking molecule operative with a photoresponsive key.
复制标题
DOI：
10.1021/ja0632308
复制
发表时间：
2006-08
影响因子：
15
通讯作者：
T. Muraoka;K. Kinbara;T. Aida
中科院分区：
文献类型：
--
作者：
T. Muraoka;K. Kinbara;T. Aida
旋转宿主1，由二茂铁单元作为旋转模块组成，通过锌卟啉和苯胺单元之间的双分子内Zn-N配位，在极性溶剂（如苯）中被内部构象锁定，连接到每个环戊二烯（Cp）环。将顺式1,2-双吡啶乙烯（顺-2）加入(+)-1([顺-2]/[(+)-1]= 5.0)（1的对映体）后，(+)-1中的分子内Zn-N配位键很容易断裂，形成外锁的环二聚体一对一配合物(+)-1亚群顺-2，并伴随二茂铁模块的旋转，如CD光谱所示。相反，在其他方面与上述条件相同的情况下，使用反式-2代替顺式-2，不会导致释放(+)-1的内部双锁。2的同分异构体对宿主1的亲和力如此之大的差异，以及它们光化学相互转化的能力，使得1的可逆自锁操作得以证明。即，连接2的顺式到反式光化学异构化使2从1释放后，1的外锁态以1超链-2的形式自发地恢复到内锁态，而在1存在的情况下，2的反向光化学异构化导致1切换到其外锁态。
Rotary host 1, composed of a ferrocene unit as a rotary module, is conformationally locked internally in apolar solvents such as benzene by a double intramolecular Zn-N coordination between the zinc porphyrin and aniline units, attached to each cyclopentadienyl (Cp) ring. Upon addition of the cis form of 1,2-bispyridylethylene (cis-2) to (+)-1 ([cis-2]/[(+)-1] = 5.0), an enantiomer of 1, the intramolecular Zn-N coordination bonds in (+)-1 are readily cleaved to form an externally locked, cyclodimeric one-to-one complex (+)-1 subset cis-2, accompanying a rotation of the ferrocene module, as visualized by CD spectroscopy. In contrast, use of trans-2, in place of cis-2, under otherwise identical conditions to the above, did not result in releasing the internal double lock of (+)-1. Such a large difference between the isomers of 2 in the affinity toward host 1, along with their capabilities of photochemical interconversion, allowed for the demonstration of a reversible self-locking operation of 1. Namely, the externally locked state of 1, as in the form of 1 supersetcis-2, spontaneously retrieves the internally locked state, after the release of 2 from 1 upon cis-to-trans photochemical isomerization of ligating 2, while the backward photochemical isomerization of 2 in the presence of 1 results in switching of 1 to its externally locked state.