Construction of supramolecular system toward the investigation of biological events

基于主客体络合物形成的分子识别是一种基本的化学过程。酶、抗体、受体和携带者都使用分子识别事件。为了理解和模拟分子识别过程，主客体化学扮演着非常重要的角色，简化的人工受体有助于从分子水平上理解结合的性质。我们已经成功地合成了几种与非极性有机客体结合的人工受体，如富勒烯和几个杂环。采用杯芳烃作为空腔携带单元。研究发现杯[5]芳烃是富勒烯的一种有用的受体，通过共价或非共价键将受体的两个单元连接起来，导致了富勒烯的强烈结合。在有机介质中使用具有尿素官能团的自组装杯芳烃主体，无论有没有质酸，富勒烯的吸收和释放都可以很容易地控制。还合成了几个具有极性官能团的杯芳烃主体，考察了氢键和其他非方向力(van del Waals和CH-π相互作用等)对环脲和二酮基哌嗪等极性客体有效结合的协同作用。用分子动力学模拟和核磁共振化学位移模拟程序分析了结合客体的运动自由度。为了研究有机介质中平面客体与电荷转移型相互作用的有效结合，还合成了分子钳型主体。超分子络合物中既有给体-受体-给体层状排列，也有供体-受体-受体夹心型层状排列。

Molecular recognition based on the formation of host-guest complex is a fundamental chemical process. Enzymes, antibodies, receptors, and carriers all use the molecular recognition events. For the purpose of understanding and mimicking molecular recognition processes, host-guest chemistry playing a very important roll and simplified artificial receptors are useful to understand the nature of the binding on a molecular level. We have succeeded in synthesizing several artificial receptors for binding apolar organic guests such as fullerenes and several heterocycles. Calixarenes were employed as the cavity carrying unit. It was found that the calix[5]arene is a useful receptor for fullerene and connecting the two units of the receptor by covalent or non-covalent bonds resulted in the strong binding of the fullerenes. Both the uptake and release of the fullerene can be easily controlled with or without the protic acid in organic media using a self-assembling calixarene host having urea functionality. Several calixarene hosts having polar functionalities were also synthesized to examine the cooperative role of the hydrogen bonding and other non-directional forces (van del Waals and CH-π interactions and so on) for the effective binding of the polar guest such as cyclic ureas and diketopiperazines. The freedom of movement of the bound guests was analyzed by both the molecular dynamic simulation and nmr chemical shift simulation procedure. Molecular tweezers type hosts were also synthesized in order to study the effective binding the planar guests with charge transfer type interaction in organic media. Both donor-acceptor-donor and donor-acceptor-acceptor sandwich type layered arrangements were observed in the supramolecular complexes.