Li Qian, Sha Xiaojing, Li Shourui, Wang Kai, Quan Zewei, Meng Yue, Zou Bo
Department of Chemistry, South University of Science and Technology of China , Shenzhen, 518055, China.
Materials Genome Center, Beijing Institute of Aeronautical Materials , Beijing 100095, China.
J Phys Chem Lett. 2017 Jun 15;8(12):2745-2750. doi: 10.1021/acs.jpclett.7b01057. Epub 2017 Jun 7.
The search for effective methods to accurately control host-guest relationship is the central theme of host-guest chemistry. In this work, high pressure successfully promotes guest release in the Hofmann-type clathrate of [Ni(NH)Ni(CN)]·2CH (Ni-Bz) and restricts guest insertion into Ni(NH)Ni(CN) (Ni-Ni). Because of the weak host-guest interactions of Ni-Bz, external force gradually removes guest benzene from the host framework, leading to puckered layers. Further theoretical calculations reveal the positive pressure contribution to breaking the energy barrier between Ni-Bz and Ni-Ni, explaining guest release from an energy standpoint. Inversely, guest insertion is restricted in the synthesized host of Ni-Ni because of the steric hindrance effect at high pressure. This study not only reveals structural effects on host-guest behaviors but also proves the role of pressure in controlling host-guest interactions. This unique observation is also crucial for the further application of host-guest materials in sustained and intelligent drug release, molecular separation, and transportation.
寻找准确控制主客体关系的有效方法是主客体化学的核心主题。在这项工作中，高压成功促进了[Ni(NH)Ni(CN)]·2CH（Ni-Bz）的霍夫曼型包合物中客体的释放，并限制了客体插入到Ni(NH)Ni(CN)（Ni-Ni）中。由于Ni-Bz的主客体相互作用较弱，外力逐渐将客体苯从主体框架中移除，导致层状结构起皱。进一步的理论计算揭示了正压对打破Ni-Bz和Ni-Ni之间能垒的贡献，从能量角度解释了客体的释放。相反，由于高压下的空间位阻效应，在合成的Ni-Ni主体中客体的插入受到限制。这项研究不仅揭示了结构对主客体行为的影响，还证明了压力在控制主客体相互作用中的作用。这一独特的发现对于主客体材料在持续和智能药物释放、分子分离及运输方面的进一步应用也至关重要。
