The design of dynamic molecular hosts has been of a considerable interest in recent years. Molecular hosts such as capsules and metal-mediated assemblies have been synthesized to selectively encapsulate guests. They are now widely used to mimic enzymes, catalyze chemical reactions, stabilize unstable intermediates. Efforts in our group have been focused on design, synthesis and study of a family of novel molecular hosts called “molecular baskets”. Using metal-mediated coordination or hydrogen bonding to fold the baskets, a range of guests varying in size, shape and electronic characteristics can be enclosed inside the cavity. Via the dynamic gating, the molecular baskets are examined for regulating the in/out exchange of guests.
This thesis prescribes electrochemical behavior and regulation of molecular encapsulation upon reduction/oxidation of baskets. The phthalimide groups in baskets are capable of accepting electrons and becoming reduced. We chose to examine phenyl-based basket as a host and 1,1,1-tribromoethane as a guest. Accordingly, we found that basket responds to reduction by passing electrons to the enclosed guests, and then releasing the reduced guest. Furthermore, the basket can reduce more than one guest, thereby behaving as an electrochemical catalyst. The mechanism of guest encapsulation and release upon reduction/oxidation stimulus was proposed. Understanding how the molecular basket regulate encapsulation of guest upon redox stimulus provides an opportunity for investigating electro-catalytic use of capsules in promoting chemical reactions.